Tetrabutylammonium sulfate

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. 

A number of new procedures have been developed for the oxidation of sulfur-linked substituents on the pyridine ring at sulfur. 2- and 4-Pyridinethiols may be oxidized to the corresponding sulfonyl chloride at low temperature using sodium hypochlorite in a mixture of dichloromethane and 1M aqueous HC1 <2006JOC1080>. Treatment of the crude solution of sulfonyl chloride in dichloromethane with benzylamine results in rapid conversion to the sulfonamide. Carrying out the oxidation in the presence of KHF2 and tetrabutylammonium sulfate results in conversion to the sulfonyl fluoride. For example, 2-pyridinethiol is converted to the sulfonamide in 98% yield and the sulfonyl fluoride in 70% yield using this procedure (Scheme 27). In the same manner, 4-pyridinethiol is converted to the sulfonyl chloride in 39% yield and 2-quinolinethiol is converted to the sulfonyl chloride and sulfonyl fluoride in 80% and 49% yield, respectively. 

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. 

For the HPLC assay, IMP, sAMP, GTP, GDP, and AMP are separated by ion-paired, reversed-phase HPLC (Qg) with a mobile phase of 65 mM potassium phosphate (pH 4.4), 1 mM tetrabutylammonium sulfate, and 10% methanol. Detection was at 254 nm. A representative chromatogram is shown in Figure 9.112. 

Examples of phase-transfer catalysis applications include methylation of benzimidazole in 38yo yield <81AJC1729>, benzylation (76% yield) and tritylation (80%) of the same substrate <85H(23)2895>, and other benzimidazole alkylations <91BSF255>. Tetrabutylammonium sulfate has been used in the aminoalkylation of imidazole (60%) and benzimidazole (50%) with 2-chloroethylamine <91SC535>, while methylene-l,r-diimidazole and other di-imidazoles and -benzimidazoles were made with the appropriate dichloroalkane under phase transfer conditions <83JHC1245, 88JHC771,92H(34)1365>. See also <83CHE1141 >. 

Mobile phase MeCN 10 mM tetrabutylammonium sulfate 28 72, final apparent pH adjusted to 3.5... 

Sample preparation 0.5-1 mL Plasma + 500 jxL 4-8 p,g/mL IS in water + 500 p,L buffer + 4 mL dichloromethane n-propanol 99 1, extract on a rotamixer, centrifuge at 1200 g. Remove the organic layer and evaporate it to dryness under a stream of air at 30°, add 5 drops toluene, evaporate to dryness under a stream of air at 30°, reconstitute the residue in 200 p,L 50 mM triethylamine in MeCN, add 100 p,L 60 mM ethyl chloroformate in MeCN, after 30 s add 100 pL 1 M 1-leucinamide hydrochloride in MeOH containing 1 M triethylamine, after 2 min add 500 pL 250 mM HCl, extract with 4 mL ethyl acetate. Evaporate the organic layer to dryness under a stream of air at 30°, reconstitute the residue with 100 pL MeCN, add 400 pL 10 mM pH 6.5 phosphate buffer, inject a 60 pL aliquot. (Prepare buffer as follows. Neutralize a 1 M solution of tetrabutylammonium sulfate in water with NaOH, wash 5 times with dichloromethane, wash twice with heptane. Prepare a 100 mM pH 9.6 sodium carbonate buffer containing 0.5 M of the neutralized and washed tetrabutylammonium salt.)... 

Sample preparation Condition a Baker CIS SPE cartridge with three 1 mL portions of MeOH, three 1 mL portions of water, and three 1 mL portions of buffer. Add a 200 p,L aliquot of plasma, bile, or liver homogenate containing the IS to 200 pL buffer and add this mixture to the SPE cartridge, wash with two 200 pL portions of buffer, allow cartridge to dry, elute with two 100 pL portions of MeOH, combine the eluates, add an equal volume of water, iiyect a 40 pL aliquot. (Buffer was 200 mM pH 7.5 sodium phosphate containing 8 mM tetrabutylammonium sulfate.)... 

Mobile phase MeCN 200 mM pH 7.5 sodium phosphate + 8 mM tetrabutylammonium sulfate 5 95 (Wash column overnight with MeOH.)... 

PIC A is tetrabutylammonium sulfate PIC B5 is pentanesulfonic acid PIC B6 is hexanesulfonic acid PIC B7 is heptanesulfonic acid PIC B8 is 1-octanesulfonic acid PIC D4 is dibutylamine phosphate... 

Tissue, urine Reversed phase Potassium phosphate (14.7 mmol 1 ), tetrabutylammonium sulfate (2.3 mmol 1 ), pH 5.0 Phosphocreatine... 

Crystals of the tetrabutylammonium sulfate complex of receptor 28 were obtained by slow evaporation of a DMSO solution of the receptor in the presence of excess tetrabutylammonium sulfate. The crystal structure reveals that the sulfate is centrally bound by all eight hydrogen bond donors from the receptor (Figure 29). 

PIC A is tetrabutylammonium sulfate PIC B5 is pentanesulfonic acid PIC B7 is heptanesulfonic acid. 

Tetrabutylammonium chloride Tetrabutylammonium fluoride Tetrabutylammonium hydroxide Tetrabutylammonium iodide Tetrabutylammonium sulfate Tetrabutylphosphonium bromide... 

Derivatization with pentafluorobenzyl bromide (PFBBr) via extraction with ethyl acetate and tetrabutylammonium sulfate (TBAS) LOD = 1 pM (CN ) and LOD < 50 nM (SCN )... 

Cii-Cis alkanesulfonates separation by chain length and primary sulfonate content Merck LiChrosorb RP-8 4.6 x 250 mm MeOH/H20,0.01 M tetrabutylammonium sulfate Refractive index 42 X (a b A... 

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