Meta-and para-phenylene-bis-(4-hydroxymethylene-phthalic acids and the diester and tetraester thereof
United States Patent [1 Cohen et al.  
 [ Apr. 1,1975  
 [54] META-AND I PARA-Pl-IENYLENE-BIS(4-HYDROX- YMETHYLENE-PHTHALIC ACIDS AND THE DIESTER AND TETRAESTER THEREOF [75] Inventors: Choua Cohen; Pierre Giuliani;  
 Bernard Sillion, all of Grenoble, France [73] Assignee: lnstitut Francais du Petrole des Carburants et Luhrifiants, Rueil-Malmaison, France [221 Filed: Aug. 31, 1973 l 1 Appl. No.1 393.334  
 Related U.S. Application Data [60] Division ol&#39;Scr. No. 28l.l96, Aug. 16. 1972, Pat. No. 3.793.291. which is a continuation-in-part of Scr. No. 9.40). Feb. 6. I970. abandoned.  
 [30] Foreign Application Priority Data Feb. I0. 1969 France 69.03109 [52] U.S. Cl. 260/473 R, 260/520 [51] Int. Cl. C07c 69/78 [58] Field of Search 260/473 R, 520  
 [56] References Cited FOREIGN PATENTS OR APPLICATIONS 2,005,587 9/1970 Germany 260/520 Primary Examiner-John F. Terapane Attorney, Agent, or FirmMillen, Raptes &amp; White I&#39; 57] ABSTRACT mor p-Phenylene-bis-(4-hydroxymethylenephthalic acid, and the diester and tetraester thereof useful as intermediates to prepare soluble. high molecular weight. carbinol-containing polyimides.  
 2 Claims, No Drawings META-AND PARA-PHENYLENE-BlS(4-HYDROXYMETHY- LENE-PHTHALIC &#39;AGJIDS) AND THE DIESTER AND .TETRAESTER THEREOF I CROSS-REFERENCE &#39;10 RELATED APPLICATION This is a division of application Ser. No. 281,196. filed Aug. 16. 1972, now US. Pat. No. 3.793.291. issued Feb. 19. 1974. which application is a continuationin-part of application Ser. No. 9.4U9,fi1ed Feb. 6. 1970. now abandoned.  
  This invention relates to new carbinol-containing aromatic polyimides. their manufacture and uses.  
  An object of this invention is to provide new carbinol-containing aromatic tetracarlmxylic compounds (tetra-acids. diester-diacids and tetraesters), usable as starting materials for the manufacture of said new carbinol-containing aromatic polyimides.  
  It is well-known that .polyimides cannot be manufactured and processed easily since they are insoluble and infusible Conversely the polyimides of this invention are soluble in numerous organic solvents, although their molecular weight is high. This outstanding property is thought to be attributable to the carbinol groups joining the aromatic rings oftheir molecule. The polyimides of this invention also exhibit. in their various shapes. superior mechanical properties at high temperature. In addition. with respect to the manufacture of composite materials containing glass or silica fibers, there is exhibited a remarkable adhesivity of these new polyiniides on glass or silica fibers and is believed due to the presence of these carbinol groups in their molecule.  
  The new carbinol-comaining aromatic tetracarboxylic compounds of this invention are the following:  
 meta-phenylene bis(4-hydroxymethylene phthalic Another object of the invention is to provide new acid) and para-phenylene bis(4-hydroxymethylene carbinol-containing aromatic polyimidcs, which exhibit 30 phthalic acid) respectively having the formulae:  
 HOOC \\V/COOI1 caor caon IA aooc l \COOH and nooc  
  G ca0a coo nooc caon 1 IB cooa a good solubility in numerous organic solvents, in spite of their high molecular weight.  
  A further object of this invention is to describe processes for manufacturing said polyimides, as well as some uses thereof. particularly as raw materials for manufacturing composite materials, adhesive compositions. varnishes. molded materials.fi1ms, fibers and cellularmaterials.  
  diester-diacids and tetraesters of these two tetracarboxylic acids. respectively having the formulae:  
 &#39; cooa in which R is a monovalent hydrocarbon radical, preferably containing 1-12 carbon atoms and R is a hydrogen atom or a monovalent hydrocarbon radical, prefer- 50 ably containing 1-12 carbon atoms.  
  These tetracarboxylic compounds may be manufactured from compounds of general formulae:  
 l IIIB ll /R I (j IIIA in which R, R R and R are identical or different alkyl radicals, each preferably containing l3 carbon atoms.  
  Several methods for manufacturing compounds lll( A or B) may be used; for example an organomiagnesium compound can be reacted with isophthalic (or terephthalic) dinitrile, or 1,3-(or 1.4-) bis-(chloromethyl)- benzene can be reacted with an ortho-dialkylbenzene under the conditions of a Friedel and Crafts reaction. followed by an oxidation of the methylene groups. However, a preferred method consists of condensing isophthaloyl (or terephthaloyl) chloride with an orthodialkyl aromatic hydrocarbon in the presence of an HOOC and  
 nooc  
 acid catalyst according to Friedel and Crafts method.  
