Distillation distn fractional

Conductivity grade benzonitrile (specific conductance 2 x 10" mho) was obtained by treatment with anhydrous AICI3, followed by rapid distn at 40-50° under vacuum. After washing with alkali and drying with CaCl2, the distillate was vac distd several times at 35° before being fractionally crystd several times by partial freezing. It was dried over finely divided activated alumina from which it was withdrawn as required [Van Dyke and Harrison J Am Chem Soc 73 402 7957]. 

Purification methods described for the mixed isomers are applicable. The individual isomers can be separated by very efficient fractional distn, followed by fractional crystn by partial freezing. The cz5-isomer reacts preferentially with AICI3 and can be removed from the /ranj-isomer by stirring the mixture with a limited amount of AICI3 for 48h at room temperature, filtering and distilling. 

Dried with Linde type 5A molecular sieves, BaO or sodium, and fractionally distd. The distillate (200g) was heated with benzene (500mL) and cone HCl (150mL) in a Dean and Stark apparatus on a water bath until water no longer separated, and the temperature just below the liquid reached 80°. When cold, the supernatant benzene was decanted and the 2,4-lutidine hydrochloride, after washing with a little benzene, was dissolved in water (350mL). After removing any benzene by steam distn, an aqueous soln of NaOH (80g) was added, and the free... 

Fractionally distd under reduced pressure. Dried with sodium and again fractionally distd or refluxed with boric anhydride and distd (b 195-205°/5mm), the distillate being neutralised with NaOH and again fractionally distd. Also purified by distn from Raney nickel and by preparative GLC. 

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