Tetrabutylammonium hydroxide, and

A solution of 72.08 g (0.19 mol) of 5-bromo-l-pentanyl acetate in 1.4 L of MeOH was treated with 38 mL of a 1.0 molar solution of tetrabutylammonium hydroxide and the mixture was stirred at room temperature for 3.0 h, 3.0 mL of AcOH was added and the solution was evaporated at 35°C. The residue was dissolved in 400 mL of EtOAc and the solution was washed with saturated NaHC03, brine, dried, and evaporated to give 60.45 g (94% yield) of the intermediate hydroxy ester (an analytical sample may be obtained by crystallization from 70% EtOAc in hexane, m.p. 58-61°C. A stirred solution of 60.25 g of the hydroxyester in 700 mL of EtOAc was cooled to 5°C and treated with 75.5 mL (3 equiv.) of triethylamine and 32.6 mL (2.35 equiv.) of methanesulfonyl chloride. The mixture was stirred at 6°C for 2.0 h, transferred to a separatory funnel and washed sequentially with water, 2 N HCI, and brine. Concentration of the EtOAc to ca. 300 mL and dilution cooled to 0°C and treated with 75.5 mL (3 equiv.) of triethylamine and 32.6 mL (2.35 equiv.) of methanesulfonyl chloride. The mixture was stirred at 6°C for 2.0 h transferred to a separatory funnel and washed sequentially with water, 2 N HCI, and brine. Concentration of the EtOAc to ca. 300 mL and dilution with 250 mL of hexane led to crystallization (0°C, 18 h). The product was collected by filtration and washed with some cold hexane - EtOAc (1 1) to give 66 g (84% yield) of methyl (R,S)-6-acetyl-3,4-dihydro-7-[5-[(methylsufonyl)oxy]pentyloxy]-2H-l-benzopyran-2-carboxylate m.p. 73-76°C. 

Chromatographic conditions were optimized to follow the reaction in which ATP phosphorylates UDP. These nucleotides, and the products, ADP and UTP, were separated on a Beckman Ci8 LTltrasphere IP column (4.6 mm x 250 mm, 5 /u,m). The mobile phase was adjusted to pH 5.0 with H3P04 and contained 100 mM potassium phosphate, 20 mM potassium acetate, 5 mM tetrabutylammonium hydroxide, and 12% acetonitrile. The effluent was monitored at 254 nm, and quantitation was based on the percentage conversion of UDP to UTP. 

To a 1 liter 4-neck flask containing 728 g 7% NH4OH at 70°C was added 3-chlorobenzyl chloride (0.5 mol), benzaldehyde (0.5 mole) and 0.1 g tetrabutylammonium hydroxide and the mixture stirred 4 hours. It was cooled to ambient temperature whereupon an oil phase appeared. The oil phase was isolated and heated to 80 °C for 30 minutes. In a separate flask, 548 g 5% HCl and 300 g chlorobenzene were charged and added to the oil followed by 69 g chlorobenzene. The chlorobenzene phase was isolated and washed with 48% aqueous sodium chloride solution, whereupon a second oil phase appeared. The oil phase was washed, dried, distilled at 20 Torr, and the product isolated in 73% yield. 

Several reversed-phase methods were also developed which do not use a C18 column. A reversed-phase method using a C8 Spherisorb column has been reported (54) to quantitate diltiazem and two of its metabolites (N-monodemethyl diltiazem and desacetyl diltiazem). A 10 pm particle size PRP-1 column (55), mobile phase of 60% acetonitrile and 0.01 M aqueous KH2PO4, 40% 0.005M aqueous tetrabutylammonium hydroxide and UV absorbance detection at 254 nm was used to determine diltiazem present in plasma. Several HPLC methods have been developed which use a cyano-bonded column. One such method was developed for the determination of diltiazem and its metabolite desacetyl diltiazem in human plasma (56). The analytes are extracted from plasma made basic with 0.5M aqueous dibasic sodium phosphate (pH 7.4) using 1% 2-propanol in hexane. The method uses a cyanopropylsilane column with a mobile phase of 45% acetonitrile and 55% 0.05M aqueous acetate buffer (pH 4.0). The minimum detectable limit was 2 ng/mL in plasma. A similar HPLC method was developed by Johnson and Pieper (57) for the determination of diltiazem and three of its metabolites. Also, an HPLC method was developed (58) for the analysis of diltiazem and desacetyl diltiazem in plasma using UV detection at 237 nm, a Zorbax CN 6 pm particle size column and a mobile phase of 45% methanol, 55% 0.05M aqueous ammonium dihydrogen phosphate and 0.25% triethylamine adjusted to pH 5. 

PolgSr and Vereczkey applied gas chromatography with a glass capillary column for the determination of apovincaminic acid, the main metabolite of apovincaminic acid ethylester (vinpocetine) in human plasma. Apovincaminic acid was recovered from plasma by addition of tetrabutylammonium hydroxide and extraction with chloroform. It was transformed into its... 

The addition of even minute amounts of sodium carbonate has a particularly strong effect on the retention behavior of multivalent anions. These comprise, for example, the two iron cyanide complexes Fe(CN)63 and Fe(CN)64, whose separation is obtained with an eluent containing only 3 10 4 mol/L sodium carbonate (see Fig. 5-9), apart from tetrabutylammonium hydroxide and acetonitrile. Lowering the acetonitrile content in favor of sodium carbonate, the resolution between both signals will decrease drastically, although the peak shape of the iron(II) complex will be distinctly improved. 

