Vicinal glycol esters

Jn a potentially far reaching application for melt catalysis by the transition metals, we at Texaco have demonstrated the synthesis of a range of commodity chemicals and fuels directly from CO/H2 via the use of ruthenium-containing molten salt catalysis. Products include ethylene glycol, Ci-C4 alcohols, acetic acid, acetate esters, C2+ olefins and vicinal glycol esters. In its simplest form, this new class of melt catalyst comprises one or more ruthenium sources, e.g. ruthenium carbonyls, oxides, complexes, etc. dispersed in a low-melting (m.p. <150 C) quaternary phosphonium or ammonium salt (e.g. tetrabutylphos-phonium bromide). The key components are selected such that ... 

In an extension of our work on vicinal glycol esters described in Section 2.2., we have demonstrated an alternative process scheme for making ethylene-rich light olefins (69). The first stage is CO hydrogenation in the presence of an aliphatic carboxylic acid coreactant this yields the corresponding ethyl and propyl esters as a major product fraction (eq. 6 and 21). Pyrolysis of the intermediate ethyl and propyl esters would yield ethylene and propylene. 

In addition to the sulfonyloxy displacement reaction which may occur on halogenation with triphenyl phosphite complexes, the possibility of acetal migration (with appropriate structure) should not be overlooked. Thus, 1,2 5,6-di-O-isopropylidene-a-D-glucofuranose with triphenyl phosphite dibromide in benzene for 48 hours afforded " (presumably) 6-bromo-6-deoxy-l,2 3,5-di-O-isopropylidene-a-D-glucofiiranose, which was hydrolyzed to 6-bromo-6-deoxy-D-glucose in 10% overall yield. In some compounds, steric factors may prevent the introduction of halogen. With vicinal glycols and triphenyl phosphite methiodide, phosphonic ester formation occurs instead of halide production, but this reaction may be eliminated by use of triphenylphosphine in carbon tetrachloride. 

Lappaconitine (C32H44N2O8). This is the iV-acetylanthranilic ester of a tri-hydroxy-trimethoxy base, lappaconine (C23H37O6N). A recent chemical study located some of its functions on a presumed lycoctonine skeleton. The sequence in equation (2) uniquely located the vicinal glycol group if this skeleton were correct. A methoxy-group was placed on C-14 because of its exceptional ease of hydrolysis (presumably in the diketone). However, )3-methoxy elimination... 

Castanogenol (184), from the bark of Castanospermum australe, has been prepared by lithium aluminium hydride reduction of bayogenin methyl ester (18 5). The structure of entagenic acid (186) has been revised. The vicinal glycol... 

Methods have been reported for the ultrastructural localization of complex carbohydrates, including glycoproteins, in rat macrophages and monocytes, by employing the reactivity of vicinal glycols to periodate ions and the presence of carboxy- and sulphate ester-groups. ... 

A classical method for the vicinal hydroxylation of a double bond involves treatment with osmium tetroxide to give a cyclic ester, followed by reductive cleavage to the glycol ... 

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