121-33-5Relevant articles and documents
Oxidative deoximation with H2O2 and MCM-41
Vijayakumari,Reddy, Balakrishna,Nagarapu, Lingaiah
, p. 407 - 410 (2006)
A simple and mild method of oxidative deoximation with 30%H 2O2 and MCM-41 is described. This method is effective for deprotection of ketones and aldehydes.
A chemical model of catechol-O-methyltransferase. Methylation of 3,4- dihydroxybenzaldehyde in methanol solution
Sugata
, p. 1007 - 1011 (1993)
The reaction of 3,4-dihydroxybenzaldehyde (LH2) and dimethyl sulfate (DMS) in forming m- and p-O-methylated products (vanillin and isovanillin, respectively) in a methanol buffer solution was studied kinetically as a chemical model of catechol-O-methyltransferase (COMT). The O-methylations, especially m-O-methylations, were catalyzed by divalent metal ions such as Cu(II), Mg(II) and Zn(II). A clear Mg(II) catalysis was observed for the first time in this medium. As Mg(II) is an important metal in the COMT catalyzed reaction in vivo, this observation is very interesting. Kinetic analyses of the present data and recalculation of a part of the previous data offered the following evidence. In Cu(II) catalysis, a 1:2 complex(CuL2) was more active than the 1:1 complex (CuL). On the other hand, in Mg(II) catalysis and Zn(II) catalysis, ML was more active than ML2. These facts show that ML2 is not always more active than ML, contrary to previous reports. Methanolysis of DMS, a significant side reaction of this model reaction, and dissociation of LH2 were studied thoroughly as bases for these kinetic analyses.
Oxidation of model lignin compounds with peracetic acid under homogeneous catalysis with polyoxometalates
Popova,Beloglazova,Bogolitsyn,Tortseva,Verkholomova,Pokryshkin
, p. 2092 - 2097 (2014)
Oxidation of lignin model compounds with peracetic acid using polyoxometalate manganesecontaining sodium vanadomolybdophosphate Na11[PMo6V5O39Mn(OH)] as a catalyst has been studied. The effect of pH, concentration and nature of the oxidized compound, concentration of the catalyst and peracetic acid, and temperature on kinetics of oxidation and the products composition has been investigated.
Continuous flow study of isoeugenol to vanillin: A bio-based iron oxide catalyst
Filiciotto, Layla,Márquez-Medina, María Dolores,Pineda, Antonio,Balu, Alina M.,Romero, Antonio A.,Angelici, Carlo,de Jong, Ed,van der Waal, Jan C.,Luque, Rafael
, p. 281 - 290 (2021)
The use of a biorefinery co-product, such as humins, in combination with an iron precursor in a solvent-free method yields a catalytic material with potential use in selective oxidative cleavage reactions. In particular, this catalyst was found active in the hydrogen-peroxide assisted oxidation of a naturally extracted molecule, isoeugenol, to high added-value flavouring agent, vanillin. By carrying out the reaction in continuous flow, not only a better understanding of the reaction mechanism and of the catalyst deactivation can be achieved, but also important insights for optimised conditions can be developed. The findings of this paper could pave the way to a more sustainable process for the production of a valuable food and perfume additive, vanillin.
Unprecedented oxidative properties of mesoporous silica materials: Towards microwave-assisted oxidation of lignin model compounds
Badamali, Sushanta K.,Luque, Rafael,Clark, James H.,Breeden, Simon W.
, p. 1 - 4 (2013)
The unusual oxidative ability of mesoporous silicas towards oxidation of an important lignin model molecule, 1,2-(4-hydroxy-3methoxy-phenoxy) ethanol, apocynol under microwave irradiation is presented in this work. Mesoporous MCM-41, HMS, SBA-15 and amorphous silica were employed as catalysts in the present study. Different reactivities were obtained for the various silica materials. It was assumed that the substrate conversion and product selectivity were highly influenced by the nature of mesoporous silica materials. Based on the nature of the catalysts and reaction product profile, a plausible mechanism has been proposed.
Immobilization of Pd(OAc)2 in ionic liquid on silica: Application to sustainable Mizoroki-Heck reaction
Hagiwara, Hisahiro,Sugawara, Yoshitaka,Isobe, Kohei,Hoshi, Takashi,Suzuki, Toshio
, p. 2325 - 2328 (2004)
(Equation Presented) Palladium acetate was supported on amorphous silica with the aid of an ionic liquid, [bmim]PF6. The immobilized catalyst was highly efficient in promoting the Mizoroki-Heck reaction without a ligand in n-dodecane for at least six reuses, in 89-98% yields. The TON and TOF reached 68 400 and 8000, respectively.
