Synthesis tetrabutylammonium hydrogen

The solubility of the components in the solvent must be sufficient. To improve the solubility, cosolvents can be used. Another possibility is the application of a two-phase system or an emulsion in the presence of phase-transfer catalysts. A two-phase system also has advantages in product isolation and continuous electrolysis procedures. A typical example is the synthesis of p-methoxy benzonitrile by anodic substitution of one methoxy group in 1,4-dimethoxybenzene by the cyanide ion (Eq. 22.21). The homogeneous cyanation system (acetonitrile, tetraethylammonium cyanide) [24] can be efficiently replaced by a phase-transfer system (dichloro-methane, water, sodium cyanide, tetrabutylammonium hydrogen sulfate) [71]. 

Gomberg-Bachmann biphenyl synthesis. Reaction of stable arenediazonium tet-rafluoroborates or hexafluorophosphates in an aromatic solvent with potassium acetate (2 equiv.) and a phase-transfer catalyst results in biar Is in high yield. Crown ethers, Aliquat 336, and tetrabutylammonium hydrogen sulfate arc all effective catalysts. The reaction is useful for synthesis of unsymmetrical biaryls. The ortho-isomer predominates in reactions with a monosubstituted benzene. The most selective method is to couple a substituted arenediazonium salt with a symmetrical arene. 

Tetrabutylammonium Hydrogen Silicate Synthesis, Chemical, Thermal, and Crystallographic Properties... 

Gerke, H., Gies, H. and F. Liebau (1982) "Tetrabutylammonium Hydrogen Silicate Synthesis Chemical, Thermal and Crystallographie Properties", in J.S. Falcone (ed). Soluble Silicates, ACS Symposium Series, 194, American Chemical Society, Washington D.C., pp. 305-318. 

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. 

A solution containing 105.0 g (31 mmol) of tetrabutylammonium hydrogen sulfate (recrystallized once from acetone) in 150 mL of triply distilled water is placed in a plastic beaker (500 mL) and placed in an ice th to cool. Then a solution of 95% HFSO3 (18.8 mL, 31 mmol) (Aldrich) is added dropwise with stirring. A white precipitate immediately forms. This precipitate is filtered and washed with copious amounts of ice-cold triply distilled water until the wash solution shows pH near 7.0. The precipitate is then dried and twice recrystallized from ethyl acetate to yield 9 g (8% of theoretical yield) of colorless, platelike crystals of very pure [CH3(CH2)3]4NFS03 (mp = 179-180°C). A neutral salt of very high purity is essential for any electrocrystallization portions of this synthesis, otherwise spurious reactions occur and crystal growth fails. 

Aiken, III, J.D. and Finke, R.G., Nanocluster formation synthetic, kinetic, and mechanistic studies. The detection of, and then methods to avoid, hydrogen mass-transfer limitations in the synthesis of polyoxoanion- and tetrabutylammonium-stabilized, near-monodisperse 40 6 A Rh(0) nanoclusters, J. Am. Chem. Soc., 120, 9545, 1998. 

The efficiency of the [2 + 2]-cycloadditions of 417 was utilized in a strategy for the synthesis of cephalosporin derivatives that carry an acetone or acetic acid ester group in the 3-position (Scheme 6.88) [175]. Liberated in the presence of 2-(trimethylsilyl-oxy)propene, 417 underwent cycloaddition leading to 435, treatment of which with tetrabutylammonium or hydrogen fluoride furnished the A3-cephalosporin 436 admixed with the A2-isomer. This mixture was converted to pure 436 by an oxidation-reduction sequence. In addition to the trimethylsilylenol ether of acetone, the... 

A recent literature report described a green procedure for the condensation of arylacetonitriles with cyclic ketones using phase-transfer catalysis. This process was applied to the synthesis of venlafaxine, which was realized in overall 30% yield in two steps from commercially available 14. The condensation step was run in aqueous sodium hydroxide in the presence of tetrabutylammonium sulfate, to provide quantitative yield of intermediate 15. Hydrogenation in a formalin-methanol mixture provided the final product venlafaxine (1) in 30% overall yield. This protocol did not necessitate intermediate purification steps, making it attractive from the commercial standpoint. 

The key compounds in the synthesis of 4,4 -dithiocello- and -xylotrioses are the per-acetylated 1,4-dithiodisaccharides (43 a, 43 b) (Scheme 14) which are obtained from acylated (39 a, 39 b) by hydrogen bromide treatment and displacement of the halide by potassium or tetrabutylammonium thioacetate. Total deacetylation of the donors and reaction with triflated acceptors (34 a) or (34b) afforded the expected trisaccharides which can be converted after conventional treatment, into free trisaccharides (44d,44e,44g and 44 h) [40]. Using the same stepwise procedure, but with activation of the donor by selective in situ S-de-acetylation and activation, the cellotetraoside (44 i) and cellopentaoside (44j) were obtained in good yield [41]. 

Fig. 10. Reaction profiles for synthesis of 2-hydroxyoctyl sulfonate from 1,2-epoxyoctane and hydrogen sulfite using either a two-phase system with or without added Q salt or a microemulsion with added Q salt as reaction medium. Q stands for tetrabutylammonium (from [51])...

The chiral switch of the metolachlor was achieved in 1997. It was put on the market with a content of approximately 90% of the Sc active diastereomers. The key step of the large-scale enantioselective synthesis is the catalytic hydrogenation of the MEA imine shown in Figure 17. A mixture of [IrCl(l,5-cyclooctadiene)]2, the chiral diphosphine (i ,5)-xylyphos, iodide (as tetrabutylammonium or sodium salts) and acetic (30%) or sulfuric (at low... 

The easy access to acyl radicals by photocatalyzed selective abstraction of the carbonyl hydrogen atom in aldehydes has originated further convenient applications. For example, trapping of these nucleophilic radicals by electrophilic olefins gave rise to unsymmetrical ketones. A low amount (2mol.%) of tetrabutylammonium decatungstate (TBADT) as the photocatalyst was sufficient. Scheme 2.8 shows as an example the synthesis of p-ketoester 16 in 63% yield upon photolysis of an acetonitrile solution of heptaldehyde and dimethyl maleate." ... 

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