The synthesis of terephthalic acid from Benzonitrile and potassium carbonate has been studied under various conditions. In addition to terephthalic acid, the reaction products identified were benzoic, isophthalic, and trimesic acids, and potassium cyanate. Significant amounts of benzoic, isophthalic, and trimesic acids were initially formed and their yields decreased with the reaction time. The yield of terephthalic acid, on the other hand, increased mainly at the expense of benzoic acid. The changes in the product composition occured during the reaction showed similar patterns to that observed in the potassium benzoate-carbonate-cyanate systems. The reversible formation of benzonitrile from potassium benzoate and cyanate is suppressed by the presence of excess potassium carbonate. Meta- and p-toluic acids were obtained from the corresponding tolunitriles under similar conditions . The reaction mechanisms may be summarized as follows : Firstly, potassium benzoate and cyanate were formed from benzonitrile and potassium carbonate by the reversible bimolecular reaction. Terephthalic acid was then produced by the competitive reactions, namely, the disproportionation of potassium benzoate and the direct carboxylation of potassium benzoate with potassium carbonate. Sodium carbonate, however, failed to react with benzonitrile at 385°C.
Like ethyl benzoates, the alkaline hydrolysis of 2-methyl substituted ethyl benzoates in 85% ethanol-water at 25°C followed the Hammett rule, though the ρ value increased from 2.50 to 2.76 due to the presence of the ortho-methyl group . Under the same conditions, the ρ value for the ionizations of substituted anilines was 3.34, which is considerably higher than 2.77 observed in water . The 4- or 5-substituent effects on the ortho effect in the alkaline hydrolysis of ethyl 2-methylbenzoates have been discussed based on the substituent effects in the original systems as well as in the product systems . Though marked differences were noted between the ortho effect in the dissociation of various benzoic acids and that in the hydrolysis of their esters, the substituent effects on the ortho effect were alike. If the ester group in the transition state is treated as a substituent, the .D value (-0.09--0. 17) is found to be on the considerably negative side from σm-CO2θ. The carbonyl character may thus be masked to a considerable extent in the transition state.
Potassium trimellitate was heated under CO2 pressure in the presence of CdI2 and K2CO3 under various conditions so as to clarify the effects of reaction temperature, reaction time, additives of CdI2 and KHCO3, and the degree of neutralixation of the original trimellitic acid salt. As by-products, varieties of benzene carboxylic acids such ass phthalic, isophthalic, and prehnitic (1, 2, 3, 5-benzene tetracarboxylic) acids were identified. Tripotassium trimellitate underwent decarboxylation-carboxylation reaction under relatively mild conditions. The decarboxylation reaction appears to take place with the following order of readiness : 4-position>l-position>2-position.
N, N'-Di-p-acetoxybenzoylmelamine (4) was synthesized from melamine and p-acetoxybenzoic anhydride in dioxane through the intermediate, N p-acetoxybenzoylmelamine (1). Upon hydrolysis with 5% aqueous ammonia, (1) and (4) gave N-p-hydroxybenzoyl melamine (3) and N, N'-di-p-hydroxybenzoylmelamine (5), respectively. (3) was also obtained by hydrolyzing the N', N"-diacetyl derivative (2) of (1). The crude product obtained from (4) and p-acetoxybenzoic anhydride in dioxane was hydrolyzed to give N, N', N"-tri-p-hydroxybenzoylmelamine (6). A dye (DS→(3)) was formed when diazotized sulf anilic acid (DS) was coupled with (3) in the presence of pyridine, although the yield was low. However, when diazotized p-nitroaniline-o-sulf onic acid was used, an abnormally coupled product was formed. In order to eliminate the undesired reaction, the N', N"-diphenyl derivative (8) of (3) which had been prepared from the N', N"-diphenyl derivative (7) of (1) through hydrolysis was used for the coupling reaction to obtain the expected product in good yield. None of the compounds (1) through (8) had previously been reported in the literature.