Org. Synth. 1945, 25, 69
DOI: 10.15227/orgsyn.025.0069
METHYL ω-CYANOPELARGONATE
[Pelargonic acid, θ-cyano-, methyl ester]
Submitted by W. S. Bishop
Checked by C. F. H. Allen and J. VanAllan.
1. Procedure
Caution! Tetrachloroethane is toxic; the operations should be conducted in a hood.
In a
1.5-l. Erlenmeyer flask to which is attached a
reflux condenser,
190 g. (0.88 mole) of methyl sebacamate (p. 613) is dissolved in
200 ml. of boiling tetrachloroethane. The solution is allowed to cool to 40–50°
(Note 1),
95 g. (0.67 mole) of phosphorus pentoxide is added
(Note 2), and the mixture is stirred well by means of a
glass rod. The mixture is heated in an
oil bath to 120° (
thermometer in oil), and a second
95-g. portion of phosphorus pentoxide is added. After the mixture has been heated at 145° for 30 minutes with occasional hand stirring, the liquid is decanted. The residue is heated at 145° with
200 ml. of tetrachloroethane for 30 minutes with occasional stirring, and the liquid is decanted. This process is repeated once. The combined extracts are placed in a
1-l. flask, and most of the solvent is distilled under the reduced pressure of a
water pump. The residue is transferred to a
300-ml. flask, and the remainder of the solvent is removed
(Note 3). When no more distillate comes over, the
receiver is changed, the water pump is replaced by an
oil pump, and the residue is fractionated
(Note 4). The yield of
methyl ω-cyanopelargonate boiling at
121–124°/1 mm. (Note 5) is
119–124 g. (
69–71%).
2. Notes
1.
The slush that results on cooling is easily mixed with the
phosphorus pentoxide.
2.
The
phosphorus pentoxide is weighed rapidly on a piece of paper, from which it can be slid quickly into the flask.
3.
About
550–560 ml. of tetrachloroethane is recovered. Ground-glass equipment is preferable for the distillations.
4.
There is no fore-run. At 1 mm., the thermometer reads about 118° when the first drop appears at the end of the side tube of the distilling flask. There is a
5- to 6-g. fraction, b.p.
124–135°/1 mm., and some residue.
5.
Other boiling points are
154°/5 mm. and
170°/14 mm.
3. Discussion
Methyl ω-cyanopelargonate has also been prepared by esterification of
ω-cyanopelargonic acid with
methyl sulfate1 or
methanol,
2 and by dehydration of
methyl sebacamate with
phosphorus pentoxide3 or
thionyl chloride.
4 The procedure described appears in the literature.
1,3
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Pelargonic acid, θ-cyano-, methyl ester
methanol (67-56-1)
thionyl chloride (7719-09-7)
methyl sulfate (75-93-4)
tetrachloroethane (630-20-6)
Methyl ω-cyanopelargonate (53663-26-6)
Methyl sebacamate (53663-35-7)
ω-CYANOPELARGONIC ACID (5810-19-5)
phosphorus pentoxide (1314-56-3)
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