Tetra-n -butylammonium chloride

Tetra-n-butylammonium chloride [1112-67-0] M 277.9, m 15.7". Crystd from acetone by addition of diethyl ether. Very hygroscopic and forms crystals with 34H2O. 

A final observation consistent with rate-determining cycli-zation is that the reaction rate is relatively insensitive to added electrolyte. Addition of 0.5 equivalents of tetra-n-butylammonium chloride or tetra-n-butylammonium azide to chloroform solutions of... 

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. 

Oxiranes undergo ring opening with trialkylsilyl chlorides to yield trialkylsilyl chloroethyl ethers [51]. The reaction has been shown to be catalysed by tetra-n-butylammonium chloride, although most studies have used triphenylphosphine as the catalyst. Substituted oxiranes are cleaved by haloalkanes to yield the corresponding l-ch oro-2-aIkoxy-2-substituted alkanes [52] (see Section 9.3). 

The reaction of sodium azide with N-aryl chloroimines, obtained from benzanilides and thionyl chloride, to form 1,5-disubstituted tetrazoles is catalysed by tetra-n-butyl-ammonium bromide (Scheme 5.26, Table 5.40) [18] in variable yields, but generally <85%. 5-Butyl-2,3-diphenyltetrazolium salts have also been used as catalysts [18, 19]. 1,5-Disubstituted tetrazoles are also obtained from a one-pot sequential reaction of carbodimides with sodium azide and an aroyl chloride in the presence of tetra-n-butylammonium chloride [20]. 5-Chlorotetrazoles are obtained from the catalysed reaction of aryldichloroisocyanides with sodium azide (Scheme 5.26) [21],... 

It has been reported that the conversion of carbonyl compounds into their oximes, which is normally acid-catalysed, can be effected under basic conditions in the presence of tetra-n-butylammonium chloride [37]. Good yields are generally obtained with most aldehydes and ketones with the exception of benzophenone. 

Unsaturated nitriles have been obtained from the SN. reaction of 3-chloroalk-1 -enes [22] using tetra-n-butylammonium iodide as the catalyst. Under the basic reaction conditions, isomerism occurs such that not only is the 1-cyanoalk-2-ene obtained, but also the conjugated 1-cyanoalk-l-ene. Surprisingly, when tetra-n-butylammonium chloride is used, direct SN displacement of the chloro group occurs, followed by isomerization, to give the 3-cyanoalk-2-ene. 

P-Phenylation of a,p-unsaturated ketones in high yield (75-85%), using the palladium catalysed reaction with phenylmercury(II) chloride or tetraphenyltin(IV), is promoted by tetra-n-butylammonium chloride [37],... 

Optimum yields of (3-vinyl-y-butyrolactols from the Pd(II) promoted reaction of vinyl triflates with Z-but-2-en-l,4-diol (Scheme 6.33) are attained when tetra-n-butylammonium chloride is added (47]. The lactol is conveniently oxidized to the lactone with celite-supported silver carbonate. The corresponding arylbutyrolactols are obtained in high yield (70-80%) from an analogous reaction of iodoarenes with the enediol. The yields of 2-alkenyl-2,5-dihydrofurans, resulting from the Pd(0) catalysed reaction of cyclic alkynylcarbonates with acrylic esters via tandem C-C and C-0 bond forming reactions, are enhanced by the presence of tetra-n-butyl-ammonium fluoride (e.g. Scheme 6.33) (48]. 

Compared with primary and secondary amines, tertiary amines are virtually unreac-tive towards carbenes and it has been demonstrated that they behave as phase-transfer catalysts for the generation of dichlorocarbene from chloroform. For example, tri-n-butylamine and its hydrochloride salt have the same catalytic effect as tetra-n-butylammonium chloride in the generation of dichlorocarbene and its subsequent insertion into the C=C bond of cyclohexene [20]. However, tertiary amines are generally insufficiently basic to deprotonate chloroform and the presence of sodium hydroxide is normally required. The initial reaction of the tertiary amine with chloroform, therefore, appears to be the formation of the A -ylid. This species does not partition between the two phases and cannot be responsible for the insertion reaction of the carbene in the C=C bond. Instead, it has been proposed that it acts as a lipophilic base for the deprotonation of chloroform (Scheme 7.26) to form a dichloromethylammonium ion-pair, which transfers into the organic phase where it decomposes to produce the carbene [21]. 

Benzyltriethylammonium chloride is frequently used as the phase-transfer catalyst, but it has been noted that the catalyst itself produces phenylacetic acid under the carbonylation conditions [6]. Trimethyl(phenyl)ammonium chloride and tetra-n-butylammonium chloride both catalyse the reaction efficiently. 