  Ortho-xylene is preferred as the ortho-dialkyl aromatic hydrocarbon since its use results in a compound containing 4 methyl groups, i.e., a compound which loses the minimum of atoms during the subsequent oxidation to the tetra-acid.  
  Reference is made, for example, to OLAl-ls book Friedel-Crafts and Related Reactions, Volume III, for a discussion of the well-known conditions of the Friedel and Crafts reaction, the useful acid catalysts and solvents.  
  With reference to ortho-xylene, any excess of the latter may act as a solvent. The selected catalyst, for example. aluminum chloride used in a preferred amount of 2-3 moles per mole of acid chloride, is added. portionwise, to the solution of the acid chloride in orthoxylene; the latter may be used in excess since any excess may be recovered by the end of the reaction.  
  The catalyst is added at such a rate that the temperature does not rise too fast, said temperature being advantageously maintained between and C. After termination of the catalyst addition, the temperature may be increased to a value between 40C and the boiling temperature of the mixture, preferably between and C, so as to complete the reaction. Finally, acidified water may be added and the formed product may be separated from any excess of ortho xylene by distillation, or else by steam-stripping which also results in a complete hydrolysis of aluminum derivatives.  
  In this process, no isomerization of the alkyl substituents of the benzene ring takes place, contrary to what could be feared. Thus, the excess of ortho-xylene may be recycled after mere decantation and drying.  
  The tetra-alkyl compounds of formulae llI(A or B) are thus obtained with a molar yield of -98 percent; they have a sufficient purity to be directly oxidized to the tetraacids of the formulae:  
 IVA  
 coon  
  ll c cooz-i l IVB l l cooa 30 This oxidation reaction, in particular with R,=R- ,=R;,=R =CH may be carried out according to most of the oxidation processes. For example, oxygen may be used together with cobalt catalysts. Such chemicals. as for example, potassium permanganate, may also be used, at first with pyridine, and then with sodium hydroxide. However, a preferred process consists of working with dilute nitric acid under pressure at a temperature between l()0-200C. A small excess of nitric acid may be used without trouble. The molar yield of tetra-acid is in the range of 95-98 percent.  
  From the sodium or potassium salts of the tetracarboxylic acids of formula [WA or B). the meta- (and para-) phenylene bis(4-hydroxymethylene phthalic acid) of formulae l(A and B) may be prepared, for example, by a catalytic hydrogenation of said slats, for example, in the presence of palladium.  
  The manufacturing of the diester-diacids of the formulae Il(A and B) wherein R is the hydrogen atom may be carried out as follows:  
  The tetra-acid of the formula lV(A or B) is dehydrated to the corresponding di-anhydride of the formula: I  
  /C0\ 0 v A co CO (I O &#39;CO/ according to any known technique. The preferred technique. however. consists of heating the tetra-acid for 2-8 hours at 7()-90C in an excess of acetic anhydride. The product is then cooled down, filtered and dried under vacuum at ll80C. This results in the dianhydride of formula V A (M.P. 218C) or the dianhydride of formula V B (M.P. 278-279C) with a molar yield of 75-95 percent.  
  These dianhydrides are condensed with a hydroxy compound of the formula R-OH to give a mixture of diester-diacid isomers of the general formula:  
  Further, another method consists of reacting the tetraacid IV (A or B) or the dianhydride V (A or B) with an excess of alcohol or phenol in a solvent such as benzene in the presence of a strong acid such as, for example, sulfuric acid or benzene-sulfonic acid. Water is continuously separated by distillation in the form of an azeotrope.  
  The diesters or the tetraesters of the formulae VI (A and B) are thereafter hydrogenated. for example, in an 10 alcohol, preferably methanol or ethanol, and in the presence of palladium on charcoal. This hydrogenation The R-(,)H compound is selected from the aliphatic alcohols containing. for example. from 1-12 carbon atoms and the phenols containing. for example. from 6-12 carbon atoms.  
  The following hydroxy compounds may be used: examples of aliphatic alcohols are methanol, n-propanol, isopropanol. butanols. pentanols, hexanols, Z-ethyl hexanol. iso-octyl alcohol. lauric alcohol and allylic alcohol; an example of substituted aliphatic alcohol is cyanoethanol&#39;. examples ofphenols are ordinary phenol are substituted phenols such as the cresols.  
  The reaction is eventually conducted in the presence of a catalyst. for example, a tertiary amine.  
  The manufacturing of the tetraesters may be carried out by separating the excess of alcohol or phenol by distillation or extraction. and treating the diester-diacid with a chloride to obtain the corresponding diesteris generally carried out at a hydrogen pressure between 10-100 kg/cm and at a temperature lower than 60C. Hydrogen is used in an amount which is approximately the theoretical amount.  
