Tetra-«-butylammonium

Compton R G, Spaokman R A, Wellington R G, Green M L H and Turner J 1992 A Cgg modified eleotrode. Eleotroehemioal formation of tetra-butylammonium salts of Cgg anions J. Electroanal. Chem. Interfacial... 

The method of choice for determining carboxyl groups in lignin is based on potentiometric titration in the presence of an internal standard, /)-hydroxybenzoic acid, using tetra- -butylammonium hydroxide as a titrant (42). The carboxyl contents of different lignins are shown in Table 6. In general, the carboxyl content of lignin increases upon oxidation. 

Catalyst Cation. The logarithms of extraction constants for symmetrical tetra- -alkylammonium salts (log rise by ca 0.54 per added C atom. Although absolute numerical values for extraction coefficients are vastly different in various solvents and for various anions, this relation holds as a first approximation for most solvent—water combinations tested and for many anions. It is important to note, however, that the lipophilicity of phenyl and benzyl groups carrying ammonium salts is much lower than the number of C atoms might suggest. Benzyl is extracted between / -propyl and -butyl. The extraction constants of tetra- -butylammonium salts are about 140 times larger than the constants for tetra- -propylammonium salts of the same anion in the same solvent—water system. 

Benzyltriethylammonium chloride [56-37-1] is the most widely used catalyst under strongly basic conditions. Methyltrioctylammonium chloride [5137-55-3] (Ahquat 336, Adogen 464) is probably the least expensive catalyst. Others of high activity and moderate price are tetra- -butylammonium chloride [1112-67-0] bromide [1643-19-2] hydrogen sulfate [32503-27-8], tetra- -butylphosphonium chloride [2304-30-5], and other phosphonium salts of a similar number of C atoms. Many other onium salts can also be utilized. 

Af HF, 0.1 MNaF, pH 5, THF, 25°, 2 days, 77% yield. In this substrate a mixture of products resulted from attempted cleavage of the t-bu-tyldimethylsilyl ether with tetra- -butylammonium fluoride, the reagent generally used. ... 

The fluoride anion has a pronounced catalytic effect on the aldol reaction between enol silyl ethers and carbonyl compounds [13] This reacbon proceeds at low temperature under the influence of catalytic amounts (5-10 mol %) of tetra-butylammonium fluoride, giving the aldol silyl ethers in high yields (equation 11). 

Reaction of the secondary silylnitronate 4 with acetaldehyde, catalyzed by anhydrous tetra-butylammonium fluoride, furnished only 20% of the desired product 5 as a 56 44 (R, S )j (R, R ) mixture. With tetrabutylammonium fluoride trihydrate as base the yield increased to 89% while the diastereoselectivity remained low16. 

Interessante Trimere liefert 2-Mcthyl-propanal. Bei der Beschickung der beiden Elek-trodenraume einer geteilten Zelle (Platin-Elektroden) mit 2-Methyl-propanal/Tetra-butylammonium-hexafluorophosphat entsteht an der Anode 2,4,6-Triisopropyl-1,3,5-trioxan (95% d. Th.) und an der Kathode 4-Hydroxy-5,5-dimethyl-2,6-diisopropyl-l,3-dioxan (90% d. Th.), jeweils in sehr hoher Ausbeute1 ... 

The interface between an aqueous solution containing a strongly hydrophilic electrolyte, e.g., LiCl, and a nitrobenzene solution containing a strongly hydrophobic salt, e.g., tetra-butylammonium tetraphenylborate (TBATPhB), schematically shown below ... 

FIG. 9 Upper potential values, a.sds lower potential values, b.sds of the first oscillation at the interface between phases o and wl of the octanol membrane (A), interfacial potential of a two-phase octanol-water system in the absence of SDS, c.sds (B) and those in the presence of 10 mM SDS (in the case of inorganic electrolyte, 1 mM), d.sds (C)- TMACI tetramethylammonium chloride TEACI tetraethylammonium chloride TPACI tetrapropylammonium chloride TBACI tetra-butylammonium chloride AcNa sodium acetate PrNa sodium propionate, BuNa sodium n-butyrate VaNa sodium w-valerate. (Ref 27.)... 

Figure 9 (C) and (B) show interfacial potential of the two-phase system in the presence of SDS and inorganic and organic electrolytes in the aqueous phase and tetra-butylammonium chloride in the octanol phase, iiD,sDS> and interfacial potential in the absence of SDS, iJc.sDS respectively. The potential of the octanol phase was measured in reference to the aqueous phase. The effects of electrolytes on c,sds and i D,sDS were the same for the most part as those on a,sds and iJs.sDS respectively, and differences between Eqsds and Tsdsds were essentially as much as those between a,sds and...

