Kinetics of the reaction of benzoyl chloride and beta-methylalanine under inverse phase transfer catalysis

The reactions of benzoyl chloride (PhCOCl) and sodium salts of five alpha-a mino acids ((R'NH)CHRCOOH) in a two-phase H2O/CH2Cl2 medium under inverse p hase-transfer catalysis (IPTC) were investigated. Pyridine (Py), Pyridine 1 -oxide (PNO) and 4-dimethylamino-pyridine (DMAP) were used as the inverse p hase-transfer catalysts. A high yield (85-100%) of the main product PhCO(NR ')RCOOH was generally obtained, The order of reactivities of amino acids to ward reaction with PhCOCl is (N-methylglycine, L-proline)>>glycine>>DL-alph a-alanine>beta-methylalanine>>acetic acid. The characteristics of the PNO-c atalyzed reaction of PhCOCl and sodium salts of beta-methylalanine are simi lar to those of the PNO-catalyzed reaction of PhCOCl and sodium benzoate. T he PNO-catalyzed reaction of benzoyl chloride and sodium salts of beta-meth ylalanine follows a pseudo-first order kinetics. The observed rate coeffici ent is a linear function of the concentration of pyridine 1-oxide (PNO). Th e order of reactivities of catalysts in catalyzing the two-phase reaction o f PhCOCl and beta-methylalanine is DMAP>PNO>Py. The experimental results ar e rationalized.