A Manual of the Chemistry of the Carbon Compounds

TEE CARBON COMPOUNDS, 269
Another monochlorocrotonio acid, melting at 94°, and boiling at
about 208°, is formed, together with the isotneric monochloroquartenic
add, by acting with phosphorus pentachloride on ethyl acetonecarbonate
(so called diethylacetic acid); ethyl ohloride and hydrochloric
acid are given off, and the residue contains besides phosphorus
oxychloride, the chlorides of the two acids. On distilling it with
water, monochloroquartenic acid, being the most volatile, distils first;
it is an oily liquid, wliioh with sodium amalgam and water yields
quurknic add C^HgOj, an oily liquid smelling like butyric acid, and
boiling at 172". On fusing it with potash it yields, like crotonic acid,
only acetic acid.
Tetrolic Add C.H40g is produced by digesting the second monochloTOcrotonic
acid with potash •:—
C4H6C1O2 = HC1 + C4H4O8
It crystallizes in deliquescent, colourless, transparent, rhombic
plates, melting at 76°'5, and boiling at 203°. The first modification
of inonochlorocrotonic acid is not acted upon by potash.
Methwrylys Add C4H0O2.—The ethyl-ether of this third isomeric
acid is obtained by treating ethyl oxy-kobutymte with, phosphorus
trichloride. The acid is an oily liquid which by fusion with caustic
potash is resolvedinto carbon dioxide and propionic acid :—
CH8
CH3
=CH, + 8K0H = OH, + ILCO, + 2H,
CO.OH CO.OK
An-gelic Add C5H802 is found, together with acetic acid and
valerianic acid, in tlie root of Angelica Anhangdica and other
mnbelliferce. The root is boiled with milk of lime, and the concentrated
nitrate distilled with sulphuric acid. The distillate after
being neutralized with soda-crystala is evaporated, and the counentrated
liquid again distilled with snlphuric acid. On allowing the filtrate to
stand for some time, angelic acid separates out in large crystals.
After the acid lias been purified by crystallization it melts at 45°,
and boils at 191°^; it possesses a peculiar, aromatic odour.
By fusion with caustic potash it is resolved into noetic acid and
propionic acid; and by heating with hydriodic acid aod phosphorus
to 200°, it is converted into valerianio acid.
Angdicaldehyde C6H.O is contained, together with a hydrocarbon
C1OHW, in the oil of chamomile (Antliemis nohilis). It has not yet
been obtained in a pure state, as the hydrocarbon cannot be separated
by distillation, and the aldehyde does not form crystalline compounds
with the acid sulphites of the alkali-inetals. When the oil is heated
with caustic potash the hydrocarbon volatilizes, and potassium angelate
is formed :—
C.H,0 + KOH = C,H7KO.? + R,