稀酸氯盐体系转化竹浆制备5-氯甲基糠醛的研究

Conversion of Bamboo Pulp to 5-Chloromethylfurfural in a Diluted HCl-chloride System

5-氯甲基糠醛(CMF)是近年来受到广泛关注的生物质基平台化合物。传统CMF制备在浓盐酸体系中进行,浓盐酸的高腐蚀性对其放大生产带来了挑战。为解决此问题,构建了一种基于酸性CaCl_(2)溶液的反应系统,研究了反应条件、物料浓度等参数对竹浆在该体系中制备CMF的影响,研究结果表明:水相中饱和或者近饱和的氯离子可有效抑制CMF水解为HMF从而提高体系中CMF的稳定性,减少了酸性条件下不稳定中间产物HMF向腐殖质的转化;CaCl_(2)在体系中具有极佳的催化性能,取得了最高59.2%的CMF产率,1,1,2-三氯乙烷、1,3-二氯丙烷、1,2,3-三氯丙烷等较高沸点溶剂均具有取代萃取剂1,2-二氯乙烷(DCE)的潜力。实验进一步研究了竹浆原料的不同预处理条件对其制备的CMF产率的影响,结果表明:水解氯代反应较优工艺即竹浆初始质量浓度16 g/mL,8 g H_(2)O,1.33 mol/L HCl,5.33~6.66 mol/L CaCl_(2),25 mL DCE,反应温度130℃,反应时间1 h,此条件下CMF得率为59.2%。NaHSO_(3)或固体碱活性氧蒸者(CAOSA)处理所得竹浆更适于制备CMF。稀酸氯盐水相循环性能的实验结果表明:通过补充一定量的盐酸可使本体系具有循环使用能力。对竹浆制备CMF的反应进行15倍放大实验,取得了51.8%的CMF产率,CMF粗产品在DCE溶液中具有良好的稳定性,经过4~12 d存放没有明显变质。

5-Chloromethylfurfural(CMF)was a biobased platform compound that had received considerable attention in recent years.The traditional CMF preparation process required a concentrated hydrochloric acid system,and its high corrosivity remained as a challenge to its scale-up production.To solve this problem,a reaction system based on acidic CaCl_(2)solution was established,and the influence of reaction conditions,material concentration and other parameters on the preparation of CMF from bamboo biomass in this system was studied.The results showed that saturated or nearly saturated chloride ion in the water phase could effectively inhibit the hydrolysis of CMF to HMF,thereby improving the stability of CMF in the system,and thus reducing the conversion of unstable intermediate products(i.e.,HMF)to humins under acidic conditions.CaCl_(2)had excellent catalytic performance in the system,and the highest CMF yield of 59.2%was obtained.1,2-Trichloroethane,1,3-dichloropropane,1,2,3-trichloropropane and other solvents with higher boiling point had the potential to replace extractant of 1,2-dichloroethane(DCE).The effects of different pretreatment conditions on CMF yield of bamboo pulp were further studied,and the optimal hydrolysis chlorination conditions were:initial bamboo pulp mass concentration of 16 g/mL,8 g of H_(2)O,1.33 mol/L of HCl,5.33-6.66 mol/L of CaCl_(2),130℃,1 h and 25 mL of DCE.Under these conditions,the CMF yield was 59.2%,and bamboo pulp samples pretreated by NaHSO_(3)or Cooking with Active Oxygen and Solid Alkali(CAOSA)method were more better for CMF preparation than those of treated with traditional alkali methods.The acidic CaCl_(2)phase could be recycled and then reused after supplementing a certain amount of HCl.The conversion of bamboo pulp to CMF was scaled up by 15 times and provided the CMF yield of 51.8%.The CMF crude product had good stability in dichloroethane solution,and there was no significant deterioration after 4-12 days of storage.