Triazolines have been aromatized in good yield under two-phase conditions using potassium permanganate in the presence of tetra-n-butylammonium chloride [49]. 

It has been claimed that chromium trioxide reacts with tetra-n-butylammonium chloride in water to produce tetra-n-butylammonium chromate, n-Bu4N+HCr04- [7], whereas benzyltriethylammonium dichromate is obtained from the closely analogous reaction of benzyltriethylammonium chloride with chromium trioxide in dilute hydrochloric acid [8]. 

Methoxyphenol (6.21 g) and tetra-n-butylammonium chloride hydrate (100 mg) were dissolved in dichloromethane (40 mL) in a 100 mL three-necked flask. 

PDI = 1.5) when carried out at —15°C [Katayama et al., 2001]. The reaction converts to LCP with PDI <1.2 when the polymerization temperature is lowered to —78°C or tetra-n-butylammonium chloride is added. Mild nucleophiles such as esters, ethers, sulfides, and pyr-idines are also useful to decelerate the reaction rate, narrow PDI, and yield LCP [Aoshima and Higashimura, 1989 Cho et al., 1990 Kishimoto et al., 1989]. 

In a similar fashion, the absorption of DSCG was improved by the addition of tetraalkylammonium salts. The fat solubility of the salt correlated with its ability to improve penetration. That is, the rank order of lipophilicity and the ability to improve the permeation of DSCG is choline chloride, tetraethylammonium chloride, tetra-n-butylammonium chloride. 

An automatic titrator is used in conjunction with a glass indicating electrode and a calomel reference electrode. The saturated KC1 electrolyte in the calomel electrode must be replaced by 1M tetra-n-butylammonium chloride (TnBACl) in water which is available as polarographic grade material (Southwestern Analytical Chemicals, Austin, TX). The electrode is stored in the TnBACl solution when not in use. A nitrogen flow of 50 ml min-1 is maintained over the solution in the titration vessel. 

One of the oldest techniques for overcoming these problems is the use of biphasic water/organic solvent systems using phase-transfer methods. In 1951, Jarrouse found that the reaction of water-soluble sodium cyanide with water-insoluble, but organic solvent-soluble 1-chlorooctane is dramatically enhanced by adding a catalytic amount of tetra-n-butylammonium chloride [878], This technique was further developed by Makosza et al. [879], Starks et al. [880], and others, and has become known as liquid-liquid phase-transfer catalysis (PTC) for reviews, see references [656-658, 879-882], The mechanism of this method is shown in Fig. 5-18 for the nucleophilic displacement reaction of a haloalkane with sodium cyanide in the presence of a quaternary ammonium chloride as FT catalyst. 

Phenylation of enones. This reaction can be conducted with C HsHgCl or Sn(C6Hs)4 and with PdCl2 and tetra-n-butylammonium chloride (TBA CI ) as catalysts in acidic CH2CI2-H2O. The active catalyst is probably TBA PdClj". An acidic medium is essential. ... 

Dichlorocarbene addition to aikenes. Dehmiow and LisseP have examined the reaction variables in the generation of dichlorocarbene by PTC. Optimal conditions include use of 4 molar excess each of CHCI3 and 50% aqueous NaOH, 1 mole % of catalyst, and efficient stirring. The reaction should be conducted initially at 0-5°, then at 20° for 1-2 hours, and finally at 50° for 2-4 hours. Most quaternary ammonium salts are suitable as catalysts the anions should be chloride or hydrogen sulfate. From the point of cost/efficiency, the most useful are benzyltriethylammonium chloride, tetra-n-butylammonium chloride, Aliquat 336, and tri-n-propylamine. The reaction rate is strongly dependent on the nucleophilicity of the alkene. 

This oxidation reagent is obtained by addition of tetra-n-butylammonium chloride to an aqueous solution of chromium trioxide. It oxidizes primary and secondary alcohols to carbonyl compounds in generally good yield. The main advantages are the homogeneous conditions and the requirement for only a small excess of oxidant. ... 

Scheme 8, Reagents i, chloroform, NaOH (50%), tetra-n-butylammonium chloride ii, methanol, sodium carbonate iii, toluene, reflux iv, LiAlH4, AICI3, tetrahydrofuran v, H2, 10% Pd/C, sodium acetate, ethanol.

