ZerZ-Butyl chloride

ZerZ-Butyl chloride [507-20-0] M 92.6, f.p. -24.6°, b 50.4 , d 0.851, n 1.38564. Purification methods commonly used for other alkyl halides lead to decomposition. Some impurities can be removed by photochlorination with a small amount of chlorine prior to use. The liquid can be washed with ice water, dried with CaCh or CaCl2 + CaO and fractionally distd. It has been further purified by repeated fractional crystn by partial freezing. 

In a 250 ml. separatory funnel place 25 g. of anhydrous ZerZ.-butyl alcohol (b.p. 82-83°, m.p. 25°) (1) and 85 ml. of concentrated hydrochloric acid (2) and shake the mixture from time to time during 20 minutes. After each shaking, loosen the stopper to relieve any internal pressure. Allow the mixture to stand for a few minutes until the layers have separated sharply draw off and discard the lower acid layer. Wash the halide with 20 ml. of 5 per cent, sodium bicarbonate solution and then with 20 ml. of water. Dry the preparation with 5 g. of anhydrous calcium chloride or anhydrous calcium, sulphate. Decant the dried liquid through a funnel supporting a fluted Alter paper or a small plug of cotton wool into a 100 ml. distilling flask, add 2-3 chips of porous porcelain, and distil. Collect the fraction boiling at 49-51°. The yield of ferf.-butyl chloride is 28 g. 

Lewis superacid-catalyzed direct alkylation of alkanes is also possible with alkyl cations prepared from alkyl halides and SbFs in sulfuryl chloride fluoride solution. " Typical alkylation reactions are those of propane and butanes by 2-butyl and ZerZ-butyl cations. The ClfU-Sbfs and C2H5F-SbF5 complexes acting as incipient methyl and ethyl cations besides alkylation preferentially cause hydride transfer. Since intermolecular hydride transfer between different carbocations and alkanes are faster than alkylation, a complex mixture of alkylated products is usually formed. A significant amount of 2,3-dimethylbutane was, however, detected when propane was propylated with the 2-propyl cation at low temperature [Eq. (6.36)]. No 2,2-dimethylbutane, the main product of conventional acid-catalyzed alkylation, was detected, which is a clear indication of predominantly nonisomerizing reaction conditions. 

In a I-l. round-bottomed, three-necked flask, fitted with a thermometer, an efficient mechanical stirrer (Note i), and a 35-cm. Vigreux column fitted to a condenser and receiver protected by a calcium chloride tube, are placed 345 g. (400 cc.) of dry xylene, 120 g. (117 cc., i mole) of dry acetophenone, and 135 g. (0.55 mole) of aluminum ZerZ.-butoxide (p. 8) (Note 2). The stirrer is started and the flask heated in an oil bath so that the temperature of the reaction mixture is held between 133° and 137°. ZerZ.-Butyl alcohol slowly distils at a temperature in the vapor of 80-85°. The distillation of the alcohol can be accomplished by maintaining the temperature of the heating bath between 150° and 155° for two hours after distillation has commenced (Notes 3 and 4). 

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