88246-12-2Relevant articles and documents
Ru/SiO2 Catalyst for Highly Selective Hydrogenation of Dimethyl Malate to 1,2,4-Butanetriol at Low Temperatures in Aqueous Solvent
Chen, Can,Jiang, Junxiang,Li, Guangci,Li, Xuebing,Wang, Da,Wang, Zhong,Yu, Pei
, (2022/01/12)
Catalytic selective hydrogenation of esterified malic acid to produce 1,2,4-butanetriol (1,2,4-BT) using H2 as the reducing reagent suffers from the low 1,2,4-BT selectivity. Here, Ru/SiO2 catalyst was employed for selective hydrogenation of dimethyl malate (DM) to produce 1,2,4-BT, which gave abnormal high DM conversion (100%) and 1,2,4-BT selectivity (92.4%) in aqueous solvent at 363?K, especially, the 1,2,4-BT yield even is higher than the optimal catalyst reported (Ru-Re, 79.8%). The reaction pathways for the DM hydrogenation on Ru/SiO2 were also proposed, suggesting that extremely high 1,2,4-BT selectivity require for the much high hydrogenation rates at low temperatures, where side-reaction transesterification rates are relatively low. The extremely high hydrogenation activity and 1,2,4-BT selectivity on Ru/SiO2 in aqueous solvent at low temperatures arise from that H2O may coordinate to Ru2+ and prevent the reduction of Ru2+ to Ru under high H2 pressure. Ru/SiO2 surface presents abundant Ru2+ in aqueous solvent, can activate H2 through heterolytic cleavage mode to form hydride, which can significantly increase hydrogenation rates of C = O groups at low temperatures. In addition, the activity and 1,2,4-BT selectivity on Ru/SiO2 catalyst only reduced by 2.3% and 2.6%, respectively over a period of 550?h. Graphical Abstract: [Figure not available: see fulltext.]
PROCESS FOR THE HYDROGENATION OF ESTERS OF ALPHA-SUBSTITUTED CARBOXYLIC ACIDS
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Page/Page column 10-12, (2008/06/13)
There is provided a process for the hydrogenation of esters of alpha-substituted carboxylic acids which comprises reacting an ester of an alpha-substituted carboxylic acid with hydrogen in the presence of a catalyst under substantially homogeneous supercritical conditions. Preferably, the ester of an alpha-substituted carboxylic acids is an ester of formula (1): wherein: R1 and R2are each independently an optionally substituted hydrocarbyl group or an optionally substituted heterocyclic group; and Y is a heteroatom or an optionally substituted heteroatom group. More preferably, the ester of an alpha-substituted is carboxylic acids is an ester of formula (2): wherein: R3 is an optionally substituted hydrocarbyl group or an optionally substituted heterocyclic group; R4and R5 are each independently hydrogen, an optionally substituted hydrocarbyl group or an optionally substituted heterocyclic group; Y is a heteroatom or an optionally substituted heteroatom group; Q is a functional group; and n 1. Most preferably, the ester of an alpha-substituted carboxylic acids is an ester of formula (3): wherein: R3 and R6 are each independently an optionally substituted hydrocarbyl group or an optionally substituted heterocyclic group; R4 and R5 are each independently hydrogen, an optionally substituted hydrocarbyl group or an optionally substituted heterocyclic group; Y is a heteroatom or an optionally substituted heteroatom group; and n 1.