Process for producing dl-tartaric acid
O United States Patent H 1 3,875,223 Yonemitsu et al. Apr. 1, 1975 PROCESS FOR PRODUCING DL-TARTARIC [58] Field of Search 260/535, 536  
 ACID  
 [75] Inventors: Eiichi Yonemitsu, Kashiwa; Hiroshi [56] References Cited g &#39;z l Qfi a i zf l FOREIGN PATENTS OR APPLICATIONS awaa, asus l a; usu I 0 Takeda, Matsudo; Yukio Sasaki l,3l7.907 l/l963 France 260/535 Katsushika, all of Japan Q Primary Examuzer-Iorrame A. Wemberger [73] AssIgnee: Mltsublshl Gas Chemical Company, Assl&#39;sm, p Killos Inc-9 y Japan Attorney, Agent, or Firm-Stewart and Kolasch, Ltd. [22] Filed: Jan. 7, 1974 211 App]. No.; 431,559 [57] ABSTRACT dl-Tartaric acid is produced by hydrolysis of epoxysuccinic acid in the presence of a catalyst of a metal [30] Forelgn Apphcauon pnomy Data compound of aluminum, iron, tin or bismuth. Conver- Jan, 13, 1973 Japan 48-6317 sion f epoxysuccinic acid as we&#34; as Selectivity to 52 US. Cl. 260/536 tartaric acid are very high [51] Int. Cl. C07c 59/14 8 Claims, N0 Drawings PROCESS FOR PRODUCING DL-TARTARIC ACID This invention relates to a process for producing dltartaric acid. More particularly, this invention relates to an improvement of the process for producing dltartaric acid by hydrolysis of epoxysuccinic acid.  
  dl-Tartaric acid has been widely used as, for example, food additives or industrial chemicals. It has heretofore been known to produce dl-tartaric acid by allowing hydrogen peroxide to react with maleic acid in the presence of a tungsten compound catalyst. According to this method, it is known that epoxysuccinic acid is formed as an intermediate which is then hydrolyzed to produce dl-tartaric acid. However, epoxysuccinic acid, as different from other epoxy compounds, contains an oxirane ring in the molecule which is very stable. Therefore, preparation of dl-tartaric acid by hydrolysis of this compound is not easy. In the absence of a catalyst, even after boiling of an aqueous solution of epoxysuccinic acid which is continued as long as, for example, 5 hours, only 73.8% of said compound is hydrolyzed.  
  As catalysts for hydrolysis of oxirane rings, acids or bases have heretofore been generally known. However, to the best of our knowledge, when sulfuric acid, for example, is used as a catalyst for the preparation of dltartaric acid by hydrolysis of epoxysuccinic acid, there are drawbacks such that a great amount of sulfuric acid has to be used, that it takes a long time to carry out the reaction and that the yield of dl-tartaric acid is low. On the other hand, when bases such as caustic alkalis are used as catalysts, the products are in the form of alkali salts of dl-tartaric acid and which is disadvantageous in the production of free dl-tartaric acid. Furthermore, it is generally known that a part of the dl-tartaric acid salt thus formed is further hydrolyzed into lower carboxylic acid salts such as the acetic acid salt or oxalic acid salt to result in a disadvantageous increase in byproducts and decrease in yield of the dl-tartaric acid salt (see, for example, G. Peyronel, Gazetta Chimica Italiana, vol. 81, p.177,1951).  
  The object of the present invention is to provide an industrially advantageous process for producing dltartaric acid from epoxysuccinic acid in a very short time with good conversion as well as selectivity.  
  It has now been found that a certain kind of metal compounds effectively catalyzes the hydrolysis of epoxysuccinic acid. Namely, the present invention provides a process for producing dl-tartaric acid from epoxysuccinic acid, comprising incorporating a compound of aluminum, iron, tin or bismuth into an aqueous solution of epoxysuccinic acid.  