  The disappearance of the carbonyl group may be monitored by U.V. and LR. spectrometry.  
  There are respectively obtained carbinol-containing aromatic diester-diacids and tetraesters of this invention.  
  These diester-diacids and tetraesters are usable as plasticizers and additives for lubricants. However, their most important use. as well as for the tetracarboxylic acids themselves, is as starting materials for the manufacturing of the polyimides of the invention.  
  The new carbinol-containing aromatic polyimides of this invention are characterized in that they contain recurring units of the formula:  
 or recurring units of the formula:  
 diacid chloride. This reaction is usually carried out with thionyl chloride. phosphorus chlorides or oxalyl chloride. by way of examples.  
  The diester-diacid chloride is thereafter reacted with an alcohol or a phenol. identical to or different from the alcohol or phenol used for manufacturing the diester-diacid.  
  Another method consists of treating the diesterdiacid with diazomethane. so that the dimethyl tetraester is obtained.  
 in which M is an aliphatic. alicyclic, aromatic or alkyl aromatic. carbocyclic or heterocyclic divalent radical. preferably containing from 6-30 carbon atoms.  
 This radical may be substituted with various radicals or atoms. for example. fluorine or chlorine atoms. alkyl or alkoxy groups. in particular. methyl and methoxy.  
  The polyimides of the present invention have an inherent viscosity of at least 0.10. preferably at least 0.20 dl/g. as measured in a 0.5 percent by weight solution in N-methylpyrrolidone at 30C.  
  In the formulae \&#39;ll A and B). M may particularly be a radical -Ar,X -.-\r. in which Ar and Ar are aromatic or cycloaliphatic divalent radicals and X is a single bond or is selected from the group consisting of in which n is an integer from 1 t 3, and A and A are alkyl radicals such as methyl or ethyl. or aryl radicals such as phenyl.  
  For example, the radical M is derived from metaphenylene diamine, paraphenylene diamine, 4,4diamino-diphenyl propane, 4,4&#39;-diamino-diphenyl methane, benzidine. 4.4-diamin0-diphenyl sulfide. 4,4- diamino-diphenyl sulfone, 3,3&#39;-diamino-diphenyl sulfone, 4,4-diamino-diphenyl ether, 2,6-diaminopyridine, bis-(4-amino-phenyl)diethyl silane, bis-(4; amino-phenyl)diphenyl silane, 3,3-dichloro-benzidine, bis-(4-amino-phenyl)ethyl phosphine oxide, bis-(4- amino-phenyl)phenyl-phosphine oxide, bis-(4-aminophenyli-N-phenyl amine, bis-t4-amino-phenyl)-N- methyl amine, l,5-diamino-naphthalene, 3,3- dimethyl-4,4&#39;-diamino-biphenyl, 3,4-dimethyf3 4- diamino-biphenyl, 3,3-dimeth0xy-benzidine, 2,4- bis(B-amino-t-butyl )toluene, bis( para-B-amino-t-butylphenyl)ether, para-bis-(2-methyl-4-aminopentyl)benzene, para-bis-( l,l-dimethyl-5-aminopentyl) benzene, m-xylylene diamine, p-xylylene diamine, 1,3-diamino adamantane, 3,3&#39;-diamino-l,ldiadamantane, 3,3&#39;-diaminomethyl -l ,l diadamantane bis(para-amine cyclohexyl)methane. hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, 3-methylheptamethylene diamine, 4,4-dimethylheptamethylene diamine, 2.1 ldiaminododecane, l,2-bis-( 3-amino-propoxy) ethane, 2,2-dimethyl propylene diamine, 3-methoxyhexamethylene diamine, 2,5-dimethylhexamethylene diamine, 2,5-dimethylheptamethylene diamine, 5- methylnonamethylene diamine, l,l-diaminocyclohexane, l-lZ-diamino-octadecane, 2,5-diaminol, 3,4 oxadiazole. 2,2-bis (4-aminophenyl)hexafluoro propane, N-(3-aminophenyl)-4-aminobenzamide or 4-aminophenyl-3-amino benzoate.  
  The polyimides, according to this invention, may be obtained by poly-condensation of the mixture of isomeric diester-diacid described hereabove and a primary diamine at a temperature usually between 100 and 400C.  
