Tetra-n-butylammonium hydrogen sulfate

AcCl, NaOH, dioxane, Bu4N HS04 , 25°, 30 min, 90% yield. Phase-transfer catalysis with tetra-n-butylammonium hydrogen sulfate effects acylation of sterically hindered phenols and selective acylation of a phenol in the presence of an aliphatic secondary alcohol. 

Amides from nitriles. One classical reagent for this reaction is H202-Na0H in a suitable solvent.3 This reaction can be carried out advantageously under phase-transfer catalyzed conditions.4 Tetra-n-butylammonium hydrogen sulfate is satisfactory the effectiveness varies with the structure of the nitrile. An excess of 30% H202 is used the solvent system is CH2C12 20% NaOH. Yields are 85-95%. 

A two-phase mixture of methyl propiolate (5.0 g, 59.5 mmol), boric acid (5.5 g, 89 mmol), sodium benzenesulfinate (9.75 g, 59.5 mmol), and tetra-n-butylammonium hydrogen sulfate (3.0 g, 8.75 mmol) (Note 1) in tetrahydrofuran water (200 mL, 1 1) is stirred vigorously at room temperature for 48 hr (Note 2). The solution is acidified to pH 4 (2 N hydrochloric acid) and extracted into diethyl ether (4 x 50 mL) (Note 3). The organic layer is dried (MgSCU) and concentrated under reduced pressure to afford 13.75 g of yellow oil (Note 4) which is subjected to flash column chromatography (1.5 1 hexanes-diethyl ether) to afford initially methyl (E)-3-(benzenesulfonyl)prop-2-enoate (400 mg, 2.9%) and then the desired Z-isomer (10.89 g, 81%) as a pale yellow solid, pure by spectral study (Note 5). 

Amino acid synthesis (8, 389). Alkylation of the aldimine (1) from glycine ethyl ester and /j-chlorobenzaldehyde under phase-transfer conditions offers a general route to amino acids. Either liquid-liquid phase-transfer or solid-liquid phase-transfer catalytic conditions are satisfactory with active halides, but alkylation with allylic halides and less active alkyl halides is best effected under ion-pair extraction conditions (6,41), with 1 equiv. of tetra-n-butylammonium hydrogen sulfate (76-95% yields).1... 

Fig. 4. Gradient elution separation of ribonucleotides. Mobile phase (A) 0.025 M tetra-n-butylammonium hydrogen sulfate, 0.050 M KHjP04,0.080 M NH4CI buffered at pH 3.90 (B) 0.025 tetravt-butylammonium hydrogen sulfate, 0.10 M KHjPO, 0.20 M NH4CI buffered at pH 3.4, 30% methanol. Operating conditions 40-min gradient program (concave 8) at 1 ml/min. Reprinted with permission from Hoffman and Liao (H19). Copyright by the American Chemical Society.

Dehydrohalogenation. Aryl vinyl ethers are prepared conveniently by dehy-drohalogenation of aryl 2-haloethyl ethers with aqueous sodium hydroxide with tetra-n-butylammonium hydrogen sulfate as phase-transfer catalyst (equation I). 

Solid-liquid phase-transfer catalysts. Diphenylphosphinic hydrazide (1) is not alkylated efficiently under usual phase-transfer conditions, but is alkylated by use of solid Na0H-K2C03 with benzene as solvent. The reaction is strongly accelerated by tetra-n-butylammonium hydrogen sulfate. The role of K2CO3 is not clear. The products are hydrolyzed by 15% HCl to pure monoalkylhydrazines. 

Tetra-n-butylammonium di-r-butyl phosphate, [(CH3)3CO]2PON[C4Hg-n]4 (1). Mol. wt. 451.7, m.p. 108-110°. The salt is prepared by reaction of potassium di-(-butyl phosphate with tetra-n-butylammonium hydrogen sulfate in aqueous NaOH-CHjCU (96% yield). 

Hydroxydithiocinnamic acids (1) can be converted into the monosalt by treatment with tetra-n-butylammonium hydrogen sulfate and NaOCHj, which on alkylation gives the dithioesters (2) in high yield. Mercaptals (3) can be prepared in 70-88% yield by treatment of (2) with thallous ethoxide (2, 407 411) and an alkyl halide. 

