Org. Synth. 1950, 30, 5
DOI: 10.15227/orgsyn.030.0005
p-AMINOTETRAPHENYLMETHANE
[p-Toluidine, α,α,α-triphenyl-]
Submitted by Benjamin Witten and E. Emmet Reid
1.
Checked by Richard T. Arnold and Jerome J. Rosenbaum.
1. Procedure
Into a 1-l. round-bottomed flask equipped with a reflux condenser are introduced 100 g. (0.385 mole) of technical grade triphenylcarbinol (Note 1), 105 g. (0.81 mole) of dry aniline hydrochloride (Note 2), and 250 ml. of glacial acetic acid. The mixture is heated at the reflux temperature for 3 hours. During the period of reflux a clear brown homogeneous solution is formed. The solution while still hot is poured with stirring into a 4-l. beaker containing 2 l. of water. p-Aminotetraphenylmethane hydrochloride, which is not very soluble in water, separates as a light-brown solid. It is collected on a Büchner funnel and washed with 1 l. of water. The solid is then put back into the beaker, and a solution of 40 g. of sodium hydroxide in 2 l. of water is added. The mixture is heated to boiling for 1 hour to convert the hydrochloride to the free base (Note 3), which likewise is not very soluble in water. The mixture is allowed to cool to room temperature and is filtered with suction through a Büchner funnel. The solid material is washed with 500 ml. of water and is dried in an oven at 110–120°. The crude substance melts at 243–247°. It is purified by crystallization from 1.7 l. of toluene. The purified product (90–95 g., 70–74%) melts at 249–250° (Note 4).
2. Notes
1.
Technical grade triphenylcarbinol is satisfactory, provided it is dry. The checkers obtained a final product having a higher melting point by starting with
Eastman Kodak Company purest grade triphenylcarbinol.
2.
The
aniline hydrochloride must be dry if a good yield of product is to be obtained.
Aniline hydrochloride can be prepared conveniently by mixing
75 g. of aniline and
80 ml. of concentrated hydrochloric acid in an
evaporating dish and evaporating to dryness. The
aniline hydrochloride should be dried in an oven at 110–120° before use.
Aniline hydrochloride (Merck) which has been washed with
ether and dried at 110–120° can be employed satisfactorily.
3.
The mixture tends to bump during the period of heating. This bumping can be overcome by stirring the solution mechanically.
4.
A product melting at
256–257° (uncor.)
2 was obtained by the checkers
(Note 1).
3. Discussion
The procedure given is similar to one described by Ullmann and Münzhuber,
2 except that one-half as much
aniline hydrochloride and two-thirds as much glacial
acetic acid are used, and the time of reflux is reduced from 6 to 3 hours.
p-Aminotetraphenylmethane can be prepared from
triphenylchloromethane and
aniline hydrochloride, following the same procedure outlined for
triphenylcarbinol and
aniline hydrochloride, except that a reaction time of 1 hour is sufficient. It has been prepared also from
triphenylchloromethane and
aniline.
3
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
hydrochloric acid (7647-01-0)
acetic acid (64-19-7)
ether (60-29-7)
aniline (62-53-3)
sodium hydroxide (1310-73-2)
aniline hydrochloride (142-04-1)
toluene (108-88-3)
Triphenylchloromethane (76-83-5)
Triphenylcarbinol (76-84-6)
p-Aminotetraphenylmethane,
p-Toluidine, α,α,α-triphenyl- (22948-06-7)
p-Aminotetraphenylmethane hydrochloride
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