Abstract:
Phenylisocyanurate is reacted with ethyl-chloroacetate in an inert solvent at 25°C. to 150°C. to produce crystalline 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate. The 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate is then heated with a mineral acid to produce crystalline 1,3-bis(carboxymethylene)-5-phenylisocyanurate. A novel polyester of the formula ##SPC1## 
     Is made wherein N=1, M is a diol having at least two carbon atoms, and X is a whole number greater than 1 by condensing 1,3-bis(carboxymethylene)-5-phenylisocyanurate with a polyol such as 1,4-butanediol.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Copending U.S. Pat. application entitled Novel Isocyanurate Compounds and Preparative Processes by William J. Kauffman, Ser. No. 537,689 filed 12-31-74, relates to the novel crystalline isocyanurate compound 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate and its crystalline hydrolysis product 1,3-bis(carboxymethylene)-5-phenylisocyanurate and processes for preparing same. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to novel isocyanurate organic compounds and processes. More particularly, it relates to 1,3-bis(carboxymethylene)-5-phenylisocyanurate and intermediates thereof. Additionally, it relates to certain processes related to the preparation of the above compounds and to novel polyesters prepared from 1,3-bis(carboxymethylene)-5-phenylisocyanurate. 
     2. Description of the Prior Art 
     Isocyanurate compositions such as those disclosed in U.S. Pat. No. 3,407,200-Little et al are useful as intermediates in the preparation of amorphous synthetic polymers from which fibers are prepared. These fibers are useful in the manufacture of rope, wearing apparel, and carpeting. 
     Of particular interest are crystalline isocyanurate compositions which are useful as intermediates in the preparation of crystalline synthetic polymers from which fibers of superior strength and elasticity man be prepared. 
     It is, therefore, an object of the present invention to provide the novel crystalline isocyanurate compound 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate and its crystalline hydrolysis product 1,3-bis (carboxymethylene)-5-phenylisocyanurate. 
     It is a further object of this invention to provide a process whereby a novel compound, 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate and its novel hydrolysis product 1,3-bis(carboxymethylene)-5-phenylisocyanurate will be produced. 
     It is a further object of the present invention to provide the novel polyesters produced by condensing 1,3-bis(carboxymethylene)-5-phenylisocyanurate with a polyol such as 1,4-butanediol. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, it has now been discovered that 1,3-bis(carboxymethylene)-5-phenylisocyanurate is produced by a process which comprises reacting disodium phenylisocyanurate with ethyl-chloroacetate in an inert solvent to yield crystalline 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate as illustrated by the following reaction: ##SPC2## 
     Thereafter, the resultant subject compound is hydrolyzed, by heating the diester compound with aqueous mineral acid, such as hydrochloric acid, or aqueous alkali to the corresponding crystalline 1,3-bis(carboxymethylene)-5-phenylisocyanurate. 
     Novel polyesters made by condensing 1,3-bis(carboxymethylene)-5-phenylisocyanurate with a polyol such as 1,4-butanediol exhibit excellent strength and high elasticity rendering them useful in the preparation of fibers. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     1,3-bis(carboxymethylene)-5-phenylisocyanurate is a solid dibasic carboxylic acid, readily obtainable in crystalline form. It is useful in a number of applications, particularly in the preparation of its polymers such as polyesters. Because of its crystalline structure, extremely strong polyester fibers may be prepared which are useful in the production of wearing apparel and carpeting. It is also useful in forming coatings and molded plastic articles. 
     1,3-bis(carboxymethylene)-5-phenylisocyanurate can be prepared by the alkylation of a reactive cyanuric acid salt, e.g., an alkali metal salt of cyanuric acid with at least two mole equivalents of ethylchloroacetate in an inert solvent to form the diester 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate. The diester is then hydrolyzed as by exposure to a strong mineral acid, such as concentrated hydrochloric acid to form the diacid. 
     It has been found preferred to employ disodium phenylisocyanurate in the reaction. However, potassium and other salts can be employed with satisfactory results. Workable concentrations of disodium phenylisocyanurate in the reaction mixture will be about 5 to 50% by weight based on the total weight of the reaction mixture. 
     Any reaction medium which is inert and which will form a suitable reaction mixture at elevated temperatures can be used. For use in the above reaction, the lower dialkyl substituted amides of lower carboxylic acids, such as dimethylformamide, diethylformamide, and dimethylacetamide, are suitable solvents. It is preferred to employ dimethylformamide as the inert reaction medium. 
     The reaction is carried on at an elevated reaction temperature for a time sufficient to bring satisfactory yields. The ethyl-chloroacetate is added at a reasonable rate to an inert reaction medium containing disodium phenylisocyanurate maintained at a temperature of 25°C. to 150°C., about 70°C. usually being suitable. The reaction will be carried on for a time sufficient to ensure an adequate yield, about two to ten hours being ordinarily ample, depending upon the concentration of the reactants employed, the reaction temperature, and the like. 
     The 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate is isolated from the reaction mixture by evaporation of the inert reaction medium under reduced pressure. The intermediate compound may be further purified by recrystallization from any suitable solvent such as dimethylformamide, acetonitrile, or carbon tetrachloride. 
