Kinetic studies on the reaction between substituted benzyl phosphonates and substituted benzaldehydes

Abstract

The kinetics of Wittig-Horner reaction between several middle-active phosphonates and substituted benzaldehydes, and the effect of substituents which bond on phosphonates and benzaldehydes respectively on the reaction rate have been studied. Experimental findings are consistent with intermediate formation being the rate-determining step. The substituents on phosphonates play an important part in the formation of the intermediate. Large negative entropy values provide further evidence for the rate-detemining step, and for the intermediate, which probably has a four-membered cyclic structure.

Hydrophilic Conjugated Polymers Prepared by Aqueous Horner–Wadsworth–Emmons Coupling

“…HWE reactions are typically overall third-order (first-order each in aldehyde [A], phosphonate [P], and base [B]) with carbanion addition to the aldehyde representing the rate-limiting step (Figure S6). − The reaction of phosphonate 5 with zwitterionic benzaldehyde 19 was monitored by varying reactant concentration, finding the expected linear relationship between reaction rate and [A]­[P]­[B] (Figure S8 and Table S1). Subsequent experiments compared the reaction rates of the aromatic bisphosphonates 5 , 8 , and 12 (Figure A and Figure S9 and Tables S2 and S3) and hydrophilic benzaldehydes 19 – 21 (Figure B and Figure S9 and Tables S2 and S3), with additional examination of the effect of DMSO as a cosolvent with water (Figure C and Table S4).…”