Vapor-phase hydrogen transfer reaction of carbonyl compound with alcohol
This application is a division of application Ser. No. 802,183, filed Nov. 25, 1985, now abandoned. 
    
    
     This invention relates to a catalyst for use in a vapor-phase hydrogen transfer reaction between a carbonyl compound having an alkenyl or aryl group and a primary or secondary alcohol, for example, schematically shown below. ##STR1## wherein R a  and R b  both represent a substituent having an alkenyl or aryl group, or one of them is a substituent having an alkenyl or aryl group and the other is hydrogen, and each of R c  and R d  represents hydrogen, an alkyl, hydroxyalkyl, alkenyl, phenyl or substituted phenyl group. 
     Alcohols of formula (III) that can be produced by this reaction have a wide range of applications, and are useful, for example, as important raw materials or intermediates in the fields of perfumes, medicines and polymers. 
     With regard to the production of alcohols (III) by selective hydrogenation of the carbonyl groups of carbonyl compounds of formula (I), the Nagase et al. method comprising hydrogenating the carbonyl compound in ethanol using a catalyst prepared by adding a trivalent iron compound to a Raney-type catalyst composed of silver and zinc [Chem. Lett., 1615, (1983)], and a method comprising hydrogenating the carbonyl compound in the presence of a rhodium catalyst and an amine [Bull. Chem. Soc., Jap., 50 (8), 2148, (1977)], for example, have been known heretofore. These methods are carried out under an elevated pressure of 50 to 80 kg/cm 2  -G, and moreover, the resulting alcohols should be separated from the solvent or the amine after the reaction. Hence, these methods require many process steps and much labor, and raise many problems in economy and productivity from the viewpoint of industrial production. 
     On the other hand, a method of selectively hydrogenating the carbonyl group of such a carbonyl compound as that of formula (I) by vapor-phase hydrogenation reaction would be very advantageous in regard to productivity. Such a method is described in the prior literature. For example, German Pat. No. 1,230,012 describes a method in which crotonaldehyde is converted to crotyl alcohol at a temperature of 200° C. and a pressure of 15 atmospheres by using a catalyst comprising cadmium, copper and magnesium. U.S. Pat. Nos. 4,072,727 and 4,096,193 describe a method in which acrolein is converted to allyl alcohol at a temperature of 100° to 200° C. and a pressure of 250 psi to 2,500 psi using a catalyst comprising silver and cadmium. These methods, however, require relatively high pressures. Furthermore, because the olefin bond portion of the starting carbonyl compound is hydrogenated at a high ratio, the selectivity of the desired alcohol is insufficient, and the method is far from being satisfactory. 
     One known method for hydrogen transfer reaction between an aldehyde and an alcohol as in the present invention is disclosed, for example, in U.S. Pat. No. 2,767,221. According to this method, acrolein is reacted with ethanol using a catalyst comprising magnesium oxide and zinc oxide to produce allyl alcohol (in a yield of 71.7% based on the consumed acrolein) and acetaldehyde. In this method, however, the conversion of the unsaturated aldehyde is low, and the primary or secondary alcohol must be used in a large excess relative to the unsaturated aldehyde. In addition, a tendency to a decrease in yield is observed after this catalyst is used for ten and several hours. Because of these disadvantages, the method of the above U.S. patent does not prove to be satisfactory from a practical viewpoint. 
     Generally, the production of an alcohol by hydrogenating a carbonyl compound having an alkenyl or aryl group in the vapor phase has the following problems. 
     (1) Since the alkenyl group is more easily hydrogenated than the carbonyl group, a large amount of a saturated aldehyde or saturated alcohol forms as a by-product. 
     (2) When an aldehyde having an aryl group is used as the carbonyl compound, side reactions such as the hydrogenation of the aryl group or the hydrogenolysis of the starting aldehyde occur, and it is difficult to obtain the desired alcohol in a high yield. 
     (3) In particular, when an alpha,beta-unsaturated carbonyl compound is used as the starting material, the selective hydrogenation of the carbonyl group becomes more difficult because of conjugation between its olefin bond and the carbonyl group. To increase the selectivity for an alpha,beta-unsaturated alcohol, relatively mild reaction conditions are required. This inevitably leads to a low conversion. Furthermore, even under the mild reaction conditions, the amount of saturated aldehyde and saturated alcohol as by-products are still large, and the yield of the desired alcohol is low. 
     It is an object of this invention therefore to provide a catalyst which can be used, without the inconveniences of the prior art discussed above, in a reaction of selective catalytic hydrogenation of the carbonyl group of a carbonyl compound having an alkenyl or aryl group using a primary or secondary alcohol as a hydrogen source (vapor phase hydrogen transfer reaction). 
     The vapor-phase hydrogen transfer reaction is a reaction whereby the starting carbonyl compound is converted to an alcohol by hydrogenation and the starting alcohol is converted to an aldehyde or ketone by dehydrogenation, and has the dual advantage that useful aldehydes and ketones can be simultaneously produced by properly varying the type of the starting alcohol. 
     Examples of suitable carbonyl compounds having an alkenyl or aryl group are shown below without any intention of limiting the invention thereto. Examples of carbonyl compounds having an alkenyl group are unsaturated aliphatic aldehydes or ketones having 3 to 10 carbon atoms such as (a) acrolein, (b) methacrolein, (c) crotonaldehyde, (d) methyl vinyl ketone, (e) senecioaldehyde, (f) 3-buten-1-one, (g) ethyl vinyl ketone and (h) 5-hexen-2-one. They will respectively be converted to the corresponding alcohols, i.e. (a&#39;) allyl alcohol, (b&#39;) methallyl alcohol, (c&#39;) crotyl alcohol, (d&#39;) 3-buten-2-ol, (e&#39;) 3-methyl-2-buten-1-ol, (f&#39;) 3-buten-1-ol, (g&#39;) 1-penten-3-ol and (h&#39;) 5-hexen-2-ol. 
     Examples of suitable carbonyl compounds having an aryl group are aromatic aldehydes or ketones represented by the following formula ##STR2## wherein each of R 1 , R 2  and R 3  represents hydrogen or an alkyl group having 1 or 2 carbon atoms, R 4  represents hydrogen or an alkyl or alkoxy group having 1 to 4 carbon atoms, and n represents an integer in the range of 0 to 3. Specific examples of these are (i) benzaldehyde, (j) acetophenone, (k) phenylacetaldehyde, (l), m-tolualdehyde, (m), anisaldehyde and (n) cumic aldehyde. They will be converted respectively to (i&#39;) benzyl alcohol, (j&#39;) alpha-phenethyl alcohol, (k&#39;) beta-phenethyl alcohol, (l&#39;) 3-methylbenzyl alcohol, (m&#39;) anisyl alcohol, and (n&#39;) cumic alcohol. 
     Suitable examples of carbonyl compounds having both an alkenyl and an aryl group are aromatic aldehydes or ketones represented by the following formula ##STR3## wherein each of X 1  and X 2  represents hydrogen or ##STR4## provided that they are not hydrogens at the same time, and R 1 , R 3  and R 4  are as defined hereinabove. Specific examples of these are (o) cinnamic aldehyde and (p) atropaldehyde which will be converted respectively to (o&#39;) cinnamic alcohol and (p&#39;) 2-phenyl-2-propen-1-ol. 
     As primary or secondary alcohols used as a source of hydrogen suitable are alcohols having 1 to 9 carbon atoms represented by the formula ##STR5## wherein each of R 5  and R 6  are selected from hydrogen, C 1  -C 8  alkyl groups, C 1  -C 8  hydroxyalkyl groups, C 1  -C 8  alkenyl groups, a phenyl group and a benzyl group, provided that the sum of the number of carbons of R 5  and the number of carbons of R 6  is 0 to 8. Specific examples are monoalcohols such as methanol, ethanol, propanol, isopropanol, benzyl alcohol and phenethyl alcohol, and glycols such as ethylene glycol and 1,4-butanediol. 
     According to this invention, there is provided a catalyst capable of producing the desired alcohol in a high yield stably over an extended period of time in such a vapor phase hydrogen transfer reaction while the aforesaid problems of the prior art have been fully solved. This catalyst is represented by the general formula 
     