     As mentioned above, the intermediate is convertible to the desired 1,3-bis(carboxymethylene)-5-phenylisocyanurate by acid hydrolysis with, for example, a concentrated mineral acid such as concentrated hydrochloric acid. The hydrolysis can be conveniently effected by heating the hydrolysis mixture of the intermediate at an elevated temperature for a sufficient period of time to convert to the desired 1,3-bis(carboxymethylene)-5-phenylisocyanurate. An hydrolysis time of about one to ten hours at reflux temperature is usually sufficient to bring about the desired hydrolysis with hydrochloric acid. 1,3-bis(carboxymethylene)-5-phenylisocyanurate is recovered and isolated from the hydrolysates by following conventional procedures. Customarily, the diacid is relatively insoluble in most of the mineral acids employed for the hydrolysis, for example, in concentrated hydrochloric acid, and can be recovered from the cooled hydrolysate conveniently by following simple filtration procedures. The 1,3-bis(carboxymethylene)-5-phenylisocyanurate compound can be recrystallized as desired, as from distilled water. 
     Usable polyesters can be formed by condensing as by heating at elevated temperatures 1,3-bis(carboxymethylene)-5-phenylisocyanurate with the required amounts of a diol having at least two carbon atoms, and preferably two to ten carbon atoms. Suitable diols include, for example, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, alpha-propylene glycol, and decamethylene glycol. The relative quantities of the 1,3-bis(carboxymethylene)-5-phenylisocyanurte and diol can be varied somewhat to alter average polymer chain links, degree of esterification of the carboxyl groups, and the like. To form a largely linear polymer, at least about one mole of diol is applied for each mole of 1,3-bis(carboxymethylene)-5-phenylisocyanurate. 
     Polyesters made by condesing 1,3-bis(carboxymethylene)-5-phenylisocyanurate with a polyol as described above exhibit excellent strength and high elasticity making them extremely useful in the preparation of fibers for carpets and wearing appparel. 
     Moreover, 1,3-bis(carboxymethylene)-5-phenylisocyanurate and the fibers derived therefrom are extremely thermally stable, and produce low smoke upon combustion. 
     The following illustrative examples more fully describe the preparation of the 1,3-bis(carboxymethylene)-5-phenylisocyanurate. 
     Example 1 
     Preparation of 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate 
     A quantity of 249 g. (1.0 mile) of disodium phenylisocyanurate is added to 2,000 ml. of dimethylformamide with stirring. Ethyl-chloroacetate (269.6 g., 2.2 mole) is added, and the mixture is heated at 75°C. for eight hours. The dimethylformamide is then removed on a rotary evaporator at reduced pressure, leaving a white solid product. The residue is treated with 2,000 ml. of methylene chloride and washed with water. Evaporation, after drying over sodium sulfate, yields crude 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate. Recrystallization from carbontetrachloride yields (90%) pure 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate (338 g., 0.9 mole). 
     Preparation of 1,3-bis(carboxymethylene)-5-phenylisocyanurate 
     1,3-bis(carbethoxymethylene)-5-phenylisocyanurate (50 g., 0.13 mole) is refluxed (100°C.) with 400 ml. of concentrated hydrochloric acid for eight hours. Upon cooling to 5°C., a solid precipitates from solution. The solid is collected by filtration and is recrystallized from 800 ml. of water to yield (53%) of 1,3-bis(carboxymethylene)-5-phenylisocyanurate (29 g., 0.07 mole). 
     PREPARATION OF THE POLYESTER 
     A mixture of 20 g. of 1,3-bis(carboxymethylene)-5-phenylisocyanurate, 50 g. 1,4-butanediol, and 0.2 g. dibutyltindilaurate is heated at 200°C. for eight hours to complete the direct esterification. The excess diol is distilled off as the vacuum is lowered to 1.0 mm. over thirty minutes. The polycondensation is conducted at this temperature for twenty-four hours. A nearly quantitative yield of polymer is obtained after cooling to room temperature. The number average molecular weight as determined by the vapor phaseasometry is 7,500. 
     EXAMPLE 2 
     Preparation of 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate 
     In accordance with the procedure of Example 1, a total of 74 g. (0.3 mole) of disodium phenylisocyanurate is added to 800 ml. of dimethylformamide with stirring. Ethyl-chloroacetate (80 g., .65 mole) is added, and the mixture is heated at 70°C. for four hours resulting in a quantitative yield of crude 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate which, upon recrystallization from carbon tetrachloride, yields 80% pure 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate (90 g., 0.24 mole). 
     Preparation of 1,3-bis(carboxymethylene)-5-phenylisocyanurate 
     In like fashion, to Example 1, 50 g. (0.13 mole) of 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate is refluxed (100°C.) with 400 ml. of concentrated hydrochloric acid for eight hours. Upon cooling to 5°C., a solid precipitates and is filtered by suction and recrystallized from 800 ml. of water to yield (53%) of 1,3-bis(carboxymethylene)-5-phenylisocyanurate (29 g., .07 mole). 
     Preparation of the Polyester 
     A mixture of 20 g. of 1,3-bis(carbethoxymethylene)-5-phenylisocyanurate, 20 g. of 1,6-hexanediol, 0.02 g. zinc acetate, and 0.02 g. of stannous oxalate is heated at 200°C. under nitrogen flow and the liberated ethanol collected for four hours. The pressure is lowered to 0.2 mm. and the melt temperature increased to 240°C. over forty-five minutes. After four hours, the melt becomes too viscous to stir. The resin is brought to atmospheric pressure and removed while hot. Fibers of excellent strength and color may be recovered from the melt.