ZrOCl2催化琼脂糖制备5-羟甲基糠醛和乙酰丙酸

以琼脂糖为原料，分别采用CuCl₂、NiCl₂、MnCl₂、MgCl₂、FeCl₃、AlCl₃、ZrOCl₂、SnCl₄为催化剂催化转化制备5-羟甲基糠醛（5-HMF）和乙酰丙酸（LA），筛选适用于琼脂糖转化的优选催化剂，并对制备条件如溶剂含水量、催化剂用量、反应温度以及反应时间等影响因素进行了考察。研究结果表明：以50mg琼脂糖为原料，ZrOCl₂为催化剂，二甲基亚砜（DMSO）为反应溶剂，在1 mL DMSO/H₂O（体积比为8:2）混合溶剂中，ZrOCl₂用量为琼脂糖中单糖物质的量的10%，140℃下反应60 min，5-羟甲基糠醛（5-HMF）的得率为26.9%，乙酰丙酸（LA）的得率为24.7%。对制备机理分析表明：反应过程中琼脂糖首先水解为醛型单糖，然后在催化剂作用下醛型单糖异构化再脱水转化为5-HMF，部分5-HMF在酸的作用下进一步转化为LA。

Catalytic Synthesis of 5-Hydroxymethylfurfural and Levulinic Acid from Agarose with ZrOCl2 as Catalyst

Agarose was used as the starting material, and CuCl₂, NiCl₂, MnCl₂, MgCl₂, FeCl₃, AlCl₃, ZrOCl₂ and SnCl₄ were respectively used as catalysts to convert agarose into 5-hydroxymethylfurfural(5-HMF) and levulinic acid(LA). Preferred catalysts were screened out for the conversion of agarose. The effects of reaction parameters such as water content, catalyst loading, reaction temperature and reaction time on the reaction were investigated in detail. The results demonstrated that when 50 mg of agarose was used as the feedstock with ZrOCl₂ as the catalyst and DMSO as the solvent, 5-HMF yield of 26.9% and LA yield of 24.7% could be achieved in 1 mL DMSO/H₂O mixed solvent with a volume ratio of 8:2 and ZrOCl₂ loading of 10% to the amount of substance of monosaccharide in agarose at 140℃ for 60 min. Mechanism analyses indicated that agarose was hydrolyzed into aldose, which underwent subsequent isomerization and dehydration to produce 5-HMF. 5-HMF could be further converted into LA catalyzed by acid catalyst.