Prepn from butyryl chloride: Brown, Tsukamoto, J. Am. Chem. Soc. 83, 2016 (1961); by reduction of corresponding nitrile: Gaiffe, Pallaud, Compt. Rend. 254, 496 (1962); by alkali aluminum hydride reduction of methyl butyrate: Zakharkin et al., Tetrahedron Lett. 1963, 208; by oxidation of butanol: Harrison, Proc. Chem. Soc. London 1964, 110. Usually manuf by catalytic dehydrogenation of butanol, catalytic hydrogenation of crotonaldehyde, or by the oxo process from propene, e.g., see: Dunbar, Arnold, J. Org. Chem. 10, 501 (1945); Horn, Ind. Eng. Chem. 51, 655 (1959); W. L. Faith et al., Industrial Chemicals (John Wiley, New York, 3rd ed., 1965) pp 183, 304-305. Toxicity study: Smyth et al., Arch. Ind. Hyg. Occup. Med. 4, 119 (1951). Review: P. D. Sherman in Kirk-Othmer Encyclopedia of Chemical Technology vol. 4 (Wiley-Interscience, New York, 3rd ed., 1978) pp 376-386.