Organic Syntheses, CV 4, 665
Submitted by Milton J. Rosen
1
Checked by R. T. Arnold and William K. Witsiepe.
1. Procedure
In a
500-ml. three-necked round-bottomed flask fitted with a mechanical stirrer and a reflux condenser are placed
50 g. (0.48 mole) of styrene (Note
1) and a previously cooled solution of
100 ml. of concentrated sulfuric acid in 150 ml. of water. The mixture is stirred vigorously (Note
2) and heated under reflux in an
oil bath for approximately 4 hours.
Without interrupting stirring or heating,
50 ml. of concentrated sulfuric acid is added slowly through the condenser, and the mixture is stirred and heated for an additional 12 hours (Note
3).
The reaction mixture is cooled, cautiously poured into 250 ml. of cold water with stirring, and allowed to separate into layers. The upper hydrocarbon layer is removed, and the lower layer is extracted with three
50-ml. portions of ether. The combined
ether extracts and hydrocarbon layer are washed successively with about
30 ml. each of a saturated solution of sodium bicarbonate, water, and a saturated solution of
calcium chloride, and then dried over
anhydrous calcium chloride. The
ether is removed by distillation, and the product is distilled under reduced pressure. The yield of
1-methyl-3-phenylindane, b.p.
168–169°/16 mm. (Note
4),
n20D 1.5811 ± 0.0005, is
38.5–40.5 g. (
77–81%) (Note
5).
2. Notes
1. Commercial
styrene, distilled from a
water bath at about 80–100 mm. pressure just before use, is employed.
2. It is essential to use an efficient stirring device, capable of forming a dispersion of the
styrene in the acid layer.
3. The
sulfuric acid is added in two portions in order to minimize higher-polymer formation.
2
4. The product also distils at
150–151°/6.5 mm.
3. Discussion
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