This alcohol does not appear to occur in fusel oil, or not in appreciable quantity. It was first obtained by Berthelot in 1855 from propylene and sulphuric acid, and somewhat later (1862) Friedel prepared it from acetone by the action of sodium amalgam and water. A modern method of using acetone for the purpose is to pass a mixture of acetone vapour and hydrogen over catalytic nickel heated to 115 - 125°. Chemically, the alcohol is best prepared from isopropyl iodide, itself obtained by distilling glycerine with hydriodic acid and amorphous phosphorus. These give first allyl iodide: -

C3H5(OH)3 + 3HI = C3H6I + 3H1O + I2.

1 Compt. rend., 1853, 37, 410. 2 Ann. Chem. Pharm., 1868, 148, 251.

3 Young andFortey, Traits. Chem. Soc, 1902, 81, 735.

With excess of hydriodic acid, this passes into isopropyl iodide: -

C3H5I + 2HI = C3H7I +12.

On boiling the isopropyl iodide under a reflux condenser with 10 parts of water and some freshly-prepared lead hydroxide, the isopropyl alcohol is produced, and may be distilled off and concentrated by dehydration and re-distillation. It is a colourless, mobile liquid with a spirituous odour, having the sp. gr. 07897 at 15.6°/l5-6° (07887 at 20°/4°), and boiling at 827°. According to Erlenmeyer, it forms a hydrate, 2C3H8O,H1O, which boils constantly at 80° and has the same percentage composition as ethyl alcohol. Young and Fortey (loc. cit.) give the boiling point of the constant-boiling mixture as 80.37°, the percentage of alcohol being 87.90, by weight.

Isopropyl alcohol in a mixture may be determined quantitatively by oxidising it to acetone with potassium bichromate and sulphuric acid. The acetone is distilled off' after neutralising the mixture, and estimated by Messinger's method, as described under "wood naphtha."

Butyl alcohols, C4H9 OH. Mol. wt,, 74 08.

Four isomers are theoretically possible, two of which are primary, one secondary, and one tertiary (see p. 115).

(1) Normal butyl alcohol (n-Fropyl carbinol; 1-butanol),

CH8(CH1)2CH1OH, has been found in the fusel oil of brandy, and is formed by the fermentation of glycerol with certain bacteria. Together with acetone, it is also formed in the fermentation of starch solutions with special cultures of micro-organisms (Fernbach's process); but is not produced in the fermentation of sugar brought about by elliptical yeast.1 It may be obtained by adding sodium amalgam gradually to an aqueous solution of normal butyl aldehyde, kept slightly acid with dilute sulphuric acid. The alcohol is then distilled off, and concentrated as usual. Butyric acid and butyryl chloride also yield the alcohol on reduction with sodium amalgam. It is a colourless, highly refracting liquid, with a peculiar irritating odour. At 0° it has the sp. gr. 08233, or 0.8099 at 20°/4°. It boils at 117.2° (Bruhl)2 or at 116.8° (Richter).

Butyl alcohol burns with a luminous flame. It is soluble in 12 parts of water at 22°, and is separated from its aqueous solutions by addition of calcium chloride. Its index of refraction μa = 1.39909.

1 Claudon and Morin, J. Chem. Soc, 1887, 52, 714.

2 Annalen, 1880, 203, 10.

Sabatier and Gaudion have recently shown that normal butyl alcohol can be obtained from paraldehyde, which itself may be produced synthetically from calcium carbide. (See Chap. II.) The aldehyde is " crotonised " by passing it over thorium, titanium, or uranium oxide at about 360°. On separating the product into two fractions, (1) of b. p. 90 - 130°, and (2) of b. p. 130 - 220°, and passing these separately with hydrogen over hot reduced nickel, the first fraction yields normal butyl alcohol, and the second normal hexyl alcohol. The nickel catalyst is heated to 170 - 180° for the first fraction, and to about 200° for the second.1