Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts

Yuen Wai Lui, Bun Chan, Matthew Y. Lui*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Dimethyl sulfide, a major byproduct of the Kraft pulping process, was used as an inexpensive and sustainable catalyst/co-reagent (methyl donor) for various methylations with dimethyl carbonate (as both reagent and solvent), which afforded excellent yields of O-methylated phenols and benzoic acids, and mono-C-methylated arylacetonitriles. Furthermore, these products could be isolated using a remarkably straightforward workup and purification procedure, realized by dimethyl sulfide‘s neutral and distillable nature and the absence of residual salts. The likely mechanisms of these methylations were elucidated using experimental and theoretical methods, which revealed that the key step involves the generation of a highly reactive trimethylsulfonium methylcarbonate intermediate. The phenol methylation process represents a rare example of a Williamson-type reaction that occurs without the addition of a Brønsted base.

Original languageEnglish
Article numbere202102538
JournalChemSusChem
Volume15
Issue number3
Early online date15 Dec 2021
DOIs
Publication statusPublished - 8 Feb 2022

Scopus Subject Areas

  • Energy(all)
  • Chemical Engineering(all)
  • Materials Science(all)
  • Environmental Chemistry

User-Defined Keywords

  • alkylation
  • dimethyl carbonate
  • green solvent
  • lignin
  • organocatalysis
  • Sulfides
  • Salts
  • Formates
  • Methylation

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