Chloroform, boiling point fractional distillation

A. Maleic acid. Assemble the apparatus shown in Fig. Ill, 28, 1. Place 45 g. of dry mahc acid in the 200-250 ml. distilling flask and cautiously add 63 g. (57 ml.) of pure acetyl chloride. Warm the flask gently on a water bath to start the reaction, which then proceeds exothermically. Hydrogen chloride is evolved and the malic acid passes into solution. When the evolution of gas subsides, heat the flask on a water bath for 1-2 hours. Rearrange the apparatus and distil. A fraction of low boiling point passes over first and the temperature rises rapidly to 190° at this point run out the water from the condenser. Continue the distillation and collect the maleic anhydride at 195-200°. Recrystallise the crude maleic anhydride from chloroform (compare Section 111,93) 22 g. of pure maleic anhydride, m.p. 54°, are obtained. 

Butyllithium (23% in hexane) (63 ml, 0.15 mol) was added dropwise to diethyl phosphite (25 g, 0.18 mol) at -20 to -30°C over a period of 2 h. To the resulting mixture was added A/-methoxy pyridinium meth-osulfate in dimethyl phosphite (40 ml) over a period of 1 h at -15°C. The reaction mixture was stirred at room temperature overnight, and water (100 ml) was then added. The mixture was extracted with chloroform (3 x 75 ml), and the combined organic extracts were separated into neutral and basic fractions by extraction (4 N HC1), bas-ification, and reextraction with chloroform. The basic portion was distilled yielding diethyl pyridine-2-phosphonate (22.9 g, 67%) of boiling point (bp) 105-112°C/0.08 torr. 

FIGURE 8.45 The temperature-composition diagram showing a high-boiling-point azeotrope (such as acetone and chloroform). When this mixture is fractionally distilled, the (less volatile) azeotropic mixture is left in the flask. 

Liquid chromatography (Hostettman et al., 1986) in its many forms is a separation technique based on the polarity of the analytes and their partition between the mobile and stationary phases, and is therefore complementary to fractional distillation, which separates materials by their boiling point. The usual sequence for fractionating an essential oil or extract is to distil it first and then apply liquid chromatography to the distillation fractions as a further fractionation procedure, rather than as an analytical tool. The selectivity of the technique is achieved by choosing a stationary phase, usually from the various activities of silica gel, and varying the polarity of the mobile phase, the solvent, by mixing a non-polar component (such as hexane or pentane) with different amounts of a more polar component (such as diethyl ether, ethyl acetate or chloroform). 

Octene-1 (28 g., 0.25 mole), chloroform (120 g., 1 mole), and benzoyl peroxide (0.5 g.) were mixed and heated under 20 cm excess pressure for ten hours during which time the boiling point of the mixture rose from 80 to 92°C. After 4 h, an additional amount of benzoyl peroxide (1.0 g., total 0.006 mole) was added. On distillation of the reaction mixture, about 1.5 g. of unchanged octene was recovered on further distillation, a fraction boiling at 65-75 (0.1 mm.) was obtained. When redistilled, this material gave a product which was shown to be 1,1,1-trichlorono-nane, 13 g. (22%) b.p. 65-70°C (0.5 mm.). 

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