Org. Synth. 1951, 31, 40
DOI: 10.15227/orgsyn.031.0040
β,β-DIMETHYLGLUTARIC ACID
[Glutaric acid, 3,3-dimethyl-]
Submitted by Walter T. Smith and Gerald L. McLeod
1.
Checked by William S. Johnson and Donald D. Cameron.
1. Procedure
A solution of 218 g. (5.45 moles) of sodium hydroxide in 300 ml. of water in a 3-l. three-necked flask is cooled to room temperature. To this solution 1250 g. of ice is added, and a stream of chlorine is passed in rapidly through a delivery tube having a small opening and extending almost to the bottom of the liquid. The passage of the chlorine is continued until 161 g. (2.27 moles) has been absorbed. The flask is then fitted with a mechanical stirrer, a thermometer, and a 500-ml. separatory funnel.
Seventy grams (0.5 mole) of methone2 is dissolved in a solution of
65 g. (1.16 moles) of potassium hydroxide in 525 ml. of water. The solution is cooled to room temperature, poured into the separatory funnel, and run slowly with stirring into the
sodium hypochlorite solution. The temperature rises gradually to 35–40° during the addition. After the addition has been completed, the solution is stirred for 6–8 hours until the temperature drops to room temperature.
Without interrupting the stirring, 50 g. of sodium sulfite is added to decompose the excess sodium hypochlorite, and the solution is acidified to Congo red by adding concentrated hydrochloric acid slowly with stirring to avoid foaming. The acid solution is then concentrated by distillation until salts just begin to precipitate (Note 1).
The mixture is then cooled to room temperature, 300 ml. of ether and enough water are added to dissolve all of the precipitate, and the whole is transferred to a 3-l. separatory funnel. The layers are separated, and the aqueous portion is extracted with three 200-ml. portions of ether. The ether extracts are combined and dried for several hours over 15–20 g. of anhydrous magnesium sulfate. The ether is then removed by distillation. This may be conveniently carried out by fitting a 250-ml. Claisen flask with a separatory funnel in order to add the solution as the ether distils. When only 150–200 ml. of solution remains in the flask, the distillation is stopped and the residue is poured into a small beaker. The remaining ether is removed by heating on a steam bath, and the residue solidifies on cooling. The colorless, crystalline β,β-dimethylglutaric acid is dried in air. The yield is 73–77 g. (91–96%), m.p. 97–99°. Crystallization from 100–125 ml. of benzene gives 65–73 g. (81–91%) of acid, m.p. 100–102° (Note 2).
2. Notes
1.
The
chloroform formed in the reaction comes over during the early stages of this distillation. The precipitation of salts usually begins after the solution has been concentrated to about one-half the original volume.
2.
The melting points given in the literature are
101°,
3 101–102°,
4 103–104°,
5 and
98–100°.6
3. Discussion
β,β-Dimethylglutaric acid has been prepared by heating
dimethylpropanetricarboxylic acid above its melting point;
3 by hydrolysis of the condensation product of
ethyl cyanoacetate and
ethyl β,β-dimethylacrylate;
7 by the action of
sulfuric acid on
diethyl β,β-dimethyl-α,α'-dicyanoglutarate;
8 by hydrolysis of the nitrile obtained by the action of
calcium cyanide on
β,β-dimethylbutyrolactone;
4 by the action of
sulfuric acid on
β,β-dimethyl-α,α'-dicyanoglutarimide;
9 and by the action of
sodium hypobromite on
methone.
5 The present procedure is essentially that of Walker and Wood.
6
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
diethyl β,β-dimethyl-α,α'-dicyanoglutarate
β,β-dimethyl-α,α'-dicyanoglutarimide
sulfuric acid (7664-93-9)
hydrochloric acid (7647-01-0)
Benzene (71-43-2)
ether (60-29-7)
sodium sulfite (7757-83-7)
sodium hydroxide (1310-73-2)
chloroform (67-66-3)
chlorine (7782-50-5)
potassium hydroxide (1310-58-3)
Ethyl cyanoacetate (105-56-6)
calcium cyanide (592-01-8)
sodium hypochlorite (7681-52-9)
sodium hypobromite
magnesium sulfate (7487-88-9)
methone (126-81-8)
β,β-Dimethylglutaric acid,
Glutaric acid, 3,3-dimethyl- (4839-46-7)
dimethylpropanetricarboxylic acid
ethyl β,β-dimethylacrylate (638-10-8)
β,β-dimethylbutyrolactone
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