         Mg.sub.a X.sub.b Y.sub.c O.sub.d 
    
     wherein X represents at least one element selected from the group consisting of boron, aluminum, silicon, phosphorus, titanium, vanadium, iron, yttrium, zirconium, niobium, tin, antimony, lead, bismuth, lanthanum and cerium, Y represents at least one element selected from alkali metals and alkaline earth metals excepting magnesium, O represents oxygen, and a, b, c and d represent atomic ratios of the individual elements, and when a is 1, b represents a number of 0.01 to 0.5, c represents a number of 0 to 0.5, and d is represents a number determined by the atomic valences and atomic ratios of the individual elements. 
     The catalyst of this invention is prepared from various raw materials such as the oxides, hydroxides, halides, sulfates, nitrates and oxide sols of magnesium and the individual elements added (components X and Y). The use of the oxides or hydroxides is convenient in order to simplify the catalyst preparation method and minimize the evolution of gases during calcination. 
     For example, the catalyst of this invention may be prepared by a method which comprises dissolving or suspending the raw materials in water, and heating and concentrating the solution or suspension with stirring, followed by drying, molding and calcining; a method which comprises dissolving or suspending the raw materials in water, adding aqueous ammonia to form a hydroxide, followed by filtration, washing with water, drying, molding and calcining; or a method which comprises mixing the oxides or hydroxides of the individual elements in powder form, adding a suitable molding aid (such as water or alcohols), molding the mixture and drying and calcining the mixture. 
     The catalyst of this invention may be used as supported on a known inert carrier [preferably silica, alumina, Celite (trade name), etc.]. 
     The temperature for catalyst calcination varies depending upon the type of the raw material, and can be in a wide range of 300° to 800° C., preferably 400° to 700° C. 
     The catalyst of this invention exhibits high activity when used in catalytic vapor-phase hydrogen transfer reaction between a carbonyl compound having an alkenyl or aryl group and a primary or secondary alcohol, and the selectivity of the desired alcohol is very high. 
     Even when this reaction is carried out for an extended period of time continuously, no deterioration in activity of the catalyst is observed, and the activity of the catalyst and the yield of the desired product are stable. Accordingly, the catalyst of this invention offers a full solution to the problem of the early deteriorating phenomenon which is considered to be most important in industrial production. 
     It has been noted that the catalyst of this invention exhibits much superior activity and selectivity to MgO or known hydrogen transfer reaction catalysts (such as MgO-ZnO). Presumably, this can be ascribed to the following mechanism. The addition of the component X in the present invention to magnesium element results in the addition of the active sites of the component X to the active sites (acid sites and base sites) of MgO and by the interaction of MgO with the component X, active sites having new properties appear. These active sites have an acidic nature and a basic nature suitable for the present reaction. In the acid sites the carbonyl group of the starting carbonyl compound is activated, and at the same time, the reaction of extracting hydrogen from the starting alcohol is activated at the base sites. Eventually, the activity of the catalyst to catalyze the desired hydrogen transfer reaction is increased. 
     The addition of the component Y which is an alkaline component is very effective for increasing the selectivity of the desired alcohol. This is presumably because the various acid sites formed by the addition of the component X are subtly controlled both qualitatively and quantitatively by the component Y so that they are suitable for the present reaction. 
     It is also noted that the performance of the catalyst of this invention is maintained over a surprisingly long period of time. Presumably, this is for the following reason. On the active sites of the catalyst of this invention as described above, the cycle of the catalytic reaction comprising the adsorption of the reactants and the desorption of the product is stably carried out. Furthermore, since the desorption of adsorbent materials such as water, carbon dioxide gas and carboxylic acids which are regarded as having a poisoning action on catalysts of this type takes place sufficiently rapidly, the phenomenon of deterioration in activity, which is generally regarded as being due to the extraordinarily strong adsorption of the absorbent materials does not occur. 
     In using the catalyst of this invention, the reactor may be a fixed bed flowing type or a fluidized bed type. The starting gas is prepared by mixing the starting carbonyl compound and primary or secondary alcohol in a mole ratio of from 1:0.5 to 1:20, preferably from 1:1 to 1:6, and if required, diluting the mixture with an inert gas such as nitrogen, helium or argon to a starting gas concentration of 1 to 80% by volume, preferably 2 to 50% by volume. The reaction is carried out usually under atmospheric pressure, but as required at elevated or reduced pressures. The reaction temperature is 150° to 400° C., preferably 200° to 350° C. The suitable space velocity of the starting gas varies depending upon the concentration of the starting gas, but is suitably 100 to 5,000 hr -1 , preferably 500 to 3,000 hr -1 . 
     The following examples illustrate the present invention more specifically. 
     In the examples, the conversion, selectivity and one-pass yield are defined as follows: 
    
