| A sustainable future for the chemical industry requires feedbacks based on the renewable rather than steadily depleting resources. Inability to effectively transform five or six-carbon carbohydrates into building blocks derived from the nature is the major barrier towards this challenging goal. Presently, most of the carbon sources are obtained from non-renewable fossils (petroleum, natural gas, and coal). Chemicals, such as ethanol, lactic acid,1,3-propanediol, and succinic acid. Lactic acid could be produced in large quantities through the fermentation of glucose. However, the fermentative processes usually coproduce large amount of waste water and waste solids, and also suffer from high energy cost in product isolation.We designed a type of new homogeneous reaction system, which could directly convert glucose to lactate. The new reaction system was designed to economically convert glucose to lactic acid environment-friendly. Hydrophobic ionic liquids were chosen as solvent that can promote the decomposition reaction of glucose, and the catalytic performance of the solid bases was evaluated. Both the reaction temperature, time, type of bases, and amount of bases can affect the yield of lactic acid. The evaluation of an unique characetistic of ionic liquids’separation and reusability shows the ionic liquids is the key for better reaction effect. The1H NMR spectra and HPLC-MS were used to identify the formation of the lactic acid and variations of ionic liquid. Water can be used as solvent to extract calcium lactate. This shows a great potential of hydrophobic ionic liquids in the solid bases catalyzed reaction that is limited by the weak solubility of solid bases in organic and water solution.Sucrose, starch, and celluloses are the most abundant renewable carbon sources, which are ideal feed stocks for lactic acid synthesis. Methyl lactate and lactic acid were synthesized by hydrolysis of starch and cellulose using SnCU catalyst. The use of ionic liquids as the solvent was the key factor for the successful hydrolysis. The influence of catalyst, type of ionic liquids, reaction temperature and time on the product yield were investigated. The results indicated that methyl lactate and lactic acid can be obtained via liquid phase transformation catalyzed by SnCl4in1,3-dimethylimidazolium methylsulfate ionic liquid at140℃for2h, the yield was54%for starch and15.1%for cellulose conversion. In the presence of SnCl4-DMIMMS, fructose was almost stoichiometrically converted to LAML (95%yield) at140℃, At the same reaction conditions,65%of LAML yield was achieved for glucose reaction over SnCl4-DMIMMS. The combinations of13-dialkylimidazolium salts (DAIMS) with metal halides could be good Lewis acid catalysts, which could access any "site" of the polysaccharide chain. The HNMR study shows that adding SnCl4into DMIMMS raised the electron density of the1,3-dimethylimidazolium ([DMIM]+) cation. The most possible way for [DMIM]+to interact with SnCl4is through Cl" ion, which bridges between Sn4+and [DMIM]+(Sn4+—Cl-[DMIM]+). The interaction explains why the combination of SnCl4.5H2O-DMIMMS forms the active catalyst. The high LAML yields in fructose reaction and the relatively low LAML yields in glucose reaction suggest that, before forming lactic acid, the glucose must be primarily converted to fructose through isomerization reaction over SnCl4-DMIMMS, and then through the succeeding "retro-aldol’" reaction to form lactic acid and methyl lactate.Sn(CH3SO3)2can replace SnCl4as catalyst which has an advantageous performance for not hydrolysis. |
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