Reaction Kinetics and Catalysis Letters, Vol. 4, No. 1 , 4 3 - 4 7 (1976) NEIGHBORING AMIDE GROUP PARTICIPATION IN ESTER AMINOLYSIS IN APROTIC SOLVENTS T. Komives, A. F. Marton and F. Dutka Central Research Institute for Chemistry of the Hungarian Academy of Sciences H - 1 5 2 5 Budapest, Hungary Received October 3, 1975 The piperidinolysis of 8-quinolyl- f p-nitrophenyl-, o-, and p-piperidino- carbonylphenyl acetates in acetonitrile and in chlorobenzene was studied at o 25 C. The strictly second order kinetic behaviour and the weaks solvent-de- pendence of the rate of the reaction of o-piperidinocarbonylphenyl acetate indicate anchimeric assistance by the o-amide group, and support the sug- gestion that amide groups of hydrophobic enzyme active sites may act as general base catalysts. Bbin HCCJieAOBaH nHnepHflHHOJiH3 8 - x h h o j i h j i -, n—hhtpocJjshhji—, o- h n-nHnepHflHH0Kap60HHJic[)eHHJi aueTaTOB b aueTOHHTpmie h xjic>p6eH30Jie npn 25 ° C . KnHeTHHecKoe noBeaeHne CTporo BToporo nopaflKa h c j i a S a a 3aBHCHMOCTb ckopocth peaKUHH 0-nHnepHflHH0Kap60HHJi4)eHHJi aueTaTa OT pacTBopHTejia yKa3biBaioT Ha aHXHMepHHecKoe BJinaHHe o-aMHflHoft rpynnbi h noflTBepjKflaiOT to npeAnojio>KeHHe, corjiacHo KOTopoMy aMHAHbie rpynnn aKTHBHbix ueHTpoB rHflpo(J)o6Hbix 3H3HMOB fleflCTByKDT KaK o6bIHHbie OCHOBHbie KaTaJIH3aTOpbI. Functional groups of enzyme active sites lie in non-polar locations, which have solvent properties resembling hydrophobic media/l/. Thus, enzyme model reactions which were extensively studied in water may give important information 43