    
     EXAMPLE 1 
     Magnesium hydroxide (25 g) and 0.6 g of boron oxide were suspended in 100 ml of water, and with sufficient stirring, the suspension was concentrated at 90° C. to give a white slurry-like mixture. The mixture was evaporated to dryness on a hot water bath, molded into a cylindrical form having an outside diameter of 5 mm and a height of 5 mm, and dried in an air atmosphere at 230° C. The dried product was calcined in an air atmosphere at 600° C. for 2 hours to prepare a catalyst. 
     Thirty milliliters of the catalyst was packed into a stainless steel U-shaped tube having an inside diameter of 20 mm, and a starting gas composed of acrolein, isopropyl alcohol and nitrogen in a volume ratio of 5:20:75 was passed through the tube at a space velocity of 1600 hr -1  (STP) and continuously reacted. The reaction product was analyzed by gas chromatography, and the results shown in Table 1 were obtained. 
     EXAMPLE 2 
     Example 1 was repeated except that methacrolein and isopropanol were used as the raw materials. The results are shown in Table 1. 
     COMPARATIVE EXAMPLE 1 
     A catalyst was prepared in the same way as in Example 1 except that magnesium hydroxide alone was used as the raw material. By using this catalyst, the same reaction as in Example 1 was carried out. The results are shown in Table 1. 
     COMPARATIVE EXAMPLE 2 
     The same reaction as in Example 2 was carried out by using the catalyst prepared in Comparative Example 1. 
     EXAMPLE 3 
     Methacrolein and methanol were reacted by using the catalyst prepared in Example 1, and the results shown in Table 1 were obtained. 
     COMPARATIVE EXAMPLE 3 
     A catalyst having the composition Mg 1 .0 Zn 0 .25 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 8.77 g of zinc oxide was used instead of 0.6 g of boron oxide as a raw material for the component X. This catalyst had nearly the same composition as the catalyst disclosed in a working example in U.S. Pat. No. 2,767,221. 
     The same reaction as in Example 1 was carried out by using the resulting catalyst. The results are shown in Table 2. 
     COMPARATIVE EXAMPLE 4 
     The same reaction as in Example 2 was carried out except that the catalyst prepared in Comparative Example 3 was used. The results are shown in Table 2. 
     EXAMPLE 4 
     A catalyst having the composition Mg 1 .0 Ce 0 .05 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 3.71 g of cerium oxide was used instead of 0.6 g of boron oxide as a raw material for the component X. By using this catalyst, methacrolein and ethanol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 5 
     A catalyst having the composition Mg 1 .0 Si 0 .02 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.52 g of silicon oxide was used instead of 0.6 g of boron oxide as a raw material for the component X. By using this catalyst, methacrolein and benzyl alcohol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 6 
     A catalyst having the composition Mg 1 .0 Bi 0 .04 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.48 g of bismuth hydroxide was used instead of 0.6 g of boron oxide as a raw material for the component X. By using this catalyst, crotonaldehyde and n-butanol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 7 
     A catalyst having the composition Mg 1 .0 Zr 0 .03 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 1.59 g of zirconium oxide was used instead of 0.6 g of boron oxide as a raw material for the component X. By using this catalyst, methyl vinyl ketone and 1,4-butanediol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 8 
     A catalyst having the composition Mg 1 .0 La 0 .05 (excepting oxygen) was prepared in the same way as in Example 1 except that 3.51 g of lanthanum oxide was used instead of 0.6 g of boron oxide as a raw material for the component X. By using this catalyst, ethyl vinyl ketone and 3-methyl-1-butanol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 9 
     A catalyst having the composition Mg 1 .0 Ti 0 .05 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 1.72 g of titanium dioxide was used instead of 0.6 g of boron oxide as a raw material for the component X. By using this catalyst, 5-hexen-2-one and phenethyl alcohol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 10 
     A catalyst having the composition Mg 1 .0 B 0 .01 Ce 0 .05 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.15 g of boron oxide and 3.71 g of cerium oxide were used as raw materials for the component X. By using this catalyst, 2-cyclohexen-1-one and cyclohexanol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 11 
     A catalyst having the composition Mg 1 .0 P 0 .01 Ti 0 .1 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.50 g of phosphoric acid (85%) and 3.45 g of titanium oxide were used as raw materials for the component X. By using this catalyst, senecioaldehyde and 2-butanol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 12 
     A catalyst having the composition Mg 1 .0 Al 0 .01 Zr 0 .02 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.22 g of aluminum oxide and 1.06 g of zirconium oxide were used as raw materials for the component X. By using this catalyst, 3-buten-1-one and n-hexanol were reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 13 
     A catalyst having the composition Mg 1 .0 Si 0 .05 Pb 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 1.29 g of silicon dioxide and 1.43 g of lead nitrate were used as raw materials for the component X. By using this catalyst, methacrolein and n-propanol was reacted in the same way as in Example 1. The results are shown in Table 1. 
     EXAMPLE 14 
     A catalyst having the composition Mg 1 .0 B 0 .03 Nb 0 .02 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.45 g of boron oxide and 1.15 g of niobium pentoxide were used as raw materials for the component X. By using this catalyst, the same reaction as in Example 2 was carried out. The results are shown in Table 1. 
     EXAMPLE 15 
     Magnesium hydroxide (25 g) and 2.59 g of silicon dioxide as a source of the component X were suspended in 100 ml of water, and with thorough stirring, the suspension was heated to 90° C. Then, a solution of 0.24 g of potassium hydroxide as a source of the component Y in 10 ml of water was added, and the mixture was concentrated under heat to give a white slurry-like mixture. The mixture was evaporated to dryness over a hot water bath, molded into a cylindrical form having an outside diameter of 5 mm and a height of 5 mm, and calcined in an air atmosphere at 600° C. for 2 hours to give a catalyst having the composition Mg 1 .0 Si 0 .1 K 0 .01 (atomic ratio excepting oxygen). 
     By using this catalyst, methacrolein and isopropanol were reacted in the same way as in Example 1 except that the mole ratio of methacrolein to isopropanol was adjusted to 3 and the reaction temperature was varied as indicated in Table 1. The results are shown in Table 1. 
     EXAMPLE 16 
     A catalyst having the composition Mg 1 .0 Al 0 .01 V 0 .01 Cs 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 0.22 g of aluminum oxide and 0.39 g of vanadium pentoxide were used as raw materials for the component X and 0.65 g of cesium hydroxide was used as a raw material for the component Y. By using this catalyst, the same reaction as in Example 15 was carried out. The results are shown in Table 1. 
     EXAMPLE 17 
     A catalyst having the composition Mg 1 .0 P 0 .02 Y 0 .01 Li 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 0.99 g of 85% phosphoric acid and 0.49 g of yttrium oxide were used as raw materials for the component X and 0.10 g of lithium hydroxide was used as a raw material for the component Y. By using this catalyst, the same reaction as in Example 15 was carried out. The results are shown in Table 1. 
     EXAMPLE 18 
     A catalyst having the composition Mg 1 .0 Si 0 .08 Sb 0 .04 Ba 0 .01 Rb 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 2.07 g of silicon dioxide and 2.51 g of antimony trioxide were used as raw materials for the component X, and 0.74 g of barium hydroxide and 0.44 g of rubidium hydroxide were used asd raw materials for the component Y. By using this catalyst, acrolein and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 1. 
     EXAMPLE 19 
     A catalyst having the composition Mg 1 .0 B 0 .02 Si 0 .1 Ca 0 .01 Na 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 0.30 g of boron oxide and 2.59 g of silicon dioxide were used as raw materials for the component X, and 0.32 g of calcium hydroxide and 0.17 g of sodium hydroxide were used as raw materials for the component Y. By using this catalyst, crotonaldehyde and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 1. 
     EXAMPLE 20 
     A catalyst having the composition Mg 1 .0 Si 0 .05 Sn 0 .05 Na 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 1.29 g of silicon dioxide and 2.90 g of stannous oxide were used as raw materials for the component X, and 0.17 g of sodium hydroxide were used as a raw material for the component Y. By using this catalyst, 5-hexen-2-one and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 1. 
     EXAMPLE 21 
     A catalyst having the composition Mg 1 .0 Si 0 .2 Ti 0 .1 Sr 0 .03 K 0 .02 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 5.17 g of silicon dioxide and 3.44 g of titanium dioxide were used as raw materials for the component X, and 1.57 g of strontium hydroxide and 0.48 g of potassium hydroxide were used as raw materials for the component Y. By using this catalyst, methyl vinyl ketone and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 1. 
     EXAMPLE 22 
     A catalyst having the composition Mg 1 .0 Si 0 .1 Fe 0 .05 La 0 .02 K 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 2.59 g of silicon dioxide, 1.72 g of ferric oxide and 1.40 g of lanthanum oxide were used as raw materials for the component X, and 0.24 g of potassium hydroxide were used asd raw materials for the component Y. By using this catalyst, methacrolein and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 1. 
     
