Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

TKIPHBNYLCHLOKOMBTHANB 347
of 80 g. of pure dry carbon tetrachloride and 200 g. of benzene. At
first the flask is kept cool with water and the reaction is not allowed
to become too violent. The copious fumes of hydrogen chloride are
absorbed as described in similar cases, e.g. in the preparation of
bromobenzene (p. 103). When all the aluminium chloride has been
added and the main reaction is over, the mixture is heated under
reflux on the boiling water bath for half an hour longer and the
brownish-yellow reaction mixture, after cooling, is poured, with
constant shaking, into a sufficiently large separating funnel containing
a mixture of 100-200 g. of ice with 200 c.c. of concentrated
hydrochloric acid. If the ice melts before the whole of the mixture
has decomposed, more ice and an equal amount of concentrated
hydrochloric acid are added. The purpose of the hydrochloric acid
is to prevent the hydrolysis of the triphenylmethyl chloride. When
the two layers of liquid in the funnel have separated—perhaps after
the addition of fresh benzene—the aqueous portion is removed, and
extracted again, if necessary, with benzene. The combined benzene
solutions are dried with calcium chloride and then as much benzene as
•possible is evaporated on the water bath. The residue is digested
with an equal volume of ether and cooled for some hours in ice.
Then the crystalline sludge is filtered at the pump on a wide filter
plate and the solid, after being pressed down well, is washed several
times with a little ice-cold ether. A second, less pure, crop of
crystals is obtained by concentrating the mother liquor (ultimately
in vacuo), digesting the residue with a little cold ether, and filtering
at the pump. Yield 110-120 g.
For purification the still yellow crude product is dissolved in very
little warm benzene, four volumes of light petrol are added, and
crystallisation is induced by cooling in ice and stirring with a glass
rod. The crystals are washed with cold petrol ether.
Distillation in a high vacuum also yields a very pure preparation
(Lecher).
5. 2 : 4-DIHYDR0XYACET0PHEN0NE FROM RESORCINOL AND
ACETONITRILE x
Finely powdered anhydrous zinc chloride (2 g.) is added to a
solution of 5-5 g. of resorcinol and 3 g. of acetonitrile in 25 c.c. of
absolute ether, the mixture is kept cool in ice and saturated with
hydrogen chloride. After standing for some hours in a closed vessel
1 K. Hoesch, Ber., 1915, 48 .11221 1917, 50, 462.