 The diamines used are represented by the following (all amino-phenyl) diethyl silane, bis-(4-aminophenyl it&#39;liphenyl silane. 3,3-dichlorohenzidine, bis-(4- amino-phcnyllethyl phosphine oxide. bis-(4-aminophcnvl) phenyl phosphine oxide. bis-(4-aminopheny J-N-phcnyl amine, bis-t4-amino-phenyll-N- methyl amine, l,5--diamim&#39;maphthalcne. 3,3&#39;-dimethyl- -l.-l-&#39;-diamino hiphenyl., -dimcthyl-3,4-diaminohiphenyl. 3,3&#39;-dimethoxybcnzidine. ZA-hiflB-aminot--lutylitoluene. his!para,B-amino-t-butylphenyl )ether. Pitf2l l7l-ll-l11Lll&#39;lYl-4 lllflll10- pentyl )bcnzene, para-lust l,l dimcthyl-S-aminopentyl)benzene m-xylylene diamine, p-xylylene diamine. 1,3-diamino adamantane. 3.3&#39;diamino-l,l diadamantane, 3,3-diaminomethyl-l .l diadamantane, bistpara-amino-cyclohexyl) methane, hexamethylene diamine, heptamethylene diamine, 0ctamethylene diamine, nonamethylene diamine, decamethylene diamine, 3-methylheptamethylene diamine, 4,4-dimethylheptamethylene diamine, 2,1 l-diaminododecane, l,2-bis-(3-amino-propoxy) ethane, 2,2- dimethyl propylene diamine, 3-methoxyhexamethylene diamine, 2,5-dimethylhexamethylene diamine, 2,5-dimethylheptamethylene diamine, 5- methylnonamethylene diamine, 1,1- diaminocyclohexane, l-l2-diamino-octadecane, 2,5- diaminol ,3 ,4-oxadiazole, 2,2-bisl 4-aminophenyl )hexafluoro propane, N-( 3-aminophenyl )-4- aminobenzamide and 4-aminophenyl-B-amino benzoate.  
  The diester-diacid and the diamine may be reacted in substantially stoichiometrical amounts, However. for specific uses, for example, the manufacture of adhesive compositions, an excess of the diamine, such as 5 to mols of diamine per mols of diester, may be advantageous.  
  The poly-condensation reaction may be carried out with the molten or dissolved reactants.  
  The preferred solvents are polar solvents substantially non-reactive with respect to the monomers and the polymers and able to dissolve the polymers up to a given conversion degree.  
  These solvents may be used. for example, at their boiling temperature or at a higher temperature in an autoclave.  
  By way of examples. dimethylformamide, dimethylacetamide N-methyl pyrrolidone, dimethylsulfoxide, hexamethylphosphoramide. pyridine, quinoline, phenol. cresols and chlorophenols may be mentioned. These solvents may be used individually or as mixtures: less active solvents such as benzene, toluene, xylene. dioxane and cyelohexane may be added thereto.  
  The reaction temperature is preferably in the range of to 250C.  
  When working in the molten state of the monomers, the latter are heated up to a temperature from 150C to 400C.  
  In the two cases. the polymerization reaction proceeds with the release of such volatile products as water and alcohol, and the latter may be removed in an intermediate stage.  
 Irrespective of the initial conditions, the reaction may be completed with a treatement under reduced pressure or in inert atmosphere at a temperature from 200 to 400C. During this treatment, the conversion to imides is completed. thus resulting in thermostablc high polymers.  
 In some cases. it may be advantageous to isolate a temperature between 100 and 220C. The reaction is.  
 terminated when the inherent viscosity, determined at on a 0.5 percent by weight solution in N-mcthyl pyrrolidone. is between 0.06 and 0.70 dl/g and preferably between 0.15 and 0.30 dl/g During this treatment. it is often advantageous to separate the major part of the solvent. The process is thus carried out more easily.  
  According to this invention, polyimides may also be obtained by the poly-condensation of a tetraester of formula ll(A or B) hereabove. wherein both R and R are monovalent hydrocarbon radicals; preferably containing 1 to 12 carbon atoms, with a primary diamine as previously defined.  
  A mixed aliphatic and aromatic tetraester is preferably used which makes possible to utilize the different reactivities of these two kinds of groups.  
  The polyimide may be obtained by heating at 200-300C the t&#39;ctraester and the diamine. this resulting in a molten composition. The heating may be interrupted before the viscosity attains 0.7 and preferably 0.2 dl/g. A composition of relatively low molecular weight is thus obtained. This composition may be transformed to a high molecular weight polyimide by further heating at 200 to 400C. preferably under reduced pressure or in an inert atmosphere.  
  &#34;The solutions of monomers may be modified by adding other monomeric or pre-polymeric compositions up to a proportion of percent. lnert constituents may also be added. such as pigments, dyes. inorganic or or ganic fillers. metal fillers. adhesive powders or stabilizmg agents with respect to heat and oxidation.  
  lt is also possible to prepare the polyimides of the invention directly from meta-(or para-l phenylene bis(4- hydroxymethylene phthalic acid), by heating said acid with the diamine in a polar solvent, for example. dimethyl formamide. dimethyl sulfoxide. dimethyl acet amide. N-methylpyrrolidone. pyridine. phenol or cresols. l&#39;he reaction is generally conducted at a temperature above C. preferably between 100 and 250C. until a solution having a sufficient viscosity is obtained. said viscosity. measured as the inherent viscosity at 25C in a 0.5 percent by weight solution in metacresol. being usually from 0.2 to 2.0 dl/g.  
