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Study of epoxy compounds. Part VI. Curing reactions of epoxy resin and acid anhydride with amine, acid, alcohol, and phenol as catalysts

1964; Inderscience Publishers; Volume: 2; Issue: 8 Linguagem: Inglês

10.1002/pol.1964.100020804

1542-6246

Yoshio Tanaka, Hiroshi Kakiuchi,

Oxidative Organic Chemistry Reactions

Abstract The curing reaction of an epoxy resin and acid anhydride with an amine and/or acid, alcohol, and phenol was studied kinetically by using commercial epoxy resins and acid anhydrides. No etherification reaction occurred at 70–140°C., even in the case of epoxide/acid anhydride/HA (acid, alcohol, or phenol) and of epoxide/acid anhydride tertiary amine/HA, and the initial reaction rate was proportional to the concentrations of epoxide, acid anhydride, and catalysts such as tertiary amine, acid, alcohol, and phenol. The apparent activation energy of the reaction system of Epikote 828/methyl‐bicyclo(2,2,1)heptene‐2,3‐dicarboxylic anhydride/triethanol amine/HA was obtained as about 14.7 kcal./mole, and the low frequency factors and large negative entropies of activation for the reaction might confirm that the curing reaction of epoxy resins and anhydrides belongs to the type of nucleophilic bimolecular displacement reaction. The effects of the substituents, R, of acid, alcohol, and phenol as cocatalyst on the curing reaction of epoxy resin/acid anhydride/tertiary amine/HA were studied. The reaction constants, p , obtained positively for HA's, indicate that electron‐withdrawing substituents of HA increase the rate of curing reaction of system of epoxide/acid anhydride/amine/HA. Differences in the catalytic and cocatalytic effects among benzoic acid, benzyl alcohol, and phenol in these reaction systems might be considered to depend on the donating power of hydrogen bond which is the important role rather than a general electrostatic interaction effect as solvent effects in nucleophilic substitution reactions. These results supported the proposed mechanisms reasonably.