Acta Chim. Sinica ›› 2017, Vol. 75 ›› Issue (8): 788-793.DOI: 10.6023/A17050199 Previous Articles     Next Articles

Communication

酸性体系V催化木质素β-O-4模型物C-C键高选择性切断

刘新鑫, 严龙, 傅尧   

  1. 安徽省生物质洁净能源重点实验室 化学与材料科学学院 中国科学技术大学 230026
  • 收稿日期:2017-05-08 出版日期:2017-08-15 发布日期:2017-06-15
  • 通讯作者: 傅尧,E-mail:fuyao@ustc.edu.cn E-mail:fuyao@ustc.edu.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.21325208,21272050,21402181,21572212)、合肥物质科学技术中心方向项目培育基金(No.2014FXCX006)、中国科学院项目基金(Nos.KFJ-EW-STS-051,XDB20000000,YZ201563)、高等学校博士学科点科研专项基金(No.20123402130008)、中央高校基础研究经费(Nos.WK2060190025,WK2060190040)、安徽省科技攻关计划(No.1604a0702027)及教育部长江学者和创新团队发展计划资助.

Lignin C-C Bond's Cleavage by Vanadium Catalyzed with High Selectivity in Acid Environment

Liu Xinxin, Yan Long, Fu Yao   

  1. Anhui Province Key Laboratory of Biomass Clean Energy, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026
  • Received:2017-05-08 Online:2017-08-15 Published:2017-06-15
  • Contact: 10.6023/A17050199 E-mail:fuyao@ustc.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos.21325208,21272050,21402181,21572212),the Index Program Directive Foundation of Hefei Centre for Physical Science and Technology (No.2014FXCX006),the Science Foundation of the Chinese Academy of Sciences (Nos.KFJ-EW-STS-051,XDB20000000,YZ201563),the Specialized Research Fund for the Doctoral Program of Higher Education (No.20123402130008),the Fundamental Research Funds for the Central Universities (Nos.WK2060190025,WK2060190040),the Key Technologies R&D Program of Anhui Province (No.1604a0702027) and the Program for Changjiang Scholars and Innovative Research Team in University of the Ministry of Education of China.

Lignin is a potential resources of aromatic compound that can be obtained from renewable biomass. There are many ongoing research efforts to utilize lignin as a sustainable alternative to petroleum derived aromatic compounds. Because of the complex three-dimensional structure, the depolymerization of lignin into monomer molecule became a core challenge for the utilization of lignin. The β-O-4 structure is the most abundant linkage in lignin. Owing to its abundance, the β-O-4 structure has been representatively studied in many aspects of scientific research on lignin degradation. Among the different reported strategies for the cleavage of β-O-4 ether bonds, C-C bond cleavage is one of the most important approaches to depolymerizing lignin. In this study, we accomplished the oxidative C-C bond cleavage of the β-O-4 structure by the catalysis of NH4VO3 using the pre-oxidized 2-phenoxy-1-phenylethanone (1a) as a model compound of lignin. In the DMSO-HOAc solvent system, benzoic acid and phenol were produced in a moderate condition, the yeild of benzoic acid and phenol were 82.1% and 88.1%, respectively. The reaction process was investigated via 1H NMR and X-ray photoelectron spectra (XPS) characterizations and the possible reaction pathway was further proposed. As the results shown, two possible reaction routes existed in this catalytic system. Pathway one:the 2-hydroxyacetophenone and phenol formed after the C-O bond cleavage of 1a in the acidic system, then, the intermediate 2-hydroxyacetophenone was converted to benzoic via the cleavage of C-C bond. Pathway two:benzoic acid and phenol yielded by the C-C bond of 1a cleaved directly over the catalyst. In addition, the catalyst characterization results confirmed that the oxovanadium(V) directly catalyzed the depolymerization of the β-O-4 structure and generated oxovanadium(IV), then oxovanadium(IV) was oxidized by O2 and finish the catalytic cycle. All reactions were carried out by the following general procedure. This reaction was carried out in glass tube and heated by oil bath. 0.5 mmol of 1a was added into 2 mL of DMSO-HOAc (V:V=3:1) with 30 mol% NH4VO3 (17.5 mg) under an oxygen atmosphere (101 kPa, in balloon). The reactor was heated to 100℃ with a powerful stirring. After 8 h, the reaction was cooled to room temperature, then 5 mL of ethyl acetate was added into the mixtures. Ash black precipitate was removed by filtration and the liquid mixture was detected by GC.

Key words: lignin, depolymerization, C-C bond cleavage, V-catalyzed reaction, oxidation reaction