Triphenylphosphine with alcohols

By constant-current electrolysis of triphenylphosphine with alcohol and benzoic or succinic acid the alkoxyphosphonium perchlorates can be obtained434 (reaction 123). 

A halogenating system related to the preceding case is formed by the reaction of triphenylphosphine with molecular bromine or chlorine. The system is not as sensitive to moisture as the phosphine-carbon tetrahalide system (see preceding section), but it suffers from the disadvantage that hydrohalic acids are produced as the reaction proceeds. Nevertheless, sensitive compounds can be successfully halogenated by the system, as exemplified by the preparation of cinnamyl bromide from the alcohol. 

Triphenylphosphine dichloride exhibits similar reactivity and can be used to prepare chlorides.18 The most convenient methods for converting alcohols to chlorides are based on in situ generation of chlorophosphonium ions19 by reaction of triphenylphosphine with various chlorine compounds such as carbon tetrachloride20 or hexachloroacetone.21 These reactions involve formation of chlorophosphonium ions. 

Diphenylphosphoryl azide reacts with alcohols in the presence of triphenylphosphine and DEAD.76 Hydrazoic acid, HN3, can also serve as the azide ion source under these conditions.77 These reactions are examples of the Mitsunobu reaction. 

Wilson and Tebby have studied the reaction of triphenylphosphine with different acetylenic esters in alcohol medium and have shown that /3-alkoxyvinylphosphonium ylides and vinyl ethers are formed through the alcoholysis of vinyl phosphonium intermediates. Thus, triphenylphosphine reacts with DMAD in methanol to give the phosphorane (432) [Eq. (62)]. The reaction with propiolic esters, on the... 

Kinetics of the transformations of the N-F class of fluorinating agents in water, acetonitrile, alcohols, and aqueous solutions of alkali metal hydroxides have been studied.159 Other kinetic studies include die reactions of triphenylphosphine with 3-methoxy- or 3-acctoxy-4,4,5,5-tetrasubstitutcd-1,2-dioxolanes,160 the reactions of 2-amino-5-chlorobenzophenone witii HC1 in MeOH-H20 (die aspect of nucleophilic aliphatic substitution lies in certain products arising from attack of AH2 on CH3OH there are six products in all, and rate constants are evaluated for die formation of each of them),161 and the hydrolysis of derivatives of diazidophenyhnethane.162... 

Finally triphenylphosphine with carbon tetrachloride (or carbon tetra-bromide) results in the conversion of allylic alcohols into the corresponding chlorides (or bromides) with little or no rearrangement.86... 

The reaction of triphenylphosphine and tetrahalomethanes (CC14, CBr4) with alcohols is a ready method to convert an alcohol to the corresponding alkyl halide under mild conditions. The yields are normally high. 

The triphenylphosphine cation reacts with alcohols to form an alkoxy-carbonyl which yields the hydride on reaction with water. 

Recent years have also witnessed an increasing interest in the use of halo-genoselenuranes as reagents for interconversions of basic functional groups. As early as 1986 it was reported in a conference communication [68a] that tibe easily available dichloroselenuranes 137 react with alcohols 136 in the presence of equimolar amounts of triphenylphosphine with the clean formation of the corresponding chlorides 138 (Eq. 31). 

The combination of triphenylphosphine with esters of trihaloacetic acids provides a reagent system for the stereo- and regio-selective conversion of alcohols into alkyl halides.The bromine-triphenylphosphine adduct has been used at low temperatures (-50 C in dichloromethane) for the removal of the tetrahydropyranyl protecting group from tetrahydropyranyl ethers derived from secondary and tertiary alcohols.The reactions of tertiary phosphines (and other trivalent phosphorus compounds) with iodine in aprotic solvents have received further study, a range of species being identified.The first reported study of the reactions of trivalent phosphorus compounds with monopositive astatine has led to the identification of stable complexes with triphenylphosphine, trioctylphosphine, and triethylphosphite. 

Reaction with alcohols and phenols. Horner and co-workers introduced use of the reagents for the preparation of alkyl and aryl halides from alcohols or phenols, and Wiley and co-workers established that the reagents have considerable advantage over phosphorus pentahalides in the C—OH—C—X conversion and discussed the mechanism. For the preparation of n-butyl bromide the Wiley group added bromine under nitrogen to a solution of n-butanol and triphenylphosphine in dimethyl-formamide until 2 drops persisted in giving the solution an orange tint. Volatile... 

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