Acetic acid, bromo-, ethyl ester drying

A suspension of 5.0 g of l-bromo-4,4-bis(3-methylthien-2-yl)but-3-ene, 3.4 g of nipecotic acid ethyl ester and 3.3 g of potassium carbonate in 150 ml of dry acetone was kept under reflux for 15 h. The reaction mixture was evaporated and, after addition of 30 ml of water, the resulting solution was extracted twice with 50 ml of ethyl acetate. The ethyl acetate extracts were dried and evaporated leaving 7.3 g of an oil. By column chromatography on silica gel using methanol as eluent, N-(4,4-bis(3-methylthien-2-yl)but-3-enyl)nipecotic acid ethyl ester was isolated. 

Kawahara [156] introduced pentafluorobenzyl esters, prepared by the following procedure. A mixture of four acids (0.8 mg of each) was dissolved in 100 ml of acetone, and 250 mg (25-fold excess) of a-bromo-2,3,4,5,6-pentafluorotoluene and 50 mg (10-fold excess of potassium carbonate were added (it can be replaced with an ethanolic solution of potassium hydroxide). After refluxing for 3 h, the mixture was diluted with 500 ml of diethyl ether and 20 ml of ethyl acetate, washed with 10 ml of water and dried with 8 g of anhydrous sodium sulphate. After filtration, the sulphate and the filter were washed with 50 ml of diethyl ether, the solvent was removed and the residue was dried at 40°C and 50 mmHg it was further dissolved in 100 ml of -hexane and, after an additional 100-fold dilution, 6 /il were injected. The ECD response to pentafluorobenzoate was almost the same as that to aldrin. A method for the preparation of p-substituted benzyl esters of lower monocarboxylic acids on the micro-scale [157] is based on the same reaction scheme. A 10-pl volume of an ethanolic solution of carboxylic acids (ca. 1 pg/pl)... 

Metallic zinc (8 g., 0.12 gram atom) is added to a solution of 18.2 g. (0.10 mole) of benzophenone and 20 g. (0.12 mole) of ethyl bromo-acetate in 90 ml. of sodium-dried benzene. The mixture is warmed cautiously on a water bath under a reflux condenser until initiation of reaction, at which point the heating bath is removed and the flask is cooled as needed to keep the reaction mder control but not enough to stop the reaction. The mixture is then heated to reflux for 45 minutes. The cooled mixture is treated with excess dilute sulfuric acid, the benzene layer is separated and washed with dilute acid, and the benzene is allowed to evaporate. The residual ester is... 

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