Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

TBTKAPHBNYLHYDKAZINB 355
sibly as a complex ion with SO2). Such a solution does not exhibit the
typical band spectrum and does not react with oxygen. Consequently
the sharp distinction between radicle and ion exists here in the same way
as is known, for instance among the metals, between atom and ion.
The triphenylmethyl ion is also, very probably, present in the orangeyellow
products of the salt and complex salt type which are produced
from triphenylcarbinol with concentrated sulphuric acid and from
triphenylchloromethane with metallic chlorides (ZnCl2, A1C13, 8nCl4,
SbClg).
Experiment.-—Dissolve a few granules of triphenylcarbinol or of
triphenylchloromethane in 0-5 c.c. of concentrated sulphuric acid by
rubbing with a glass rod. Add a little water: the deep orangeyellow
solution is completely decolorised. Simultaneously the
unchanged carbinol is precipitated.
In the same way the above-mentioned complex salts of triphenylchloromethane
are readily decomposed by water. In both cases a
hydrolysis occurs which causes the triphenylmethyl ion to lose its
charge, and the carbinol to be re-formed.
The formation from neutral substances (triphenylcarbinol) of
coloured, salt-like reaction products which are more or less easily decomposed
by water is a phenomenon called " halochromism ". The halochromic
salts of triphenylcarbinol are regarded as carbonium salts :
this follows at once from the above discussion. A quinonoid formula,
by which various authors explain the colour, seems less probable.
Recently the attempt has been made to attribute complex formulae to
the carbonium salts (Hantzsch), in accordance with Werner's scheme
for ammonium salts. Such formulae express the fact that, in the ion,
the charge is not localised at the methane carbon atom, but spread over
the field of force of the whole radicle. The simplest carbonium salt
of the group, the yellow perchlorate (K. A. Hofmann), would accordingly
have the following structural formula :
rc6H5.c.c6H5i OC1O
L C6H5 J
8. TETRAPHENYLHYDRAZINE
Diphenylamine (34 g., 0-2 mole) is dissolved in 200 c.c. of pure
acetone in a bottle (capacity about 400 c.c.) having a well-fitting
glass or rubber stopper. (Commercial acetone is usually stable
towards permanganate. If not, add powdered potassium permanganate
until the colour persists even on boiling the mixture for
about half an hour under reflux, then distil. Acetone so treated is