P-Lactams.1 /(-Amino acids are converted to /(-lactams by dehydration with methanesulfonyl chloride under phase-transfer conditions. Tetra-n-butylammonium hydrogen sulfate is the most useful ammonium salt (equation I). 

Tetra-n-butylammonium hydrogen sulfate [32503-27-8] M crystallises from acetone. It has been used as a phase transfer catalyst. 

Tetra-n-butylammonium hydrogen sulfate, [CH3(CH2)314NHS04 . Mol. wt. 339.54, m.p. 169-171°. Suppliers Aldrich, Fluka. 

Ether synthesis. Ethers can be prepared in high yield by the reaction of primary or secondary alcohols with primary aUcyl chlorides in a two-phase system composed of excess 50% aqueous sodium hydroxide and the alkyl chloride functioning as the organic solvent. Tetra-n-butylammonium hydrogen sulfate (3-5 mole %) is used as the phase-transfer catalyst. Primary alcohols are alkylated in 3-4 hr secondary alcohols require longer reaction times or larger amounts of catalyst. Yields are unsatisfactory with secondary alkyl chlorides. 

Tetra- -butylammonium bromide, 601 Tetra-n-butylammonium fluoride, 78, 81 Tetra-n-butylammonium halides, 565 Tetra-n-butylammonium hydrogen sulfate,... 

Sodium hydroxide I potassium carbonate tetra-n-butylammonium hydrogen sulfate <-N-Alkylation of carboxylic acid amides CONH -+ CONR... 

Potassium per oxymonosulfate j tetra-n-butylammonium hydrogen sulfate Ar. nitro compds. from amines NH2... 

A mixture of 2 -hydroxychalcone in dichloromethane, 5 M NaOH soln., NaBH4, and 1.5 eqs. tetra-n-butylammonium hydrogen sulfate stirred at room temp, for 6-8 h - flavan-4-ol. Y 80%. F.e.s. D. Jyotsna, A.V. Subba Rao, Synth. Commun. 18,1009-14 (1988). 

Methyltrioctylammonium tetrakis(diperoxotungsto)phosphate Tetra-n-butylammonium hydrogen sulfate s. under NaBH Bu N HSOf... 

Sodium hydroxide I tetra-n-butylammonium hydrogen sulfate NaOH BuJSf HSO ... 

Figure 22 Chromatogram of a reference mixture of pyridine compounds. Conditions column, ODS-2 Spherisorb (125 X 4.6 mm, i.d.) mobile phase, gradient elution with 0.1 M KH2PO4, containing 6 mM tetra-n-butylammonium hydrogen sulfate, at pH 5.5 (eluant A), and methanol (eluant B). Initial conditions 96% A and 4% B, increasing stepwise to 10% B in 5 min, 12% B at 10 min, and 30% B from 13 to 15 min, followed by a return to initial conditions (96% A and 4% B) from 19 to 20 min. Flow rate, 1 mL/ min detection wavelength, 254 nm column temperature, ambient. (From Ref 59.)...

Benzyl chloride added dropwise during 2 hrs. at pH 7.5-8 to a soln. of chloro-(glycinato)(tri-n-butylphosphine)platinum(II), NaOH, and tetra-n-butylammonium hydrogen sulfate in acetone containing a little water, and stirred 3 hrs. at room temp. -> chloro(phenylalaninato)(tri-n-butylphosphine)platinum(II). Y 70-80%. - This is part of a method for the synthesis of a-aminocarhoxylic acids. F. e. with dimethyl sulfate and aldehydes s. W. Beck and M. Girnth, B. 109, 965 (1976). 

A mixture of diethyl N-benzylphosphoramidate, 1.5 moles -butyl bromide, aq. 50%-NaOH, toluene, and tetra-n-butylammonium hydrogen sulfate as phase transfer catalyst refluxed 4 hrs. with vigorous stirring, the crude intermediate (Y 97.5%) dissolved in tetrahydrofuran, satd. with HCl-gas, and allowed to stand 12 hrs. at room temp. -> crude benzyl-n-butylamine (Y 99.5%). - This is a method for the prepn. of sec. from prim, amines. F. e. and limitations s. A. Zwierzak and J. Brylikowska-Piotrowicz, Ang. Ch. 89, 109 (1977). 

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