Esterification of chlorophenoxy acids and of pentachlorophenol has been assessed using tetrabutylammonium hydroxide and methyl iodide in methanol, and has been shown to be as effective as the standard procedure using diazomethane (Hopper 1987). A further development has examined the application of methanol/-benzyl-trialkylammonium for simultaneous extraction and methylation of 2,4-dichlorophenoxyacetic acid in soil (Li et al. 1991) the quaternary ammonium hydroxide may, in this case, also play a significant role in releasing the "bound" analyte. 

Carbon-11 can also be inserted into an aromatic ring Methyl chloroformate has been converted into carbon-11 labelled oxalic acid in a three-step synthesis. The first step (equation 75) was done in a water-dichloromethane mixture using tetrabutylammonium hydroxide and CN" under phase transfer catalysis conditions. The conversion to the diethyl ester and to the oxalic acid were done in high yields in 0.5 and 0.25 minute, respectively, in a microwave cavity. 

When the synthesis was modified by adding ethylenediamine en)y diethylenetriamine dien) or triethylenetetramine trien) to the aqueous solution of tetrabutylammonium hydroxide and... 

Literature proposed CZE methods for phenols and derivatives using test mixtures based on aqueous buffered systems (phosphate-borate and borate " ), volatile electrolytes (ammonium hydrogencarbonate, diethylmalonic acid/dimethylamine in isopropanol and L-cysteic acid, 3-amino-1-propanesulfonic acid, aminomethanesulfonic acid, and diethylmalonic acid ), andnon-aqueous media (ammonium acetate in ACN/acetic acid in MeOH acetate, bromide, chloride, and malonate in ACN and diprotic acids/tetrabutylammonium hydroxide and maleate in MeOH ). 

A mixture of 6-methyl-5-nitrouracil, 2 moles methanolic 25%-tetrabutylammonium hydroxide, and dimethylformamide evaporated to a sirup, redissolved in dimethyl-formamide, benzyl chloride added at room temp., and stirred 1 hr. 3-benzyl-6-methyl-5-nitrouracil. Y 65%. F. e., also with aq. NaOH, s. H. U. Blank and J. J. Fox, J. Heterocyclic Chem. 7, 735 (1970). 

In eqn [13], pK corresponds to the titrant. The most common titrant solution for the titration of acids in non-aqueous solvents is tetrabutylammonium hydroxide, and stable commercial solutions use methyl or isopropyl alcohol as solvents. The addition of isopropyl alcohol to 7-butyl alcohol can be neglected because their relative permittivity values are not very different. Methanol addition causes larger variations in pKg, values. Thus, the use of titrants without or with low contents of methanol is strongly recommended. For application of eqn [13], pKt values of tetrabutylammonium hydroxide are 2.58 in isopropyl alcohol and 4.91 in 7-butyl alcohol. 

Fig. 3. Qeft) Separation of the diastraeomeric c-NAD and y-c-NAD by reversed phase HPLC. A C-18 Dynamax scout column (4.6 nun x 25 cm 8 micron packing Rainin Instrument Co., Woburn, MA) was used, with an eluent of 20 mM N 2F 4 pH adjusted to 6.0 using tetrabutylammonium hydroxide, and run at a flow rate of 1 ml/min.

Urine and serum samples were analyzed for olpadronate ([3-dimethylamino-l-hydroxypropylidine] bisphosphonate) level through extraction followed by derivati-zation with 9-fluorenylmethylchloroformate (FMOC). Separation was accomplished on a Cjg column (2 = 274 nm, ex 307 nm, em) using a 72.5/27.5 water (30 mM phosphate at pH 7 with 5 mM tetrabutylammonium hydroxide and 2 mM etidronate)/ acetonitrile mobile phase [1526]. Elution was complete in 6 min. A linear range of... 

Mix equal volumes of 0.001 M tetrabutylammonium hydroxide and sodium dodecyl sulphate to form salt A, which is cationic surfactant-selective. 

Tsai et al. (41) measured extracellular ascorbic acid of brain cortex or ventricular myocardium of anesthetized rats. They used an automatic continuous microdialysis system for collecting the perfusates and injecting the dialysates into the HPLC system. The mobile phase was a sodium acetate buffer with EDTA, tetrabutylammonium hydroxide, and 7.5% methanol, pH 4.75. HPLC comprised of a C18 column and an amperometric detector set to 600 mV versus Ag/AgCl electrode. 

A direct reaction between titanium alkoxides and tetraalkylammonium hydroxides brought quite interesting results. The addition of titanium isoprpoxide into aqueous solution of 15% tetramethylammonium hydroxide afforded an opaque colloidal solution. This opaque solution turned transparent within a few hoius, and a clear 1 mol/1 solution was obtained. The solution was basic with pH 13. The use of tetrabutylammonium hydroxide and tetrapropylammonium hydroxide also led to the same reaction (Ohya et al., 2002). The clear solution consisted of colloidal particles, which could be recognized by laser scattering, and the diameter of the particle was 15 nm, estimated by a dynamic laser scattering. 

Non-aqueous titration of methyl salicylate using lithium methoxide with quinaldine red as indicator or with tetrabutylammonium hydroxide and a potentiometric finish (see p. 794) has been applied by Allen. This method is applicable to the ester itself and to the liniment, but with ointments the end-point tends to be somewhat sluggish although probably adequate for routine laboratory control. 

---