  Addition of benzene. toluene or cyclohexane is desirabl&#39;efor removing the water formed during the reaction.  
  lt is further possible to use. instead of the diamines. .\&#39;.;\&#34;-diac \l derivatives thereof. with meta-(or para-l phcnylene bist-l-hydroxymethylene phthalic acid).  
  The polyimides of this invention may be used in the preparation of matrix for composite materials and in the preparation of adhesive compositions. insulating varnishes. molded materials, films or fibers. Cellular products such as foam may also be iminufactured.  
 The following examples illustrate the invention:  
 EXAMPLE 1 Preparation ofmeta bisl 3.4-dimethy&#39;lbenzoyl )bcnzene. (303 g of isophthaloyl chloride (3 moles) are dissolved in 6 liters of ortho-xylene. and 708 v (6 moles) of aluminum chloride are stepwise added thereto. During the addition of aluminumchloride, the temperature is maintained at 2025C by means of a cooling bath. The condensation is terminated by heating at 85C for 2 hours. The product is then cooled down to 30C and hydrolyzed by means of ice and 25 cc of concentrated hydrochloric acid.  
  The hydrolysis is terminated by steam-stripping so as to eliminate ortho-xylene acting as solventv The latter must be separated completely since the synthesis product is very soluble in ortho-xylenev After cooling. the precipitate is filtered. washed with water up to neutrality. and then with alcohol, and finally dried. The molar yield of product melting at 137138C is 94 percent.  
  EXAMPLE 2 meta-bis( 3.4-dicarboxybenzoyl )benzene.  
  68.4 g (0.2 mole) of the tetra-methyl product of Example l are admixed with 250 cc of dilute nitric acid cc of nitric acid of sp.w. 1.38 together with 125 cc of water).  
  The oxidation is carried out in an autoclave under pressure at C for 3 hours. After cooling. the yellowish green product is collected. The nitrogenous vapors are separated by means of an air stream. The solu tion of the tetra-acid is evaporated to dryness and dried. The molar yield is 95 percent.  
  The IR. spectrum shows acid groups and anhydride groups indicating some dehydration during the cvapo ration.  
 EXAMPLE 3 Dianhydride of meta-bis( 3 .4-dicarboxybenzoyl )benzene.  
  90 g of the tetra-acid produced by Example 2 are admixed with 500 cc of acetic anhydride. The mixture is heated for 4 hours at 90C, then cooled down to 20C and kept under crystallization conditions for 24 hours. The product is filtered and dried at 150C under 20 Tons pressure. 82.6 g of product are obtained whose MP. is 218C. The molar yield of dianhydride is 84.6 percent.  
  The LR. spectrum shows anhydride absorptions at 1770 and 1855 cm.  
 EXAMPLE 4 Methyl hemiester of meta-bis( 3 .4-dicarboxybenzoyl )benzene.  
  54.4 g of the dianhydride produced by Example 3 are boiled for 4 hours in 300 cc of anhydrous methanol. The product is filtered when hot; it is then evaporated to dryness and dried. 49.9 g ofa mixture ofthc isomeric methyl di-esters is thus obtained. The molar yield is 80 percent.  
  The infrared spectrum shows carbonyl groups of the ester type and no longer anhydride groups.  
 EXAMPLE 5 Hemiester of meta-phenylene bis(4 hy&#39;dromethy&#39;lene phthalic aei l).  
 50 g of the methyl diesters produced by Example 4 are admixed in an autoclave with 600 cc of anhydrous methanol and 2.5 g of palladium on charcoal (percent Pdz5l. The hydrogenation is conducted at room tem perature and 50 bars for 2 hours.  
  Palladium is filtered. the liquid phase is evaporated to dryness. The weight of product of 46.9 g. The molar yield of methyl hemiesters of meta-phenylene bis (4- hydroxymethylene phthalic acid) is 93.5 percent, the LR. spectrum shows no peak at 1660 cm, corresponding to the C= group.  
 EXAMPLE 6 Synthesis of parabis-(3,4-dimethyl-benzoyl)benzene.  
  Into a 1 liter flask, there are introduced 135 cc of orthoxylene, and then 70 g of finely divided aluminum chloride. The mixture is agitated for 30 minutes to obtain a brownish red solution. Into this solution there is introduced a second solution during a period of 1 hour, this second solution being prepared by admixing 40 g of terephthaloyl chloride and 100 cc of orthoxylene, at a temperature of 7-l 2C. The resultant mixture of the two solutions is then heated at 60C for about /2 hour and then at 90C for another half hour. After cooling, excess orthoxylene is removed by vacuum distillation under 1 mm Hg.  
