Org. Synth. 1954, 34, 56
DOI: 10.15227/orgsyn.034.0056
HEMIMELLITENE
[Benzene, 1,2,3-trimethyl-]
Submitted by W. R. Brasen and C. R. Hauser
1.
Checked by William S. Johnson, Donald W. Stoutamire, and A. L. Wilds.
1. Procedure
A 3-l. round-bottomed three-necked flask, fitted with a reflux condenser and a sealed stirrer, is charged with 2 l. of hot water and 100 g. (0.33 mole) of 2,3-dimethylbenzyltrimethylammonium iodide (Note 1). The stirred suspension is heated on the steam bath, and 2760 g. of 5% sodium amalgam (Note 2) is added in 200- to 250-g. portions over a period of 45 minutes. Stirring and heating are continued for 24 hours; then the mixture is steamdistilled until no more oily material comes over. The distillate (1–1.5 l.) is extracted with three 50-ml. portions of ether. The combined extracts are washed with 50 ml. of 10% hydrochloric acid and 50 ml. of saturated sodium chloride solution, and dried over anhydrous calcium chloride. After removal of the ether by distillation, the residue is distilled from a Claisen flask, giving 33.5–35.5 g. (85–90% yield) of colorless hydrocarbon, b.p. 171–174°. On redistillation 85–90% of the material distils at 173–174°, nD25 1.5116–1.5120.
2. Notes
1.
The methiodide is prepared from
2,3-dimethylbenzyldimethylamine according to the procedure for producing the lower homolog (
p. 587, Notes 5 and
8).
2.
The
sodium amalgam is prepared in a
1-l. filter flask fitted with a
two-hole rubber stopper carrying a
dropping funnel and an
outlet tube. The flask is charged with
138 g. (6 g. atoms) of sodium and 300 ml. of mineral oil. With a stream of
nitrogen passing through the side arm of the flask, the flask is heated on a hot plate covered with an asbestos pad until the
sodium melts, and then
2622 g. of mercury is added rapidly from the dropping funnel over a 1–2 minute period with swirling. The whole operation is carried out in a large pan to catch material in case of breakage. A vigorous exothermic reaction occurs, and the hands must be adequately protected with several layers of cloth or heavy gloves as the temperature approaches 400°. If the addition is rapid enough, the amalgam will be a liquid; otherwise the material will be partially solid and must be heated vigorously to produce a homogeneous melt. The mineral oil is decanted from the molten amalgam, which is poured into a shallow metal pan while still warm and is cut or broken (with a hammer) into small pieces as it solidifies. It is finally washed with
petroleum ether and stored in a tightly
stoppered bottle or under
petroleum ether.
3. Discussion
Hemimellitine has been prepared by the action of
sodium on
2,3-dimethyliodobenzene and
methyl iodide,
2 by the reduction of the chloromethylation product of
o-xylene,
3 by the catalytic hydrogenolysis of
2,3-dimethylbenzyl alcohol,
4 and by treatment of
1,5,5,6-tetramethyl-1,3-cyclohexadiene with a catalyst prepared from
sodium and
o-chlorotoluene.
5 The present procedure is based on the method of Kantor and Hauser.
6
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
petroleum ether
calcium chloride (10043-52-4)
hydrochloric acid (7647-01-0)
ether (60-29-7)
sodium chloride (7647-14-5)
nitrogen (7727-37-9)
mercury (7439-97-6)
sodium (13966-32-0)
o-Chlorotoluene (95-49-8)
Methyl iodide (74-88-4)
Hemimellitene,
Benzene, 1,2,3-trimethyl-,
Hemimellitine (526-73-8)
2,3-dimethylbenzyltrimethylammonium iodide
2,3-dimethylbenzyldimethylamine (15848-75-6)
2,3-dimethyliodobenzene (31599-60-7)
2,3-dimethylbenzyl alcohol (13651-14-4)
1,5,5,6-tetramethyl-1,3-cyclohexadiene
o-Xylene (95-47-6)
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