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The substitution reactions of XC 6 H 4 COCl [X=2-, 3-, or 4-CH 3 ; 2-, 3-, or 4-CH 3 O; 2-, or 4-I; or 2-, 3-, or 4-NO 2 ] and YC 6 H 4 COONa [Y=2-, 3-, or 4-CH 3 ; 2-, 3-, or 4-CH 3 O; 2-I; 4-NO 2 ; or H] in a two-phase H 2 O/CH 2 Cl 2 medium using pyridine-1-oxide (PNO) as an inverse phase transfer catalyst were investigated. In general, the kinetics of the reaction follows a pseudo-first-order rate law, with the observed rate constant being a linear function of the concentration of PNO in the water phase. In contrast to other analogous reactions, the hydrolysis reaction of 2-, 3-, or 4-NO 2 C 6 H 4 COCl in H 2 O/CH 2 Cl 2 medium is catalyzed considerably by PNO and reaches an equilibrium. In the PNO-catalyzed reaction of XC 6 H 4 COCl and XC 6 H 4 COONa in H 2 O/CH 2 Cl 2 medium, the order of reactivities of XC 6 H 4 COCl toward reaction with PNO in CH 2 Cl 2 is 2-IC 6 H 4 COCl>4-IC 6 H 4 COCl>(C 6 H 5 COCl,3-CH 3 OC 6 H 4 COCl)>3-CH 3 C 6 H 4 COCl>(2-CH 3 C 6 H 4 COCl,4-CH 3 C 6 H 4 COCl)>4-CH 3 OC 6 H 4 COCl>2-CH 3 OC 6 H 4 COCl. Combined with the results of other analogous reactions, good Hammett correlations with positive reaction constant were obtained for the meta - and para -substituents, which supports that the XC 6 H 4 COCl–PNO reaction in CH 2 Cl 2 is a nucleophilic substitution reaction. |
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