Synthesis of Butyl Levulinate Based on α‐Angelica Lactone in the Presence of Easily Separable Heteropoly Acid Catalysts

Abstract

A series of choline (Ch)-exchanged heteropoly acids (HOCH CH N(CH ) ) H P W O [abbreviated as Ch H P W O , 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 H P W O 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 H P W O 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. Ch H P W O 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 H P W O could be successfully reused five times without significant loss of activity.

Angelica Lactones: From Biomass‐Derived Platform Chemicals to Value‐Added Products

“…Next, acid‐catalyzed addition of the alcohol is followed by ring opening of protonated intermediate 8 , and elimination of an alcohol molecule affords the desired alkyl levulinate product. The same group has also reported the use of heteropolyacid catalysts to promote the conversion of α‐AL into butyl levulinate …”

“…The same group has also reported the use of heteropolyacid catalysts to promote the conversion of a-AL into butyl levulinate. [33] 3.1.2. Hydrogenation/hydrodeoxygenationo fangelica lactones andtheir derivatives for the production of fuel and additives…”

Highly Efficient Synthesis of Alkyl Levulinates from α-Angelica Lactone, Catalyzed with Lewis Acidic Trifloaluminate Ionic Liquids Supported on Carbon Nanotubes

“…In all cases, after n-hexane was evaporated from the organic phase, n-butyl levulinate was obtained with high purity (>99%) and high isolated yield (99%). The structure and purity were confirmed using 1 H, 13 The reaction started with 5 mmol of each reagent, and the catalyst has been demonstrated to remain active for six consecutive runs (Figure 1). With every addition, the catalyst concentration was decreased, which is the probable cause of lower yields achieved in the last three runs even if the longer reaction times were applied.…”

“…La(III), Bi(III) triflates, sulphuric acid, ethanol, n-butanol (n-BuOH), 2-ethyl-1-hexanol and 2-methyl-1propanol were purchased from Sigma-Aldrich; MWCNTs were supplied from CheapTubes™. 1 H NMR spectra of LAEs were recorded using Agilent 400-MR, at the following operating frequencies: 1 H 399.89 MHz, 13 C 150.90 MHz. NMR spectra of ionic liquids were recorded using Bruker AVANCE 400, at the following operating frequencies: 1 H 399.78 MHz, 13 C 100.53 MHz.…”

“…1 H NMR spectra of LAEs were recorded using Agilent 400-MR, at the following operating frequencies: 1 H 399.89 MHz, 13 C 150.90 MHz. NMR spectra of ionic liquids were recorded using Bruker AVANCE 400, at the following operating frequencies: 1 H 399.78 MHz, 13 C 100.53 MHz. Chemical shifts are reported as parts per million in reference to tetramethylsilane (TMS).…”