Coupling of alcohols to ethers: The dominance of the surface S{sub N}2 reaction pathway
- Lehigh Univ., Bethlehem, PA (United States)
Coupling of alcohols to ethers, important high value oxygenates, proceeds on acid catalysts via general pathways that uniquely control product composition, oxygen retention, chirality inversion, and kinetics. The dominant pathway is the S{sub N}2 reaction with competition of the alcohols for the surface acid sites. This is exemplified by formation of methyl(ethyl) isobutylether (M(E)IBE) from methanol(ethanol)/isobutanol mixtures, retention of oxygen ({sup 18}O) of the heavier alcohol, and optimum rate as a function of concentration of either reactant alcohol. The S{sub N}2 pathway in the confinement of zeolite pores exhibits additional features of a near-100% selectivity to dimethylether (DME) in H-mordenite and a near-100% selectivity to chiral inversion in 2-pentanol/ethanol coupling to 2-ethoxypentane in HZSM-5. A minor reaction pathway entails olefin or carbenium intermediates, as exemplified by the formation of methyl tertiarybutyl ether (MTBE) from methanol/isobutanol mixtures with oxygen retention of the lighter alcohol. Calculations of transition state and molecular modeling of the oxonium-involving pathways dramatically demonstrate how the reaction path selects the products.
- OSTI ID:
- 468001
- Report Number(s):
- CONF-960652--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanistic studies of the pathways leading to ethers via coupling of alcohols
Isobutanol coupling with ethanol and methanol to ethers over sulfonated resin catalysts: Activities and selectivities