Critical Review of the Various Reaction Mechanisms for Glycerol Etherification

• Published in: Catalysts Vol. 12; no. 11; p. 1487
• Main Authors: Palanychamy, Prakas, Lim, Steven, Yap, Yeow Hong, Leong, Loong Kong
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2022
• Subjects: Acids; Additives; alcohol solvent; Benzyl alcohol; Biodiesel fuels; Biofuels; Butanol; Butylene; Catalysts; Chemical reactions; Cosmetics; Energy industry; Ethers; Fossil fuels; Glycerin; Glycerol; glycerol etherification; Isomers; mechanism; Molybdenum; olefin solvent; Personal grooming; Reaction mechanisms; Reaction products; Renewable resources; Selectivity; solvent free; Solvents
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal12111487

This review provides in-depth coverage of numerous mechanisms available for the etherification process of glycerol, including alcohol solvent, olefin solvent and solvent-free routes along with products that are formed at various stages of the reaction. Mono tert-butyl glycerol ether (MTBG), di tert-butyl glycerol ether (DTBG), and tri tert-butyl glycerol ether (TTBG) are the three general ether compounds obtained through tert-butyl alcohol (TBA) etherification. Glycerol etherification with n-butanol results in the formation of glycerol ether products that are linked to the substituted butyl groups. These products include two mono-butyl glycerol ethers, two di-butyl glycerol ethers and a tri-butyl glycerol ether. Two mono-benzyl glycerol ether isomers, two di-benzyl glycerol ether isomers and tri-benzyl glycerol ether are the most reported results when benzyl alcohol is used as a solvent in the etherification reaction. The etherification of glycerol with 1-butene involves a series of equilibrium reactions to produce mono-ethers, di-ethers, and tri-ethers, whereas the etherification of glycerol with isobutene is carried out via tert-butylation of glycerol, yielding similar glycerol ether products when TBA is used as a solvent. As the by-product may be easily removed, the solvent-free glycerol etherification approach may have several advantages over the other conventional methods. Therefore, further studies on base-catalyzed glycerol etherification that employs a solvent-free reaction route may reveal a method for improving the conversion, selectivity, and yield of reaction products. This review study is crucial in improving knowledge of numerous mechanisms and how they relate to the effectiveness of the product’s catalytic process.