Tetrabutylphosphonium

It is known that tr-allylpalladium acetate is converted into allyl acetate by reductive elimination when it is treated with CO[242,243]. For this reason, the carbonylation of allylic acetates themselves is difficult. The allylic acetate 386 is carbonylated in the presence of NaBr (20-50 mol%) under severe conditions, probably via allylic bromides[244]. However, the carbonylation of 5-phenyl-2,4-pentadienyl acetate (387) was carried out in the presence of EtiN without using NaBr at 100 °C to yield methyl 6-phenyl-3,5-hexadienoate (388)[245J. The dicarbonylation of l,4-diacetoxy-2-butene to form the 3-hexenedioate also proceeds by using tetrabutylphosphonium chloride as a ligand in 49% yield[246]. 

Phosphonium salts are readily prepared by the reaction of tertiary phosphines with alkyl or henzylic haHdes, eg, the reaction of tributylphosphine [998-40-3] with 1-chlorobutane [109-69-3] to produce tetrabutylphosphonium chloride [2304-30-5]. 

Kinetics are slow and many hours are requited for a 95% conversion of the reactants. In the case of the subject compound, there is evidence that the reaction is autocatalytic but only when approximately 30% conversion to the product has occurred (19). Reaction kinetics are heavily dependent on the species of halogen ia the alkyl haHde and decrease ia the order I >Br >C1. Tetrabutylphosphonium chloride exhibits a high solubiHty ia a variety of solvents, for example, >80% ia water, >70% ia 2-propanol, and >50% ia toluene at 25°C. Its analogues show similar properties. One of the latest appHcations for this phosphonium salt is the manufacture of readily dyeable polyester yams (20,21). 

In addition to tetrabutylphosphonium chloride, typical phosphonium salts that can be produced include tetraoctylphosphonium bromide [23906-97-0], tetrabutylphosphonium acetate [17786-43-5] (monoacetic acid), and tetrabutylphosphonium bromide [3115-68-2]. Inmost cases, these compounds can be prepared with alternative counterions. 

Tetrabutylphosphonium fluoride, tetrabutylphosphonium hydrogen difluoride and tetrabutylphosphonium dihydrogen trifluonde can be prepared from tetrabutylphosphonium hydroxide and hydrogen fluoride (equation 19)... 

Reeently, new fluorinating agents, tetrabutylphosphonium fluoride and its mono- and dihydrofluoride, were used for preparation of fluorohydrins from epoxides [14] (equation 13). 

The alkylation of sodium 2-naphthoxide with benzyl bromide in tetrabutylam-monium and tetrabutylphosphonium halide salts was investigated by Brunet and Badri [50] (Scheme 5.1-21). The yields in this reaction were quantitative, and alkylation occurred predominantly on the oxygen atom of the naphthoxide ion (typically 93-97 %). The rate of the reaction was slower in the chloride salts, due to the benzyl bromide reacting with chloride ion to give the less reactive benzyl chloride. 

In an attempt to produce TS-1 at low cost, alternative, cheaper sources of Ti and Si and other bases such as binary mixtures of (tetrabutylammonium and tetraethylammonium hydroxides), (tetrabutylphosphonium and tetraethylpho-sphonium hydroxides), (tetrapropylammonium bromide and ammonia, water, hexanediamine, n-butylamine, diethylamine, ethylenediamine, or triethanolamine) in place of TPAOH have been used (284—294). TS-1 was synthesized in the presence of fluoride ions but the material thus formed contained extraframework Ti species (295-297). 

OH ratio on the rate of crystallization and crystallite size investigated Prehydrolysis method. Synthesis using binary mixtures of tetrabutylphosphonium hydroxide and tetraethylphosphonium hydroxide instead of TPAOH as base and template TEOS and TBOT are sources of Si and Ti, respectively. Molar gel composition, SiO2 xTiO2 0.4 ( TEPOH + (1 — jd)TBPOH) 30H2O (x = 0-0.02) temperature = 443 K and synthesis time = 4 days Influence of nature of silicon and titanium alkoxides on the incorporation of Ti Wetness impregnation method... 

