Tetrabutyl ammonium acetate

The preferred glycosylating synthon of i-lyxo configuration was the azide 69, obtained by nucleophihc displacement of 4-0-triflate with tetrabutyl-ammonium acetate, as shown in Scheme 11. Chloroacetyl ester 71 and tri-... 

The GTP, performed in the presence of trimethylsilyldimethylketene acetal as initiator in conjunction with tetrabutyl ammonium acetate catalyst, showed the formahon of cyclic oligomers in addihon to the expected linear oligomers. In contrast, PMMA prepared by radical polymerizahon does not have this functional heterogeneity. MALDl-TOF spectra of low molar mass PMMA, obtained by the polymerizahon of MMA using zir-conocene as initiator, reveal that the process is not a living polymerizahon and that a back-biting cyclizahon process is involved. ... 

Quite recently, they also succeeded in preparing naphthalene containing helical tetrasubstituted alkenes of type 49 by a two-component Pd-catalyzed threefold domino process starting from a mixture of 54 and 55 (Scheme 3.15) [21]. Reaction of this mixture with Pd(OAc)2 in the presence of PPh3 and tetrabutyl ammonium acetate led to the desired product 58 via the Sonogashira intermediate 56 and the vinylpalladium species 57 in 67-96% yield. 

The polarographic determination of metal ions such as Al3 + which are readily hydrolysed can present problems in aqueous solution, but these can often be overcome by the use of non-aqueous solvents. Typical non-aqueous solvents, with appropriate supporting electrolytes shown in parentheses, include acetic acid (CH3C02Na), acetonitrile (LiC104), dimethylformamide (tetrabutyl-ammonium perchlorate), methanol (KCN or KOH), and pyridine (tetraethyl-ammonium perchlorate), In these media a platinum micro-electrode is employed in place of the dropping mercury electrode. 

The peak capacity is not pertinent as the separation was developed by a solvent program. The expected efficiency of the column when operated at the optimum velocity would be about 5,500 theoretical plates. This is not a particularly high efficiency and so the separation depended heavily on the phases selected and the gradient employed. The separation was achieved by a complex mixture of ionic and dispersive interactions between the solutes and the stationary phase and ionic, polar and dispersive forces between the solutes and the mobile phase. The initial solvent was a 1% acetic acid and 1 mM tetrabutyl ammonium phosphate buffered to a pH of 2.8. Initially the tetrabutyl ammonium salt would be adsorbed strongly on the reverse phase and thus acted as an adsorbed ion exchanger. During the program, acetonitrile was added to the solvent and initially this increased the dispersive interactions between the solute and the mobile phase. 

The sodium and potassium salts of glutaconaldehyde are soluble only in polar solvents such as water, dimethyl sulfoxide, N,N-dimethylformamide, pyridine, and methanol. However, the stable tetrabutylammonium salt is soluble in relatively nonpolar solvents such as chloroform and ethyl acetate. It may be prepared from the potassium salt in the following manner. In a 1-1. Erlenmeyer flask equipped with a magnetic stirring bar are placed a solution of 13.6g. (0.1 mole) of crude glutaconaldehyde potassium salt in 200 ml. of water and a solution of 33.9 g. (0.1 mole) of tetrabutyl-ammonium hydrogen sulfate in 200 ml. of ice-cold water, the pH of wliich was adjusted to 10 by adding aqueous 2M sodium hydroxide. 

FIG. 8 Potential oscillation at interface o/wl with SDS as surfactant with (A) no electrolyte, (B) with lOOmM NaCl, (C) lOOmM KCl, (D) lOOmM CsCl, (E) lOOmM MgClz, (F) lOOmM CaClj, (G) lOOmM BaClj, (H) lOOmM FeClj, (I) lOOmM NaF, (I) lOOmM NaBr, (K) lOOmM Nal, (L) lOOmM sodium acetate, (M) 100 mM sodium propionate, (N) 100 mM sodium -butyrate, (O) lOOmM sodium w-valerate, ( ) lOOmM tetramethylammonium chloride, (Q) 20mM tetra-ethylammonium chloride, (R) 20 mM tetrapropylammonium chloride, and (S) 20 mM tetrabutyl-ammonium chloride in phase wl. Phase w2 contains 8mM SDS and 5M ethanol and phase o contains 5mM tetrbutylammonium chloride. (Ref. 27.)... 

The addition of a surfactant counter-ion reduced the retention factor at low pH due to the surface modification of the stationary phase material. Covering the surface of the stationary phase with the surfactant reduces the hydro-phobicity of the stationary phase material. The addition of the tetrabutyl-ammonium counter-ion increased the retention factor at high pH. The pKa of the indole acetate was 5.15 without surfactant, 4.85 with octyl sulfate ion, and 5.60 with tetrabutylammonium ion. That is, the addition of a same-charged hydrophobic ion reduced the pKa value, and the addition of the counter-ion increased the pKa value. The difference in the pKa value on the addition of surfactant is not constant it is affected by the kind of ion and the concentration. It is difficult to estimate the pKa change. 

