Tetraphenylphosphonium Chloride

Tetraphenylphosphonium chloride [2001-45-8] M 314.9, m 273-275". Crystd from acetone. Dried at 70° under vacuum. Also recrystd from a mixture of 1 1 or 1 2 dichloromethane/pet ether, the solvents having been dried over anhydrous K2CO3. The purified salt was dried at room temperature under vasuum for 3 days, and at 170" for a further 3 days. Extremely hygroscopic. 

Tetrasubstituted phosphonium halides are just as effective as their ammonium counterparts. A combination of tetraphenylphosphonium bromide and either 18-crown-6 or polyethylene glycol dimethyl ether with spray-dried potassium fluoride converts 4-chlorobenzaldehyde to 4-fluorobenzaldehyde in 74% yield [67] In addition, the halogen of a primary alkyl chloride or bromide is easily displaced by fluorine in aqueous saturated potassium fluoride and a catalytic amount of hexadecyltributylphosphonium bromide [68] (Table 7 Procedure 4, p 194)... 

Aryl chlorides are not very reactive under normal Heck reaction conditions but reaction can be achieved by inclusion of tetraphenylphosphonium salts with Pd(OAc)2 or PdCl2 as the catalysts.138... 

A full report has now appeared of solvent effects on the rates of hydrolysis of benzyltriphenylphosphonium bromide. The remarkable increase in rate in media of low polarity is largely attributable to a shift of the pre-equilibrium between phos-phonium and hydroxide ions in favour of the intermediate hydroxyphosphorane.129 In a similar vein, a study of medium and deuterium isotope effects on the rate of hydrolysis of tetraphenylphosphonium chloride in acetone-water mixtures has been reported.130... 

The formation of crystalline fulleride salts at the electrode occurs when less polar solvents and bulky cations are used for the electrosynthesis. The first fulleride salt was synthesized by Wudl by bulk electrolysis of in o-dichlorobenzene with tetraphenylphosphonium chloride as supporting electrolyte [39, 80]. This black microcrystalline material with the composition (Ph4P )3(Cgg )(Cr)2 exhibits an ESR line with a g-value of 1.9991 and a line width of 45 G at room temperature. Single crystals of the slightly different salts (Ph4P )2(Cgg )(Cr) and (Ph4P )2(C50 )(Br ) could be obtained by electrocrystallization and their crystal structure was determined [82, 83]. Magnetic measurements showed the presence of unpaired spins. 

A catalytic amount of tetraphenylphosphonium bromide is required for the preparation of 3,4-difluorobenzoyl fluoride (11) from 3,4-dichlorobenzoyl chloride (9) with potassium fluoride.32 While 11 is formed only in 23% yield, the partially fluorine substituted intermediate 10 can be treated again with potassi um fluoride and tetraphenylphosphonium bromide at 230 °C for 10 h. In this way besides the chlorine atom of the acid chloride in 9 both the aromatic chlorine atoms are also displaced.32... 

Much better yields have been obtained by using phthaloyl chloride to trap the eliminated nitrite ion and tetraphenylphosphonium bromide as a catalyst in the fluoride substitution reactions.140 The less easily accessible 3-fluorobenzonitrile derivatives have been prepared this way. Table 6 illustrates some of the nitro derivatives which have been transformed into fluoro analogs in good yield.140... 

If the assumption of this reaction sequence is correct, the photolysis of tetraphenylphosphonium chloride must then only lead to biphenyl, diphenylphosphine, ethyl diphenyl-phosphinate and triphenylphosphine and its oxidation products. After 2 h of irradiation, biphenyl, diphenylphosphine and its oxidation products, triphenylphosphine and triphenylphosphine oxide, in a ratio of 3 1 5, along with raw material, are obtained. Ethyl diphenylphosphinate was detected in trace amounts7. These results support the postulate of the reversibility of phosphoranyl radical formation in such systems and indicate one-electron transfer processes15 in the formation and decomposition of the tetraarylphosphonium cation. This reaction is comparable to the observation of an electron transfer from halide ions to hydroxyl radicals or hydrogen atoms in aqueous solutions16,... 

Tetraphenylphosphonium monoperoxysulfate can be prepared from Oxone and tetraphenyphosphonium chloride [57]. Synthesis of the iminium salt catalyst is described in the source paper (see [57]). 

Tetraphenylphosphonium benzenetellurolate was obtained as a precipitate when tetra-phenylphosphonium chloride and sodium or potassium benzenetellurolate were mixed in liquid ammonia4. 

Tetraphenylphosphonium Benzenetellurolate4 5 mmol of the alkali metal benzenetellurolate in 20 ml liquid ammonia are added to a suspension of 1.9 g (5 mmol) of tetraphenylphosphonium chloride in 80 ml liquid ammonia. The yellow-to-red precipitate is collected by filtration and then treated with a small volume of absolute ethanol. The ethanol is decanted from the oily material. The oil crystallizes on trituration with tetrahydrofuran. 

Tetraphenylphosphonium Tris[benzcnetellurolato]mercurate(II)7 0.68 g (3.0 mmol) of sodium benzenetellurolate and 2.16 g (3,3 mmol) of mercury bis[benzenetellurolatc] are dissolved in 30 ml of liquid ammonia, and this solution is poured into 70 ml of liquid ammonia containing 2.25 g (6 mmol) of tetraphenylphosphonium chloride. The resultant mixture is filtered, the solid is washed five times with boiling liquid ammonia, and then dissolved in a small amount of tetrahydrofuran. Ethanol is added to this solution to precipitate the amber-colored solid which is stable in dry air but decomposes in sunlight yield 2.8 g (80%) m.p. 130° (dec.). 

Diaryltetrachlorotellurates(IV) were also prepared by treating diaryl tellurium dichloridcs with tetraphenylphosphonium chloride in 6 M hydrochloric acid2. 

Bis[tetraphenylphosphonium] Diphenyltetrachlorotellurate(IV)2 0.71 g (2 mmol) of diphenyl tellurium dichloride are dissolved in 6 molar aqueous hydrochloric acid, the solution is stirred, and a solution of 1.4 g (4 mmol) of tetraphenylphosphonium chloride in 25 ml of water is added dropwise. The precipitated product is Altered, washed with water, and recrystallized from dichloromethane/ethyl acetate (1 /l, v/v) yield 2.1 g (100%) m.p. 230-232° (Ref.1). 

Despite its rather high acidity (pKj, = 6.58), 91a is an excellent solvent for polymers like polyamides, -esters, -acetals, and -ols 185). Hydrolysis of the anionic species 113 vide infra) in the presence of tetraphenylphosphonium chloride yields the tetrameric dianion 92. 

In this manner, tetraarylphosphonium halides, such as tetraphenylphosphonium chloride (6), may be produced in good yield. This approach has been used for the construction of an intriguing series of polyphosphonium ion dendrimer... 

There are very few examples of Lewis base-promoted allylations of aldehydes with allylstannanes. In 1992 Baba disclosed an intriguing method for allylation of aldehydes with allyl- and 2-butenyltributylstannanes in the presence of catalytic-amounts of dibutyltin dichloride and certain coactivators such as tetrabutylammo-nium iodide, tributylphosphine oxide, HMPA or tetraphenylphosphonium iodide [76]. No definitive mechanistic information is available on the role of the co-activators the authors speculate that the ligands accelerate the metathesis to form allyldibutyltin chloride which is the actual nucleophile. The same group has recently reported the use of a lead(II) iodide/HMPA catalyst for the allylation of a,yff-epoxyketones [76bj. 

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