Various additives have been added to PFSA membranes to either replace the water or to retain the water at higher temperatures. Nafion has been swollen with phosphoric acid and a conductivity of 0.05 S/cm has been achieved at 150°C. Unfortimately, the anode fails after a short period of time in these membranes so no successful FC tests have been run. 1-Butyl,3-methyl imidazolium triflate and tetrafluoroborate have also been used to swell Nafion giving a conductivity of 0.1 S/cm at 180°C. Nafion has also been swollen with heterocycle solutions, imidazole, and imidazolium salts in trifluoroacetate and trifluoro methane sulfonate solution, although the reported conductivities are more modest, 10 S/cm at 100°C. Acetic acid and tetra-n-butylammonium chloride solutions of the heteropoly acid (HPA), 12-phosphotungstic acid (PTA), have all been used with Nafion giving improved FC performance at 110°C and 120°C, respectively, vs. the undoped PFSA. ... 

Phase-Transfer Catalysis. Since the efficiency of the reaction requires that bisphenoi A be used in the form of water-soluble phenolate anions, while phosgene must be dissolved in a chemically inert and hence water-insoluble solvent, the desired reaction would have to depend on the diffusion rate of the two reactants to the interface between the immiscible solvents. The area of the interface can be increased by vigorous stirring of the two-phase reaction mixture, but a more efficient way to accelerate the process is to induce one of the reactants to migrate into a phase that is not particularly receptive to it. In this example, the sodium phenolate ions are in equilibrium with a phase-transfer catalyst such as tetra-n-butylammonium chloride, and while one of the products of the equilibrium (sodium chloride) remains in the aqueous phase, the other products of the equilibrium (the BPA anion-tetra-rc-butylammonium cation ion pairs) are of sufficiently covalent character to migrate into the nonaqueous phase where they encounter phosgene and the reaction takes place. 

Dichlorophenol containing a little tetra n-butylammonium chloride was treated with chlorine at 70C to give 2,4,6-trichloro-phenol. 

Prop-1-enyl)-2,3-dihydrobenzofuran has been synthesised in 70% yield from 2-iodophenol, vinylcyclopropane, tetra-n-butylammonium chloride and a little palladium(ll) acetate in dimethylformamide containing potassium acetate by reaction at SOX for 72 hours (ref.58). 

Alkyl iodides alkyl chlorides. These conversions can be effected in high yield by ion-pair extractions. The alkyl chloride (0.1 mole), sodium iodide (0.11 mole), and tetra-n-butylammonium iodide (0.014 mole) are refluxed in chlorobenzene—water for 90 min. Yields of the alkyl iodide are 90% or more. The reverse reaction can be effected as follows The alkyl iodide (0.1 mole) and anhydrous tetra-n-butylammonium chloride (0.108 mole) are heated under reduced pressure at a temperature below 140. The alkyl chloride is formed in over 90% yield in a few minutes. 

Silica-supported catalyst systems comprised of tetra-n-butylammonium chloride and PdCl2 with C0CI2/CUCI2 promotors (melting points ca. 60 °C) have also been used for hydrodechlorination of chloroform with hydrogen at 90-150 °C [60]. As one reason for the observed catalyst deactivation the authors propose the thermal ionic liquid decomposition ([Bu4N]Cl, Td = 170 °C), which seems very likely since tetraalkyl ammonium salts are known to undergo dealkylation under the applied conditions [61,62]. 

Epoxide Cleavage. Epoxides open by reaction with TMSCl in the presence of Triphenylphosphine or tetra-n-butylammonium chloride to afford O-protected vicinal chlorohydrins (eq 27). ... 

Halobenziodoxoles l-Chloro-l,2-benziodoxol-3-(l//)-one (88, 2X = O, Y = Cl) can be easily prepared by direct chlorination of 2-iodobenzoic acid [233], or by the oxidation of 2-iodobenzoic acid with sodium chlorite (NaC102) in aqueous hydrochloric acid media [267]. The original X-ray single-crystal analysis of l-chloro-l,2-benziodoxol-3-(l//)-one reported in 1976 was relatively imprecise [268]. More recently, Koser and coworkers reported the single-crystal X-ray structure of a 1 1 complex of l-chloro-1,2-benziodoxol-3-(l/7)-one and tetra-n-butylammonium chloride [262], The primary bond distances at iodine in this compound are consistent with expectations for a X -iodane. In particular, the I—Cl and I—O bond distances of 2.454 and 2.145 A, respectively, are greater than the sums of the appropriate covalent radii and reflect the... 

Furthermore, addition of tetra-n-butylammonium chloride improved the selectivity in certain reactions, such as in the arylation of allylic alcohols.Finally, an appropriate selection of tetraalkylammonium salt-based systems can be used to control the product pattern in certain Heck reactions (Scheme 34). In these examples, phase transfer agents have been shown to be an alternative to silver salts in directing the outcome of the reaction.t t " ... 

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