Page 8 - A TEXTBOOK OF ORGANIC CHEMISTRY

2 INTRODUCTION
oxygen, also stand in a closer relationship to each other than
do the compounds of the other elements. Partly upon grounds
of convenience, carbon itself and some of its principal com-
pounds, such as carbonc acid, which is so widely distributed
i
in the mineral kingdom, are treated of under Inorganic
Chemistry.
The expressions " organic " and " organized" substances
should not be confused; organized substances, e.g. leaves,
nerves and muscles, and also the life-processes which go on
in the interior of the organism, are treated of under Physiology
and Bio-chemistry.
Of the numerous carbon compounds actually known (some
350,000) relatively few are found in the vegetable or animal
kingdom, the large majority are laboratory products syn-
thetic products. Most of the products dealt with in the major
industries, e.g. aniline dyes, synthetic drugs, explosives,
synthetic plastics are not found in nature. In the early days
the compounds isolated from the vegetable and animal king-
doms were analysed, their molecular weights determined if
possible, their reactions studied and structural formulae allo-
cated and the final process was the confirmation of such
formulae by synthesis in the laboratory, and, in later years,
the development of synthetical methods for manufacturing
the compounds on the large scale so that in many cases the
synthetic products replaced the naturally occurring compounds.
Examples of this will be referred to in the case of alizarin
and indigo. There are, however, numerous natural products
which so far have not been obtained synthetically, e.g. the
complex compounds starch and cellulose and the simple
compound cane sugar, In the latter case syntheses have been
described but are of no practical importance.
The chief sources for the preparation of synthetic products are:
I. Coal, which when subjected to destructive distillation,
yields as one of the products coal tar, from which benzene,
naphthalene, phenol, anthracene can be isolated, and these
are the materials from which dyes, drugs and explosives are
manufactured (cf. Chap. LIX and LXV).
2. Crude petroleum, now used as the source for manufacture
of halides, alcohols, &e. (Chap. I, A.).
3. Cellulose, used for the manufacture of artificial silk,
plastics, explosives, &o.
4. Starch. for alcohol, butyl alcohol, acetone, &o.