Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

ATOPHAN. PHENYLGLYCINE 369
a-phenylquinoline-y-carboxylic acid, is the product of an analogous
condensation of aniline with benzaldehyde and pyruvic acid :
NH2
N
O:CH.C6H5 -+ /\/\c.C6Hs
O:C."COOH C.COOH
Atophan can also be obtained by alkaline condensation of isatin
with acetophenone. (Formulate.)
The CH3-group in quinaldine, like that of ketones, can condense
with aldehydes and similar substances. With phthalic anhydride
the yellow dye quinophthalone is formed.
3. INDIGO
Phenylglycine. 1 —Chloroacetic acid (19 g.) is exactly neutralised in
the cold with 100 c.c. of 2i\f-sodium hydroxide solution, 18-6 g. of
aniline are added, and the mixture is boiled for a short time under
reflux until the aniline has reacted and dissolved. On cooling, the
phenylglycine separates as an oil which soon crystallises when
rubbed. The crystalline material is kept cool in ice for some time,
collected at the pump, and washed with a little ice-cold water.
Yield 22-24 g. of dry substance.
In order to prepare the potassium salt, 20 g. of phenylglycine
are made exactly neutral to phenolphthalein with 2 i\f-potassium
hydroxide solution (about 70 c.c. are required), and the clear solution
is then evaporated to dryness on the water bath. For the indoxyl
fusion the residue of salt must be dried in an oven at 100° for several
hours.
Indoxyl Fusion. 2 —A mixture of 15 g. of sodium hydroxide and
20 g. of potassium hydroxide is fused and carefully dehydrated by
heating to about 500° in a nickel crucible. When the mass has
barely solidified it is just remelted by gentle heating and poured into
a Jena glass conical flask (capacity 100 c.c.) which is at a temperature
of 220° in an oil bath. If this procedure is adopted there need be no
fear that the glass will crack.
Sodamide (10 g.) is added to the melt in the flask and dissolves
with slight evolution of ammonia. The pure potassium phenylglycine
(20 g.) which has been completely dried at 100° in an oven is
1 J. Houben, Ber., 1913, 47, 3988.
2 According to directions supplied by Dr. J. Pfleger, Frankfurt a. M.
2B