Amine extraction of penicillins has been examined in a pilot scale extractor and its performance has been analyzed through suitable mathematical models 117-19]. Extraction efficiency as high as 90% was achieved under suitable conditions. The procedure for selection of volume ratios of the aqueous to organic phase and concentration ratio of carrier (Amberlite LA-2) to penicillin-G at a desired degree of extraction and enrichment has recently been described [20]. Ion-pair extraction of penicillin-V and phenoxy acetic acid with Amberlite LA-2 hydrochloride and tetrabutyl ammonium hydrogen sulfate can be effective in... 

Facilitated transport of penicilHn-G in a SLM system using tetrabutyl ammonium hydrogen sulfate and various amines as carriers and dichloromethane, butyl acetate, etc., as the solvents has been reported [57,58]. Tertiary and secondary amines were found to be more efficient carriers in view of their easy accessibility for back extraction, the extraction being faciUtated by co-transport of a proton. The effects of flow rates, carrier concentrations, initial penicilHn-G concentration, and pH of feed and stripping phases on transport rate of penicillin-G was investigated. Under optimized pH conditions, i. e., extraction at pH 6.0-6.5 and re-extraction at pH 7.0, no decomposition of peniciUin-G occurred. The same SLM system has been applied for selective separation of penicilHn-G from a mixture containing phenyl acetic acid with a maximum separation factor of 1.8 under a liquid membrane diffusion controlled mechanism [59]. Tsikas et al. [60] studied the combined extraction of peniciUin-G and enzymatic hydrolysis of 6-aminopenicillanic acid (6-APA) in a hollow fiber carrier (Amberlite LA-2) mediated SLM system. 

Hydroxymethyl polystyrene has been prepared from chloromethyl polystyrene, either by conversion into the acetate by nucleophilic substitution followed by saponification, or directly by treatment with a mixture of potassium acetate and tetrabutyl-ammonium hydroxide in 1,2-dichlorobenzene/water (85 °C, 2 d [61]). 

AA and IAA simultaneously Yeast Metaphosphor ic acid/cold perchloric acid extraction Precolumn ODS-IO (40 X 2.6 mm Bio-Rad). Analytical Spherisorb ODS-2 (250 X 4.6 mm, 5 jum Rainin). 35°C. Isocratic 0.1 mM EDTA and 1.0 mM tetrabutyl-ammonium phosphate in 0.08 M acetate buffer, pH 4.2 + methanol (95 + 5, v/v). No flow rate reported. Electro- chemistry + 0.72 V vs. Ag/AgCl reference electrode, glassy carbon working electrode. External standardization. Linear range = 0-60 /ug/g yeast (dry weight). Reproducibility CV 2.3% for IAA, 1.2% for A A. Recoveries quantitative for both vitamers. 59... 

Co Pell ODS 16.2 mM-tetrabutyl-ammonium bromide in 50 mM-acetate buffer (pH 4.5), containing 4% of methanol. 254 nm Analysis in boiled water without interference with metal ions. [59]... 

Substitution of the acetate group at the C-3 position of the /3-sultam 105 can occur by reaction with silyl enol ethers in the presence of zinc iodide or zinc chloride. When the diazo compound is used, after desilylation with tetrabutyl-ammonium fluoride (TBAF), photochemical cyclization gives the bicyclic /3-sultam 106 as a mixture of two cis/ fra -diastereoisomers. When silyl enol ethers derived from cyclic ketones are used, the substitution product is stabilized by a retro-Michael-type reaction leading to open-chained sulfonamides 107 (Scheme 31) <1997LA1261>. 

Alkylation of (4) with ethyl bromo acetate was effected under phase-transfer conditions with powdered potassium hydroxide and tetrabutyl ammonium bromide in tetrahydrofuran to yield compound (5), and the azide function in (5) was then reduced by catalytic hydrogenation (over Pd/C) to give (6). The aminoester (6) was resolved into its enantiomers via... 

Column uBondapak C18 (300x4 mm I.D.), mobile phase Si 0.01M tetrabutyl ammonium phosphate (pH 7.5) - methanol (53 47), S2 0.01M 1-heptane sulfonic acid (pH 3 with % acetic acid) - methanol (65 35) after 10 min changed to (45 55), flow rate 2 ml/min, detection UV 254 and 280 nm simultaneous. 

Anaerobic sediments frequently contain large amounts of elementary sulfur (S8) which may cause serious interference during GC analysis. The traditional method that is applicable to chemically stable analytes is treatment with activated copper, but an elegant and milder procedure in which elementary sulfur is converted into water-soluble thiosulfate by reaction with tetrabutyl ammonium sulfite has been developed 0ensen et al. 1977). This method cannot, however, be applied to samples containing sensitive compounds such as phenols in such cases, the sulfur may be removed from the phenol acetates by silica gel chromatography and elution with cyclohexane (Allard et al. 1991). 