The complete elimination of functional groups is often an undesirable side reaction in organic synthesis, but on the other hand it is a possibility for the recycling of environmentally harmful compounds, for example phenols and haloarenes such as polychlorinated dibenzodioxins (PCDDs or dioxins ). For example, aryl chlorides can be effectively dechlorinated with Pd(0) NPs in tetra-butylammonium salts with almost quantitative conversions also after 19 runs (entry H, Table 1.4) [96]. On the other hand, a C-0 bond cleavage reaction also seems suitable for the fragmentation of sugar-based biomass such as cellulose or cello-biose in that way, sugar monomers and bioalcohol can be derived from renewable resources (entry F, Table 1.4) [164]. 

Reaction of pyrrolopyridines 241 with tosylmethyl isocyanide (TosMIC) in the presence of a phase transfer catalyst tetra- -butylammonium iodide (TBAI) provides the tricyclic pyrimidopyrrolopyrimidine derivatives 242 (Equation 30) <20000L3253, 2004JOC4974, 2005JOC4879>. 

Very interesting transformations were reported in terminal alkynes RC=CH (R = alkyl, aryl, alkoxy, carboxylate, etc.). They react readily with nitric acid, in aqueous nitromethane (1 1) and in the presence of catalytic amounts of tetra-butylammonium tetrachloroaurate to give 3,5-disubstituted isoxazoles 15 in 35% to 50% isolable yield (92). The reaction might proceed via a nitrile oxide intermediate by attack of an electrophile (AuCh or H+) and of a nucleophile (N02 ) on the triple bond to form a vinyl nitrite, which is converted to a nitrile oxide by the action of gold(III) or of nitric acid (Scheme 1.8). 

CP/MAS- C-NMR identification of occluded tetrapropyl- and tetra-butylammonium ions in ZSM-5 and ZSM-11 zeolites The CP/MAS 13c-NMR spectrum of tetrepropylammonium (TPA) ions occluded in ZSM-5 zeolite and that of tetrabutylammonium (TBA) ions in ZSM-ll zeolite are reported in Figure 8. They show clearly that the occluded entities are chemically intact in the zeolitic channels. 

Acyl chlorides are converted in good yield into symmetrical carboxylic acid anhydrides upon treatment with dilute aqueous sodium hydroxide at -I0°C in the presence of a tetra- -butylammonium salt [76, 77]. Yields are considerably lower when Aliquat is used. In a similar manner, chloroformates and ethyl oxalyl chloride are converted into carbonic hemi-ester anhydrides. 

It is also possible to effect the cyclization of alkoxycarbonylglycinamides to yield hydantoins (Scheme 5.10) using an excess of tetra-/ -butylammonium fluoride, which acts as a basic catalyst [42]. The procedure has been extended to a range of N-alkoxycarbonylpeptides. 

EXPLOSIVELY UNSTABLE compounds [4, 6-9]. It has been reported that solid benzyltriethylammonium permanganate is considerably less stable than the tetra-butylammonium salt both compounds are sensitive to impact, but the benzyl-ammonium salt may explode violently at room temperature [4] and it is more readily handled by absorption on alumina [4]. 

The Birch-type electrochemical reduction (460) (461) has been shown to proceed through the action of tetra-butylammonium amalgam in the steps (460)— (462)— (463), in contrast to a direct electron transfer from the electrode to the aromatics (Scheme 158) [548]. The preparative-scale reduction of anisole, of l,2,3,4-tetrahydro-6-methoxynaphthalene, and several aromatic steroids is performed in an H20-Bu4N0H-(Hg) system. The unique aspect of the reduction is the proposed formation of a tetrabutylammo-nium amalgam complex, BU4N (Hg) (465)... 

In practice, reduction of 35 (—2.43 V vs SCE) in the presence of 3,5-dimethylphenol as a proton donor, tetra- -butylammonium hexafluorophos-phate as the supporting electrolyte, and DMF as the solvent, led to the y-hydroxy ester 40 and lactone 41 [22]. No sign of any material resulting from cyclization onto the alkene was detected. It was concluded that radical cyclization does not occur in this instance, and that the homogeneous electron transfer rate exceeds that of a 5-exo-trig radical cyclization, thereby implying the operation of either a radical anion or carbanion cyclization pathway. 

Solvents, base electrolytes As solvents for the organic phase, liquids with relative dielectric constants above 10 are suitable. So far, nitrobenzene has been used almost exclusively, but dichloroethane can also be employed [7]. Tetra-butylammonium tetraphenylborate [ 1 ] is the most commonly used base... 

For this section, yield of the head-to-head product is relevant. In DMF with 0.1 M of tetra-butylammonium perchlorate, electrolysis of acetophenone at the potential of the first one-electron wave produces this dimer in 30% yield. This is in accord with the earlier-mentioned prediction that all the three directions of this dimerization are equally probable. If lithium perchlorate is the supporting electrolyte in the same solution, the head-to-head dimer yield rises to 70% (GuTtyai et al. 1987a). Hence, head-to-head coupling becomes the main route of dimerization. 

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