Issue 22, 2023

Room-temperature tandem conversion of cyclic alkenes into 1,2-diols using molecular oxygen and β-MnO2 heterogeneous catalyst

Abstract

In the cyclic alkene epoxidation reactions using molecular oxygen as oxidant, aldehyde is generally added as co-oxidant to assist transition metal catalyst to activate the oxygen molecule, oxidizing cyclic alkene and producing the corresponding epoxide; however, the added aldehyde would be converted into byproduct carboxylic acid. Herein, we report the room-temperature tandem conversion of cyclic alkenes into 1,2-diols through the application of byproduct carboxylic acid as a catalyst for epoxide hydration reaction, realizing effective utilization of the byproduct and saving energy consumption. Four kinds of nanosized MnO2 specimens, including α-, β-, δ-, and γ-MnO2, were hydrothermally synthesized and applied as heterogeneous catalysts for the room-temperature tandem conversion of cyclohexene into 1,2-cyclohexanediol using molecular oxygen as oxidant and isobutyraldehyde as co-oxidant. The characterization results demonstrated that the obtained β-MnO2 sample had the maximum Mn4+/Mn3+ ratio of 1.42 and the minimum Oads/OLatt ratio of 0.34, consistent with its least oxygen vacancies evidenced by EPR measurement. Accordingly, the β-MnO2 sample revealed the quickest alkene epoxidation reaction rate and could achieve a 99.2% cyclohexene conversion within 1 h, and meanwhile, a 73.6% 1,2-cycloheanediol yield could be attained within 24 h. A plausible mechanism for the tandem conversion of cyclohexene into 1,2-cyclohexanediol over the β-MnO2 heterogeneous catalyst was proposed and further verified by quenching experiments and DFT calculations. Furthermore, the synthesized β-MnO2 catalyst sample could be reused more than ten times, and meanwhile, the tandem conversion way could be expanded to most of the cyclic alkene substrates, which demonstrated that the β-MnO2 catalyst was an active and stable heterogeneous catalyst for tandem conversion of cyclic alkenes into 1,2-diols.

Graphical abstract: Room-temperature tandem conversion of cyclic alkenes into 1,2-diols using molecular oxygen and β-MnO2 heterogeneous catalyst

Supplementary files

Article information

Article type
Paper
Submitted
02 Aug 2023
Accepted
09 Oct 2023
First published
10 Oct 2023

Green Chem., 2023,25, 9262-9271

Room-temperature tandem conversion of cyclic alkenes into 1,2-diols using molecular oxygen and β-MnO2 heterogeneous catalyst

S. Su, G. Lv, X. Zou, J. Wang, C. Zhou, Y. Chen, J. Shen, Y. Shen and Z. Liu, Green Chem., 2023, 25, 9262 DOI: 10.1039/D3GC02863A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements