Org. Synth. 1961, 41, 30
DOI: 10.15227/orgsyn.041.0030
4,6-DIMETHYL-1-HEPTEN-4-OL
[1-Hepten-4-ol, 4,6-dimethyl-]
Submitted by Dietmar Seyferth and Michael A. Weiner
1.
Checked by Melvin S. Newman and Clifford Y. Peery.
1. Procedure
A solution of 50 g (0.127 mole) of allyltriphenyltin (Note 1) and (Note 2) in 200 ml. of diethyl ether (Note 3) is prepared in a 1-l. three-necked flask fitted with a reflux condenser, a motor-driven glass sleeve-type stirrer, nitrogen-inlet tube, and a 250-ml. dropping funnel with pressure-equalizing side arm. After the system has been flushed thoroughly with prepurified nitrogen, 113 ml. of a 1.13N solution of phenyllithium (0.127 mole) in diethyl ether (Note 4) is added rapidly to the stirred allyltriphenyltin solution. Precipitation of tetraphenyltin occurs immediately, and the reaction mixture is stirred for 30 minutes in an atmosphere of prepurified nitrogen. Through the dropping funnel is then added 12.0 g. (0.12 mole) of 4-methyl-2-pentanone (Note 5) in 25 ml. of diethyl ether at such a rate that moderate reflux is maintained. Subsequently the reaction mixture is refluxed for 1 hour, allowed to cool to room temperature, and hydrolyzed by adding 100 ml. of distilled water (Note 6). The solid tetraphenyltin is filtered (53.5 g. = 98% yield), and the filtrate is transferred to a separatory funnel. The aqueous layer is separated and extracted with three 30-ml. portions of ether. The ethereal extracts and the organic layer are combined and dried over anhydrous magnesium sulfate. After removal of the ether by distillation at atmospheric pressure, the residue is filtered through a sintered-glass funnel into a 250-ml. distilling flask and fractionally distilled at reduced pressure using a vacuum-jacketed Vigreux column equipped with a still head of the total-condensing, partial-takeoff type. 4,6-Dimethyl-1-hepten-4-ol, b.p. 70–71°/20 mm., nD20 1.4403, is obtained in 70–75% yield (12.0–12.8 g.) (Note 7).
2. Notes
1.
Allyltriphenyltin is prepared as follows. To a
3-l. three-necked flask fitted with a reflux condenser, a motor-driven stirrer, nitrogen-inlet tube, and a 1-l. dropping funnel with pressure-equalizing side arm are added
50 g. (2.1 g. atom) of magnesium turnings and
800 ml. of diethyl ether (Mallinckrodt reagent grade). The dropping funnel is charged with a solution of
120 g. (1.0 mole) of allyl bromide (Eastman Kodak white label) and
250 g. (0.65 mole) of triphenyltin chloride (Metal Thermit Corporation) in
600 ml. of tetrahydrofuran (Electrochemicals Department, E. I. du Pont de Nemours and Company, Inc.) which has been freshly distilled from
lithium aluminium hydride. This solution is added to the vigorously stirred, refluxing
magnesium suspension during 7 hours. After the addition is complete,
500 ml. of dry benzene is added and the reaction mixture is refluxed overnight at 60°. It is then hydrolyzed by careful addition of
150 ml. of a saturated ammonium chloride solution. The organic phase is decanted from the solids, and the latter are washed twice with
ether. The combined organic layer and ethereal extracts are evaporated at reduced pressure with the aid of a
rotary evaporator. The solid residue is recrystallized from
350 ml. of ligroin. The yield of product, m.p.
73–74°, is
190–205 g. (
75–80%).
Allyltriphenyltin can also be prepared by using the reaction of preformed
allylmagnesium bromide with
triphenyltin chloride.
2 However, the submitters prefer the simpler procedure described above for large-scale preparations of allyltin compounds.
2.
Tetraallyltin,
triallylphenyltin, and
diallyldiphenyltin may be used in place of
allyltriphenyltin.
3.
The
diethyl ether used is Mallinckrodt reagent grade and is distilled from
lithium aluminum hydride before use.
4.
Ethereal
phenyllithium, prepared from
lithium and
bromobenzene,
3 may be standardized by adding an aliquot to water and titrating with standard
sulfuric acid.
5.
The
4-methyl-2-pentanone used is Eastman Kodak white label grade.
6.
The first few milliliters of water should be added dropwise.
7.
The reported
4 physical constants for
4,6-dimethyl-1-hepten-4-ol are b.p.
68–69°/20 mm.,
nD20 1.4402.
3. Discussion
This procedure is essentially that reported previously.
5 4,6-Dimethyl-1-hepten-4-ol has also been prepared by the reaction between
allylmagnesium bromide and
4-methyl-2-pentanone,
4 by the treatment of
magnesium with a mixture of
allyl bromide and
4-methyl-2-pentanone,
6,7 and by the treatment of
zinc with a mixture of
allyl iodide and
4-methyl-2-pentanone.
84. Merits of Preparation
The present synthesis of
4,6-dimethyl-1-hepten-4-ol is an example of the preparation and use of
allyllithium. The same general procedure may be used to prepare
vinyllithium from ether solutions of any of the compounds (CH
2=CH)
nSn(C
6H
5)
4−n(
n = 1–4),
9 and
benzyllithium from any of the (C
6H
5CH
2)
nSn(C
6H
5)
4−n (
n=1–4) compounds.
10Allyllithium is of particular value in the preparation of allylmetal derivatives.
5 Allyllithium may also be prepared by transmetalation between
phenyllithium and
tetraallyltin11 or by cleavage of
allyl phenyl ether with
lithium in
tetrahydrofuran.
12
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ligroin
sulfuric acid (7664-93-9)
Benzene (71-43-2)
ether,
diethyl ether (60-29-7)
ammonium chloride (12125-02-9)
magnesium (7439-95-4)
Allyl bromide (106-95-6)
nitrogen (7727-37-9)
allyl iodide (556-56-9)
zinc (7440-66-6)
bromobenzene (108-86-1)
4-methyl-2-pentanone (108-10-1)
Phenyllithium (591-51-5)
lithium (7439-93-2)
magnesium sulfate (7487-88-9)
Tetrahydrofuran (109-99-9)
lithium aluminum hydride,
lithium aluminium hydride (16853-85-3)
Allylmagnesium bromide (1730-25-2)
4,6-Dimethyl-1-hepten-4-ol,
1-Hepten-4-ol, 4,6-dimethyl- (32189-75-6)
Allyltriphenyltin (76-63-1)
tetraphenyltin (595-90-4)
triphenyltin chloride (639-58-7)
Tetraallyltin (7393-43-3)
triallylphenyltin
diallyldiphenyltin (10074-32-5)
Allyllithium
vinyllithium (917-57-7)
benzyllithium
allyl phenyl ether (1746-13-0)
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