Vol. s1 indicated two OH bands a t 3.03 and 9.5 p and the C = 0 band a t 5.8 p .Infrared spectra of the products isolated from reduction of the dimers showed OH bands a t 3.0 and 9.5 p . The C=O band was absent in the spectra of these products. Experimental4Synthesis of Ketenes.-The ketenes employed in this study were synthesized by slight modification of the method reported previously.2 Physical constants and analyses of the ketenes are shown in Table I.Preparation of Derivatives of Ketenes.-Substituted hydrazides were prepared by treating samples of the ketene monomers with 2,4-dinitrophenylhydrazine reagent'; dihydrazones of the dimers were prepared similarly. Physical constants and nitrogen analvses of the 2,4-dinitrophenylhydrazides of the ketene monomers and the 2,4dinitrophenylhydrazones of the dimers are given in Table 11.Lithium Aluminum Hydride Reduction of Ketenes.-The procedure followed for reduction of the ketenes was essentially the same as that reported in an earlier study.1 T o a suspension of 2 g. (0.05 mole) lithium aluminum hydride in SO0 ml. of dry diethyl ether was added P-t-butylphenoxyn-butylketene monomer (17.4 g.). The reaction mixture mas heated for 21 hours, cooled, hydrolyzed, and extracted with ether. Distillation of the dried extract gave two re-(4) All melting pomts are corrected action products: @-t-butylphenol, b.p. 149-152" (9 mm.) (m.p. 95-96"); and 2-n-butyl-2-(p-t-butylphenoxy)-3-keto-
synopsisThe investigation of the condensation equilibrium of the hydrolytic polymerization is described for systems obtained by polymerizing caprolactam in the presence of water (or aminocaproic acid) and any of the following additives: mono-di-, and tricarboxylic acids, mono-and diamines, and the salts derived from a monoamine and either a monoor dicarboxylic acid. Relationships in terms of the equilibrium constant Kz, the equilibrium conversion (&), and the initial composition were derived for the calculation of the molecular weights of the corresponding equilibrium polymers. Very good agreement between calculated and experimental data was observed. The results show that the thermodynamical quantities derived for the pure caprolactam-water system are also valid for polymerizations that involve the participat,ion of organic acids, amines, and their salts in the initiation and equilibration.Caprolactam. High-purity-grade commercial (Allied) caprolactam was distilled prior to use under nitrogen a t 1 mm Hg. rived by Majury.' * An equivalent relationship for the system caprolactam-water-acetic acid was de-POI~YMERIZATlON OF CAPROLACTAM 2345 e-Aminocaproic Acid. A commercial product (Eastern Chemical Co.) was purified by carbon treatment of a hot aqueous solution and repeated recrystallizations from water-ethanol. Sebacic Acid and Trimesic Acid. Commercial products (EastmanOrganic Chemicals) were purified by carbon treatment of the hot aqueous solutions and repeated recrystallizations from water.
Rate and extent of both decarboxylation and desamination in the temperature range of 250–290°C were studied on equilibrium polymers obtained by the hydrolytic polymerization of ε‐caprolactam. Mechanisms have been proposed that are characterized by the participation of the equilibrium monomer in the considered decomposition reactions. The mechanisms suggested accommodate both the experimental results of this study and findings of previous investigations as reported in the literature.
The peroxidation of caprolactam has been studied at 84°C, 100°C and 120°C. The decomposition of the initially formed ε‐caprolactam hydroperoxide was found to be catalyzed by adipic acid monoamide which is formed by hydrolysis of adipimide. This imide results from the decomposition of the hydroperoxide and was found to act as oxidation inhibitor. The molecular weights of the polyamides obtained by polymerizing the peroxidized caprolactam were found to decrease as the extent of peroxidation and thus the concentration of adipic acid monoamide and other decomposition products increased. In all of these polyamides the concentration of acidic functions was appreciably higher than that of the titratable amino endgroups.
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