Organic Syntheses, CV 4, 786
Submitted by R. L. Shriner and Philip R. Ruby
1.
Checked by Richard T. Arnold, W. E. Parham, and John E. Franz.
1. Procedure
In a
2-l. round-bottomed flask, fitted with a
reflux condenser and
mechanical stirrer, are placed
675 g. (8.3 moles) of 37% formalin,
48 g. of sulfuric acid (sp. gr. 1.84), and
312 g. (3 moles) of styrene. The resulting mixture is gently refluxed and stirred for 7 hours. The mixture is cooled, and
500 ml. of benzene is stirred in. The layers are separated, and the aqueous layer is extracted with
500 ml. of benzene. The
benzene solutions are combined and washed with two 750-ml. portions of water. The
benzene is removed by distillation, and the residual liquid is fractionated under reduced pressure. At 2 mm. pressure a forerun is collected separately, up to a temperature of 96° (Note
1); then the main fraction is collected at
96–103°/2 mm. The yield of
4-phenyl-m-dioxane amounts to
353–436 g. (
72–88%):
n20D 1.5300–1.5311:
d204 1.092–1.093 (Note
2).
2. Notes
1. The amount of fore-run and the yield depend on the efficiency of the fractionation. With a 7-cm. distilling head, a fore-run of
75 g. boiling at
84–96°/2 mm. was collected, whereas with a heated
Vigreux column (2 cm. by 35 cm.) the fore-run amounted to only
11 g. and the higher yields were obtained. The fore-run may be refractionated to obtain additional product. The checkers used a
2 cm. by 20 cm. column packed with stainless-steel helices, and collected their product (
72–75% yield) over a 1° boiling range (94–95°/2 mm.,
n20D 1.5300).
2. This modification of the Prins
2 reaction has been applied to other olefins.
3 The aryl olefins give the best yields; see the tabulation.
3. Discussion
This preparation is referenced from:
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