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Title: Mechanistic studies of the pathways leading to ethers via coupling of alcohols

Abstract

The reaction mechanisms for the solid acid-catalyzed dehydrative coupling of methanol and ethanol with isobutanol and 2-pentanol to form ethers were examined by using isotope labelling and chiral inversion experiments. When the reactions were carried out it 110{degrees}C and 1 MPa with {sup 18}O-ethanol and {sup 16}O-isobutanol over the Amberlyst-35 resin catalyst, 95% of the major product ethyl isobutyl ether (EIBE) contained {sup 16}O, while 96% of the minor product ethyl tertiarybutyl ether (ETBE) contained {sup 18}O. Similar results were obtained with methanol and isobutanol over Nafion-H and Amberlyst-35 catalysts, with methyl isobutyl ether (MIBE) and methyl tertiarybutyl ether (MTBE) as the products. These results indicate that EIBE (MIBE) was produced by a surface-catalyzed S{sub N}2 reaction, while the ETBE (MTBE) product arose via a carbenium intermediate. The analogous reaction carried out over Nafion-H and HZSM-5 catalysts with chiral 2-pentanol verified the surface-mediated S{sub N}2 reaction, wherein chiral inversion of the product ether was observed relative to the S- and R-2-pentanol reactants.

Authors:
; ; ;  [1]
  1. Zettlemoyer Center for Surface Studies, Bethlehem, PA (United States)
Publication Date:
OSTI Identifier:
433265
Report Number(s):
CONF-950402-
Journal ID: ACFPAI; ISSN 0569-3772; TRN: 97:000007-0028
Resource Type:
Journal Article
Resource Relation:
Journal Name: Preprints of Papers, American Chemical Society, Division of Fuel Chemistry; Journal Volume: 40; Journal Issue: 1; Conference: 209. American Chemical Society (ACS) national meeting, Anaheim, CA (United States), 2-6 Apr 1995; Other Information: PBD: 1995
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; ALCOHOLS; SYNTHESIS; ETHANOL; CONVERSION; ETHERS; METHANOL; ZEOLITES; CATALYTIC EFFECTS; CATALYSTS; FUEL ADDITIVES; 2-METHYLPROPANOL; PENTANOLS; OXYGEN 18; OXYGEN 16; TRACER TECHNIQUES