                                           TABLE 1-a                               
__________________________________________________________________________
Catalyst composition                                                      
(atomic ratio         Starting materials                                  
                                      Mole ratio of                       
excepting oxygen)     Carbonyl        the alcohol to                      
Example                                                                   
     Mg Component X                                                       
               Component Y                                                
                      compound                                            
                              Alcohol carbonyl compound                   
__________________________________________________________________________
 1   1  B  0.04                                                           
               --     acrolein                                            
                              isopropanol                                 
                                      4                                   
 2   1  B  0.04                                                           
               --     methacrolein                                        
                              isopropanol                                 
                                      4                                   
 3   1  B  0.04                                                           
               --     methacrolein                                        
                              methanol                                    
                                      4                                   
 4   1  Ce 0.05                                                           
               --     methacrolein                                        
                              ethanol 4                                   
 5   1  Si 0.02                                                           
               --     methacrolein                                        
                              benzyl alcohol                              
                                      4                                   
 6   1  Bi 0.04                                                           
               --     crotonaldehyde                                      
                              n-butanol                                   
                                      4                                   
 7   1  Zr 0.03                                                           
               --     methyl vinyl                                        
                              1,4-butanediol                              
                                      4                                   
                      ketone                                              
 8   1  La 0.05                                                           
               --     ethyl vinyl                                         
                              3-methyl-1-                                 
                                      4                                   
                      ketone  butanol                                     
 9   1  Ti 0.05                                                           
               --     5-hexen-2-one                                       
                              beta-phenethyl                              
                                      4                                   
                              alcohol                                     
10   1  B  0.01                                                           
               --     2-cyclohexene-                                      
                              cyclohexanol                                
                                      4                                   
        Ce 0.05       1-one                                               
11   1  P  0.01                                                           
               --     senecioaldehyde                                     
                              2-butanol                                   
                                      4                                   
        Ti 0.1                                                            
12   1  Al 0.01                                                           
               --     3-buten-1-one                                       
                              n-hexanol                                   
                                      4                                   
        Zr 0.02                                                           
13   1  Si 0.05                                                           
               --     methacrolein                                        
                              n-propanol                                  
                                      4                                   
        Pb 0.01                                                           
14   1  B  0.03                                                           
               --     methacrolein                                        
                              isopropanol                                 
                                      4                                   
        Nb 0.02                                                           
15   1  Si 0.1 K  0.01                                                    
                      methacrolein                                        
                              isopropanol                                 
                                      3                                   
16   1  Al 0.01                                                           
               Cs 0.01                                                    
                      methacrolein                                        
                              isopropanol                                 
                                      3                                   
        V  0.01                                                           
17   1  P  0.02                                                           
               Li 0.01                                                    
                      methacrolein                                        
                              isopropanol                                 
                                      3                                   
        Y  0.01                                                           
18   1  Si 0.08                                                           
               Ba 0.01                                                    
                      acrolein                                            
                              isopropanol                                 
                                      3                                   
        Sb 0.04                                                           
               Rb 0.01                                                    
19   1  B  0.02                                                           
               Ca 0.01                                                    
                      crotonaldehyde                                      
                              isopropanol                                 
                                      3                                   
        Si 0.1 Na 0.01                                                    
20   1  Si 0.05                                                           
               Na 0.01                                                    
                      5-hexen-2-one                                       
                              isopropanol                                 
                                      3                                   
        Sn 0.05                                                           
21   1  Si 0.2 Sr 0.03                                                    
                      methyl vinyl                                        
                              isopropanol                                 
                                      3                                   
        Ti 0.1 K  0.02                                                    
                      ketone                                              
22   1  Si 0.1 K  0.01                                                    
                      methacrolein                                        
                              isopropanol                                 
                                      3                                   
        Fe 0.05                                                           
        La 0.02                                                           
__________________________________________________________________________
 
