Tetra-n-butylammonium hydroxide

Water samples showing contamination by phenols are best examined by extracting the phenol into an organic solvent tri-n-butyl phosphate is very suitable for this purpose. Photometric measurements can be carried out on the extract, and the requisite alkaline conditions are achieved by the addition of tetra-n-butylammonium hydroxide. 

Tetra-n-butylammonium hydroxide (0.1 M solution in methanol). Prepare an anion exchange column using an anion exchange resin such as Duolite A113 or Amberlite IRA-400, convert to the hydroxide form and after washing with water, pass 300-400 mL of methanol through the column to remove water (see Section 7.2). 

Prepare an alkaline solution of the phenol concentrate by placing 4.0 mL of a tri-n-butyl phosphate layer in a 5 mL graduated flask and then adding 1.0 mL of the tetra-n-butylammonium hydroxide do this for each of the four solutions. The reference solution consists of 4 mL of the organic layer (in which the phenol is undissociated) plus 1 mL of methanol. Measure the absorbance of each of the extracts from the four test solutions and plot a calibration curve. 

Determination of organic compounds. The application of photometric titrimetry to organic compounds may be exemplified by the titration of phenols. This can be carried out by working at the /max value (in the ultraviolet) for the phenol being determined (see Section 17.50). It has been shown that by titrating with tetra-n-butylammonium hydroxide and using propan-2-ol as solvent, it is possible to differentiate between substituted phenols.24... 

Valproic acid can be potentiometrically titrated with standardized 0.1 N tetra-n-butylammonium hydroxide in chlorobenzene using a modified glass-calomel electrode system, in which 1.0 M aqueous tetra-n-butylammonium chloride has been substituted for potassium chloride, and employing acetone as the sample solvent. 

Alkylation of the more acidic hydrazo [25] and triazene [26] systems proceeds readily under liquiddiquid two-phase conditions, using tetra-n-butylammonium hydroxide and benzyltriethylammonium chloride, respectively, as the catalysts (Tables 5.5 and 5.6). 

Tris(tetra-n-buty (ammonium) hydrogen pyrophosphate, 1(ihC4H,)4N]3HP207 (1). Mol. wt. 417.42. The salt is prepared by treatment of Na2H,P,07 (Stauffer) with an acidic ion-exchange resin and then with tetra-n-butylammonium hydroxide. 

Butyl derivatives make possible the resolution of compounds the methylation of which lead to the same derivatives [518]. They were prepared in an analogous manner, by injection of substrates with a 25% methanolic solution of tetra-n-butylammonium hydroxide into the injection port heated at 270°C. The analysis can be performed on 3% OV-17 at 220°C Fig. 5.31 illustrates an example of the separation of several barbiturates in the form of methyl and butyl derivatives. Mephobarbital and phenobarbital, which being methylated give rise to the same compound, could be resolved after their conversion into butyl derivatives in addition, the different retention times of the derivatives could be utilized for the identification of barbiturates. 

A series of variously substituted chloro-androstanes (17 examples), bromo-androstanes (14 examples), and amino-androstanes (29 examples) prepared from the corresponding alcohols and oximes has been described.65 It was noted during the course of this work that all ring A, B, or C oximes were reduced by lithium aluminium hydride to yield over 90% of the corresponding axial amine, except at C-3 where 65% of the equatorial amine was isolated. This is in line with the lithium aluminium hydride reduction of 5a-cholestan-3-one where the equatorial hydroxy-steroid predominates. The observation was also made that when 3/8-, 7/3-, and 16/3-tosy oxy-5a-androstanes are heated with tetra-n-butylammonium hydroxide in... 

The procedure described below was developed by Pobiner (1983) and consists of the nonaqueous potentiometric titration of lignin with tetra-n-butylammonium hydroxide in the presence of an internal standard, p-hydroxybenzoic acid. As is true also for conductometric titrations of lignin (see Chap. 7.7), phenolic hydroxyl and sulfonic acid groups may be coincidentally determined by this procedure. 

Tetra-n-butylammonium octamolybdate, [(C4Hq)4N]4Mo8026. Mol. wt. 2153.39. The amine salt is prepared in 80% yield by reaction of sodium molybdate, Na2Mo04 2H20 (Alfa), with a 40% solution of tetra-n-butylammonium hydroxide in a ciircfully controlled ratio (cf. Klemperer and Shum ). 

