Macrocyclic Complexes Lab Report

Macrocyclic complexes pramaters for hydrolysis of esters

Anuj Kumar, Prashant Tevatia, Sweety and Randhir Singh 1Department of Chemistry, Gurukula Kangri University, Haridwar-249404, India

Abstract

In the present studies, the hydrolysis of 4-nitrophenyl-2-benzamido carbonate, 4-nitrophenyl-4-benzamido carbonate and 4-nitrophenyl acetate has taken into account. The hydrolysis of 4-nitrophenyl-2-benzamido carbonate can be depicted as proceeding either through oxygen or nitrogen intermolecular attack. In contrast the hydrolysis of 4-nitrophenyl-4-benzamido carbonate proceeds through normal H2O or OH- attacks. The hydrolysis of 4-nitrophenyl-4-benzamido carbonate proceeds about 900 times faster than that of 4-nitrophenyl-4-benzamido carbonate. This has been confirmed by isolation of Salicylamide as the final product. The pH independent reaction can be unimolecular breakdown of the compound or it may involve a water reaction. The macrocyclic complex [CoL(NCS)(OH)]+ promoted hydrolysis of 4-nitrophenyl acetate, 4-nitrophenyl-2-benzamido

1: Plot of log kobs vs pH for the hydrolysis of (a) 4-nitrophenyl-2-benzamido carbonate and (b) 4-nitrophenyl-4-benzamido carbonate. The drawn lines are the theoretical best fits of the experimental data.

The hydrolysis of (1) can be represented as follows (Scheme 1):

This reaction assumes an intramolecular nitrogen attack during the cyclisation process. If an oxygen attack is assumed the reaction scheme would be (scheme 2): Thy hydrolysis of (2) can be represented as follows (scheme