Experimental

A mixture of 90.1g (1 mole) 1,4-butanediol, 4g of copper chromite catalyst and 0.15g of powdered reagent grade sodium hydroxide (or better KOH) was stirred vigorously and heated under reflux. At about 200°C, a lively evolution of hydrogen occurred, and the temperature dropped about 10°C and the dehydrogenation proceeded smoothly. The evolution of hydrogen gas (2 molar equivalents per mole of 1,4-butanediol reacted, on this 1 mole scale this equals 0.39 m³) ceased in about 3h. The reaction mixture was cooled to room temperature, filtered from the catalyst and distilled under reduced pressure to give gamma-butyrolactone in about 80% yield and unreacted 1,4-butanediol in about 10% yield.