Org. Synth. 1943, 23, 55
DOI: 10.15227/orgsyn.023.0055
l-MENTHOXYACETYL CHLORIDE
[Acetyl chloride, (menthyloxy)-, l-]
Submitted by M. T. Leffler and A. E. Calkins.
Checked by R. L. Shriner and C. H. Tilford.
1. Procedure
A
1-l. three-necked round-bottomed flask is mounted on a steam cone and is fitted with a
250-ml. separatory funnel and a
reflux condenser connected to a trap
(Note 1) for absorbing gases. In the flask is placed
325 g. (198 ml., 2.73 moles) of thionyl chloride (Note 2), and to it is added, during the course of 1 hour,
125 g. (0.58 mole) of l-menthoxyacetic acid (p. 544). The flask is shaken frequently during the addition of the acid and, if necessary, is warmed to start the reaction. When all the acid has been added
(Note 3), the reaction mixture is refluxed gently for 5 hours. After the reaction is complete, the excess of
thionyl chloride is removed by distillation on the
steam bath (Note 4) and the residue is distilled under reduced pressure. The yield of
l-menthoxyacetyl chloride boiling at
117–120° /3 mm. (
120–125° /5 mm.),
[α]25D −89.6°, amounts to
115–118 g. (Note 5) (
85–87%). The product turns dark on standing; it should be stored in a
glass-stoppered amber bottle.
2. Notes
2.
The commercial grade (b.p.
74–78°) of
thionyl chloride was used.
3.
Owing to the high viscosity of the acid, it is desirable to rinse the separatory funnel with a little
thionyl chloride which is then added to the reaction mixture.
4.
The recovered
thionyl chloride may be redistilled for future runs. It is best to remove the last traces of
thionyl chloride by heating the crude product to about 140° under the vacuum of the
water pump.
5.
The submitters report the same yields (per cent) when twice the amounts of materials are used.
3. Discussion
The procedure given above is adapted from that described by Read and Grubb.
1 No other methods for the preparation of
l-menthoxyacetyl chloride have been described.
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
thionyl chloride (7719-09-7)
l-MENTHOXYACETIC ACID (40248-63-3)
L-Menthoxyacetyl chloride,
Acetyl chloride, (menthyloxy)-, l- (15356-62-4)
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