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Phosphite esters are typically prepared by treating phosphorus trichloride with an alcohol. For alkyl alcohols the displaced chloride ion can attack the phosphite, causing dealkylation to give a dialkylphosphite and an organochlorine compound. [1] [2] The overall reaction is as follows: PCl 3 + 3 C 2 H 5 OH → (C 2 H 5 O) 2 P(O)H + 2 HCl + C 2 ...
Phosphite esters with tertiary alkyl halide groups can undergo the reaction, which would be unexpected if only an S N 2 mechanism was operating. Further support for this S N 1 type mechanism comes from the use of the Arbuzov reaction in the synthesis of neopentyl halides, a class of compounds that are notoriously unreactive towards S N 2 reactions.
Phosphites, sometimes called phosphite esters, have the general structure P(OR) 3 with oxidation state +3. Such species arise from the alcoholysis of phosphorus trichloride: PCl 3 + 3 ROH → P(OR) 3 + 3 HCl. The reaction is general, thus a vast number of such species are known.
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
Diethyl phosphite hydrolyzes to give phosphorous acid. Hydrogen chloride accelerates this conversion.: [2] Diethyl phosphite undergoes transesterification upon treating with an alcohol. For alcohols of high boiling points, the conversion can be driven by removal of ethanol: [8] (C 2 H 5 O) 2 P(O)H + 2 ROH → (RO) 2 P(O)H + 2 C 2 H 5 OH
The phosphite esters and tertiary phosphines also effect reduction: ROOH + PR 3 → P(OR) 3 + ROH. Cleavage to ketones and alcohols occurs in the base-catalyzed Kornblum–DeLaMare rearrangement, which involves the breaking of bonds within peroxides to form these products.
Since orthophosphoric acid has three −OH groups, it can esterify with one, two, or three alcohol molecules to form a mono-, di-, or triester. See the general structure image of an ortho- (or mono-) phosphate ester below on the left, where any of the R groups can be a hydrogen or an organic radical. Di- and tripoly- (or tri-) phosphate esters ...
This reaction is the basis of methods for analysis of organic peroxides. [5] Another way to evaluate the content of peracids and peroxides is the volumetric titration with alkoxides such as sodium ethoxide. [6] The phosphite esters and tertiary phosphines also effect reduction: ROOH + PR 3 → OPR 3 + ROH