Apparatus Vigreux column

Apparatus 1-1 flask (see Fig. 1) for the addition of bromine 1-1 two-necked flask, provided with a dropping funnel and a 40-cm Vigreux column, for the dehydrohalo-genation the Vigreux column was connected to a condenser and receiver, cooled at -75°C. 

The precipitate of triphenylphosphine oxide is filtered and washed with 50 ml. of pentane. The solvent is removed from the combined filtrate at the rotary evaporator under water aspirator pressure at room temperature. Distillation of the residue through a 2-cm. Vigreux column attached to a short-path distillation apparatus (Note 4) provides 13.0-14.0 g. (75-81%) of geranyl chloride, b.p. 47-49° (0.4 mm.), w2Sd = 1.4794 (Note 5). 

The checkers employed a modified Widmer column1 (Fig. 4) that has been used in many organic laboratories, but not officially described. They also used a Vigreux column (50 cm. effective length, 2.7 cm. inside diameter) the first distillation then required ninety minutes, and the yield was 82-83 Per cent. The final temperature of the reaction mixture and observed boiling point will depend upon the type of apparatus used. 

The best results appeared to be obtained when the oil being distilled filled the flask to about two-thirds its capacity, the Vigreux column was no longer than 10 cm. in length, the whole apparatus was kept as small as possible, and the distillation was conducted as rapidly as possible. 

In a 1-1. three-necked round-bottomed flask, wrapped with aluminum foil to exclude light, and equipped with a mechanical stirrer, a reflux condenser, and an addition funnel, is suspended 37 g. (0.17 mole) of red mercuric oxide (Note 1) in 330 ml. of carbon tetrachloride (Note 2). To the flask is added 30.0 g. (0.22 mole) of 3-chlorocyclobutaneearboxylic acid (Note 3), and the mixture is heated to reflux while stirring. To the mixture is added dropwise a solution of 40 g. (0.25 mole) of bromine in 180 ml. of carbon tetrachloride as fast as possible (4-7 minutes) without loss of bromine from the condenser (Note 4). After a short induction period, carbon dioxide is evolved at a rate of 150-200 bubbles per minute (Note 5). The solution is allowed to reflux until the rate of carbon dioxide evolution slows to about 5 bubbles per minute. This will usually take 25-30 minutes (Note 6). The mixture is then cooled in an ice bath, and the precipitate is removed by filtration. The residue on the funnel is washed with carbon tetrachloride, and the filtrates are combined. The solvent is removed by distillation using a modified Claisen distillation apparatus with a 6-cm. Vigreux column, and vacuum distillation of the residual oil gives 13-17 g. (35-46%) of... 

Apparatus 1-1 two-necked flask connected to a 40-cm Vigreux column, condenser and receiver on the other neck of the flask is placed a dropping funnel. 

Apparatus 1 -1 round-bottomed flask, which is connected to a distillation system consisting of a 30-cm Vigreux column, condenser and receiver, cooled at -78 C (fig. 14). 

Apparatus 1-1 round-bottomed, three-necked flask, equipped with a dropping funnel, a mechanical stitrer and a 40-cm Vigreux column, connected to a condenser and a receiver, cooled at -20 C stirring is carried out at a moderate rate all connections should be made gas-tight. 

Into a 3-L three-neck round-bottom flask equipped with a thermometer, a KPG stirrer and a 20-cm Vigreux column linked to a distillation apparatus with three cooled traps (MeOH/dry ice) were placed rw-4.5-(thiocarbonyldioxy)spiro[2.3]hexane (50 98.2 g, 0.63 mol) and freshly distilled tributyl phosphite (472 g, 1.89 mol). The mixture was heated at 115 120 0C/17 Torr for 44 h. The condensed distillates in the traps were combined, dried over 4 A molecular sieves and fractionally distilled through a 40-cm Vigreux column to give the product 51 yield 40 g (80%) bp 66.5 nC (760 Torr). 

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