22479-95-4Relevant articles and documents
Product-oriented chemical surface modification of a levansucrase (SacB): Via an ene-type reaction
Ortiz-Soto, Maria Elena,Ertl, Julia,Mut, Jürgen,Adelmann, Juliane,Le, Thien Anh,Shan, Junwen,Te?mar, J?rg,Schlosser, Andreas,Engels, Bernd,Seibel, Jürgen
, p. 5312 - 5321 (2018)
Carbohydrate processing enzymes are sophisticated tools of living systems that have evolved to execute specific reactions on sugars. Here we present for the first time the site-selective chemical modification of exposed tyrosine residues in SacB, a levansucrase from Bacillus megaterium (Bm-LS) for enzyme engineering purposes via an ene-type reaction. Bm-LS is unable to sustain the synthesis of high molecular weight (HMW) levan (a fructose polymer) due to protein-oligosaccharide dissociation events occurring at an early stage during polymer elongation. We switched the catalyst from levan-like oligosaccharide synthesis to the efficient production of a HMW fructan polymer through the covalent addition of a flexible chemical side-chain that fluctuates over the central binding cavity of the enzyme preventing premature oligosaccharide disengagement.
Crystal growth, structure, and polymorphic behavior of an ionic liquid: Phthalate derivative of N -Butyl, N -methylimidazolium Hexafluorophosphate
Brandel, Clement,Gbabode, Gabin,Cartigny, Yohann,Martin, Claudette,Gouhier, Geraldine,Petit, Samuel,Coquerel, Gerard
, p. 4151 - 4162 (2014)
After the multistep synthesis of an original imidazolium hexafluorophosphate ionic liquid, [pbmim][PF6], two polymorphic forms were isolated from methanolic solution and characterized by XRPD, DSC, and Raman spectroscopy. Stable Form A (mp 90.3 °C) was obtained by conventional crystallization at a moderate cooling rate (10 K/min) was applied. Structural analyses carried out by using single-crystal (Form A) and powder (Form B) X-ray diffraction revealed a rotational disorder of anionic octahedrons and, more interestingly, large conformational differences between cationic moieties caused by their molecular flexibility. Crystal growth of [pbmim][PF6] (Form A) in methanol often leads to numerous crystal defects and revealed that most of them consist of liquid inclusions. The supersaturation ratio (β) appeared to be the predominant factor influencing the crystal growth behavior under isothermal and stagnant conditions. At low β values, a morphological transition from rod-shaped crystals to platelets was observed, presumably caused by a change in the growth mechanism of specific faces. Using high β values promotes either the formation of microscopic (5 μm) liquid inclusions that become easily detectable upon heating or the appearance of macroscopic inclusions with an hourglass shape.
Correlations between carbon-13 nuclear magnetic resonance chemical shifts and reactivities of siloxybutadienes and siloxyazabutadienes in the Diels-Alder reaction with dimethyl acetylenedicarboxylate
Igarashi,Kawakami,Kinoshita,Furukawa
, p. 1832 - 1835 (1990)
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Method for promoting iron-catalyzed oxidation of aromatic compound carbon - hydrogen bond to synthesize phenol by ligand
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Paragraph 0108-0109; 0129, (2021/09/21)
The method comprises the following steps: iron is used as - a catalyst metal; a sulfur-containing amino acid or cystine-derived dipeptide is a ligand; and under the common action of hydrogen peroxide as an oxidizing agent, an aromatic compound is synthesized to prepare a phenol. Under the action of an acid as an accelerant and hydrogen peroxide as an oxidizing agent, the aryl carbon - hydrogen bond is directly hydroxylated to form a phenolic compound, and the method for preparing the phenol by the catalytic oxidation reaction has a plurality of advantages. The reaction raw materials, the oxidant and the promoter are wide in source, low in price, environment-friendly and good in stability. The aromatic compound carbon - hydrogen bonds directly participate in the reaction to react in one step to form phenol. The reaction condition is mild, the functional group compatibility and the application range are wide. The reaction selectivity is good; under the optimized reaction conditions, the target product separation yield can reach 85%.
Automated on-line monitoring of the TiO2-based photocatalytic degradation of dimethyl phthalate and diethyl phthalate
Salazar-Beltrán, Daniel,Hinojosa-Reyes, Laura,Maya-Alejandro, Fernando,Turnes-Palomino, Gemma,Palomino-Cabello, Carlos,Hernández-Ramírez, Aracely,Guzmán-Mar, Jorge Luis
, p. 863 - 870 (2019/04/17)
A fully automated on-line system for monitoring the TiO2-based photocatalytic degradation of dimethyl phthalate (DMP) and diethyl phthalate (DEP) using sequential injection analysis (SIA) coupled to liquid chromatography (LC) with UV detection was proposed. The effects of the type of catalyst (sol-gel, Degussa P25 and Hombikat), the amount of catalyst (0.5, 1.0 and 1.5 g L-1), and the solution pH (4, 7 and 10) were evaluated through a three-level fractional factorial design (FFD) to verify the influence of the factors on the response variable (degradation efficiency, %). As a result of FFD evaluation, the main factor that influences the process is the type of catalyst. Degradation percentages close to 100% under UV-vis radiation were reached using the two commercial TiO2 materials, which present mixed phases (anatase/rutile), Degussa P25 (82%/18%) and Hombikat (76%/24%). 60% degradation was obtained using the laboratory-made pure anatase crystalline TiO2 phase. The pH and amount of catalyst showed minimum significant effect on the degradation efficiencies of DMP and DEP. Greater degradation efficiency was achieved using Degussa P25 at pH 10 with 1.5 g L-1 catalyst dosage. Under these conditions, complete degradation and 92% mineralization were achieved after 300 min of reaction. Additionally, a drastic decrease in the concentration of BOD5 and COD was observed, which results in significant enhancement of their biodegradability obtaining a BOD5/COD index of 0.66 after the photocatalytic treatment. The main intermediate products found were dimethyl 4-hydroxyphthalate, 4-hydroxy-diethyl phthalate, phthalic acid and phthalic anhydride indicating that the photocatalytic degradation pathway involved the hydrolysis reaction of the aliphatic chain and hydroxylation of the aromatic ring, obtaining products with lower toxicity than the initial molecules.