Salen complexes with bulky substituents as useful tools for biomimetic phenol oxidation research
Haikarainen, Anssi,Sipil?, Jussi,Pietik?inen, Pekka,Pajunen, Aarne,Mutikainen, Ilpo
, p. 1633 - 1638 (2001)
The catalytic properties of bulky water-soluble Co-, Cu-, Fe- and Mn-salen complexes in the oxidation of phenolic lignin model compounds have been studied in aqueous water-dioxane solutions (pH 3-10). Mn catalysts were found to oxidize coniferyl alcohol in a same reaction time as horseradish peroxidase (HRP) enzyme and Mn and Co catalysts showed different regioselectivity suggesting a different substrate to catalyst interaction in the oxidative coupling. When the oxidation of material more relevant to plant polyphenolics was studied, the results indicated that the complexes catalyze one- and two-electron oxidations depending on the bulk of the substrate. Copyright
A three-enzyme-system to degrade curcumin to natural vanillin
Esparan, Vida,Krings, Ulrich,Struch, Marlene,Berger, Ralf G.
, p. 6640 - 6653 (2015)
The symmetrical structure of curcumin includes two 4-hydroxy-3-methoxyphenyl substructures. Laccase catalyzed formation of a phenol radical, radical migration and oxygen insertion at the benzylic positions can result in the formation of vanillin. As vanillin itself is a preferred phenolic substrate of laccases, the formation of vanillin oligomers and polymers is inevitable, once vanillin becomes liberated. To decelerate the oligomerization, one of the phenolic hydroxyl groups was protected via acetylation. Monoacetyl curcumin with an approximate molar yield of 49% was the major acetylation product, when a lipase from Candida antarctica (CAL) was used. In the second step, monoacetyl curcumin was incubated with purified laccases of various basidiomycete fungi in a biphasic system (diethyl ether/aqueous buffer). A laccase from Funalia trogii (LccFtr) resulted in a high conversion (46% molar yield of curcumin monoacetate) to vanillin acetate. The non-protected vanillin moiety reacted to a mixture of higher molecular products. In the third step, the protecting group was removed from vanillin acetate using a feruloyl esterase from Pleurotus eryngii (PeFaeA) (68% molar yield). Alignment of the amino acid sequences indicated that high potential laccases performed better in this mediator and cofactor-free reaction.
An efficient environmentally friendly CuFe2O4/SiO2catalyst for vanillyl mandelic acid oxidation in water under atmospheric pressure and a mechanism study
Mao, Haifang,Wang, Hongzhao,Meng, Tao,Wang, Chaoyang,Hu, Xiaojun,Xiao, Zuobing,Liu, Jibo
, p. 982 - 992 (2021)
With the aim of the green production of vanillin, a highly efficient environmentally friendly oxidation system was introduced to oxidize vanillyl mandelic acid (VMA) with a porous CuFe2O4/SiO2 component nano-catalyst in aqueous solution under atmospheric pressure. The N2 adsorption-desorption pattern indicated that CuFe2O4/SiO2 possessed a much higher specific surface area (49.98 m2 g-1) than that of CuFe2O4 (5.02 m2 g-1), which further indicated that the SiO2 substrate restrained the aggregation of CuFe2O4 nanoparticles. The conversion for VMA and selectivity for vanillin reached 98% and 96%, respectively, under atmospheric pressure. The excellent catalytic performance was attributed to the synergistic effect of the catalytic capacity of CuFe2O4 and the adsorption capacity for the reactant of SiO2. Simultaneously, the effect of different reaction conditions for catalyst activity and selectivity were investigated. Furthermore, the probable mechanism of VMA oxidation was investigated by in situ ATR-FTIR, H2-TPR, XPS and 1H NMR. More importantly, the decarboxylation was verified to proceed in basic conditions rather than in conventional acidic conditions. This journal is
An immobilised Co(ii) and Ni(ii) Schiff base magnetic nanocatalyst via a click reaction: A greener approach for alcohol oxidation
Bhat, Pooja B.,Bhat, Badekai Ramachandra
, p. 4933 - 4938 (2015)
A Schiff base immobilised nanocatalyst was synthesized via copper catalysed alkyne azide cycloaddition (CuAAC) on a magnetic support. The nanocatalyst exhibited high accessible active sites with a surface area of 76 m2 g-1 for a cobalt complex and 57 m2 g-1 for a nickel complex. A strong interaction between the magnetic support and the Schiff base was achieved by avoiding leaching during the course of reaction. The nanocatalyst efficiently oxidised both primary and secondary alcohols to carbonyl with improved yield in a solventless system rendering a greener approach.
