Reactivity of glycerol/acetone ketal (solketal) and glycerol/formaldehyde acetals toward acid-catalyzed hydrolysis

Journal of the Brazilian Chemical Society

Leonardo P. Ozorio¹  Rafael Pianzolli¹  Maria Beatriz S. Mota¹  Claudio J. A. Mota¹ 

[1] ,Universidade Federal do Rio de Janeiro Escola de Química Rio de Janeiro RJ ,Brazil

关键词: glycerol;    biodiesel;    hydrolysis;    solketal;    acetals;   

DOI  :  10.1590/S0103-50532012000500019

来源: SciELO

【 摘 要 】

The effect of temperature, molar ratio and catalyst loading on the acid-catalyzed hydrolysis of glycerol/acetone ketal (solketal) and glycerol/formaldehyde acetals was studied. The reactivity of the solketal was significantly higher than the glycerol/formaldehyde acetals. At 80 ºC, 5:1 water/ketal molar ratio and 3.0 mmol of catalyst loading (amberlyst-15) the hydrolysis of the solketal was almost complete, whereas the glycerol/formaldehyde acetals showed around 40% conversion. The higher reactivity of solketal toward hydrolysis is associated with the formation of a tertiary carbocation intermediate, whereas in the case of glycerol/formaldehyde acetals hydrolysis takes place through direct nucleophilic displacement. DFT theoretical calculations of the relative stability of the ketal and acetal isomers, having five and six-membered rings, explain the experimental distribution.

【 授权许可】

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