By Bromination of Tetrahydronaphthalene

The tetrahydronaphthalene is placed in a flask fitted with a dropping funnel and a delivery tube. Dry air should be bubbled through the liquid for at least 30 minutes to remove water. If water is present, the yields of gaseous hydrogen bromide will be greatly lowered. The bromine 

Submitted by John M. Schneiderf and W. C. Johnsont Checked by Charles SlobutskyJ and L. F. AudriethI 

Apparatus. A pyrex tube D, 50 cm. in length and 4 cm. in diameter (Fig. 29), is filled with approximately 300 g. of platinized silica gel packed at each end with a plug of glass wool. The catalyst tube is wrapped with asbestos paper and placed in the electric furnace E. The tube is drawn down at each end, and a 200-ml. distilling flask B 

Analysis of the water solution in two experiments gave a yield of 93 per cent of the theoretical, corresponding to a conversion of 46.5 per cent of the bromine used to hydrobromic acid. 

The distilling flask is fitted with a dropping funnel C, the stem of which reaches well below the side arm, and an inlet tube, extending to the bottom of the flask. Rubber stoppers may be used for the flask and funnel connections, 

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