  The metal compound to be used in the present invention is a compound of aluminum, iron, tin or bismuth which is soluble in water or an aqueous solution of epoxysuccinic acid. Any compound may be used, so long as these metals can exist as ions in the reaction system. Among these metal compounds, inorganic acid salts such as aluminum chloride, iron chloride, iron sulfate and tin chloride and organic acid salts such as basic aluminum acetate are preferred. Above all, aluminum chloride and ferric chloride are particularly preferred, because they are high in solubility in water or an aqueous solution of epoxysuccinic acid as well as in catalytic activity. These metal compounds may be used either alone or in mixtures with each other, to catalyze the hydrolysis reaction of epoxysuccinic acid.  
  The concentration of the metal compound in the aqueous solution of epoxysuccinic acid may vary depending upon the concentration of the aqueous epoxysuccinic acid solution and the temperature at the time of hydrolysis, but preferably ranges from 0.01 to 3 mol particularly preferably from 0.1 to 1 mol in terms of the ratio of the metal compound to epoxysuccinic acid.  
  The epoxysuccinic acid used as the starting material may be produced in any way. For example, it may be produced according to the known method as mentioned above by allowing hydrogen peroxide to react with maleic acid in an aqueous solution in the presence of a tungsten compound catalyst. Alternatively, it may be produced according to the method invented by the present inventors, comprising allowing hydrogen peroxide to react with acid calcium maleate in an aqueous solution in the presence of a tungsten compound catalyst to prepare acid calcium epoxysuccinate and then subjecting this acid calcium epoxysuccinate to acid decomposition. Furthermore, epoxysuccinic acid from the decomposed liquid obtained by acid decomposition of an epoxysuccinic acid salt or ester may also be used. The decomposed liquid itself may also be available. The concentration of an aqueous epoxysuccinic acid solution is not particularly limited, so long as it is a homogeneous aqueous solution at the reaction temperature. Industrially, however, it is preferred to use a concentration of 1 to 10 mol of epoxysuccinic acid per litre of water.  
  The reaction temperature may be the reflux temperature of an aqueous epoxysuccinic acid solution or lower. When the concentration of the metal compound in the aqueous solution of epoxysuccinic acid is within the preferred range as mentioned above, the reaction temperature may be 60C or higher. Preferably, however, the reaction temperature is near the reflux temperature of the aqueous solution of epoxysuccinic acid, namely, from to C.  
  After being treated with an H-form cation exchange resin or without any such treatment, the reaction product thus formed is concentrated and cooled or cooled without concentration, to precipitate crystals of dltartaric acid which are then separated and recovered, or evaporated to dryness to obtain crystals of dl-tartaric acid.  
  According to the process of the present invention, dl-tartaric acid can be obtained in a very short time and in high yield. Selectivity to dl-tartaric acid from epoxysuccinic acid is also very high. Therefore, the filtrate after removal of the crystals can be recycled for re-use without any particular treatment. The present invention is also industrially advantageous in this respect.  
  The present invention is further illustrated with reference to the following Examples.  
 EXAMPLE 1 An aqueous solution having 13.2 g of epoxysuccinic acid and 0.1158 g of aluminum chloride hexahydrate dissolved in 100 g of water was refluxed for one hour under heating over an oil bath. As the result, the conversion of epoxysuccinic acid was 98.3%. The reaction mixture after the reaction contained 14.7 g of dltartaric acid, which corresponded to a 98.1% yield of dl-tartaric acid based on the amount of epoxysuccinic acid charged.  
  The reaction mixture thus prepared was treated with an llforn1 cation-exchange resin to remove aluminum ions and evaporated to dryness to obtain 10.8 g ofcrystals of dl-tartaric acid (tnonohydrate) with a purity of acid and 2.6 g of 95.4% sulfuric acid dissolved in 50g of water was refluxed for one hour under heating over an oil bath, whereby the conversion of epoxysuccinic acid was 341% and the yield of dl-tartarie acid based on the amount of epoxysuccinic acid charged was 3l.(i%. When the solution was further refluxed under heating for an additional four hours, the conversion of epoxysuceinic acid was 87.5% and the yield of dltartaric acid based on the amount of epoxysuceinic acid charged was 8l.(l%.  