  Into the resultant mixture freed of orthoxylene, there is slowly introduced 250 cc of water, maintaining the temperature at about 30C. There is thus formed a white precipitate which is filtered, and washed with 400 cc of alcohol and then with a small quantity of ether. The residual solid which melts at 177C is dissolved in 1200 cc of boiling methylethylketone containing g of carbon black. The solution is filtered while warm and then the filtrate is then allowed to cool to form a further precipitate which is again filtered, washed with ether, and dried at 7075C for several hours under a vacuum of 100 mm Hg.  
  The resultant product, 56.5 g of para-bis-( 3,4- dimethyl-benzoyl)-benzene, is a white solid melting at 178C.  
 EXAM PLE 7 para-bis-( 3 ,4-dicarboxy-benzoyl )-benzene.  
  Into a 1 liter autoclave there are introduced 17.1 g of para-bis(3,4-dimethyl-benzoyl)-benzene, 75 g of sodium bichromate dihydrate and 350 cc of water. The mixture is heated at 250C under agitation for 5 /2 hours, and after cooling, the resultant precipitate is filtered. Into the filtrate, there is introduced a solution made by adding 70 cc of N hydrochloric acid and 60 cc of water, and there is thus obtained a white flocculant precipitate which is then filtered and washed with 350 cc of water.  
  The residual solid is recrystallized by dissolution in boiling water, then slow cooling at 7C. The precipitate is filtered, washed with water, and dried at 60C overnight under 1 mm mercury, resulting in 15.1 g of parabis-(3,4-dicarboxybenzoyl)-benzene, a white solid melting at 291C.  
 EXAMPLE 8 Dianhydride of para-bis-( 3 ,4-dicarboxy-benzoyl )-benzene At 200C, there is heated 10.5 g of the final product of Example 7 for 9 hours, thereby producing 9.7 g of the dianhydride thereof. This product is a white solid melting at 278-279C.  
 EXAMPLE 9 Methyl hemiesters of para-bis-( 3 .4-dicarboxy-benzoyl)-benzene.  
  Ten g of the dianhydride produced by Example 8 is boiled for 3 hours under reflux conditions in cc of methanol in the presence of 1 cc of triethylamine. The resultant solution is then evaporated under vacuum, thereby producing 9 g of a mixture of methyl diesters in the form of a white solid. By infrared analysis, it is seen that the product does not exhibit an anhydride band, but instead there is shown an acid and ester band.  
 EXAMPLE 10 Hemiesters of p-phenylene bis-(4-hydroxymethylene-phthalic acid).  
  Into a 1 liter autoclave, there is introduced 50 g of the diester-diacid obtained according to Example 9, 300 cc of methanol and a suspension of 2 g of palladium deposited on carbon black in 300 cc of methanol. A hydrogenation reaction is then conducted by introducing hydrogen into the autoclave for a period of 2 /2 hours under a pressure of 40 bars and at ambient temperature. After the reaction, the catalyst is filtered out and the methanol evaporated. The yield of the hemiesters is 94 percent. The identification of the hemiesters of p-phenylene bis-(4-hydroxymethylene-phthalic acid) is conducted by infrared wherein there no longer appears at 6.0a the groups Ar-CO-Ar.  
 EXAMPLE 1] Time Temperature ninh* a) 2 h 220C 0.47 h) 4 h 30 220C 0.59 e) 7 h 30 220C 0.61 d) 2 h C 0.28 e) 0 h 25C 0.06  
 The inherent viscosity was determined at 30C as 110.59? by weight of solution in methyl pyrrolidone.  
 EXAMPLE 12 Example 1 l is repeated except that oxydianiline was substituted with 1.603 g of methylenedianiline (4,4&#39;- diamino-diphenylmethane).  
 a. after 30 minutes in a bath at 175C, the inherent viscosiity at 0.5% and 30C is 0.14 dl/g.  
 b. after 7 h and a half at 220C. the obtained dark yellow viscous solution had an inherent viscosity of 0.94 dl/g.  
 EXAMPLE 13 a. The viscous solution (b) of Example 11 is used to form a film on a glass plate. It is dried at 1 10C in an air stream and the temperature is increased to 300C. This results in a flexible yellow film which adheres strongly to the glass.  
  The LR. spectrum shows peaks at 1725 and 1780 cm which are characteristic of the imide group.  
  b. The solution manufactured as described in Example 12 (b) is used to form a film which is treated as described in (a). The resulting film is strong and flexible but separates easily from the glass.  
 EXAMPLE 14 80 g of methyl hemiesters of meta phenylene bis-(4- hydroxymethylene phthalic acid) and 32.06 g of methylenedianiline are reacted in N-methyl pyrrolidone as described in Example 12 (a). The resulting 50 percent solution of the polymer in N-methyl pyrrolidone has an inherent viscosity of 0.19 dl/g. It is used to impregnate a glass tissue E-181 A-l 100. After impregnation, it is dried at 80C for 16 hours in an air stream. This results in an impregnated cloth containing 43 percent polymer. Several laminates were manufactured as follows:  
  a. 8 layers of cloth are piled up and placed between the plates of a brass heated at 120C; the material is maintained for 5 minutes between plates of a 3 mm thickness. The plates are then removed and a pressure of 14 bars is applied thereon. A temperature of 300C is maintained for minutes. Pressure is maintained during cooling.  
