Butyl Alcohols

Butyl Alcohols 

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