Organic Syntheses, Coll. Vol. 4, p.108 (1963); Vol. 38, p.8 (1958).
The residue is transferred to a 125-ml. Claisen flask
modified so that the distilling arm carries an 18 × 180 mm. section packed with glass helices. Nitrogen
is led into the capillary, and, after a forerun of 1–3 g.
, there is collected 28–31 g.
) of 4-bromo-2-heptene
, b.p. 70–71°/32 mm.
1.4710–1.4715 (Note 5)
. A residue of 7–10 g.
remains in the distilling flask (Note 6)
The 2-heptene was the pure grade material purchased from Phillips Petroleum Company, Bartlesville, Oklahoma
. This olefin is comparable to material prepared by a Boord synthesis. The N-bromosuccinimide was obtained from Arapahoe Chemicals, Inc., Boulder, Colorado
. The benzoyl peroxide was used as received from Distillation Products, Rochester, New York
. The carbon tetrachloride was reagent grade, from J. T. Baker Chemical Company, Phillipsburg, New Jersey
The reaction is not rapid, and benzoyl peroxide
is necessary to effect reaction. Longer reflux times lead to darkening of the reaction mixture.
recovered corresponded to 97–98%
of the theoretical amount and analyzed for 0.4% active bromine
Removal of the carbon tetrachloride
at a lower pressure results in loss of product. Distillation at a pressure much above 200 mm. causes considerable darkening of the liquid. Carbon tetrachloride
removed at the higher pressure gives no precipitate with aqueous silver nitrate
; this indicates the absence of product.
When first distilled, the product is nearly colorless. On standing under nitrogen
in the refrigerator for several days, the material acquires a pale yellow color. Evidence for the identity of the product as 4-bromo-2-heptene
is outlined in Reference 2
This includes the liquid wetting the helices as well as the small amount of dark residue in the flask.
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