Whilst the alcohols, as already stated, are neutral bodies, they have some resemblance to bases on the one hand, and to acids on the other. Thus they react with acids to form esters, or ethereal salts, e.g., C2H5.O.N.O2, ethyl nitrate; also the alkali metals react with the alcohols, giving the alcoholates, for example C2H5.ONa, sodium alcoholate or ethylate. In the first case, the hydrogen atom of

1 Ber., 1909, 42, 2675; Abst. Analyst, 1909, 34, 410.

The OH-group itself can be replaced by halogens, most readly by using the halogen compounds of phosphorus: -

C2H5OH + PC15 = C2H5C1 + POCI3 + HC1.

In the case of the iodides, phosphorus and iodine can be used instead of the phosphorus iodide, as already shown in connection with the distinction of the primary, secondary, and tertiary alcohols from one another.

The boiling points of the normal alcohols increase regularly with the increase of the molecular weights; the difference for each increment of CH1 in the formula being about 20° as we pass from ethyl alcohol upwards: -

Name.

Formula.

B.p.

Methyl alcohol ...........................

CH3.OH

66°

Ethyl

"' ..............................

C2H5.OH

78

Propyl

" ..............................

C3H7.OH

97

Butyl

" ..............................

C4H9.OH

117

Amyl

" ..............................

C5H11.OH

137

Hexyl

" ..............................

C6H13.OH

157

The primary alcohols boil at a higher temperature than the secondary alcohols that are isomeric with them. Similarly, the latter have higher boiling points than their tertiary isomerides. (Ex., primary butyl alcohol, b.p. 117°; secondary butyl alcohol, b.p. 100°; tertiary butyl alcohol, b.p. 83°.)

As regards obvious properties, the lower alcohols, from methyl to butyl, are mobile liquids; the intermediate members are of a more viscous, oily character (fusel "oil"); and the higher alcohols, containing twelve carbon atoms and upwards, are solids at the ordinary temperature (dodecatyl alcohol, C12H15OH, melts at 24°). Up to and including the propyl alcohols, they are miscible with water in all proportions. The butyl alcohols are only partly miscible with water, and from the amyl members upwards the solubility diminishes rapidly. All the alcohols are colourless or slightly yellow; the lower members have a characteristic spirituous smell, the intermediate ones are unpleasant, and the solid alcohols are odourless and tasteless. They are all lighter than water The higher alcohols decompose, on distillation, into water and hydrocarbons.