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Development of rapid and selective epoxidation of α-pinene using single-step addition of H₂O₂ in an organic solvent-free process

Lookup NU author(s): Mohamad Gunam Resul, Abdul Rehman, Ana Fernandez, Dr Valentine Eze, Professor Adam HarveyORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2021 The Royal Society of Chemistry. This study reports substantial improvement in the process for oxidising α-pinene, using environmentally friendly H2O2 at high atom economy (∼93%) and selectivity to α-pinene oxide (100%). The epoxidation of α-pinene with H2O2 was catalysed by tungsten-based polyoxometalates without any solvent. The variables in the screening parameters were temperatures (30-70 °C), oxidant amount (100-200 mol%), acid concentrations (0.02-0.09 M) and solvent types (i.e., 1,2-dichloroethane, toluene, p-cymene and acetonitrile). Screening the process parameters revealed that almost 100% selective epoxidation of α-pinene to α-pinene oxide was possible with negligible side product formation within a short reaction time (∼20 min), using process conditions of a 50 °C temperature in the absence of solvent and α-pinene/H2O2/catalyst molar ratio of 5 : 1 : 0.01. A kinetic investigation showed that the reaction was first-order for α-pinene and catalyst concentration, and a fractional order (∼0.5) for H2O2 concentration. The activation energy (Ea) for the epoxidation of α-pinene was ∼35 kJ mol-1. The advantages of the epoxidation reported here are that the reaction could be performed isothermally in an organic solvent-free environment to enhance the reaction rate, achieving nearly 100% selectivity to α-pinene oxide.

Publication metadata

Author(s): Mukhtar Gunam Resul MF, Rehman A, Lopez Fernandez AM, Eze VC, Harvey AP

Publication type: Article

Publication status: Published

Journal: RSC Advances

Year: 2021

Volume: 11

Issue: 52

Pages: 33027-33035

Online publication date: 07/10/2021

Acceptance date: 01/10/2021

Date deposited: 13/12/2021

ISSN (electronic): 2046-2069

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/d1ra05940h

DOI: 10.1039/d1ra05940h

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