CHAPTER VI.
COMPLEX NON-ELECTROLYTES.IN this chapter are brought together a number of different kinds of sub-
stances, many of them containing organic radicals, and all of them showing
very little, if any, tendency to undergo electrolytic dissociation. The ability
of these substances to dissociate otherwise than electrolytically is slight, and
most of them can, like many of the pure organic compounds, be distilled with-
out undergoing decomposition. It is characteristic of them, however, that in
the presence of water they suffer hydrolysis (saponification) instead of elec-
trolytic dissociation (cf. p. 60). Here, as in the case of organic substances, it
is permissible to develop structural formulas, and thus the probable structure
of the products of hydrolysis can be derived. For example, it is possible to
deduce the structure of certain inorganic acids from the graphic formulas of
their chlorides and esters. Cf. Cyanic Acid, p. 113; Oxy-acids of Sulphur,
p. 126; Acids of Phosphorus p. 135.
ACID CHLORIDES.- Sulphuric Acid Dichloride (Sulphuryl Chloride), SO 2 C1 2 , and
Sulphuric Acid Monochloride (Chlorosulphonic Acid), HO.SO 2 C1.
By the term add chloride is understood a substance which is converted
into an oxy-acid when its chlorine atoms are replaced with hydroxyl groups.
Sulphuryl chloride, SO 2 C1 2 is the chloride of sulphuric acid:
SO 2 C1 2 + 2 H 2 O = SO 2 (OH) 2 + 2 HC1.
It is produced by the direct union of sulphur dioxide and chlorine in the sun-
light; the combination takes place more readily, however, in the presence of
catalyzers such as anhydrous acetic acid, porous charcoal, or, most efficient
of all, camphor.
Sulphuric acid monochloride is formed by the partial hydrolysis of sul-
phuryl chloride, but it can also be prepared from sulphuric acid and phos-
phorus pentachloride by a reaction which is of very general applicability.
Phosphorus pentachloride acts upon substances which contain hydroxyl in
such a way that phosphorus oxychloride, hydrogen chloride, and a chloro-
substitution product of the original material are formed:
R.OH + PC1 5 = RC1 + POC1 3 + HC1
In certain cases the phosphorus oxychloride itself also acts as a chlorinating
agent.
201