1993 amide formation, amide hydrolysis amide formation, amide hydrolysis O 0320 10 -142 Catalysis Using Phosphorus Compounds in the Reaction of Benzoic Acid with Aniline. -Phosphorus compounds of different nature catalyze the formatiom of benzanilide from benzoic acid and aniline (18 examples). P(III) compounds are found to be more active in comparison with P(V) compounds. Possible catalysis mechanisms are discussed of which an intermediary formation of acyl phosphites is most probable. -(SHTEINBERG, L. YA.; BOIKO, V. D.; KONDRATOV, S. A.; SHEIN, S. M.; SHTEINBERG, YA. B.; Zh. Org.

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We formerly studied [16] synthetic approaches, the effect of substituents and catalysts on reactions of direct acylation, namely on formation of anilides in reactions of aromatic amines with aromatic carboxylic acids.Here we report on investigation of the solvent effect on the model reaction (1) in the presence of activated [5] titanium(IV) butoxide (0.02 mol per 1 mol of benzoic acid) aimed at finding optimum conditions for anilides synthesis.Reaction (1) can proceed only at vigorous boiling and distilling off the forming water obviously in order to shift the equilibrium (1) to the right side. For instance, at boiling in o-xylene (145°C) reaction (1) within 1 h gave rise to 58% of benzanilide, whereas the acylation at 144°C in 1,3,5-trichlorobenzene, benzyl alcohol, or o-xylene without boiling and water distillation in 12 h yielded only 18% of benzanilide, and the results were irreproducible.Reaction (1) proceeded best of all in aprotic media of low polarity (toluene, xylenes, decene, o-chlorotoluene, chlorobenzene etc.). The initial rate grows with increasing boiling point, and the log relative initial rate depends linearly on the reciprocal boiling point (see the figure). (The relative initial rates were calculated with respect to the initial reaction rate in o-xylene at equal reagents and catalyst concentrations). This dependence demonstrates that the rate of reaction (1) is governed mainly by the boiling point of the nonpolar solvent.With growing polarity of the solvent the rate of reaction (1) considerably decreased. For instance, the yield of benzanilide after 4 h of boiling in nitrobenzene (32%, at 211°C) was nearly the same as after 30 min of boiling in mesitylene (38%, at 155°C). In reaction (1) carried out in boiling toluene and 1-butanol having close boiling points the yield in the former solvent was twice as high as in the latter one (30 and 15% in 2 h respectively).In solvents of high polarity capable of coordination (DMF, HMPA, DMSO, and sulfolane) reaction (1) did not occur. Moreover, the small portions of these solvents added to the reaction mixture (10 mol% to the amount of benzoic acid) completely inhibited reaction (1) in o-xylene. This fact is apparently due to the competing complexing of these compounds with Ti(IV) preventing the entrance of reagents into the coordination sphere of titanium and thus inhibiting the catalytic process. &22+ 1+ &21+ + + 2 (1) ± ± 7 ERLO OQ U H O Log relative initial rate (ln v rel ) of reaction (1) as a function of reciprocal boiling point (1/Ò boil ) of nonpolar solvent.

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.