  The resulting translucent light yellow laminate of 1.5 mm thickness contains 20 percent of resin and 13.3 percent void space. Its specific weight is 1.91. It withstands 75.9 hectobars in flex tests at room temperature.  
 b. 8 sheets of cloth were piled up and introduced between the plates of a press at 250C. The material is&#39; maintained for 5 minutes between plates of 3 mm; the plates are removed and a pressure of 14 bars is applied thereto. A temperature of 350C is applied and maintained for 3 hours. The material is then cooled under pressure.  
 This results in a brown laminate of 1.7 mm thickness on one face with 2 sheets of the adhesive composition and finally dried at 1 10C.  
  The painted ribbons are joined two by two in order to cover 12.7 mm. An impregnated cloth of 22.7X mm is placed between the two ribbons and has 5 mm free around the joined section. The composition is formed by heating at 325C and 5 Bars for 1h 30, and then reheated for 8 hours at 300C and 5 hours at 325C.  
  The resulting compositions subjected to a traction test were drawn at a rate of 1.25 mm per minute. The results of the test expressed in Bars, as given herebelow, were obtained after a l0minute exposure.  
  ninh Resin (ll/g 5 5C 250C 300C 316C EX. 116) 0.06 124 165 90 91 EX. lld) 0.28 134 158 120 92 EX. l 1a) 0.47 170 133 37 Ex. llc) 0.61 110 134 53 EXAMPLES 16 to 20 lnhcrent Viscosity (dl/g) No. of Ex. Diamine After 2 h After 4 /zh 16 meta&#39;phenylene diamine 0.25 0.43  
 17 4.4&#39;-diamino diphenyl (1.31 0.52  
 sulfone l8 4.4&#39;diamino diphenyl 0.29 (1.53  
 sulfide l9 benzidine (1.33 0.49  
 20 4.4&#39;-diamino benxophcnone 0.27 0.46  
 which contains 25 percent of resin and 10.5 percent of vacuum. lts specific weight is 1.86. It withstands 69.5 hectobars in flex tests at room temperature.  
 EXAMPLE 15 Solutions of polymers manufactured as described in Example 1 l have been used to join titanium according to ASTM standard D-l002-64.  
  Ribbons of titanium of l02.4 25.4 1.6 mm were degreased with trichloromethylene and then dried. (They were immersed for 2 minutes in an aqueous solution of hydrochloric acid. phosphoric acid&#39;and hydrofluoric acid. They were also washed with tap water and dried at C).  
  Aluminum powder and arsenic thioarsenate were added to the solution of the used polymer and the whole was crushed finely. The obtained adhesive composition was used to impregnate a glass cloth E type 1 12-1 12 with as many sheets as required to have a material of 400 g/m&#39;- weight; each sheet was dried at l 10C. The degreased ends of the ribbons were painted The obtained viscous solutions were used as described in Examples 13 to 15 for manufacturing films. laminates and adhesives.  
  The mechanical properties of these materials are substantially the same as those mentioned in Examples 13 to 15.  
 EXAMPLE 21 being isolated by precipitation. The isolated polymer is substantially identical to the polymerobtained by Example 1 l in exhibiting characteristic imide and alcohol functions.  
 EXAMPLE 22 There are introduced into a 250 cc reactor the following reactants:  
 9.328 g of metaphenylene bis-t4-hydroxymethylenephthalic acid).  
 3.966 g of 4.4diamino-diphenylmethane. and  
  g of nietacresol.  
  The mixture is heated to 130C for a period of 2 hours under agitation. the resultant inherent viscosity of the mixture being 0.37 dl/g. and after heating for a further hour at 165C. an inherent viscosity of 1.30 dl/g (the inherent viscosity is measured as in Example 21). The viscous solution is then deposited on a glass plate where it is heated to 120C to form a film. and then to 300C to harden same.  
 EXAMPLE 23 The same ingredients as in Example 21 are introduced into the reactor except dimethylacetamide is used to replace metacresol. The inherent viscosities. however. are measured in the same manner as in Example 21.  
  The mixture is heated under agitation for a period of 2 hours and 30 minutes at 130C, then for 2 hours at 160C, the final resultant inherent viscosity being 0.26 dl/g. The polyimide is then isolated by precipitation from toluene.  