 EXAMPLE 4 An aqueous solution having 6.6 g of epoxysuccinic acid and 0.00065 g of ferric chloride hexahydrate dis- )l&#39;i. l &#39;71. (corrcspomling to I47 g of dl-tartaric acid con- 5 taining no water of crystallization).  
 l&#39;lXAMlLli 2 When ferric chloride, ferrous sulfate, stannous chlw ride, stannic chloride, bismuth trichloride or basic aluto minum acetate lAlt()ll)((&#39;ll; is used in place of aluminum chloride, the other conditions being followed according to the procedure of Example I, the results as shown in Table l were obtained.  
 &#39;lahle l Yield of dl tartaric l-x (oavcrsion acid based pen Metal compound of epoxy on charged lltenl Amount sueciaic c mxysuccinic No Kind (g) acid (&#39;71) acld (/1-) |&#39;c(&#39;l;,.oll 0.120s was 97.7 |&#39;t&#39;S() .7&#34; U. l 134 M5 M9 t s&#34;(|,.2n,o a. also 17.x 071 4 Sn(&#39;l,.ll.,() (LIMQ. 94. H3. s an 1 0.1514 mm )LI (1 AIM) 0.0744 98.1 97.4  
 t alealatril hunt the amount of traction IIHXIIIH&#39; lllt tllll&#39;t&#39;ll and respective concentrations ol t&#39;|i||\Y\lN lltllt aeal and dl tartaric acid cnlttinnei and roinpalative examples) &#34;Univ m this case, the ltlltllllll time was tlure ltnan (In other cases, one hoai EXAMPLE 3 Table 2 Yield of illtartaric acid Amount (onverbased on H Amount of ferric Reaction sion of charged peliof epoxychloride tcinpcrepoxyepoxyment sacciaic hexahydrate ature succiaic succinic Nu. acid (g) (g) acid (/1) acid (Z l (.0 (Nil Hit) 95.7 95.3 2* an 0,005 on 85.7 was i (v.6 0.27 (it) KLK 88.8 J [9.8 0.005 lUtl 9H,] 97.1  
 (inh- In this casr. the traction time was two hours COMPARATIVE EXAMPLE I An aqueous solution having l3.2 g of cposysnccinic acid dissolved in I00 g of water was refluxed for one hour under heating over an oil bath, whereby the conversion of epoxysucciuic acid was 22.0% and the yield of (ll-tartaric acid based on the amount of cpoxysuceinic acid charged was 2l.o%. When the solution was further refluxed under heating for an additional four hours. the conversion of cpoxysuccinic acid was 73.8% 05 and the yield of ill-tartaric acid based on the amount of epoxysucciaic acid charged was 72.5%.  
 COMPARATIVE EXAMPLE 2 An aqueous solution having 6.6 g of epoxysucciaie therein (same in the following lzxample solved in 50g of water was refluxed for one hour under heating over an oil bath. As the result, the conversion of epoxysuccinic acid was 38.1% and the yield of d]- tartaric acid based on the amount of epoxysuccinie acid charged was 37.2%.  
 What we claim is:  
  l. A process for producing dl-tartaric acid, which comprises hydrolyzing epoxysuccinic acid in the presence of at least one compound selected from the group consisting of metal compounds of aluminum, iron, tin and bismuth, which is soluble in water or an aqueous solution of epoxysuccinic acid.  
  2. A process according to claim 1 wherein the amount of the metal compound is from 0.01 to 3 mol in terms of the ratio of the metal compound to epoxysuccinic acid.  
  3. A process according to claim I wherein the amount of the metal compound is from 0.1 to 1 mol in terms of the ratio of the metal compound to epoxysuccinie acid.  
  4. A process according to claim 1 wherein the metal compound is an inorganic or organic acid salt.  
  5. A process according to claim 4 wherein the metal compound is aluminum chloride or ferric chloride.  
  6. A process according to claim 1, wherein the epoxysuccinic acid is hydrolyzed at a temperature in the range from 60C to the reflux temperature of an aqueous epoxysuccinic acid solution.  
  7. A process according to claim I, wherein the epoxysuccinic acid is hydrolyzed at a temperature in the range from to l0()C.  
  8. A process according to claim I, wherein the metal compound is aluminum chloride. ferric chloride. ferrous sulfate. stannous chloride. stannie chloride. bis-