This is found in fusel oil, especially in that from potato-spirit, and is separated by fractional distillation. It may be obtained pure by first preparing the iodide from the separated alcohol, since the iodide can be more readily purified by distillation than can the alcohol itself. The iodide is then re-converted into the alcohol by the methods already described. Alternatively, isobutyric aldehyde may be reduced with sodium amalgam to give the alcohol.

Isobutyl alcohol boils at 108.4°, and has the sp. gr. 0 8020 at 20°/4°, or 0.80624 at 15.6o/15.6°. It is a colourless liquid with an odour of fusel oil, soluble in 10.5 parts of water, and mostly thrown out of solution again by addition of calcium chloride or common salt. Its index of refraction μβ = 14007. Its azeo-tropic mixture with water boils at 89.92°, and contains 66.80 per cent. of the alcohol by weight. (Young and Fortey, loc. cit.)

1 Compt rend., 1918, 166, 632.

2 "Treatise on Chemistry," III, 1881, 581.