نتایج جستجو برای: amines
تعداد نتایج: 20593 فیلتر نتایج به سال:
The reactions of a 5-chloro-2,3-diphenyltetrazolium salt with amines have been examined. In the presence of an inorganic base such as NaHCO(3), primary and secondary amines undergo a nucleophilic substitution to give the corresponding 5-aminotetrazolium salts. When triethylamine is used as a base, primary amines give 3-phenylazo-1,2,4-triazoles. A plausible dual-path mechanism is proposed for t...
Fluorinated amines are important synthetic building blocks in the design of antimetabolites and drugs because fluorine causes minimal structural changes and maximal shifts in electron distribution. Fluorine lowers the basicity of amines and improves oral absorption, suppresses metabolism, and thus increases the bioavailability of a target drug. Among the fluorinated amines, a-difluoromethyl ami...
Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been substantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammonia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a micros...
The transition-metal-catalyzed amination of aryl halides has been the most powerful method for the formation of aryl amines over the past decades. Phenols are regarded as ideal alternatives to aryl halides as coupling partners in cross-couplings. An efficient palladium-catalyzed formal cross-coupling of phenols with various amines and anilines has now been developed. A variety of substituted ph...
A novel Pd/Cu-catalyzed chemoselective aerobic oxidative N-dealkylation/carbonylation reaction has been developed. Tertiary amines are utilized as a "reservoir" of "active" secondary amines in this transformation, which inhibits the formation of undesired by-products and the deactivation of the catalysts. This protocol allows for an efficient and straightforward construction of synthetically us...
[structure: see text] A new system for the double amplification of the molecular chirality of simple chiral amines in achiral liquid crystalline media is described. It involves a conformationally flexible phosphoric acid based receptor that by binding to chiral amines induces chirality in the liquid crystalline matrix. Efficient cholesteric phase formation was shown by several chiral amines tha...
Enantioselective synthesis of β-chiral amines has been achieved via copper-catalyzed hydroamination of 1,1-disubstituted alkenes with hydroxylamine esters in the presence of a hydrosilane. This mild process affords a range of structurally diverse β-chiral amines, including β-deuterated amines, in excellent yields with high enantioselectivities. Furthermore, catalyst loading as low as 0.4 mol% c...
[1] Field observations and quantum chemical calculations suggest that amines can be important for formation of nanometer size particles. Amines and ammonia often have common atmospheric emission sources and the similar chemical and physical properties. While the effects of ammonia on aerosol nucleation have been previously investigated, laboratory studies of homogeneous nucleation involving ami...
The identity of the c-caprolactone products from polymerization under the influence of amines has been studied, and conclusion about alkyl oxygen fission of the lactone ring at polymerization has been made. The main kinetic features of polymerization and molecular-weight distribution change on forming poly-C-caprolactone are discussed. On the basis of these data, polymerization mechanisms for l...
The objective of this study was to investigate the antimicrobial activities of saturated fatty acids and fatty amines against methicillin-resistant Staphylococcus aureus (MRSA). The antimicrobial activity of saturated fatty acids and fatty amines was determined by oxygen meters with multi-channels and disposable oxygen electrode sensors (DOX-96). Lauric acid, the most effective among the satura...
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