2173-56-0Relevant articles and documents
Unraveling the role of low coordination sites in a cu metal nanoparticle: A step toward the selective synthesis of second generation biofuels
Scotti, Nicola,Dangate, Milind,Gervasini, Antonella,Evangelisti, Claudio,Ravasio, Nicoletta,Zaccheria, Federica
, p. 2818 - 2826 (2014)
The acidity of a prereduced Cu/SiO2 catalyst was extensively investigated by means of FT-IR of adsorbed pyridine and by titration with 2-phenylethylamine in cyclohexane. Comparison with the parent CuO/SiO 2 material, which was alread
Selective oxidation of primary alkanols into the "symmetrical" esters with the H2O2-MBr-HCl system
Nikishin,Sokova,Kapustina
, p. 310 - 312 (2011)
Oxidation of linear or branched primary alkanols with H2O 2-MBr (M = Li, Na, K)-HCl system in water affords the corresponding "symmetrical" esters in almost quantitative yield.
Performance of Candida rugosa lipase supported on nanocellulose-silica-reinforced polyethersulfone membrane for the synthesis of pentyl valerate: Kinetic, thermodynamic and regenerability studies
Chandren, Sheela,Elias, Nursyafiqah,Lau, Woei Jye,Wahab, Roswanira Abdul
, (2021/09/16)
The present study reports the groundwork for preparing a greener catalyst, Candida rugosa lipase (CRL), supported on biomass-based nanocellulose-silica-reinforced polyethersulfone membrane (NC-SiO2-PES) and proved its stability in synthesizing pentyl valerate. The NC-SiO2-PES/CRL-catalyzed synthesis of the ester exhibited a ping-pong bi-bi mechanism, with a high Vmax value and low Km value over the free CRL, confirming the former's greater substrate affinity. The kinetics data demonstrated that the NC-SiO2-PES/CRL was catalytically more efficient than its free counterpart. The lower Michaelis-Menten constant of NC-SiO2-PES/CRL for pentanol (Km,B = 43.53 mM) than valeric acid (Km,A = 82.03 mM) indicates that pentanol was favored over the latter. Pertinently, the higher thermal deactivation values of NC-SiO2-PES/CRL indicated that the NC-SiO2-PES membrane successfully enhanced CRL thermal stability, and the process followed first-order kinetics (R2 > 0.95). The NC-SiO2-PES/CRL has a slightly greater activation energy (Ea) and activation energy for thermal denaturation (Ed) over the free CRL. NC-SiO2-PES/CRL also exhibited extended operational stability, with a robust half-life of ～150 h and the absence of leached protein after 60 min of agitation. The NC-SiO2-PES/CRL's ability to be regenerated chemically and ultrasonically and reused without significant loss in enzyme activity denotes its potential cost-saving to produce pentyl valerate.
Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
, (2021/12/02)
Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
