Continuous Flow Esterification of a H-Phosphinic Acid, and Transesterification of H-Phosphinates and H-Phosphonates under Microwave Conditions

Abstract

The microwave (MW)-assisted direct esterification of phenyl-H-phosphinic acid, transesterification of the alkyl phenyl-H-phosphinates so obtained, and the similar reaction of dibenzyl phosphite (DBP) were investigated in detail, and the batch accomplishments were translated into a continuous flow operation that, after optimization of the parameters, such as temperature and flow rate, proved to be more productive. Alcoholysis of DBP is a two-step process involving an intermediate phosphite with two different alkoxy groups. The latter species are of synthetic interest, as precursors for optically active reagents.

The Hydrolysis of Phosphinates and Phosphonates: A Review

“…We investigated the acid-catalyzed reactions of a series of α-hydroxy-benzylphosphonates ( 43 ) in order to evaluate the effect of the ester function, and the substituents in the phenyl ring on the rate ( Scheme 22 ) [ 97 ]. The reactions were performed in water with 3 equivalents of hydrochloric acid, and depending on the substituents, the completion took 2.5–9.5 h. Electron-withdrawing substituents increased the reaction rate, while electron-releasing substituents slowed down the hydrolysis.…”

Microwaves as “Co-Catalysts” or as Substitute for Catalysts in Organophosphorus Chemistry

“…It is noteworthy that the MW-assisted continuous flow esterification of a H -phosphinic acid was also elaborated [ 40 ].…”

Synthesis of Cyclic Phosphinates by Microwave-Assisted Ionic-Liquid-Promoted Alcoholysis

“…The 31 P NMR spectra were taken on a Bruker DRX-500 spectrometer operating at 202.4, 125.7, and 300 MHz, respectively. LC-MS measurements were performed with an Agilent 1200 liquid chromatography system coupled with a 6130 quadrupole mass spectrometer equipped with an ESI ion source (Agilent Technologies, Palo Alto, CA, USA).…”

“…Supporting information for this article is available online at https://doi.org/10.1055/a-1504-8924. Included are 31 P and 1 H NMR spectra together with LC chromatograms for products 1c-g, 2b-e and 3b-e. S u p p o r t i n g I n f o r m a t i o n S u p p o r t i n g I n f o r m a t i o n…”