Benzyltriethylammonium chloride phase transfer agent

Pha.se-Tra.nsfer Ca.ta.lysts, Many quaternaries have been used as phase-transfer catalysts. A phase-transfer catalyst (PTC) increases the rate of reaction between reactants in different solvent phases. Usually, water is one phase and a water-iminiscible organic solvent is the other. An extensive amount has been pubHshed on the subject of phase-transfer catalysts (233). Both the industrial appHcations in commercial manufacturing processes (243) and their synthesis (244) have been reviewed. Common quaternaries employed as phase-transfer agents include benzyltriethylammonium chloride [56-37-17, tetrabutylammonium bromide [1643-19-2] tributylmethylammonium chloride [56375-79-2] and hexadecylpyridinium chloride [123-03-5]. 

The preparation of phosphoramidates from dialkyl phosphites, using the Todd-Atherton procedure, has been carried out in two-phase systems containing a phase-transfer agent, for example benzyltriethylammonium chloride, at 5 mole % concentration.84... 

Complexes of other metals are also capable of catalyzing useful carbonylation reactions under phase transfer conditions. For example, certain palladium(o) catalysts, like Co2(C0)g, can catalyze the carbonylation of benzylic halides to carboxylic acids. When applied to vinylic dibromides, unsaturated diacids or diynes were obtained, using Pd(diphos)2[diphos l,2-bis(diphenylphosphino)ethane] as the metal catalyst, benzyltriethylammonium chloride as the phase transfer agent, and t-amyl alcohol or benzene as the organic phase(18),... 

The only reported generation of fluoroiodocarbene involves the treatment of fluoro-diiodomethanc with sodium hydroxide in a two-phase system with benzyltriethylammonium chloride as a phase-transfer agent. Although a good yield of the fluoroiodocyclopropanc is obtained when fluoroiodocarbene is generated in the presence of styrene, with more sterically erowded substrates and unconjugated alkcnes the yields are low. 

The reaction of alkenes with alkaline potassium permanganate proceeds rapidly via formation of a cyclic manganese ester, which is hydrolyzed to the 1,2-diol. To avoid overoxidation to an acyloin (a-ketol), the pH of the reaction medium has to be monitored. Although the yields of cA-diols obtained are usually modest ( 50%), the procedure is less hazardous and much less expensive than using osmium tetroxide and thus is well suited for large-scale preparations. Improved yields of diols are obtained when the oxidation is carried out in water in the presence of a phase transfer agent such as benzyltriethylammonium chloride. 

It is worth mentioning at this point that according to Normant et al. (1975) simple polyamines such as tetramethylethylenediamine (TMEDA) are even more active than [2.2.2]-cryptand in the benzylation of acetates in acetonitrile under liquid-solid conditions. These authors suggested that the activity was due to salt solubilization by cation complexation and not to formation of a quaternary ammonium ion since the latter showed no activity. This statement, however, is not in line with the results of Cote and Bauer (1977), who were unable to detect any interaction between K+ and TMEDA in acetonitrile. Furthermore, Vander Zwan and Hartner (1978) found Aliquat 336 (tricaprylylmethylammonium chloride) to be almost as effective as TMEDA in this reaction (Table 30). It might well be, however, that in amine-catalysed benzylation reactions the quaternary salt formed in situ acts both as a reactant and as a phase-transfer catalyst, since Dou et al. (1977) have shown that the benzyltriethylammonium ion is a powerful benzylation agent. 

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