One-Pot Tandem Catalytic Epoxidation—CO2 Insertion of Monounsaturated Methyl Oleate to the Corresponding Cyclic Organic Carbonate

Roberto Calmanti,Nicola Sargentoni,Alvise Perosa,Maurizio Selva

doi:10.3390/catal11121477

Roberto Calmanti, Nicola Sargentoni + Show 2 more

Open Access

https://doi.org/10.3390/catal11121477

Copy DOI

Abstract

Conversion of unsaturated fatty acids, FAMEs or triglycerides into the corresponding cyclic organic carbonates involves two reaction steps—double-bond epoxidation and CO2 insertion into the epoxide—that are generally conducted separately. We describe an assisted-tandem catalytic protocol able to carry out carbonation of unsaturated methyl oleate in one-pot without isolating the epoxide intermediate. Methyl oleate carbonate was obtained in 99% yield and high retention of cis-configuration starting from methyl oleate using hydrogen peroxide and CO2 as green reagents, in a biphasic system and in the presence of an ammonium tungstate ionic liquid catalyst with KBr as co-catalyst.

Highlights

Ever-increasing attention has been focused in recent decades on the synthesis of cyclic organic carbonates (COCs) from carbon dioxide
To explain the synergic tungstate-bromide effect, we propose that the active [WO4·CO2]2− adduct can either insert directly into the activated epoxide (i) or react by SN2 on the bromo-alkoxide (iii), thereby generating the same stereocontrolled intermediate (ii) as in path a of Scheme 6, which immediately ring-closes to yield the methyl oleate cis-carbonate (Scheme 7)
The procedure involves one-pot epoxidation of the double bond of methyl oleate followed by insertion of CO2, yielding selectively methyl oleate carbonate

Summary

Introduction

Ever-increasing attention has been focused in recent decades on the synthesis of cyclic organic carbonates (COCs) from carbon dioxide. Recent studies suggest that only less than 1% of CO2 generated from anthropogenic emissions can be effectively recycled into chemicals [1,2] and that other trapping strategies are needed to reduce excess CO2, the preparation of COCs via the catalytic activation of CO2 remains one of the most efficient strategies in green organic synthesis for its exploitation as a C1 building block and for its fixation into stable organic products and/or polymers [3] This is even truer when renewable bio-based feedstocks such as glycerol, carbohydrates, terpenes and vegetable oils (VOs) are used [4]. These compounds find applications as lubricants [7], plasticizers for PVC [8], and building blocks for the synthesis of non-isocyanate polyurethanes (NIPUs) [9]

Methods

Results

Conclusion