Org. Synth. 1962, 42, 34
DOI: 10.15227/orgsyn.042.0034
CYCLOHEXANONE DIALLYL ACETAL
Submitted by W. L. Howard and N. B. Lorette
1.
Checked by E. J. Corey and R. A. E. Winter.
1. Procedure
A solution of 294 g. (3 moles) of cyclohexanone, 343 g. (3.3 moles) of acetone dimethyl acetal, 418 g. (7.2 moles) of allyl alcohol, 1 l. of benzene, and 0.2 g. of p-toluenesulfonic acid monohydrate (Note 1) is distilled using a good fractionating column until the acetone and the benzene-methanol azeotrope are completely removed (Note 2). The solution is cooled below the boiling point, and a solution of 0.5 g. of sodium methoxide in 20 ml. of methanol is added all at once with stirring (Note 3). Distillation is resumed, and unreacted allyl alcohol and benzene are removed at atmospheric pressure and then at reduced pressure (Note 4). Distillation is continued at a pressure in the range 5–20 mm. to remove forerun (on the order of 100 ml.) (Note 5). The cyclohexanone diallyl acetal, b.p. 84°/5 mm., 98°/10 mm., 114°/20 mm., nD25 1.4600, is then collected. The yield is 382–435 g. (65–74%). A small amount of higher-boiling residue remains.
2. Notes
1.
Commercial
acetone dimethyl acetal and allyl alcohol from The Dow Chemical Company and
cyclohexanone from Eastman Kodak Company were used without further treatment.
2.
These reaction products distil within a narrow range. The head temperature was maintained in the range 56–59°. About 750 ml. of distillate is collected, depending on the efficiency of fractionation. The combined amount of
methanol and
acetone may be estimated by washing an aliquot of the distillate with 2 volumes of water and taking the difference between the original volume and that of the residual
benzene as the volume of
methanol-acetone. Usually this is about 450 ml. The distillation should be as rapid as possible to avoid the formation of by-product
2-allylcyclohexanone. A
1.9 × 120 cm. vacuum-jacketed, silvered column packed with 0.25-in. glass helices and fitted with a vapor-dividing head controlled by a timed relay was used.
The checkers used a 1.3 × 92 cm. vacuum-jacketed, silvered column packed with 0.25-in. glass ring chains. With this column it was necessary to carry out the distillation of benzene-acetone-methanol using reflux ratios varying from 2:1 initially to 11:1 at the conclusion. The use of a shorter column is not satisfactory.
3.
Other soluble, non-volatile bases may be used to neutralize the acid. The reactants may be kept at room temperature safely after addition of base.
4.
An azeotrope of
benzene and
allyl alcohol distils at about 77°, followed by
benzene. When the temperature in the boiling flask reaches 120–130°, the pressure is reduced and the remaining
benzene is taken to a
cold trap.
5.
The forerun contains some
acetone diallyl acetal and about
35–40 g. of
2-allylcyclohexanone, b.p.
78°/10 mm.
3. Discussion
Cyclohexanone diallyl acetal has been prepared from
cyclohexanone and
allyl orthosilicate2 and by the above procedure.
3
4. Merits of Preparation
The preparation given here is operable for a large number of ketone acetals, including those formed from both primary and secondary alcohols and from alcohols and ketones containing other functional groups which are stable under the conditions used.
3This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
benzene-methanol azeotrope
Benzene (71-43-2)
methanol (67-56-1)
Cyclohexanone (108-94-1)
Allyl alcohol (107-18-6)
acetone (67-64-1)
sodium methoxide (124-41-4)
2-Allylcyclohexanone (94-66-6)
methanol-acetone (590-90-9)
acetone dimethyl acetal (77-76-9)
Cyclohexanone diallyl acetal (53608-84-7)
benzene-acetone-methanol
acetone diallyl acetal
allyl orthosilicate
p-toluenesulfonic acid monohydrate (6192-52-5)
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