[HSO3-b-mim]CF3SO3催化乙酰丙酸自缩合反应体系分析

Analysis of self-condensation of levulinic acid catalyzed by [HSO3-b-mim]CF3SO3

乙酰丙酸(LA)羟醛自缩合是制备液体生物燃料过程中重要的碳链增长反应。为克服液体酸存在的腐蚀和环境污染等缺点,弥补固体酸存在的活性温度较高和选择性较低等不足,以酸性离子液体[HS03-b-mim]CF3S03为催化剂,催化LA自缩合反应。利用液相色谱-质谱技术确定了主要产物(C9~C15),并建立了LA自缩合反应网络。结果表明,分子量为214的C10产物具有2种结构:直链结构的(Z)-3-乙酰基-4-甲基-3-庚烯二酸和(E)-4-甲基-6-氧代-4-壬烯二酸,以及环状结构的3-(2-甲基-5-氧代-2-四氢呋喃基)-4-氧代戊酸和5-(2-甲基-5-氧代-2-四氢呋喃基)-4-氧代戊酸;分子量为196的C10产物为环状结构的5-((2-甲基-5-氧代-2-四氢呋喃基)甲基)呋喃-2(3H)-酮、5-甲基-4-(2-甲基-5-氧代-2-四氢呋喃基)呋喃-2(3H)-酮和(E)-4-甲基-5-(5-氧代-4,5-二氢-2-呋喃基)-4-戊烯酸。上述结果能够为LA自缩合反应的深入开展奠定基础。

Self-condensation of levulinic acid(LA) is an important reaction of carbon-chain growth for the preparation of liquid bio-fuel.In order to solve corrosion and pollution problems of liquid acids,and requirement of high activation temperature and poor selectivity of solid acids,acidic ionic liquid [HSO3-b-mim]CF3 SO3 was used to catalyze LA self-condensation.The main products(C9 to C15) were identified using high performance liquid chromatography-mass spectrometry(HPLC-MS) and a LA self-condensation reaction network was established.The results show that(1) C10 products with a molecular weight of 214 have two structures:linear compounds of(Z)-3-acetyl-4-methyl-3-heptenedioic acid and(E)-4-methyl-6-oxo-4-decenedioic acid,and cyclic compound of 3-(2-methyl-5-oxo-2-tetrahydrofuranyl)-4-oxopentanoic acid and 5-(2-methyl-5)-oxo-2-etrahydrofuranyl-4-oxopentanoic acid;(2) the C10 products with a molecular weight of 196 are cyclic compounds of5-((2-methyl-5-oxo-2-tetrahydrofuranyl)methyl) furan-2(3 H)-one,5-methyl-4-(2-methyl-5-oxo-2-tetrahydrofuryl)furan-2(3 H)-one and(E)-4-methyl-5-(5-oxo-4,5-dihydro-2-furanyl)-4-pentenoic acid.This work can lay a foundation for further investigation of LA self-condensation.