    
     
                                           TABLE 1-b                               
__________________________________________________________________________
            Reaction                                                      
                 Conversion of      Selectivity                           
                                              One-pass yield              
     Reaction                                                             
            time the carbonyl       of the alcohol                        
                                              of the alcohol              
     temperature                                                          
            elapsed                                                       
                 compound           (based on carbonyl                    
                                              (based on carbonyl          
Example                                                                   
     (°C.)                                                         
            (hrs)                                                         
                 (mole %)                                                 
                         Alcohol formed                                   
                                    compound, mole %)                     
                                              compound, mole              
__________________________________________________________________________
                                              %)                          
 1   270    2    89.6    allyl alcohol                                    
                                    92.3      82.7                        
            150  89.4               92.6      82.8                        
 2   270    2    90.2    methallyl alcohol                                
                                    94.5      85.2                        
            150  90.8               95.5      86.7                        
 3   300    2    62.3    methallyl alcohol                                
                                    89.6      55.8                        
 4   270    2    73.3    methallyl alcohol                                
                                    92.1      67.5                        
            150  72.1               93.0      67.1                        
 5   270    2    85.6    methallyl alcohol                                
                                    96.5      82.6                        
 6   260    2    96.6    crotonyl alcohol                                 
                                    93.2      90.0                        
 7   250    2    100     3-buten-2-ol                                     
                                    96.2      96.2                        
 8   260    2    100     1-penten-3-ol                                    
                                    95.0      95.0                        
 9   260    2    97.2    5-hexen-2-ol                                     
                                    100       97.2                        
10   270    2    84.8    2-cyclohexan-1-ol                                
                                    90.6      76.8                        
11   270    2    88.3    3-methyl-2-buten-1-ol                            
                                    93.1      82.2                        
12   280    2    93.3    3-buten-1-ol                                     
                                    98.9      92.3                        
13   270    2    83.4    methallyl alcohol                                
                                    93.1      77.6                        
14   260    2    94.1    methallyl alcohol                                
                                    97.2      91.5                        
15   260    2    96.6    methallyl alcohol                                
                                    97.8      94.5                        
            150  95.7               98.3      94.1                        
16   250    2    96.9    methallyl alcohol                                
                                    88.0      85.3                        
17   270    2    96.1    methallyl alcohol                                
                                    93.8      90.1                        
18   200    2    93.8    allyl alcohol                                    
                                    96.4      90.4                        
19   200    2    95.3    crotonyl alcohol                                 
                                    89.4      85.2                        
20   230    2    98.6    5-hexen-2-ol                                     
                                    100       98.6                        
21   200    2    99.3    3-butene-2-al                                    
                                    98.3      97.6                        
22   270    2    97.8    methallyl alcohol                                
                                    98.2      96.0                        
__________________________________________________________________________
 
    
     
                                           TABLE 2-a                               
__________________________________________________________________________
       Catalyst composition                                               
       (atomic ratio    Starting materials                                
                                     Mole ratio of                        
Comparative                                                               
       excepting oxygen)                                                  
                        Carbonyl     the alcohol to                       
Example                                                                   
       Mg Component X                                                     
                 Component Y                                              
                        compound                                          
                               Alcohol                                    
                                     carbonyl compound                    
__________________________________________________________________________
1      1  --     --     acrolein                                          
                               isopropanol                                
                                     4                                    
2      1  --     --     methacrolein                                      
                               isopropanol                                
                                     4                                    
3      1  Zn 0.25                                                         
                 --     acrolein                                          
                               isopropanol                                
                                     4                                    
4      1  Zn 0.25                                                         
                 --     methacrolein                                      
                               isopropanol                                
                                     4                                    
__________________________________________________________________________
 
