154 PRACTICAL ORGANIC CHEMISTRY Required: Benzophenone, 2 g.; aluminium isopropoxide, 2-5 g.; isopropanol, 20 ml. The powdered isopropoxide and the isopropanol must be dried as described above. This experiment requires a 50 ml. flask attached by a ground-glass neck or a rubber bung (not a cork) to an efficient fraction-ating column. This may be of the type shown in Fig. U(B) (p. 26) with at least 4 inches of column packed with glass rings, and without external lagging: or a less efficient type of column, for example, one similar to that shown in the micro-model, Fig. 39 (p. 64), in which the column is 6-8 inches high. A water-condenser is fitted to the column. Place in the flask 2 g. of benzophenone, 15 ml. of isopropanol and 2-5 g. of aluminium isopropoxide. This mixture has now to be heated gently under reflux so that the temperature regis-tered by the thermometer in the column does not exceed 80°, i.e., so that only acetone distils. For this purpose, the flask should preferably be heated in an oil-bath: direct heating, even
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