Org. Synth. 1944, 24, 84
Submitted by Richard Weiss
Checked by C. F. H. Allen and F. P. Pingert.
A solution of phenylmagnesium bromide
is prepared in the usual manner1
from 11 g. (0.45 gram atom) of magnesium
, 75 g. (0.48 mole) of bromobenzene
, and 175 ml. of ether
. As soon as the metal has reacted, a solution of 58.4 g. (0.4 mole) of α-tetralone
in 60 ml. of ether
is added from a dropping funnel
as rapidly as possible so that vigorous refluxing is maintained; about 30 minutes is required. The reaction mixture is then heated under reflux for an additional 30 minutes and allowed to stand for 1 hour. The magnesium complex is decomposed by about 250 g. of ice and 40 ml. of concentrated hydrochloric acid
. The ether
layer is separated and distilled with steam to remove impurities (Note 1)
; about 6 hours is necessary, and approximately 4.5 l. of distillate is collected. The heavy residual oil is separated from the water, and 80 ml. of ether
and 10 g. of calcium chloride
are added. After 4–5 minutes, the calcium chloride
is removed by filtration, and the ether
is driven off by distillation on a steam bath
. Twenty milliliters of acetic anhydride
is then added, and the flask and contents are heated in a steam bath (Note 2)
for 20–25 minutes. The mixture is finally distilled under reduced pressure through a 15-in. Widmer column (Note 3)
. The fraction which boils at 135–140°/2 mm.
is collected; the yield is 35–40 g.
B. 1-Phenylnaphthalene. A mixture of 6 g. (0.18 mole) of powdered sulfur and 35 g. (0.17 mole) of 1-phenyldialin in a 200-ml. Claisen flask having a modified side arm is heated for 30 minutes in a metal bath the temperature of which is 250–270° (Note 4). At the end of this time the evolution of hydrogen sulfide will have ceased. The heavy oil (Note 5) is then distilled from the same flask; the yield is 32–33 g. (91–94%); the boiling range of the product is 134–135°/2 mm. or 189–190°/12 mm. (Note 6) and (Note 7)"/>.
Steam distillation removes unused bromobenzene
The reaction is best carried out in a 500-ml. Erlenmeyer flask or beaker
which can be lowered into the steam pot and held by a cloth wrap.
If a fractionating column
is not used, several distillations are necessary to secure a product with the boiling range given. When this distillation is done as described, subsequent operations are facilitated, and a column is not required for the final distillation of the hydrocarbon. Ebullition tubes are desirable in both distillations.
The temperature inside the flask should be 250°.
Significant amounts of hydrocarbon are lost with each change of flask. For this reason it is advisable to perform the dehydrogenation and distillation in the same flask.
Sometimes the hydrocarbon is blue, probably owing to traces of an azulene
. The contaminant is easily removed by dissolving the hydrocarbon in an equal volume of hexane or petroleum ether
and shaking this solution with an equal volume of 85% syrupy phosphoric acid
until the color has been removed. The hydrocarbon is then obtained on evaporation of the solvent; it does not need redistillation.
The over-all yield is 40%
, based on the α-tetralone
has been prepared by the reaction of α-halonaphthalenes with mercury diphenyl2
or with benzene
in the presence of aluminum chloride
and by means of a Grignard synthesis, starting with either bromobenzene
, or cyclohexyl chloride
or with α-bromonaphthalene
A 60% over-all yield has been reported for the Grignard preparation from cyclohexanone
The formation of the hydrocarbon through the diazo reaction8,9,10,11
appears to be less attractive than the method described. Dehydrogenation of the reduced naphthalene
has been accomplished by the use of sulfur
,5 platinum black
, or selenium
Chemical Abstracts Nomenclature (Collective Index Number);
calcium chloride (10043-52-4)
hydrochloric acid (7647-01-0)
acetic anhydride (108-24-7)
hydrogen sulfide (7783-06-4)
aluminum chloride (3495-54-3)
phosphoric acid (7664-38-2)
cyclohexyl chloride (542-18-7)
Phenylmagnesium bromide (100-58-3)
Naphthalene, 1-phenyl- (605-02-7)
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