Org. Synth. 1959, 39, 54
DOI: 10.15227/orgsyn.039.0054
β-METHYL-β-PHENYLGLUTARIC ACID
[Glutaric acid, 3-methyl-3-phenyl-]
Submitted by S. M. McElvain and David H. Clemens
1.
Checked by W. E. Parham, Perry W. Kirklin, Jr., and Wayland E. Noland.
1. Procedure
In a
3-l. round-bottomed flask fitted with a small glass paddle stirrer and a reflux condenser are placed
101 g. (0.4 mole) of β-methyl-β-phenyl-α,α'-dicyanoglutarimide (
p. 662), and a mixture of 500 ml. of water,
500 g. of concentrated sulfuric acid, and
400 ml. of glacial acetic acid. Without starting the stirrer
(Note 1), the mixture is heated under reflux for 2 hours. Then the stirrer is cautiously started, and reflux is continued for a total of 80 hours. The reaction mixture is transferred to a
6-l. Erlenmeyer flask, 3 l. of water is added and the mixture cooled in a
refrigerator overnight. The precipitated acid is filtered by suction
(Note 2), washed with 100 ml. of water, and air-dried to constant weight. The crude, dry product is swirled for 5 minutes with
200 ml. of benzene, filtered by suction, washed with two
100-ml. portions of benzene, and again air-dried. The yield of acid, m.p.
136–140°, is
64.5–68 g. (
72.5–76.5%)
(Note 3) and
(Note 4).
2. Notes
1.
Use of the stirrer during the first 2 hours of the hydrolysis results in excessive foaming.
2.
In some runs a small amount of dark tar adhered to the side of the flask. This material was not isolated in the filtration.
3.
The product is pure enough for most purposes, but it may be further purified by recrystallization from water (100 ml. for 20 g. of acid) to give material melting at
140–142° in
95% yield.
4.
If the alkyl group of a β-alkyl-β-phenyl-α,α'-dicyanoglutarimide is larger than the methyl group, the hydrolysis to the corresponding glutaric acid should be modified as described by McElvain and Clemens,
J. Am. Chem. Soc.,
80, 3915 (1958).
3. Discussion
β-Methyl-β-phenylglutaric acid has been prepared by the hydrolysis of
β-methyl-β-phenyl-α,α'-dicyanoglutarimide with
sulfuric acid, and also by acid hydrolysis of the condensation product of
1,1-dichloroethylbenzene and
ethyl sodiomalonate.
2
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
β-METHYL-β-PHENYL-α,α'-DICYANOGLUTARIMIDE
sulfuric acid (7664-93-9)
acetic acid (64-19-7)
Benzene (71-43-2)
β-Methyl-β-phenylglutaric acid,
Glutaric acid, 3-methyl-3-phenyl- (4160-92-3)
1,1-dichloroethylbenzene
ethyl sodiomalonate
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