A Manual of the Chemistry of the Carbon Compounds

THE OABBON COMPOUNDS. 81
These monobasic acids have been called fatty acids, because many
of them occur ready formed in different fats and oils. The hydroxyl
of these acids can be replaced by the elements of the chlorine group.
Thus by acting with phosphorus trichloride upon acetic acid, we
obtain acetyl uhloride:—
0 ) + PCI, -
The chlorides of the acid radicals differ from those of the alcohol
radicals by being less stable compounds ; they are rapidly acted upon
by water with the formation of the original fatty acid aud hydrochloric
acid.
The hydrogen in the hydroxyl group can also be replaced by alcohol
radicals as well as by metals; the compounds thus formed are named
saline or compound ethers. These ethers may be formed by different
reactions. Thus ethyl acetate may be obtained—
(1) By heating potassium acetate with ethyl chloride :—
(2) By acting upon ethyl alcohol with acetyl chloride:—
(3) By distilling a mixture of ethyl alcohol and sulphuric acid with
potassium acetate:—
The oxides of the acid radicals, commonly called anhydridei, are
also known. Tims we obtain acetyl oxide or acetic anhydride by
acting with acetyl chloride upon potassium acetate:—
These anhydrides are readily acted upon by water, thus:
By acting on fatty acids with phosphovns pontasulphide we obtain
so-called thio-acids:—
0 ) + P2S6= 5 ( C * H *° } S ) + P2O
P2O6
These thio-acids are also monobasic, and form salts, saline ethers,
anhydrides, &c.:—
CHOI .
2 ',. b Putassmni Thiacetate
a