Tetraethylammonium formate

Tetracyanoethylene, A 143 Tetraethylammonium bisulfate, A057 Tetraethylammonium chloride, A053 Tetraethylammonium formate, AQ.24 Tetraethylammonium hydroxide, AO56 Tetraethylthiuram disulfide, AS76... 

The development of a new synthesis of 1-hydroxyindoles 131, via a lead-promoted intramolecular reductive cyclization of the o-nitrobenzyl ketones (or aldehydes) 132 in the presence of tetraethylammonium formate (TEAF), offers a new useful route to this interesting class of compounds <03JOC9865>. 

In contrast, reaction of (1) with tetra-n-buiylammonium formate (see also Tetraethylammonium formate, I, 1137 1138) under the same conditions gave the inverted formate (2b) and thccyclopentene(3) ina ratioof 3 1. Thegreater tendency for substitution at carbon by formate ion relative to acetate ion may be owing to smaller size or to decreased basicity. 

The exact nature of the zeolite is determined by the reaction conditions, the silica to alumina ratio and the base used. For example zeolite /3, a class of zeolites with relatively large pores, in the range of 0.7 nm, of which mordenite is an example, are usually made using tetraethylammonium hydroxide as the base. This acts as a template for the formation of 12-membered ring apertures (Figure 4.3). 

In a similar manner, the diffusion of hexane into dichloromethane solutions containing mixtures of the alkylammonium salts of bromide and the olefinic acceptors o-CA and TCNE result in the formation of brown-red crystals [23]. X-ray analysis reveals the (1 1) complex of bromide with o-CA, in which the anion is located over the center of the C - C bond of the acceptor moiety (Fig. 15b) and Br - C contacts are shortened by as much as 0.6 A relative to the sum of van der Waals radii (Table 3). In bromide complexes with TCNE, the location of the anion relative to the acceptor is variable. In fact, a 2 1 complex [(Br )2,TCNE] is isolated in which both anions reside over the olefinic bond when the tetraethylammonium salt of bromide is used. In comparison, if the tetrapropyl- or tetrabutylammonium salts of the same anion are employed, the (1 1) complexes [Br ,TCNE] are formed in which the bromide donors are shifted toward the cyano substituents (Fig. 15a). In both cases however, the short intermolecular separations that are characteris-... 

It is well known that the surrounding solvent environment plays a crucial role in a chemical reaction. For example, the formation of tetraethylammonium iodide has been studied in many nonpolar and polar solvents. It is found that the rate of the reaction is quite sensitive to the solvent. From the least polar (hexane) to the most polar (nitrobenzene) solvent, the rate constant increases by 2700 times [1]. The polar transition state of this reaction is stabilized in a high dielectric constant medium. Since the... 

The application of phase-transfer catalysis to the Williamson synthesis of ethers has been exploited widely and is far superior to any classical method for the synthesis of aliphatic ethers. Probably the first example of the use of a quaternary ammonium salt to promote a nucleophilic substitution reaction is the formation of a benzyl ether using a stoichiometric amount of tetraethylammonium hydroxide [1]. Starks mentions the potential value of the quaternary ammonium catalyst for Williamson synthesis of ethers [2] and its versatility in the synthesis of methyl ethers and other alkyl ethers was soon established [3-5]. The procedure has considerable advantages over the classical Williamson synthesis both in reaction time and yields and is certainly more convenient than the use of diazomethane for the preparation of methyl ethers. Under liquidrliquid two-phase conditions, tertiary and secondary alcohols react less readily than do primary alcohols, and secondary alkyl halides tend to be ineffective. However, reactions which one might expect to be sterically inhibited are successful under phase-transfer catalytic conditions [e.g. 6]. Microwave irradiation and solidrliquid phase-transfer catalytic conditions reduce reaction times considerably [7]. 

Anodic oxidation of dialkyl ethers in methanol results in the formation of acetals [62]. Reaction is best carried out at a platinum, rather dian carbon, anode in methanol containing 10 % acetic acid with tetraethylammonium fhioroborate as... 

Initiation by hydroperoxides may be intensified by anions capable of reducing other compounds. The formation of radicals in the reaction between tert-butyl hydroperoxide and tetraethylammonium bromide was studied at 55° to 77°C. in the presence of oxygen with 1-propanol as solvent. The rate of initiation was measured by consumption of a-naph-thol that acted as acceptor of free radicals. Naphthol was determined colorimetrically. Two radicals were suggested to react with one molecule of a-naphthol. The rate of initiation was found to be (Figure 3). 

A new theoretical model will now be described aimed at attempting to provide a possible explanation for the deviations observed in Figure 3. The model assumes that significant porosity prevails in the hairless mouse stratum corneum when ethanol is present. Although it can be assumed, that at low ethanol concentrations (below 50%) ethanol fluidizes lipid bilayers, there is evidence, that ethanol at high concentration (over 50%) may induce significant pore formations in hairless mouse stratum corneum as measured by the substantial increase of tetraethylammonium bromide permeabilities (10). The permeability coefficient P of a solute across a membrane or stratum corneum under steady state conditions may be described by ... 

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