skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Selective molecular oxygen oxidation of thioethers to sulfoxides catalyzed by Ce(IV)

Abstract

The selective molecular oxygen conversion of thioethers to sulfoxides is catalyzed by ceric ammonium nitrate (CAN) with rate enhancements that are at least three orders of magnitude greater than the uncatalyzed autoxidation of thioethers. Mechanistic studies (including spectroscopic, labeling, uptake, mixed reactant, and autocatalysis studies) of this novel reaction reveal that both atoms of dioxygen are incorporated into product sulfoxide, that a novel oxygen-driven Ce(IV)Ce(III) redox cycle gives rise to the catalysis, and that molecular oxygen efficiently traps a sulfur-centered radial cation of the thioether (produced by Ce(IV) oxidation of thioether) to yield the oxygenated radical cation R/sub 2/S/sup +/OO/sup ./, which, it is proposed, reoxidizes Ce(III) to Ce(IV). The zwitterionic R/sub 2/S/sup +/OO/sup -/ intermediate (persulfoxide) reacts with thioether to yield two sulfoxide product molecules.

Authors:
; ;
Publication Date:
Research Org.:
Monsanto Company, St. Louis, MI (USA)
OSTI Identifier:
7256215
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Am. Chem. Soc.; (United States); Journal Volume: 110:1
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AMMONIUM COMPOUNDS; CATALYTIC EFFECTS; CERIUM COMPOUNDS; NITRATES; SULFIDES; OXIDATION; SULFOXIDES; CHEMICAL PREPARATION; CATALYSIS; CATALYSTS; CHEMICAL REACTION KINETICS; EXPERIMENTAL DATA; LABELLING; OXYGEN; SPECTROSCOPY; CHALCOGENIDES; CHEMICAL REACTIONS; DATA; ELEMENTS; INFORMATION; KINETICS; NITROGEN COMPOUNDS; NONMETALS; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; OXYGEN COMPOUNDS; RARE EARTH COMPOUNDS; REACTION KINETICS; SULFUR COMPOUNDS; SYNTHESIS; 400201* - Chemical & Physicochemical Properties