    
     
                                           TABLE 2-b                               
__________________________________________________________________________
              Reaction                                                    
                   Conversion of    Selectivity                           
                                              One-pass yield              
       Reaction                                                           
              time the carbonyl     of the alcohol                        
                                              of the alcohol              
Comparative                                                               
       temperature                                                        
              elapsed                                                     
                   compound         (based on carbonyl                    
                                              (based on carbonyl          
Example                                                                   
       (°C.)                                                       
              (hrs)                                                       
                   (mole %)                                               
                           Alcohol formed                                 
                                    compound, mole %)                     
                                              compound, mole              
__________________________________________________________________________
                                              %)                          
1      270    2    57.0    allyl alcohol                                  
                                    90.5      51.6                        
              20   41.8             91.6      38.3                        
2      270    2    60.2    methallyl alcohol                              
                                    91.2      54.9                        
              20   43.3             92.0      39.8                        
3      270    2    55.4    allyl alcohol                                  
                                    85.3      47.3                        
4      270    2    59.5    methallyl alcohol                              
                                    87.7      52.2                        
              50   45.1             88.6      40.0                        
__________________________________________________________________________
 
    
     EXAMPLE 23 
     Magnesium hydroxide (500 g) and 59.7 g of boron oxide were suspended in 1500 ml of water, and with stirring, the mixture was heated to 90° C. to concentrate it. The resulting white slurry was dried at 120° C. and then pulverized. Water was added to the pulverized product as a molding aid, and the mixture was extruded into a cylindrical shape having a diameter of 5 mm and a length of 5 mm. The molded product was dried at 230° C., and calcined at 600° C. for 2 hours in an air atmosphere to give a catalyst having the composition Mg 1 .0 B 0 .2 (atomic ratio excepting oxygen). 
     Thirty milliliters of this catalyst was packed into the same reaction tube as used in Example 1, and a methacrolein and isopropanol were continuously reacted in it. As a source of methacrolein used as a material in this reaction, there was used a reaction product gas containing methacrolein which obtained in the production of methacrolein by the catalytic vapor-phase oxidation of t-butanol. The product gas had the average composition shown in Table 3. 
     
                       TABLE 3                                                     
______________________________________                                    
Component         Volume %                                                
______________________________________                                    
methacrolein      4.3                                                     
Water             9.7                                                     
Methacrylic acid and                                                      
                  0.24                                                    
acetic acid                                                               
Acrolein, acetone and                                                     
                  0.08                                                    
acetaldehyde                                                              
iso-Butylene      0.3                                                     
Carbon dioxide    0.23                                                    
Carbon monoxide   0.04                                                    
Oxygen            2.4                                                     
Nitrogen          82.7                                                    
______________________________________                                    
 
    
     The reaction temperature was maintained at 290° C. and the mole ratio of isopropanol to methacrolein, at 3. Nitrogen was further supplied so that the space velocity became 1600 hr -1 . Under these conditions, the reaction was carried out continuously for 2,000 hours. The results are shown in Table 4. 
     
                       TABLE 4                                                     
______________________________________                                    
        Conversion of                                                     
                    Selectivity of                                        
                                 One-pass yield                           
        methacrolein                                                      
                    methallyl    of methallyl                             
Reaction                                                                  
        (mole %     alcohol      alcohol                                  
time    based       (mole % based                                         
                                 (mole % based                            
elapsed on          on           on                                       
(hours) methacrolein)                                                     
                    methacrolein)                                         
                                 methacrolein)                            
______________________________________                                    
  2     84.1        91.7         77.1                                     
1000    83.6        91.8         76.7                                     
2000    83.9        91.3         76.6                                     
______________________________________                                    
 
    
     EXAMPLE 24 
     The same continuous reaction as in Example 23 was carried out by using the catalyst prepared in Example 22. The results are shown in Table 5. 
     
                       TABLE 5                                                     
______________________________________                                    
        Conversion of                                                     
                    Selectivity of                                        
                                 One-pass yield                           
        methacrolein                                                      
                    methallyl    of methallyl                             
Reaction                                                                  
        (mole %     alcohol      alcohol                                  
time    based       (mole % based                                         
                                 (mole % based                            
elapsed on          on           on                                       
(hours) methacrolein)                                                     
                    methacrolein)                                         
                                 methacrolein)                            
______________________________________                                    
  2     93.5        97.2         90.9                                     
1000    93.1        97.0         90.3                                     
2000    92.0        96.8         89.1                                     
______________________________________                                    
 
