نتایج جستجو برای: acetic anhydride
تعداد نتایج: 21372 فیلتر نتایج به سال:
Acetylation with acetic anhydride, under both aqueous and anhydrous conditions, has been utilized to derivatize various biogenic amines and psychotropic drugs for subsequent analysis by gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS). Under basic aqueous conditions, acetic anhydride derivatizes phenols and amines but not alcohols; under anhydrous conditions, all three fu...
The polycondensation of tetrahydrofuran with maleic anhydride catalyzed by Maghnite-H+ (Mag-H) was investigated. Maghnite is a montmorillonite sheet silicate clay that is exchanged with protons to produce Maghnite-H [1]. It was found that the polymerization in bulk is initiated by Mag-H in the presence of acetic anhydride at 40 degrees C. The effects of the amounts of Mag-H and acetic anhydride...
The global reaction between acetic anhydride and a fatty acid yields, at equilibrium, an asymmetric acetic-aliphatic anhydride in a medium containing finally: acetic-fatty anhydride, acetic anhydride, fatty acid, acetic acid and fatty anhydride. No solvent or catalyst was used to evaluate the impact of the actual reactivity of the anhydrides. The competition between the formation of acetyl and ...
A new process for the continuous acetylation of lignocellulosic fiber has been developed. The fiber enters a pre-heated reactor and a specified concentration of acetic anhydride is applied. The fiber moves through the reactor at a rate needed for the acetylation to take place to the desired weight gain. The fiber then goes into a first stripper loop unit where the loop atmosphere consists of su...
If amino-acids are treated in glacial acetic acid solution with the theoretical amount of acetic anhydride, optically active acetamino-acids are obtained, while if a large excess of acetic anhydride is used, racemization and/or formation of azlactones takes place [Bergmann et al. 1926; Bergmann & Zervas, 1928]. Excess of acetic anhydride causes racemization even in aqueous solution in the prese...
Acetylation reaction's product(s) o f 3-[L-threo-2,3,4-trihydroxy-1-(2-naphthylhydrazono)butyl]quinoxalin-2(lH)-one (2b) were found to be dependent on the reaction condition. While the tri-O-acetyl (3b) was isolated in high yield from 2 b under the action o f acetic anhydride/ pyridine mixture, compounds 4 b and 5 b as well as trace o f 3b were obtained when 2 b was heated in acetic anhydride. ...
We describe a convenient, rapid, and reproducible method for labeling proteins in vitro by acetylation with [3H] or [14-C]acetic anhydride dissolved in small amounts of anhydrous dioxane. The reaction is carried out at neutral pH and does not require the use of detergents, water-immiscible organic solvents, oxidizing, or reducing agents. Thus undesirable solvent-induced alterations in protein s...
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