488-31-3Relevant articles and documents
PROCESSES FOR PREPARING ALDARIC, ALDONIC, AND URONIC ACIDS
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, (2021/05/29)
Various processes for preparing aldaric acids, aldonic acids, uronic acids, and/or lactone(s) thereof are described. For example, processes for preparing a C2-C7 aldaric acid and/or lactone(s) thereof by the catalytic oxidation of a C2-C7 aldonic acid and/or lactone(s) thereof and/or a C2-C7 aldose are described.
Bimetallic AuPt/TiO2Catalysts for Direct Oxidation of Glucose and Gluconic Acid to Tartaric Acid in the Presence of Molecular O2
Ding, Jie,Jin, Xin,Lai, Linyi,Liu, Mengyuan,Sun, Yu,Wang, Jinyao,Xia, Qi,Yan, Hao,Yang, Chaohe,Zhang, Guangyu,Zhang, Wenxiang
, p. 10932 - 10945 (2020/11/23)
Tartaric acid is an important industrial building block in the food and polymer industry. However, green manufacture of tartaric acid remains a grand challenge in this area. To date, chemical synthesis from nitric acid-facilitated glucose oxidation leads to only a one-pot aqueous-phase oxidation of glucose and gluconic acid using bimetallic AuPt/TiO2 catalysts in the presence of molecular O2, with ～50% yield toward tartaric acid at 110 °C and 2 MPa. Structural characterization and density functional theory (DFT) calculation reveal that the lattice mismatch between fcc Pt and bcc Au induces the formation of twinned boundaries in nanoclusters and Jahn-Teller distortion in an electronic field. Such structural and electronic reconfiguration leads to enhanced σ-activation of the C-H bond competing with π-πelectronic sharing of the C═O bond on the catalyst surface. As a result, both C-H (oxidation) and C-C (decarboxylation) bond cleavage reactions synergistically occur on the surface of bimetallic AuPt/TiO2 catalysts. Therefore, glucose and gluconic acid can be efficiently transformed into tartaric acid in a base-free medium. Lattice distortion-enhanced reconfiguration of the electronic field in Pt-based bimetallic nanocatalysts can be utilized in many other energy and environmental fields for catalyzing synergistic oxidation reactions.
Rate-limiting steps in bromide-free TEMPO-mediated oxidation of cellulose - Quantification of the N-Oxoammonium cation by iodometric titration and UV-vis spectroscopy
P??kk?nen, Timo,Bertinetto, Carlo,P?nni, Raili,Tummala, Gopi Krishna,Nuopponen, Markus,Vuorinen, Tapani
, p. 532 - 538 (2015/10/28)
A iodometric titration method was introduced to study the conversion of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) to the corresponding N-oxoammonium cation (TEMPO+) by hypochlorite in the absence and presence of bromide ion. The validity of the titration was verified with UV-vis spectroscopy combined with a multivariate curve resolution (MCR) algorithm to calculate the concentrations and spectral signatures of the pure components (i.e., TEMPO, Cl(+1) and TEMPO+). The formation of the oxoammonium cation was successfully followed during the activation of TEMPO by HOCl and HOBr. It was found that HOBr is a more effective activator for TEMPO than HOCl is. Moreover, the importance of a separate activation step for TEMPO with bromide-free TEMPO oxidations could be identified with this titration method. The content of TEMPO+ was also monitored during the TEMPO-mediated oxidation of a cellulosic pulp by hypochlorite in the absence and presence of bromide. It was found that the oxidation of the alcoholic groups by TEMPO+ was generally the rate-determining step and much slower than the regeneration of TEMPO+ through oxidation of the hydroxylamine by HOCl and HOBr. However, at high pH the latter reaction became rate-limiting.