    
     EXAMPLE 25 
     The same reaction as in Example 1 was carried out except that benzaldehyde and methanol were used as the starting materials, and the reaction temperature was changed to 290° C. The results are shown in Table 6. 
     EXAMPLE 26 
     The same reaction as in Example 1 was carried out except that benzaldehyde and ethanol were used as the starting materials. The results are shown in Table 6. 
     COMPARATIVE EXAMPLE 5 
     A catalyst was prepared in the same way as in Example 1 except that magnesium hydroxide alone was used as the raw material. By using this catalyst, the same reaction as in Example 26 was carried out. In the early stage of the reaction, an aldehyde conversion of 52.9% was obtained. On continuing the reaction, the catalyst lost its activity in about 20 hours. 
     EXAMPLE 27 
     By using the catalyst prepared in Example 7, acetophenone and n-propanol were reacted in the same way as in Example 1. The results are shown in Table 6. 
     EXAMPLE 28 
     By using the catalyst prepared in Example 11, acetophenone and isopropanol were reacted in the same way as in Example 1. The results are shown in Table 6. 
     EXAMPLE 29 
     A catalyst having the composition Mg 1 .0 B 0 .02 Zr 0 .02 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 0.30 g of boron oxide and 1.06 g of zirconium oxide were used as raw materials for the component X. By using this catalyst, cumic aldehyde and 2-butanol were reacted in the same way as in Example 1. The results are shown in Table 6. 
     EXAMPLE 30 
     A catalyst having the composition Mg 1 .0 Ce 0 .05 V 0 .01 Pb 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 1 except that 3.71 g of cerium oxide, 0.39 g of vanadium pentoxide and 1.43 g of lead nitrate were used as raw materials for the component X. By using this catalyst, m-tolualdehyde and isopropanol were reacted in the same way as in Example 1. The results are shown in Table 6. 
     COMPARATIVE EXAMPLE 6 
     The same reaction as in Example 30 was carried out by using the same catalyst (MgO) as in Comparative Example 5. As shown in Table 7, an aldehyde conversion of 62.4% was obtained in the early stage of the reaction. On continuing the reaction, however, the catalyst lost its activity in about 20 hours. 
     EXAMPLE 31 
     A catalyst having the composition Mg 1 .0 Si 0 .02 K 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 0.52 g of silicon dioxide was used as a material for the component X and 0.24 g of potassium hydroxide was used as a material for the component Y. By using this catalyst, m-tolualdehyde and 1,4-butanediol were reacted in the same way as in Example 11. The results are shown in Table 6. 
     EXAMPLE 32 
     A catalyst having the composition Mg 1 .0 Si 0 .1 Nb 0 .01 K 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 2.59 g of silicon dioxide and 0.57 g of niobium pentoxide were used as materials for the component X, and 0.24 g of potassium hydroxide was used as a material for the component Y. By using this catalyst, anisaldehyde and isopropanol were reacted in the same way as in Example 15 except that the mole ratio of anisaldehyde to isopropanol was maintained at 1:3. The results are shown in Table 6. 
     EXAMPLE 33 
     A catalyst having the composition Mg 1 .0 Bi 0 .05 Al 0 .05 Na 0 .01 Ca 0 .03 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 5.60 g of bismuth hydroxide and 1.10 g of aluminum oxide were used as materials for the component X, and 0.17 g of sodium hydroxide and 0.96 g of calcium hydroxide were used as materials for the component Y. By using this catalyst, anisaldehyde and benzyl alcohol were reacted in the same way as in Example 15. The results are shown in Table 6. 
     EXAMPLE 34 
     A catalyst having the composition Mg 1 .0 Si 0 .2 Sn 0 .05 Ti 0 .05 Li 0 .02 Sr 0 .03 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 5.17 g of silicon dioxide, 2.90 g of stannous oxide and 1.72 g of titanium dioxide were used as materials for the component X, and 0.21 g of lithium hydroxide and 1.57 g of strontium hydroxide were used as materials for the component Y. By using this catalyst, anisaldehyde and beta-phenethyl alcohol were reacted in the same way as in Example 15. The results are shown in Table 6. 
     EXAMPLE 35 
     A catalyst having the composition Mg 1 .0 B 0 .02 Ti 0 .05 Na 0 .01 Ba 0 .03 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 0.30 g of boron oxide and 1.72 g of titanium oxide were used as materials for the component X, and 0.17 g of sodium hydroxide and 2.22 g of barium hydroxide were used as materials for the component Y. By using this catalyst, phenylacetaldehyde and cyclohexanol were reacted in the same way as in Example 15. The results are shown in Table 6. 
     EXAMPLE 36 
     A catalyst having the composition Mg 1 .0 Si 0 .1 Sb 0 .05 La 0 .02 K 0 .01 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 2.59 g of silicon dioxide, 3.14 g of antimony trioxide and 1.40 g of lanthanum oxide were used as materials for the component X, and 0.24 g of potassium hydroxide was used as a material for the component Y. By using this catalyst, cinnamic aldehyde and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 6. 
     EXAMPLE 37 
     A catalyst having the composition Mg 1 .0 Si 0 .1 Fe 0 .05 Y 0 .02 K 0 .01 Ba 0 .04 (atomic ratio excepting oxygen) was prepared in the same way as in Example 15 except that 2.59 g of silicon dioxide, 1.72 g of ferric oxide and 0.97 g of yttrium oxide were used as materials for the component X, and 0.24 g of poassium hydroxide and 2.95 g of barium hydroxide were used as materials for the component Y. By using this catalyst, atropaldehyde and isopropanol were reacted in the same way as in Example 15. The results are shown in Table 6. 
     COMPARATIVE EXAMPLE 7 
     The same reaction as in Example 32 was carried out except that a catalyst composed of magnesium oxide and zinc oxide (in a mole ratio of 4:1) was used, and the mole ratio of the alcohol to aldehyde was maintained at 4:1. 
     The catalyst used in this example had the same composition as that disclosed in U.S. Pat. No. 2,767,221 as a catalyst for synthesis of unsaturated alcohols. 
     