 EXAMPLE 24 Polyimide obtained by reacting the hemiester of p-phenylene bis-(4-hydroxymethylene-phthalic acid) and 4.4&#39;-diamino-diphenyl ether.  
  into a 250 cc reactor. there is introduced a mixture of 10.00 g of the hemiester obtained according to Example 10.4.05 g of 4.4-diamino-diphenylether. and g of distilled N-methylpyrrolidone. The mixture is agitated under a nitrogen atmosphere and it is heated in a molten metal bath at 220C for a period of 4 hours. The resultant viscosity of the viscous solution is 0.7 dl/g. measured at a concentration of 05 g in g of N-methylpyrrolidone at 25C.  
  The polymer is isolated from the viscous solution by precipitation in toluene under strong agitation. infrared spectrographic analysis indicates the presence of characteristic bands ofthe imide function at 5.62 and 5142p (and characteristic bands olthe alcohol function at 2.9 and 9.6a).  
  The polymer can also be obtained in form of a film by depositing the viscous solution on a glass plate and permitting it to dry at C and then raising the temperature to 300C.  
 EXAMPLE 25 A polyimide produced by reacting pphenylcne bis-t-l-hydrosymethylene-phthalic acid) and 4.4&#39;-diamino-diphenylether in m-cresol.  
  Into a 250 ccreactor there are introduced the following products:  
 9.328 g of p-phenylene bis-(4-hydroxymethylenephthalic acid) 4.006 g of 4.4-diamino-diphenylether. and 70 g of metacresol.  
  This mixture is heated under agitation at C for 5 hours to obtain a final product exhibiting an inherent viscosity at 25C ofOQZ&#39;t&#39;lI/g. measured at a concentra tion of 0.5. g per 100 cc of metacresol. Further heating of the viscous solution is conducted for l hour at C. thereby increasing the inherent viscosity to 0.75 dl/g. measured under the same conditions.  
  The resultant polymer is isolated by precipitating in toluene under strong agitation. and is then examined by infrared analysis wherein the characteristic bands of imidc and alcohol functions are seen.  
 EXAMPLE 26 The viscous solution prepared according to Example 25 is utilized to glue stainless steel according to the standards set forth in ASTM D 1002-64. Stainless steel plates measuring 100x25 X2 mm are degreased in acetone and then in trichloroethylene vapor. They are then pickled for 10 minutes in a bath of hydrochloric, phosphoric and hydrofluoric acids. and are finally thoroughly rinsed in distilled water and dried at 70C in an oven.  
  The resultant stainless steel plates are coated on a length of about 20 mm with the viscous solution of Example 25 using two coatings with intermediate drying at 100C in an oven. After the last coating is applied. the plates are dried for 1 /2 hours at 100C. The coated plates are placed in a mold so that 2 plates have an overlapping surface of 25 ll 5 mm.  
 EXAMPLE 27 Polyimidc obtained by reacting p-phenylene bis-t 4-hydroxymethylenephthalic acid) and 4.4-diamino-diphenylmethane in m-cresol.  
  lnto a 250 cc reactor there are introduced the following reactants:  
 9.328 g of p-phenylene bis-t4-hydroxymethylenephthulic acid).  
 3.966 g of 4.4-diamino-diphenylmethane. and  
 70.00 g o1 m-cresol.  
  The resultant mixture is heated under agitation for 2 hours at 130C. the resultant inherent viscosity being 0.37 dl/g. The mixture is further heated for 1 hour at C to attain an inherent viscosity of 1.29 dl/g. A polymeric film is obtained by depositing the resultant solution on a glass plate. and then heating the solution first to C. and then to 300Cv EXAMPLE 28 Polyimide produced by reacting p-phenylene bis-t4-hydroxymethylene-phthalic acid) and 4.4&#39;-diamino-diphenylether in dimethyl-acetamide Into a reactor there is charged the following components:  
 9.328 g of p-phenylene bis-(4-hydroxymethylenephthalic acid). 4.006 g of 4.4&#39;-diamino-diphenylether, and 70.00 g of dimethylacetamide. The mixture is heated under agitation for 2 /2 hours at 130C. and then for 2 hours at 160C. the inherent viscosity of the final product being 0.25 dl/g.  
  The polymer is isolated by precipitating the viscous solution in strongly agitated toluene. The resultant 17 18 polymer exhibits an infrared spectrum identical to that 1. Meta-phenylene bis(4-hydroxymethylene phthalic polymer obtained according to Example 25. acid) of the formula HOOC CHOH CHOH OOH HOOC OOH From the foregoing description one skilled in the art 2. An ester of meta-phenylene hist4- can easily ascertain the essential characteristics of this hydroxymethylene phthalic acid) of the formula ROOC CHOHM COOR l cooR R C 2/ invention, and without departing from the spirit and in which R and R are each a monovalent hydrocarbon scope thereof. can make various changes and modificaradical of 1-12 carbon atoms or a hydrogen atom, with tions of the invention to adapt it to various usages and 20 the provision that at least one ofR and R is said monoconditions. valent hydrocarbon radical of l-l2 carbon atoms.  
 What is claimed is: i