Citation Formats

Riley, D.P., Smith, M.R., and Correa, P.E. Selective molecular oxygen oxidation of thioethers to sulfoxides catalyzed by Ce(IV). United States: N. p., 1988. Web. doi:10.1021/ja00209a028.
Riley, D.P., Smith, M.R., & Correa, P.E. Selective molecular oxygen oxidation of thioethers to sulfoxides catalyzed by Ce(IV). United States. doi:10.1021/ja00209a028.
Riley, D.P., Smith, M.R., and Correa, P.E. 1988. "Selective molecular oxygen oxidation of thioethers to sulfoxides catalyzed by Ce(IV)". United States. doi:10.1021/ja00209a028.
@article{osti_7256215,
title = {Selective molecular oxygen oxidation of thioethers to sulfoxides catalyzed by Ce(IV)},
author = {Riley, D.P. and Smith, M.R. and Correa, P.E.},
abstractNote = {The selective molecular oxygen conversion of thioethers to sulfoxides is catalyzed by ceric ammonium nitrate (CAN) with rate enhancements that are at least three orders of magnitude greater than the uncatalyzed autoxidation of thioethers. Mechanistic studies (including spectroscopic, labeling, uptake, mixed reactant, and autocatalysis studies) of this novel reaction reveal that both atoms of dioxygen are incorporated into product sulfoxide, that a novel oxygen-driven Ce(IV)Ce(III) redox cycle gives rise to the catalysis, and that molecular oxygen efficiently traps a sulfur-centered radial cation of the thioether (produced by Ce(IV) oxidation of thioether) to yield the oxygenated radical cation R/sub 2/S/sup +/OO/sup ./, which, it is proposed, reoxidizes Ce(III) to Ce(IV). The zwitterionic R/sub 2/S/sup +/OO/sup -/ intermediate (persulfoxide) reacts with thioether to yield two sulfoxide product molecules.},
doi = {10.1021/ja00209a028},
journal = {J. Am. Chem. Soc.; (United States)},
number = ,
volume = 110:1,
place = {United States},
year = 1988,
month = 1
}
  • The ability to selectively convert a particular molecule via an oxidation utilizing the abundant and cheap oxidant oxygen often represents a desirable low-cost method for upgrading the value of a raw material. The goal of much of our research has been directed toward the utilization of oxygen as a cheap and selective oxidant. During our research into better methods of selectively oxidizing waste thioethers (e.g., Me{sub 2}S) to their more valuable sulfoxides, we discovered that thioethers are subject to a novel autoxidation process which under high oxygen concentrations, elevated temperatures, and polar solvents yields almost exclusively the sulfoxide product. Themore » mechanism of this unusual autoxidation involves an initial unfavorable electron transfer step, followed by triplet oxygen in high concentration trapping the resultant radical cation. Back donation of an electron from superoxide to the oxygenated radical cation yields a zwitterionic species whose chemistry is known to yield sulfoxide upon exposure to additional thioether. Given that the initial unfavorable electron-transfer step is rate-determining in this slow autoxidation reaction, we believed that the use of a suitable one-electron oxidant would possible be capable of catalyzing or initiating the desired oxygen oxidation of R{sub 2}S to sulfoxide. We have communicated our preliminary successful attempts to catalyze this reaction using Ce(IV), and in this paper we present additional examples and mechanistic studies of the novel Ce(IV) catalyzed molecular oxygen oxidation of thioethers to sulfoxides.« less
  • Complexes of the type Ru/sup II/X/sub 2/(MeSO)/sub 2 or 3/(PR/sub 3/) are excellent catalysts for the selective oxygen oxidation of thioethers to sulfoxides. The complex RuCl/sub 2/(Me/sub 2/SO)/sub 3/(PPh/sub 3/) is an example of such a catalyst, and its solution chemistry under simulated catalytic conditions reveals that only one detectable complex is present. This presumed catalytic complex has been isolated and characterized by /sup 1/H, /sup 13/C, and /sup 31/P NMR and by an x-ray structure determination to be the chlorotri-/mu/-chlorotris(dimethyl sulfoxide)bis(triphenylphosphine)diruthenium, 2. Single crystals of 2 are monoclinic with space group P/sub 2/sub 1//c/ with a = 16.662(3)/angstrom/, bmore » = 16.576(3)/angstrom/, c = 19.282(3)/angstrom/, and /beta/ = 98.86(1)/degree/. Both Ru centers are coordinated in a distorted octahedral fashion having three /mu/-bridged chlorine atoms shared between them. Ru/sub 1/ possesses three terminal ligands, one chloride, one triphenylphosphine and a dimethyl sulfoxide. Ru/sub 2/ is terminally bonded to two Me/sub 2/SO centers and one triphenylphosphine. The /mu/-bridged chlorine atoms are bonded in an asymmetric fashion due to the differing trans-influences of the Cl/sup /minus//, (CH/sub 3/)/sub 2/SO and PPh/sub 3/ ligands bonded to the metal centers. Ru-/mu/Cl distances range from 2.436(2)/angstrom/ to 2.490(2)/angstrom/, and Ru-S distances from 2.205(2)/angstrom/ to 2.269(2)/angstrom/.« less
  • Dialkyl and diaryl sulfoxides are oxidized to sulfones by hydrogen peroxide using methyltrioxorhenium as the catalyst. The reaction rate is negligible without a catalyst. The kinetics study was performed in CH{sub 3}CN-H{sub 2}O (4:1 v/v) at 298 K with [H{sup +}] at 0.1 M, conditions which make the equilibration between MTO and its peroxo complexes more rapid than the oxygen-transfer step. The values for the rate constant for the oxygen-transfer step lie in the range 0.1--3 L mol{sup {minus}1} s{sup {minus}1}. The rate constants were significantly smaller than for the oxidation of sulfides to sulfoxides. A study of ring-substituted diarylmore » sulfoxides yielded kinetics results that are consistent with nucleophilic attack of the sulfur atom on the peroxide oxygen group since {rho} = {minus}0.65. The results cited refer to the reactions of the diperoxo from the catalyst, MeRe(O)({eta}{sup 2}-O{sub 2}){sub 2}H{sub 2}O. The monoperoxo complex showed no measurable reactivity toward sulfoxides, in contrast with the situation for nearly every other substrate. That unusual finding suggests a hydrogen-bonded interaction between the substrate and the diperoxorhenium compound which cannot exist with the monoperoxo compound.« less
  • The kinetics of oxidation of cyclohexene by molecular oxygen on a lamellar compound of graphite (LCG) with MoCl/sub 5/ has been studied in chlorobenzene solution at atmospheric pressure in the temperature range 50-75/sup 0/C. A reaction scheme has been proposed, according to which the LCG-MoCl/sub 5/ takes part in the degenerate branching stage as well as in decomposition of cyclohexenyl hydroperoxide and in chain termination. The kinetic equations obtained based on this proposed mechanism describe the experimental data quite well.
  • The selective carbon-carbon bond cleavage of 1,2-diols in the presence of an iron-porphyrin complex, molecular oxygen, and 1-benzyl-3-carbamoyl-1,4-dihydropyridine is reported. The C-C bonds of aryl-substituted ethane-1,2-diols were cleaved exclusively to aldehydes or ketones as the oxidation products at room temperature. The reaction rates were influenced by the steric hindrance of the substituents both in the catalysts and diols, but no differences in the reactivities were observed between the two stereo isomers (meso and dl) of diols. A kinetic analysis of this bond cleavage reaction is consistent with the reaction mechanism consisting of the initial binding of diol on the activemore » catalyst forming an intermediate complex and its subsequent breakdown in the rate-determining step of the catalytic cycle. The initial binding step is favorable for electron-deficient diols and is influenced by steric hindrance, whereas the rate-determining bond cleavage step is accelerated by electron-rich diols and unaffected by the steric effect. The mechanism of this diol cleavage reaction is discussed on the basis of these observations.« less