Tetraalkylammonium carboxylates

Strecker-type reaction of TMS cyanide with chiral sulfinimines gives diastereoselective cyanations at the imine carbon, at —78 °C in DMF, using simple metal-free Lewis base catalysts such as tetraalkylammonium carboxylates.73... 

A new method for the size- and morphology-selective preparation of metal colloids using tetraalkylammonium carboxylates of the type NR4 R C02 (R = octyl, R = alkyl, aryl, H) both as the reducing agent and as the stabilizer [Eq. (4)] was reported by Reetz and Maase [42]. 

The reactions of alkyl sulfonates with sodium, potassium or tetraalkylammonium carboxylates generally proceed with inversion of configuration. In the case of f-alkyl sulfonates, however, a varied amount of elimination products is invariably formed. Of all metal carboxylates, cesium salts (Scheme 43) have proved vastly superior with respect to reactivity and the suppression of undesirable side reactions. ... 

Complexation of a/S-unsaturated acids and amides has been extensively studied/ In such cases, both diastereomers of a species involving coordination of both olefin and carboxylate group are observed, usually in comparable proportions. The extent of complexation is enhanced and the rate of exchange of free and bound substrate reduced when base is added, or a preformed tetraalkylammonium carboxylate is employed. This suggests that structures (62) and (63) best describe the complex. The spectra observed are almost identical to those derived from E-dehydroamino acid derivatives, implying that the latter have structure (64) in accord with labeling studies. ... 

This method is based on the generation of the tetraalkylammonium salt of pyrrolidorle, which acts as a base. The method is compatible with a large variety of carboxylic acids and alkylating agents. The method is effective for the preparation of macrolides. 

The addition of carbanions, generated electrochemically by reduction of the carbon-halogen bond, to carbon dioxide has been examined under a variety of experimental conditions. Direct electrosynthesis of carboxylic acids in a divided cell using an aprotic solvent and a tetraalkylammonium salt as electrolyte is most sue-... 

Tetraalkylammonium bromide was found to be a good catalyst for the conjugate addition of thiols to a,p-unsaturated nitriles, carboxylic esters, ketones, aldehydes, and nitro alkenes. The reactions proceeded rapidly and gave high yields of products (typically, 90%) (160). 

Other tetraalkylammonium salts are also used in electrochemical measurements they are tetraalkylammonium nitrates, picrates, carboxylates, sulfonates, etc. They can be prepared in the laboratory, by neutralizing the corresponding acid in water with ftjNOH just to the equivalence point, removing water, and then drying. If necessary, the products are recrystallized. Some tetraalkylammonium salts form hydrates and are difficult completely to dehydrate. For practical information, see, for example, Ref. [19]. 

The lanthanides form many compounds with organic ligands. Some of these compounds are water-soluble, others oil-soluble. Water-soluble compounds have been used extensively for rare-earth separation by ion exchange (qv), for example, complexes form with citric acid, ethylenediaminetetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEEDTA) (see Chelating AGENTS). The complex formation is pH-dependent. Oil-soluble compounds are used extensively in the industrial separation of rare earths by liquid—liquid extraction. The preferred extractants are carboxylic acids, organophosphorus acids and esters, and tetraalkylammonium salts. 

To 10 mmoles of potassium carboxylate were added in a Pyrex flask 10 mmol of n-octyl bromide and 1 mmol of tetraalkylammonium salt (Aliquat 336 or Bu4NBr). After shaking, the flask was introduced in the microwave oven (or in an oil bath for control experiments) for the indicated time. The temperature was measured by introducing a Quick digital thermometer in the sample just at the end of each irradiation. Organic products were recovered by a simple elution with 50 mL diethyl ether or methylene chloride and subsequent filtration over... 

Apart from the effect of pure inorganic salts, Pandya et al. (1993) studied two series of electrolytes, one with increasing anion size (carboxylates formate, acetate, propionate, butyrate, valerate, caproate, caprylate) and the other with increasing cation size (tetraalkylammonium ions methyl,... 

Ooi, T. Sugimoto, H. Doda, K. Maruoka, K. Esterification of carboxylic acids catalyzed by in situ generated tetraalkylammonium fluorides. Tetrahedron Lett. 2001, 42, 9245-9248. 

The most common and simplest cleavage of double bonds to carboxyls is achieved with potassium permanganate [555, 841, 843, 852, 860, 869, 874] or sodium permanganate 834] in aqueous solution (equation 113) or with tetraalkylammonium permanganate in organic solvents (equation 114) [845, 872, 899]. 

The reaction of potassium carboxylates with alkyl halides without the use of a solvent in the presence of catalytic amounts of a tetraalkylammonium salt proceeds smoothly to give the corresponding esters in good to excellent yields, except for cyclohexyl bromide where elimination mainly takes place. Alkylation of o- and p-hydroxybenzoic acid selectively takes place at the CO2K group. ... 

The heteropolyacids are very soluble in water. They can form sparingly soluble or insoluble salts with ions such as ammonium, cerium, cesium, potassium, silver, and such. The acids are often soluble in organic solvents, such as alcohols, ketones, carboxylic acids, and carboxylic esters. Long-chain tetraalkylammonium salts can also be soluble in organic solvents. In a sense, heteropolyacids are soluble versions of insoluble metal oxide catalysts. They can be used as catalysts both in solution and as solids. A catalyst that is soluble in water would be a solid if used alone or in a hydrocarbon medium. They can also be placed on insoluble supports. In the insoluble forms at least, they offer the advantages of easy separation and recovery for reuse. 

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