Procedure of 1,5-Pentanediol

Please place five hundred and ten grams (5 moles) of pure tetrahydrofurfuryl alcohol and 50 g of copper chromite in a hydrogenation bomb having a void of 1.4 L. The bomb, in a suitable rocker assembly, is filled with hydrogen to a pressure of 3300 to 3500 lb. per sq. in. The bomb is rocked and heated. The pressure must not at any time be allowed to go much above 6000 lb. per sq. in. If the pressure rises higher than 6200 lb., the heating of the bomb should be stopped. In a typical run, the pressure reaches a maximum of about 6100 lb. at 255 C after 2 hours. The pressure then slowly falls to about 4400 lb. during another hour, as the temperature rises to a little over 300 °C. During the ensuing 6 hours, the pressure falls to about 3000 lb. while the temperature is held at 300–310°C.
The bomb is allowed to cool to room temperature, where the pressure should be 1000–1100 lb. The contents of the bomb are poured into a beaker, and the bomb is rinsed twice with 100ml. portions of acetone. The catalyst is removed by centrifuging, and the reaction mixture is distilled through a fractionating column. A fraction boiling in the range 60–140°C, containing α-methyltetrahydrofuran, water, and n-amyl alcohol, is distilled at atmospheric pressure. Tetrahydrofurfuryl alcohol (80–110 g) is recovered, boiling at 65–70°C/10 mm.; the 1,5-pentanediol boiling at 118–120°C/6 mm. is obtained in amounts varying from 200 g to 244 g. The yield is 40–47% of the theoretical, without allowance being made for the recovered tetrahydrofurfuryl alcohol. The residue of products boiling above the glycol amounts to 25–35 g.