Table 6). Where the expense of tetra-n-butylammonium hydroxide is a consideration, or in cases where the product carboxylic acid is poorly soluble in ether (making extractive removal of tetra-n-butylammonium salts difficult), an alternative procedure employing sodium hydroxide in a mixture of water, methanol, and ferf-butyl alcohol can be used. The mechanism of the base-induced hydrolysis reaction is believed to involve initial rate-limiting intramolecular N- O acyl transfer, followed by rapid saponification of the resulting (3-amino ester. ... 

Electrochemical methods for the reduction of aromatic substrates utilizing ammonia and amines as solvents with lithium salts as electrolytes have been successful. Toluene was reduced to the 2,5-dihydro derivative in 95% yield in methylamine-lithium chloride if an undivided cell was used, while a 53 47 mixture of 3- and 4-methylcyclohexenes was formed in a divided cell.. Of greater interest, however, are attempts to achieve these reductions in aqueous media. In one experiment utilizing a two-phase mixture of substrate in aqueous tetra-n-butylammonium hydroxide and a mercury cathode, anisole was reduced on a preparative scale (15 g) to its 2,5-dihydro derivative in 80% yield. The optimal temperature for most reductions appeared to be 60 °C and under these conditions, even suspensions of high molecular weight substrates could be successfully reduced, e.g. steroid (226) afforded a >90% chemical yield of (227). Much higher coulombic yields were obtained when a small amount of THE was added to the mixture, however. 

Tin-capped clathrochelate cobalt(III) tris-dioximates were synthesized by a procedure similar to Reaction 1 in the presence of organic bases (amines or tetra-n-butylammonium hydroxide) ... 

The blue species formed from heptasulphur imide, S7NH, in basic media has been isolated as the tetra-n-butylammonium salt and characterized as the NS4 anion.100101 The addition of tetra-n-butylammonium hydroxide to a solution of S7NH in diethyl ether at —78 °C produced a yellow-green precipitate which turned purple-blue after 3 days at room temperature. The precipitate was shown to be a mixture of orthorhombic cyclo-Sg and a blue solid of composition Bu"N(S4N). Since solution of the blue solid in HMPA or THF gave an identical visible spectrum to that of S7NH in HMPA, the following equilibria were proposed ... 

Preparation, The reagent can be prepared by neutralization of a 10% aqueous solution of tetra-n-butylammonium hydroxide with 48 % hydrofluoric acid, concentration under reduced pressure, drying by azeotropic distillation under reduced pressure using 1 1 benzene-acetonitrile, and final drying at 30° and 0.5 mm. for 20 hr. For another preparation see Fowler et al.2... 

Butylation Tetra-n-butylammonium hydroxide xanthines78, theophyl-... 

In order to obtain better gas chromatographic properties for the quite polar xanthine de-rivatives, Kowblansky et al. introduced flash heater butylation with tetra-n-butylammonium hydroxide, using the commercially availabe titrant, a 25 % methanol solution (about 1 M). 

The half wave potential (El/2 versus saturated calomel electrode) was determined as -0.98 to -1.03 volts in tetra-n-butylammonium hydroxide-phosphate-methanol buffer pH 2 . Since 1,2-Di-hydrotriamcinolone exhibits a half wave potential of ca -1.20 volts, this difference can be used to... 

On the other hand, Bonchio and coworkers suggested that [y-SiWio034(H20)2] was the active epoxidation catalyst [74]. The titration of 3a by tetra-n-butylammonium hydroxide (TBAOH) indicated that only two out of... 

Prepared by neutralization of tetra-n-butylammonium hydroxide with acetic acid.1,2... 

Mobile phase MeCN 25 mM orthophosphoric acid adjusted to pH 3.0 with 0.5 M tetra-n-butylammonium hydroxide 5 95 Column temperature 40 Flow rate 1 Iiijection volume 60 Detector F ex 280 em 445... 

Mobile phase MeCN MeOH water 1 M tetra-n-butylammonium hydroxide 3.5 3.5 91 2 containing 1.82 g Trizma base (Tris, tris(hydroxymethyl)aminomethane), pH adjusted to... 

This relatively safe azide has been prepared from hydrazoic acid and tetra-n-butylammonium hydroxide. It is conveniently prepared in quantitative yield from a mixture of tetra-n-butylammonium hydroxide and sodium azide con-... 

Each milliliter of O.IN tetra-n-butylammonium hydroxide is equivalent to 13.01 mg of fluorouracil (24). 

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