Studies on organophosphorus compounds 61 substituent effects in organophosphorus esters

✍ Scribed by Chengye Yuan; Shusen Li; Wenxiang Hu; Hainzhen Fen

• Book ID: 102846547
• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 774 KB
• Volume: 4
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.520040105

✦ Synopsis

Abstract

Examination of several model organophosphorus compounds, bicyclic phosphates (1), p‐substituted phenylphosphonates (2), and acidic alkylphosphonates (3) reveals that the polar substituent effect in organophosphorus esters parallels that of carbon compounds. No significant variation in polar effects of different alkyl groups with up to 10 carbon atoms is observed. As demonstrated by us, the commonly used Kabachnik polar constant σ~Φ~ for alkyl groups of organophosphorus compounds reflects the steric effect associated with steric hindrance to solvation of acidic anions. Therefore, a set of solvation steric parameters E^p^~s~ has been calculated from pK~a~ values of organophosphorus acids. This parameter can be applied to describe the structural effect on dissociation of organic acids and, after suitable modification, may reflect the steric effect of alkyl groups in hydrolytic reactions of organophosphorus esters.