From Freifelder:
... the pattern seen in the hydrogenation of succinic anhydride. Reduction with copper chromite at 250° and 200 atm gave only 29% of butyrolactone because of the severe conditons (66a). Under more moderate conditions hydrogenation with palladium on carbon or on alumina in ethyl acetate at 35-100° and 16-75 atm gave an 80-94% yield of lactone (66b). Reduction at atmospheric pressure (65) or at 2-3 atm (2) required a large amount of platinum oxide, 10-15% by weight. Some butyric acid was obttained in addition to the butyrolactone.
2. Unpublished work by the author.
65. McCrindle, Overton, Raphael, J. Chem. Soc., 1962, 4798.
66. (a) Wojcik and Adkins, J. Am. Chem. Soc., 55, 4939 (1933); (b) Franco-Filipasic, Koyler and Borks, Jr., U.S. Patent 3,113,138 (1963)