The reductive cleavage of the C-O bonds of aryl ethers has great potential in organic synthesis. Although several catalysts that can promote the reductive cleavage of aryl ethers have been reported, all such systems require the use of an external reductant, e.g., hydrosilane or hydrogen. Here, we report the development of a new nickel-based catalytic system that can cleave the C-O bonds of ethe...

A headspace solid-phase microextraction (HS-SPME), in conjunction with gas chromatography-flame ionization detection for use in the determination of six frequently used glycol ethers at the microg/l level is described. A 75 microm Carboxenpolydimethylsiloxane fiber was used to extract the analytes from an aqueous solution. Experimental HS-SPME parameters such as extraction temperature, extracti...

A novel approach to protecting jet fuel against the effects of water contamination is predicated upon the coupling of the rapid hydrolysis reactions of lipophilic cyclic geminal ethers, with the concomitant production of a hydrophilic acyclic hydroxyester with de-icing properties (Fuel Dehydrating Icing Inhibitors - FDII). To this end, a kinetic appraisal of the hydrolysis reactions of represen...

Hydrophobic long-chain alkyl ethers of Sephadex have been synthesized and tested for use in liquid chromatography. With columns prepared in such polar solvents as methanol, reversed-phase systems are obtained where compounds separate in order of decreasing polarity. In such non-polar solvents as heptane, straight-phase systems are formed, and separations occur in order of increasing polarity. T...

We have found that bromo(triphenylphosphine)copper(I), an air-stable and soluble copper(I) complex, can be used as a catalyst in the synthesis of diaryl ethers. Using this catalyst, we have synthesized diaryl ethers from electron-rich aryl bromides and electron-rich phenols in the presence of cesium carbonate, in 17–24 h, in NMP. We also found that electron-deficient aryl bromides couple with p...

Mechanistic studies of the enolization of 2-methylcyclohexanone mediated by lithium hexamethyldisilazide (LiHMDS; TMS(2)NLi) solvated by hindered dialkyl ethers (ROR') are described. Rate studies using in situ IR spectroscopy show that enolizations in the presence of i-Pr(2)O, 2,2,5,5-tetramethyltetrahydrofuran, and cineole proceed via dimer-based transition structures [(TMS(2)NLi)(2)(ROR')(ket...

Key words palladium catalysis - silyl enol ethers α,β-unsaturated carbonyls

Cyclohexanone and its derivatives are very important chemicals, which are currently produced mainly by oxidation of cyclohexane or alkylcyclohexane, hydrogenation of phenols, and alkylation of cyclohexanone. Here we report that bromide salt-modified Pd/C in H2O/CH2Cl2 can efficiently catalyse the transformation of aromatic ethers, which can be derived from biomass, to cyclohexanone and its deri...

The reaction of 1,4-diols with dimethyl carbonate in the presence of a base led to selective and high-yielding syntheses of related five-membered cyclic ethers. This synthetic pathway has the potential for a wide range of applications. Distinctive cyclic ethers and industrially relevant compounds were synthesized in quantitative yield. The reaction mechanism for the cyclization was investigated...

The structures of lithium 4-fluoro-, 4-chloro, 2and 4-bromo-, 4-(trifluoromethy1)-, 4-methoxy-, 2-methyl-, 2-ethyl-, 2-n-propyl-, 2-isopropyl-, 2-tert-butyl-, 2-(methoxymethyl), 3,5-dimethyl-, 3,5-dimethyl-4-methoxy-, 4-chloro-3,5-dimethyI-, 3,5-diethyl-, and 3,5-dimethoxyphenolates in solution in weakly polar, aprotic solvents such as pyridine, tetrahydrofuran, dimethoxyethane, 1,3-dioxolane, ...