Org. Synth. 1959, 39, 75
Submitted by George Wittig1
Checked by John D. Roberts, M. C. Caserio, E. S. Johnson, and L. Skattebøl.
A 200-ml. three-necked flask, equipped with a ball-and-socket sealed mechanical stirrer, a pressure-compensated dropping funnel, and a reflux condenser connected to a mercury bubbler (Note 1), is charged with 0.8 g. (0.033 g. atom) of magnesium turnings, 7.5 g. (0.042 mole) of anthracene, and 35 ml. of anhydrous tetrahydrofuran (Note 2). In the dropping funnel there is placed a solution of 5.26 g. (0.03 mole) of o-fluorobromobenzene (Note 3) in 15 ml. of tetrahydrofuran. The system is flushed with dry nitrogen for 30 minutes to remove air. The gas flow is then stopped in order to prevent extensive loss of tetrahydrofuran. The mixture is heated to and maintained at 60° (bath temperature), and one-quarter of the o-fluorobromobenzene solution is added with stirring. The appearance of a yellow color which evidences the start of reaction may not be observed immediately, and another quarter of the solution is then added dropwise over a period of about 45 minutes. When the reaction commences, the remaining solution is added dropwise over a period of 1 hour, after which the mixture is refluxed gently for 90 minutes. The almost homogeneous dark-brown mixture is poured into 100 ml. of methanol, which precipitates much of the unreacted anthracene. Without filtering, the solvents are removed under reduced pressure and the yellow residue is treated with two 50-ml. portions of 5% hydrochloric acid, filtered, and vacuum-dried. The dry, yellow residue (10 g.) is dissolved in 45 ml. of hot xylene, then 5.0 g. (0.051 mole) of maleic anhydride is added. The mixture is refluxed for 20 minutes and set aside at room temperature for 2 hours. The maleic anhydride-anthracene adduct (about 9 g.) is removed by filtration, and the brown filtrate is refluxed for 2 hours with 80 ml. of 2N sodium hydroxide solution. When cool, the organic layer is separated, washed three times with 50-ml. portions of water (Note 4), and dried over calcium chloride. The solvent is removed at reduced pressure. The brown residue is dissolved in 70 ml. of carbon tetrachloride and chromatographed on 280 g. of acid-washed alumina, using 1 l. of the same solvent to elute. After evaporation of the solvent, there remains 2.4–2.9 g. of a yellow residue which is digested with two 10-ml. portions of pentane (Note 5). The residual crude triptycene is an almost white crystalline solid of melting point 240–248°. The yield is 2.14 g. (28%) (Note 6). Recrystallization of this material from cyclohexane gives pure white crystals of melting point 255–256°.
The mercury bubbler seals the system from the air. It is connected to the top of the reflux condenser
by means of 8-mm. glass tubing more than 76 cm. high. The pressure in the system may be varied by adjusting the depth of the lower end of the tube. A constant stream of dry nitrogen
may be substituted for the mercury
bubbler, but this inevitably results in some loss of tetrahydrofuran
may be purified by distillation from lithium aluminum hydride
o-Fluorobromobenzene as supplied by the Aldrich Chemical Company, Milwaukee, Wisconsin
, may be used without further purification.
Small amounts of sodium chloride
may be added to facilitate separation of the phases.
The main impurity is a yellow oil which is readily soluble in pentane
The checkers report a yield of 1.35–1.68 g.
) of triptycene
of melting point 245–255°
has been prepared by Bartlett and co-workers2
in a seven-step synthesis. It also has been obtained by the reaction of fluorobenzene
in the presence of butyllithium3
and by the reduction of the anthracene-benzoquinone
adduct with lithium aluminum hydride
or sodium borohydride
The present method has been published.5
This preparation is referenced from:
Chemical Abstracts Nomenclature (Collective Index Number);
maleic anhydride-anthracene adduct
calcium chloride (10043-52-4)
hydrochloric acid (7647-01-0)
sodium hydroxide (1310-73-2)
magnesium turnings (7439-95-4)
sodium chloride (7647-14-5)
carbon tetrachloride (56-23-5)
maleic anhydride (108-31-6)
lithium aluminum hydride (16853-85-3)
sodium borohydride (16940-66-2)
9,10-o-Benzenoanthracene, 9,10-dihydro- (477-75-8)
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