Bile pigments in bile LiChrosorb RP-8, S Jim Acetonitrile/ethyl acetate/methanol/water (30 33 45 50) with varying pH and concentration of tetrabutyl ammonium ions As 4-iodoaniline azo- 142 derivatives UV 546 nm or 365 nm ... 

A second type of very useful behavior occurs in aprotic (or sometimes inert ) solvents, which usually exhibit very weak acid properties. Examples are dimethylformamide, dimethylsulfoxide, dioxane, ether, various nitriles, methyl isobutyl ketone, hydrocarbons, carbon tetrachloride. These solvents often permit differentiation (or stepwise titration) of a series of acidic or basic species which, in water, either titrate together or not at all. For example, perchloric, hydrochloric, salicylic, and acetic acids and phenol can be titrated stepwise in methyl isobutyl ketone solvent to obtain discernible endpoints for each compound, using tetrabutyl ammonium hydroxide in isopropyl alcohol as titrant. 

Buffer 5 mM chromate or phthalate, pH 10.00 5 mM chromate, pH 8.0 5 mM chromate, pH 11.0 (LiOH) 30 mM creatinine, pH 4.8 (acetic acid) 100 mM borate Additives 0.5 mM Nice-Pak OEM Anion-BT 0.4 mM OFM Anion-BT None 8 mM hydroxyisobutyric acid 50 mM tetrabutyl ammonium hydroxide Analytes/Sample Organic/inorganic ions Organic/inorganic ions Metal ions Inorganic OTgMiic ions References Romano et al. (1991) Jones and Jandik (1992) Lu and Cassidy (1993) Audalovic et al. (1993)... 

The pyrolysis derivatization approach may also be used. THM results in the formation of dimethyl terephthalate when PET fibers are subjected to the procedure. Tetrabutyl ammonium hydroxide may be used to replace TMAH in the reaction to confirm the presence of vinyl acetate in acrylonitrile-vinyl acetate copolymer acrylic fibers. The derivatized product is butyl acetate. ... 

Stearalkonium chloride TEA-sorbate Tea tree (Melaleuca alternifolia) extract Tetrabutyl ammonium bromide Thiabendazole 2,2 -Thiobis (4-chlorophenol) 2,2 -Thiobis (4,6-dichlorophenol) Tormentil (Potentilla erecta) extract Jriacetin Undecylenamide DEA Undecylenamide MEA Undecylenamidopropyl betaine Undecylenamidopropyl trimonium methosulfate Undecyleneth-6 Willow (Salix alba) bark extract Zinc acetate Zinc borate Zinc phenolsulfonate Zinc sulfate Zinc undecylenate... 

Benzyl trimethyl ammonium hydroxide Cetrimonium bromide Dimethyl diallyl ammonium chloride Laurtrimonium bromide Laurtrimonium chloride Methyl tributyl ammonium chloride Tetrabutyl ammonium bromide Tetrabutyl ammonium chloride Tetrabutyl ammonium fluoride Tetra-n-butyl ammonium hydrogen sulfate Tetra-n-butyl ammonium hydroxide Tetrabutyl ammonium iodide Tetrabutylphosphonium acetate, monoacetic acid Tetrabutylphosphonium bromide Tetrabutylphosphonium chloride Tetraethylammonium bromide Tetraethylammonium hydroxide Tetrakis (hydroxymethyl) phosphonium chloride Tetramethylammonium bromide Tetramethylammonium chloride Tetramethylammonium hydroxide Tetramethyl ammonium iodide Tetraphenyl phosphonium bromide Tetrapropyl ammonium bromide Tetrapropyl ammonium iodide Tributylamine Tributyl phosphine Tributyl (tetradecyl) phosphonium chloride Trioctyl (octadecyl) phosphonium iodide catalyst, phase-transfer Tetraethylammonium chloride Tetraoctylphosphonium bromide Tri-n-butyl methyl ammonium chloride Tri methyl phenyl ammonium hydroxide catalyst, phenolics Triethylamine... 

An efficient and stereoselective synthesis of 3,4,6-tri-O-acetyl-ot-D-glucopyranose 1,2-exo-alkyl ortho-acetates (67) has been achieved using DMF dialkyl acetals (68) and tetrabutyl ammonium bromide on acetobromoglucose. The DMF acetal from 1,2 3,4-di-0-isopropylidene bC-D-galactopyranose (69) was also prepared and used to synthesize the mixed sugar orthoester (70). 

Tetrabutyl ammonium bromide (TBAB) was found to be an efficient phase-transfer catalyst for the synthesis of pyrido[2,3 -d]pyrimidines by the one-pot reaction of 6-aminouracils (132), aromatic aldehydes (134), and malononitrile or ethyl cyano-acetate in water under ultrasonic irradiation (Scheme 8.45). The advantages of this method are the use of an inexpensive and readily available catalyst, short reaction times, easy workup, improved yields, and the use of water as a solvent that is environmentally benign (Hussein, 2012). 

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