Tetrabromophthalic anhydride physical properties of, 4 357t Tetrabromophthalic anhydride/diol physical properties of, 4 357t Tetrabutylammonium bromide (TBAB), 2 550t, 76 557-558, 566 Tetrabutylphosphonium hydroxide, 22 573 Tetrabutyltin, toxicity of, 24 831 Tetrabutylurea, 2 550t Tetracalcium aluminate,... 

Herriott and Picker (1975) have studied the reaction between sodium thiophenoxide and 1-bromobutane in benzene-water catalysed by various quaternary ammonium salts and by the dicyclohexyl-18-crown-6 isomers ([20] + [21]). The catalytic activities, as judged from the second-order rate constants, span a range of 104. The best catalyst appeared to be dicyclohexyl- 18-crown-6, directly followed by tetrabutylphosphonium chloride and tetrabutylammonium iodide. 

Intermediate phase transfer catalysts such as tetrabutylphosphonium and ben-zyltriethylammonium cations have no strong effect either way, and will generally give a mixture of products. 

As shown in Table IV, a number of well-known, single-site, ionic PTCs also catalyze the aromatic fluoroalkoxylation reaction, albeit at somewhat higher molar ratios than that required for the optimum conditions using PEG-8000. The most effective of these ionic materials was tetrabutylphosphonium bromide (TBPB) which is in agreement with a study by Bruneile (34c) on the PTC-mediated reaction of thiolates with polychlorobenzenes. It is interesting to note that solid-liquid conditions generally provided better conversions for the ionic PTCs than liquid-liquid conditions and that water... 

Data in Table I illustrate the production of acetic acid from 1/1 syngas catalyzed by ruthenium-cobalt halide bimetallic combinations dispersed in tetrabutylphosphonium bromide (m.p. 100°C). 

The ruthenium(111) acetylacetonate-cobalt(II) iodide couple, for example, when dispersed in tetrabutylphosphonium bromide (ex. 1) and treated with 1/1 CO/H2 at 220°C, generates a liquid product containing 76 wt % acetic acid plus 1.1 wt % propionic acid (111 mmol total acid). The liquid yield increase is 66% and the estimated carbon selectivity to acetic plus propionic acids and their esters is 84%. There is normally no metallic residue at this stage, ruthenium and cobalt recovery is essentially quantitative at the end of the run, and the product acids may be recovered in >90% purity by fractional distillation. Methane and water are the major by-products (4). 

It is clear that ruthenium-cobalt-iodide catalyst dispersed in low-melting tetrabutylphosphonium bromide provides a unique means of selectively converting synthesis gas in one step to acetic acid. Modest changes in catalyst formulation can, however, have profound effects upon liquid product composition. 

Reactions conducted in molten quaternary phosphonium salts require no other solvent (199). This material serves as both promoter and reaction medium. Care must be exercised in choosing the salt in such a reaction, since any decomposition could lead to products such as trialkylphosphines and alkyl halides which are expected to be deleterious to catalyst performance. Tetrabutylphosphonium bromide is reported to provide a stable catalyst medium which can be recycled (199, 200), but other related salts show evidence of thermal decomposition during catalytic reactions. Experiments in tetrabutylphosphonium acetate, for example, are found to produce large amounts of methyl and ethylene glycol acetate esters (199). 

Tetrabutylphosphonium hydrogen difluoride [Bu4PF (HF)] and dihydrogen trifluoride [Bu4PF (HF)2] have been shown to be expedient reagents for nucleophilic fluorination of aromatic substrates containing a chlorine or bromine atom or a nitro group under mild conditions in non polar solvents. Thus, for example l-chloro-4-nitrobenzene (28) is converted to l-fluoro-4-nitrobenzene (29) in 90% yield.219... 

ESR data obtained on y-irradiation of tetraalkylphosphonium salts in solution (96% sulphuric acid) at 77 K differ markedly from those for the trialkylphosphonium ions44. The latter irradiation produces the expected phosphabetaine radical cation and, for example, tetrabutylphosphonium iodide has features assigned previously to I2 45. On the other hand, PH was not detected44,46. Trialkylphosphonium salts, such as trimethyl and triethyl compounds, produce radicals whose ESR spectra are characteristic of the radical cations of R3P +. The central region of the ESR spectra is dominated by features from... 

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