colorless liquids with a characteristic alcohol odor. Four isomers of butyl alcohols are known: namely, (I) normal primary butyl alcohol (1-butanol), CH3CH2CH2CH2OH; (II) normal secondary butyl alcohol (2-butanol), CH3CH2CH(OH)CH3; (III) isobutyl alcohol (2-methylpropanol-l), (CH3)2CH—CH2OH; and (IV) tertiary butyl alcohol (trimethylcarbinol), (CH3)3COH.
Butyl alcohols I and II contain nonbranching chains of carbon atoms. Butyl alcohol II contains an asymmetric carbon atom (indicated by an asterisk) and therefore exists in three forms, two of which are visibly active and the third, inactive or racemic. The physical properties of all butyl alcohols are similar to some extent (see Table 1). Butyl alcohol I is obtained both by the fermentation of carbohydrates (such as glucose and starch) and by synthesis. Butyl alcohol II is formed during the hydration of pseudobutylene (β-butylene) in the presence of sulfuric acid:
CH3CH=CHCH3 + H2O → CH3CH2CH(OH)CH3
In combination with other alcohols, butyl alcohol III is obtained from a mixture of CO and H2. Butyl alcohol IV is formed during the hydration of isobutylene:
(CH3)2C=CH2 + H2O (CH3)3COH
Butyl alcohols I, II, and III are used as solvents of nitrocellulose lacquer, ethyl cellulose, and others: 1-butanol is used to obtain esters, such as dibutyl phthalate; butyl alcohol IV is used to obtain artificial musk and to synthesize detergents.
| Table 1. Some physical characteristics of butyl alcohols | |||||
|---|---|---|---|---|---|
| Alcohol | Melting point(°C) | Boiling point(°C) | Density at 4°C(g/cm)3 | Index of retraction (nD20) | Solubility (g/100 g of water) |
| I | -79.9 | 117.4 | 0.8099 | 1.3993 | 9(15°C) |
| II | -114.7 | 99.5-100 | 0.8060 | 1.3949 | 12.5 (20°C) |
| III | -108 | 107.5 | 0.8027 | 1.3878 | 10 (15°C) |
| IV | 25-25.5 | 82.9 | 0.7887 | 1.3954 | unlimited |