A Manual of the Chemistry of the Carbon Compounds

352 THE CHEMISTRY OF
DIOXVTOLUKKfiS.
Homopyrooatcchin and Creosote.—The genuine or wood-tdr creosote is
obtained from the products of dry distillation of beech-wood, and is a
mixture containing phenol, creso}, phlorol CLHJCHJjOH, guaiacol
(page 342), and creosol C6H8(CHj) j QQJJ . Creosol is a liquid boiling
at 219°, and possessing an aromatic odour; by heating it with concentrated
hydriodic acid, it yields methyl iodide, and hompyrocatechin
(OH
C6H8(CHj) \ 0H, whioh forms a syrupy liquid.
( O1T
Orcm CgH^CHg) J Q^.—All the lichens (species of Bocella and
Lecanora) which are used in the preparation of archil and litmus
contain either free orcin, or certain acids, and compound ethers, which,
under the influence of heat or alkalis, yield orcin i—
Orsellinio Acid.
CjH^CHgXOHyJOjjH = CeHgtCHjXOHJjj + COa
Erythrin.
C0Ha(CH,)(OH)2CO.O)
OreoUinic Acid. Etythrito.
2C0Ha(CH8)(OH)2COaH + C4H6(OH)4
= CJH^CH^COHJJCOJH + C4l
To prepare orcin, the lichens are macerated with milk of lime, and
the filtrate preoipitated with hydrochloric acid. The precipitate, after
being washed with water, is boiled with milk of lime in a flask
provided with a long neck, and the liquid, after nitration, freed from
the lime by carbon dioxide. The solution is then evaporated to
dryness, and the residue exhausted with benzene, whioh dissolves
orcin, and leaves impure erythrit© beMnd,
Oroin has also been produced by dissolving monochlorotoluene in
warm concentrated sulphuric acid, and converting the two isomerio
sulphonio acids, which thus are formed, into the barium salts, whioh
are easily separated by re-crystallization, one being readily soluble in
water, and the other not. On converting the latter into potassium salt,
and fusing this with potash, orcin is formed;—
C0H,(CH8) { fOaK + 2K0H = C0H8(CH3) { gg + KC1 + KaS0
Orcin is also produced together with para-oxybenzoic acid, when
aloes is fused with caustic potash.
Orcin crystallizes from water in monocliuic prisms containing one