Synthesis of Butyl Levulinate Based on α‐Angelica Lactone in the Presence of Easily Separable Heteropoly Acid Catalysts. Issue 7 (9th February 2017)

• Record Type: Journal Article
• Authors: Yi, Xiaohu; Al‐Shaal, Mohammad G.; Ciptonugroho, Wirawan; Delidovich, Irina; Wang, Xiaohong; Palkovits, Regina
• Is Part Of: ChemSusChem. Volume 10:Issue 7(2017)
• Page Start: 1494
• Page End: 1500
• Publication Date: 2017-02-09
• Subjects: alkyl levulinates -- biomass -- equimolar reaction -- heteropoly acids -- temperature-dependent solubility; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201601882
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: A series of choline (Ch)‐exchanged heteropoly acids (HOCH2 CH2 N(CH3 )3 ) x H(6− x ) P2 W18 O62 [abbreviated as Ch x H(6− x ) P2 W18 O62, x =1–6] was synthesized and used as catalysts for the reaction of α‐angelica lactone (alpha‐AL) with n ‐butanol to form butyl levulinate (BL). The solubility of Ch x H(6− x ) P2 W18 O62 in the reaction mixture was temperature dependent: The catalysts were soluble under the reaction conditions and precipitated upon cooling of the reaction mixture. This facilitated recovery of the catalysts from the liquid phase. Importantly, an increase of the Ch content caused a decrease of the catalyst solubility. Catalytic activity of Ch x H(6− x ) P2 W18 O62 for the reaction with n ‐butanol appeared to be in good agreement with the concentration of Brønsted‐acidic sites. The results suggest that the reaction proceeded through formation of pseudo‐butyl levulinate as intermediate. Ch2 H4 P2 W18 O62 exhibited the best balance between catalytic activity and temperature‐dependent solubility. The yield of BL reached 79.4 % at full conversion of alpha‐AL at a moderate temperature of 75 °C in an open system. Ch x H(6− x ) P2 W18 O62 could be successfully reused five times without significant loss of activity. Abstract : Switchable solubility : A series of heteropoly acid compounds Ch x H(6− x ) P2 W18 O62 with temperature‐dependent solubility allows an efficient butyl levulinate formation from α‐angelica lactone and an alcohol under mild conditions, thus avoiding any byproducts. The catalyst is easily separable and can be reused five times without significant loss of activity.