Tetrabutylammonium chloride phase transfer catalyst

The two-fold Michael addition of nitroethane to methyl propiolate in the presence of potassium fluoride and the phase-transfer catalyst tetrabutylammonium chloride leads to the diester 432. Treatment of nitroethane with methyl propiolate under these conditions, followed by methyl vinyl ketone, leads to the mixed adduct 433460. 

Benzophenone hydrazone (5.88 g, 20 mM) was dissolved in methylene chloride (20 ml) and over-layered with 1 M sodium hydroxide (40 ml) containing, as phase transfer catalyst, tetrabutylammonium sulfate (0.68 g) and sodium iodide (300 mg). The cathode half cell contained 1 M sodium hydroxide (60ml). The whole cell was cooled to 0°C, the anode compartment stirred and electrolysed at a current of 50 mA. Formation of DDM was followed using the DDM absorption peak at 525 nm. The chart obtained was as shown in Figure 2. 

PTC (phase-transfer catalyst) benzyltrimethylammonium chloride, benzyltriethyl chloride, or tetrabutylammonium chloride... 

To synthesize alcohol with the reversed configuration at C-2, we started with the reduction of levoglucosenone to form the well-known alcohol (4) (Scheme 11.8). It was reacted with mesyl chloride to produce mesylate (28). The nucleophilic substitution was performed in refluxing toluene (or xylene) using sodium benzoate as a nucleophile and a nonnucleophilic phase transfer catalyst (tetrabutylammonium hydrogen sulfate) to give a very good yield of the expected benzoate (29). The hydrolysis of the... 

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]. 

Difluoromethoxy-2-chloro-l,l,l-trifluoroethane and potassium fluoride produce 2-difluoromethoxy-1,1,1,2-tetrafluoroethane [50] The yield of the latter reaction is improved by adding a phase transfer catalyst or crown ether, tetra-methylammonium chlonde, tetrabutylammonium chloride, or 18-crown-6 with a solvent like sulfolane can be used for this purpose [5/] (equation 32)... 

DetkioketaKzation. Various thioacetals and thioketals are readily hydrolyzed by pyridinium bromide perbromide (1 equivalent) under phase-transfer conditions. Tetrabutylammonium bromide is used as catalyst and aqueous methylene chloride as solvent. The reaction is more efficient in the presence of pyridine as buffer. Yields are generally 75-90%.1... 

The use of mixtures of sodium hydroxide and benzyltrimethylammonium chloride or tetrabutylammonium bromide failed to enhance the DPGE alkylation of HEC by the in situ formation of the corresponding quaternary ammonium hydroxide phase transfer catalyst. These quaternary ammonium halides are too soluble in aqueous /-butyl alcohol and are preferentially extracted into the organic phase. Mixtures of benzyltrimethylammonium hydroxide and sodium acetate were also ineffective in enhancing the DPGE alkylation of HEC for the same reason, namely preferential solubility of benzyltrimethylammonium acetate in the organic phase. 

Reaction of diphenyl diselenide or dimethyl diselenide with hydrazine hydrate and sodium hydroxide generates the corresponding selenolates smoothly in solvents like DMF or diethyl ether and in the presence of tetrabutylammonium chloride as a phase-transfer catalyst [13]. The selenolates react with organic halides to give various selenides (Scheme 9). Similar conditions have been applied to the synthesis of aryl vinyl selenides from diaryl diselenides and acetylene [14]. 

Chloroform added dropwise at room temp, to a stirred mixture of N-methyl-aniline, aq. 50%-NaOH, benzyltriethylammonium chloride, and, optionally, methylene chloride, and stirring continued 1-2 hrs. -> N-formyl-N-methylaniline. Y 76%. F. e. s. J. Grafe, I. Frohlidi, and M. Muhlstadt, Z. Chem. 14, 434 (1974) s. a. M. Makosza and A. Kacprowicz, Rocz. Chem. 49, 1627 (1975) (Eng) C. A. 84, 43265 N-alkylation with alkyl halides, ibid. 49, 1203 (Eng) C. A. 84, 30793 cf. R. Brehme, Synthesis 1976, 113 with tetrabutylammonium hydrogen sulfate as phase transfer catalyst, indole derivs., cf. A. Barco et al., Synthesis 1976, 124. 

Another useful variation of the phosphine-free Suzuki reaction uses a heterogeneous system with neat water as solvent and tetrabutylammonium chloride as promoter and phase-transfer catalyst (Scheme 42). Aryl bromides were shown to give higher yields than aryl iodides, because of inhibition of phase-transfer by the hberated iodide ion. ... 

Polymer Studies. General Procedure. The desired amount of BPA (generally 45.35g), sodium or potassium hydroxide, phase transfer catalyst (Aliquat 336 or tetrabutylammonium bromide), p - t-butylphenol (0.75% as a chain stopper) and methylene chloride or methylene chloride/chlorobenzene (1/3) were heated at reflux for a period of 5 hr under nitrogen. At this point the reaction mixture was diluted with methylene chloride and filtered through Celite. The mixture was then either a) poured directly into methanol to precipitate the polymer or b) split into two portions one portion was precipitated by methanol, the second was reverse precipitated using methanol/acetone. (see below)... 

A soln. of tosylmethylisocyanide, ethyl iodide, and tetrabutylammonium iodide as phase transfer catalyst in methylene chloride stirred vigorously 3 hrs. at 0 with aq. 30%-NaOH product. Y 90%. F. e. s. A. M. van Leusen, R. J. Bouma, and O. Possel, Tetrah. Let. 1975, 3487. 

All of these results were already presented at the ACS Houston Meeting on March, 1980.11 12 Since that time, further efforts have been made to synthesize novel condensation polymers by phase transfer catalyzed polycondensation. The present article deals with our recent works on the syntheses of carbon-carbon chain polymers and new types of polysulfides.1 The following abbreviations of phase transfer catalysts have been used throughout this article tetra-methylammonium chloride (TMAC), tetraethylammonium chloride (TEAC), tetrabutylammonium chloride (TBAC), benzyltriethylammonium chloride (BTEAC), cetyltrimethylammonium chloride (CTMAC), cetyltrimethyl-ammonium bromide (CTMAB), benzyltriphenylphosphonium chloride (BTPPC), cetyltributylphosphonium bromide (CTBPB), 15-crown-5 (15-C-5), 18-crown-6 (18-C-6), dibenzo-18-crown-6 (DB-18-C-6), dicyclohexyl-18-crown-6 (DC-18-C-6), dibenzo-24-crown-8 (DB-24-C-8), and dicyclohexyl-24-crown-8 (DC-24-C-8) ... 

The second standard protocol makes use of the so-called Jeffery conditions containing a solid phase-transfer catalyst, e.g., tetrabutylammonium chloride. In addition, a solid base such as sodium carbonate or sodium acetate in A,A -dimethylformamide (DMF) is used at a somewhat lower temperature in comparison to Heck conditions (Experimental Procedure below). 

The phase-transfer technique is a simple and efficient tool for the benzylation of carbohydrates. With benzyltriethylammonium chloride or tetrabutylammonium bromide as a catalyst, a mixture of aqueous, 50 % sodium hydroxide and benzyl bromide or chloride in benzene or dichloromethane solution gives a good yield of the fully protected product [103, 104], such as methyl 2,3-di-0-benzyl-4,6-0-benzylidene c-D-glucopyranoside, when stirred at room temperature for several hours. The latter catalyst is slightly more efficient. Dichloromethane has been observed to produce methylene acetals from cis vicinal diols under comparable conditions [103]. 

---