                                           TABLE 6-a                               
__________________________________________________________________________
Catalyst composition                                                      
(atomic ratio         Starting materials                                  
                                      Mole ratio of                       
excepting oxygen)     Carbonyl        the alcohol to                      
Example                                                                   
     Mg Component X                                                       
               Component Y                                                
                      compound                                            
                              Alcohol carbonyl compound                   
__________________________________________________________________________
25   1  B  0.04                                                           
               --     benzaldehyde                                        
                              methanol                                    
                                      4                                   
26   1  B  0.04                                                           
               --     benzaldehyde                                        
                              ethanol 4                                   
27   1  Zr 0.03                                                           
               --     acetophenone                                        
                              n-propanol                                  
                                      4                                   
28   1  P  0.01                                                           
               --     acetophenone                                        
                              isopropanol                                 
                                      4                                   
        Ti 0.1                                                            
29   1  B  0.02                                                           
               --     cumic aldehyde                                      
                              2-butanol                                   
                                      4                                   
        Zr 0.02                                                           
30   1  Ce 0.05                                                           
               --     m-tolualdehyde                                      
                              isopropanol                                 
                                      4                                   
        V  0.01                                                           
        Pb 0.01                                                           
31   1  Si 0.02                                                           
               K  0.01                                                    
                      m-tolualdehyde                                      
                              1,4-butanediol                              
                                      4                                   
32   1  Si 0.1 K  0.01                                                    
                      anisaldehyde                                        
                              isopropanol                                 
                                      3                                   
        Nb 0.01                                                           
33   1  Bi 0.05                                                           
               Na 0.01                                                    
                      anisaldehyde                                        
                              benzyl alcohol                              
                                      3                                   
        Al 0.05                                                           
               Ca 0.03                                                    
34   1  Si 0.2 Li 0.02                                                    
                      anisaldehyde                                        
                              beta-phenethyl                              
                                      3                                   
        Sn 0.05                                                           
               Sr 0.03        alcohol                                     
        Ti 0.05                                                           
35   1  B  0.02                                                           
               Na 0.01                                                    
                      phenylacet-                                         
                              cyclohexanol                                
                                      3                                   
        Ti 0.05                                                           
               Ba 0.03                                                    
                      aldehyde                                            
36   1  Si 0.1 K  0.1 cinnamic                                            
                              isopropanol                                 
                                      3                                   
        Sb 0.05       aldehyde                                            
        La 0.02                                                           
37   1  Si 0.1 K  0.01                                                    
                      atropaldehyde                                       
                              isopropanol                                 
                                      3                                   
        Fe 0.05                                                           
               Ba 0.04                                                    
        Y  0.02                                                           
__________________________________________________________________________
 
    
     
                                           TABLE 6-b                               
__________________________________________________________________________
            Reaction                                                      
                 Conversion of      Selectivity                           
                                              One-pass yield              
     Reaction                                                             
            time the carbonyl       of the alcohol                        
                                              of the alcohol              
     temperature                                                          
            elapsed                                                       
                 compound           (based on carbonyl                    
                                              (based on carbonyl          
Example                                                                   
     (°C.)                                                         
            (hrs)                                                         
                 (mole %)                                                 
                         Alcohol formed                                   
                                    compound, mole %)                     
                                              compound, mole              
__________________________________________________________________________
                                              %)                          
25   290    2    78.6    benzyl alcohol                                   
                                    95.8      75.3                        
26   270    2    85.6    benzyl alcohol                                   
                                    97.2      83.2                        
            150  85.0               97.7      83.0                        
27   260    2    94.8    alpha-phenethyl                                  
                                    100       94.8                        
                         alcohol                                          
28   260    2    100     alpha-phenethyl                                  
                                    99.8      99.8                        
            150  100     alcohol    100       100                         
29   260    2    98.2    cumic alcohol                                    
                                    99.0      97.2                        
30   270    2    99.6    3-methyl   100       99.6                        
            150  99.4    benzyl alcohol                                   
                                    100       99.4                        
31   260    2    99.5    3-methyl-benzyl                                  
                                    100       99.5                        
                         alcohol                                          
32   270    2    100     anisyl alcohol                                   
                                    100       100                         
            200  99.8               100       99.8                        
33   270    2    100     anisyl alcohol                                   
                                    100       100                         
34   270    2    100     anisyl alcohol                                   
                                    100       100                         
35   270    2    99.1    beta-phenethyl                                   
                                    99.9      99.0                        
                         alcohol                                          
36   270    2    100     cinnamyl alcohol                                 
                                    97.2      97.2                        
37   270    2    100     2-phenyl-2-propen-1-ol                           
                                    95.1      95.1                        
__________________________________________________________________________
 
    
     
                                           TABLE 7-a                               
__________________________________________________________________________
       Catalyst composition                                               
       (atomic ratio    Starting materials                                
                                      Mole ratio of                       
Comparative                                                               
       excepting oxygen)                                                  
                        Carbonyl      the alcohol to                      
Example                                                                   
       Mg Component X                                                     
                 Component Y                                              
                        compound                                          
                                Alcohol                                   
                                      carbonyl compound                   
__________________________________________________________________________
5      1  --     --     benzaldehyde                                      
                                ethanol                                   
                                      4                                   
6      1  --     --     m-tolualdehyde                                    
                                isopropanol                               
                                      4                                   
7      1  Zn 0.25                                                         
                 --     anisaldehyde                                      
                                isopropanol                               
                                      4                                   
__________________________________________________________________________
 
    
     
                                           TABLE 7-b                               
__________________________________________________________________________
              Reaction                                                    
                   Conversion of   Selectivity                            
                                             One-pass yield               
       Reaction                                                           
              time the carbonyl    of the alcohol                         
                                             of the alcohol               
Comparative                                                               
       temperature                                                        
              elapsed                                                     
                   compound        (based on carbonyl                     
                                             (based on carbonyl           
Example                                                                   
       (°C.)                                                       
              (hrs)                                                       
                   (mole %)                                               
                           Alcohol formed                                 
                                   compound, mole %)                      
                                             compound, mole               
__________________________________________________________________________
                                             %)                           
5      270    2    52.9    benzyl alcohol                                 
                                   100       52.9                         
6      270    2    62.4    2-methyl benzyl                                
                                   100       62.4                         
                           alcohol                                        
7      270    2    65.4    anisyl alcohol                                 
                                   100       65.4                         
              20   33.2            100       33.2                         
__________________________________________________________________________