| Abstrakt: |
Esters have a lot of applications as fragrances, emulsifiers and solvents,[1] and the ester bond is present in numerous bioactive compounds such as local anesthetics,[2] agonists of acetylcholine receptors[3] and opioid analgetics.[4] In the classical approach, the condensation of a carboxylic acid with a large excess of alcohol proceeds in the presence of a strong mineral acid, typically HCl or H SB 2 sb SO SB 4 sb . Alcoholysis of benzamide in 2-chloroethanol (Entry M) and 2-methoxyethanol (Entry O) went to completion within 2-3 h and the result is comparable with alcoholysis of the same substrate in n-butanol (Entry K). Alcoholysis of benzamide in ethanol and n-propanol (Entries G and I) went to completion within 22 h and occurred much slower in comparison with the corresponding methanolysis (Table 1, Entry E). List of abbreviations ATR attenuated total reflectance CC column chromatography cod 1,5-cyclooctadiene DCM dichloromethane DMSO dimethylsulfoxide EtOAc ethyl acetate Hex hexane HPLC high performance liquid chromatography IR infra red Ph phenyl Me methyl NMR nuclear magnetic resonance R SB f sb retention factor Tf trifluoromethanesulfonyl (Trifyl) TfOH trifluoromethanesulfonic acid TFA trifluoroacetic acid TMS tetramethylsilane TMS-Cl trimethylchlorosilane TLC thin layer chromatography References 1 W. Riemenschneider and H. M. Bolt, "Esters, Organic, "in " Ullmann's Encyclopedia of Industrial Chemistry, "p. 245, Wiley-VCH, Weinheim, Germany, 2005. [Extracted from the article] |