Citation Formats

Sun, Qun, Lietti, L., Herman, R.G., and Klier, K. Mechanistic studies of the pathways leading to ethers via coupling of alcohols. United States: N. p., 1995. Web.
Sun, Qun, Lietti, L., Herman, R.G., & Klier, K. Mechanistic studies of the pathways leading to ethers via coupling of alcohols. United States.
Sun, Qun, Lietti, L., Herman, R.G., and Klier, K. Sun . "Mechanistic studies of the pathways leading to ethers via coupling of alcohols". United States. doi:.
@article{osti_433265,
title = {Mechanistic studies of the pathways leading to ethers via coupling of alcohols},
author = {Sun, Qun and Lietti, L. and Herman, R.G. and Klier, K.},
abstractNote = {The reaction mechanisms for the solid acid-catalyzed dehydrative coupling of methanol and ethanol with isobutanol and 2-pentanol to form ethers were examined by using isotope labelling and chiral inversion experiments. When the reactions were carried out it 110{degrees}C and 1 MPa with {sup 18}O-ethanol and {sup 16}O-isobutanol over the Amberlyst-35 resin catalyst, 95% of the major product ethyl isobutyl ether (EIBE) contained {sup 16}O, while 96% of the minor product ethyl tertiarybutyl ether (ETBE) contained {sup 18}O. Similar results were obtained with methanol and isobutanol over Nafion-H and Amberlyst-35 catalysts, with methyl isobutyl ether (MIBE) and methyl tertiarybutyl ether (MTBE) as the products. These results indicate that EIBE (MIBE) was produced by a surface-catalyzed S{sub N}2 reaction, while the ETBE (MTBE) product arose via a carbenium intermediate. The analogous reaction carried out over Nafion-H and HZSM-5 catalysts with chiral 2-pentanol verified the surface-mediated S{sub N}2 reaction, wherein chiral inversion of the product ether was observed relative to the S- and R-2-pentanol reactants.},
doi = {},
journal = {Preprints of Papers, American Chemical Society, Division of Fuel Chemistry},
number = 1,
volume = 40,
place = {United States},
year = {Sun Dec 31 00:00:00 EST 1995},
month = {Sun Dec 31 00:00:00 EST 1995}
}
  • The reaction mechanisms for the solid acid-catalyzed dehydrative coupling of methanol and ethanol with isobutanol and 2-pentanol to form ethers were examined by using isotope labelling and chiral inversion experiments. When the reactions were carried out at 110{degrees}C and 1 MPa with Et{sup 18}OH and {sup 16}O-isobutanol over Amberlyst-35, 95% of the major product ethyl isobutyl ether (EIBE) contained {sup 16}O, while 96% of the minor product ethyl tertiarybutyl ether (ETBE) contained {sup 18}O. Similar results were obtained with methanol and isobutanol over Nafion-H and Amberlyst-35 catalysts, with MIBE and MTBE as the products. These results indicate that EIBE (MIBE)more » was produced by a surface-catalyzed S{sub N}2 reaction, while the ETBE (MTBE) product arose via a carbenium intermediate. The analogous reactions carried out over Nafion-H and H-ZSM-5 catalysts with chiral 2-pentanol verified the surface-mediated S{sub N}2 reaction, where in chiral inversion of the product ether was observed relative to the S- and R-2-pentanol reactants. In addition, a remarkable shape selectivity with chiral inversion was observed over the H-ZSM-5 zeolite to selectively form 2-ethoxypentane but not 3-ethoxypentane.« less
  • The utility of the telluroxide for olefin synthesis, a reaction which previously appeared to be of little value is described. Treatment of sec-alkylphenyltellurium dibromides, except for the cyclohexyl system, with aqueous NaOH at room temperature affords olefins, allylic alcohols, and/or allylic ethers in high yields presumably via the formation of sec-alkyl phenyl telluroxides and their facile telluroxide elimination. As to the formation of linear olefins, more preference for elimination toward the less substituted carbon was observed than the selenoxide and sulfoxide eliminations. In the cyclododecyl case only trans-cyclododecene was formed as an olefin componenet in a sharp constrast to themore » selenoxide elimination that affords a 1:1 mixture of cis and trans isomers. On the contrary, in the n-alkyl and cyclohexyl cases the corresponding telluroxides are stable compounds that afford similar elimination products including vinylic ethers only by neat pyrolysis at temperatures above 200/sup 0/C.« less
  • The rate constants for the reaction of SO/sub 4//sup -/. in aqueous solution with undeuterated and deuterated alcohols (and with some ethers) were determined by a competition method which utilizes the reaction of SO/sub 4//sup -/. with 1,3,5-trimethoxybenzene (TMB) to yield TMB/sup +/. (lambda/sub max/580 nm, epsilon 5700 M/sup -1/ cm/sup 1/). The rate constant was redetermined by pulse irradiating, with 2.8-MeV electrons, argon-saturated aqueous solutions at pH 7-8 containing 1 mM K/sub 2/S/sub 2/O/sub 8/ and 0.01 to 0.1 mM TMB and monitoring the buildup of TMB/sup +/. at 580 nm. k(SO/sub 4//sup -/. + TMB) was found tomore » be (2.4 +- 0.5) x 10/sup 9/ M/sup -1/ s/sup -1/.« less
  • A steady-state tracing kinetic study of the oxidative coupling of methane reaction at 800[degrees]C over Li[sup +]-doped TiO[sub 2] catalyst was performed. In particular, the carbon and oxygen reaction pathways which lead to the formation of CO[sub 2] have been probed using [sup 13]CH[sub 4] and [sup 18]O[sub 2] isotope gases under reaction conditions. The results obtained indicate that there is practically no reversibly adsorbed CH[sub 4] on the catalyst surface, while there is a very small reservoir of carbon-containing intermediate species which eventually lead to CO[sub 2](0.1 [mu]mol/g). A large reservoir of oxygen species, participating in the formation ofmore » CO[sub 2] (at least 12.0 [mu]mol/g), was detected, while subsurface lattice oxygen species also participate in the oxygen reaction pathway to form CO[sub 2]. In addition, large amounts of inactive carbonaceous species (17.0 [mu]mol/g) accumulate on the catalyst surface after 1 h on stream. These species do not participate in the reaction route to form CO[sub 2] (spectator species). 23 refs., 7 figs.« less