نتایج جستجو برای: acid anhydrides
تعداد نتایج: 748601 فیلتر نتایج به سال:
OBJECTIVES To examine the relation between exposure to acid anhydrides and the risk of developing immediate skin prick test responses to acid anhydride human serum albumin (AA-HSA) conjugates or work related respiratory symptoms; to assess whether these relations are modified by atopy or smoking. METHODS A cohort of 506 workers exposed to phthalic (PA), maleic (MA), and trimellitic anhydride ...
Organocatalytic regioselective acylation of mono- and disaccaharides with various functionalized acid anhydrides has been developed. Acylation of octyl beta-D-glucopyranoside with acid anhydrides derived from alpha-amino acids, cinnamic acid, and gallic acid took place at C(4)-OH with 67-94% regioselectivity in the presence of catalyst 1. Regioselective acylation of disaccharides with functiona...
Mixed anhydrides with penicillinic acids (III) were unstable and gave N-acyl, amides IV. Only III with butyrolactam was stable and reacted with alcohols to give esters V. All anhydrides with cephalosporinic acids (VIlI) yielded symmetric anhydrides IX. Alcoholysis of IX gave cephalosporinic ester X, while aminolysis yielded amide. Formation of postulated isomeric mixed anhydride with O-imino ca...
Z. Naturforsch. 50b, 855-858 (1995); received November 11, 1994 Organophosphonic Acid Anhydrides, Phosphonic Acid Anhydrides, Stereochemistry, NMR Spectra The phosphonic acid anhydrides of the general formula [R P 0 2]„ have been prepared with R = Me, Et, z-Pr, r-Bu, and Ph from the corresponding phosphonic acids and their chlorides and esters. Mass spectrometric data indicate that the trimers ...
A simple method is described for the preparation of caprylic, palmitic, stearic, and oleic anhydrides. Reaction of the free fatty acid and dicyclohexylcarbodiimide in carbon tetrachloride at room temperature gives the corresponding anhydrides in high yield (87-94%).
A novel synthesis of anhydrides from twisted amides is reported. Sc(OTf)3 catalysis in the presence of water is used to synthesize anhydrides in one step from amides without external nucleophiles. Mechanistic studies indicate that the coordination of the catalyst is critical to induce the challenging N-C activation step. This process further highlights the utility of twisted amides in organic s...
A simple, rapid, solvent-free, room temperature one pot synthesis of benzene ring acylated and demethylated analogues of harmine using acyl halides/acid anhydrides and AlCl(3) has been developed. Eight different acyl halides/acid anhydrides were used in the synthesis. The resulting mixture of products was separated by column chromatography to afford 10- and 12-monoacyl analogues, along with 10,...
The use of dulcitol and mannitol as differentiating agents in bacterial culture media is well established. The mechanism of the decomposition of these compounds has been investigated by many workers. With mannitol, this field has been comprehensively reviewed by Eitel (1920). Our review of the literature, however, revealed no bacteriological investigations concerned with acid and gas formation ...
the treatment equimolar quantities of carboxylic acids with acid chlorides in the presence of zno brings abouthighly efficient unsymmetrical anhydrides at room temperature in solvent-free condition. reactivity trendsfavored formation of the product using both electron deficient and rich aryl acids and acid chlorides.
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