Kinetics and mechanism of the reaction of para-chlorophenyl aryl chlorophosphates with anilines in acetonitrile

✍ Scribed by Hai Whang Lee; Arun Kanti Guha; Ikchoon Lee

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 95 KB
• Volume: 34
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.10081

✦ Synopsis

Abstract

The kinetics and mechanism of the nucleophilic substitution reactions of p‐chlorophenyl aryl chlorophosphates (2) with anilines are investigated in acetonitrile at 55°C. Relatively large magnitudes of ρ~X~ and β~X~ values are indicative of a large degree of bond making in the TS. Smaller magnitudes of ρ~X~ (0.20 for X = H) and ρ~XY~ (−0.30) than those for the corresponding reactions with phenyl aryl chlorophosphates (1) (ρ~X~ = 0.54 for X = H and ρ~XY~ = −1.31) are interpreted to indicate partial electron loss, or shunt, towards the electron acceptor equatorial ligand (p‐ClC~6~H~4~O‐) in the bipyramidal pentacoordinated transition state. The inverse secondary kinetic isotope effects (k~H~/k~D~ = 0.64–0.87) involving deuterated aniline (ND~2~C~6~H~4~X) nucleophiles, and small Δ__H__^‡^ and large negative Δ__S__^‡^ are obtained. These results are consistent with a concerted nucleophilic substitution mechanism. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 632–637, 2002