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Free for 24 hours - Kinetics and mechanism of acetalisation of furfural to furfural diethyl acetal with Ni–Al layered double hydroxides containing Lewis acid sites

Posted on 14. March, 2018.

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Acetalisation is a viable method to protect carbonyl functionalities in organic compounds and offers a potential synthetic strategy for synthesising derived chemicals. Furfural diethyl acetal is an important perfume material, which is usually obtained by acid catalysis in the acetalisation of furfural to furfural diethyl acetal using ethanol as a renewable solvent.

During the past few decades, the catalysts utilised in the synthesis of furfural diethyl acetal have undergone the transition from mineral acid (H2SO4 or HCl) to solid catalysts (with strong Brønsted acidity). 

Owing to their superiority in recyclability and separation, heterogeneous catalysts have been becoming more attractive in practice. As a potential heterogeneous catalyst, layered double hydroxide (LDH) precursors have been extensively studied in environmentally-friendly reactions as catalysts. However, LDH precursors are seldom studied in organic synthetic procedures as acid catalysts. Such limited employment of LDH precursors as acid catalysts is possibly related to the absence of the necessary suitable acid sites [18–22]. If suitable acidic sites can be established in a suitable synthetic environment, LDH precursors should gain wider recognition as catalysts. 

Noting the wide application of Ni–Al layered double hydroxides (Ni–Al-LDHs), here we have innovatively prepared Ni–Al-LDHs under different pH conditions by the hexamethylenetetramine (HMT) hydrolysis reaction and evaluated their catalytic performance towards the synthesis of furfural diethyl acetal from furfural and ethanol. Finally, the reaction kinetics and other parameters were determined, leading to a realistic Lewis acid catalytic reaction mechanism. These basic studies may provide useful guidelines for further design of LDH catalysts and future studies on the acetalisation reaction.

Download the full article, free of charge, using this link: http://tinyurl.com/y92deysk for 24 hours only. The link expires at 4:00 pm (GMT) on 15th March 2018. 

Authors: Yali Dua, YaLin Fengb, ChunLei Zoub, Xu Wub and Wei Huanga*
aKey Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi, P.R. China
bCollege of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P.R. China
*E-mail: huangwei@tyut.edu.cn

Keywords: Ni–Al layered double hydroxide, Lewis acid site, furfural diethyl acetal, mechanism of acetalisation

Published in Progress in Reaction Kinetics and Mechanism, Volume 43, Number 1, 2018, pp. 21-29.

DOI: https://doi.org/10.3184/146867817X15066861009956

Image:  Synthesis of furfural diethyl acetal from furfural and ethanol.