Org. Synth. 1970, 50, 77
DOI: 10.15227/orgsyn.050.0077
ETHYL 1-NAPHTHYLACETATE
[1-Naphthaleneacetic acid, ethyl ester]
Submitted by Ving Lee and Melvin S. Newman
1.
Checked by Gordon F. Hambly and Peter Yates.
1. Procedure
A.
1-(Diazoacetyl)naphthalene. A solution of
30.5 g. (0.160 mole) of 1-naphthoyl chloride (Note 1) and
(Note 2) in
50 ml. of dry diethyl ether (Note 3) is added over 30 minutes to a magnetically stirred, ice-cooled solution of
6.72 g. (0.160 mole) of diazomethane [
Org. Synth., Coll. Vol. 2, 165 (1943);
(Note 4)] and
16.1 g. (0.160 mole) of dry triethylamine (Note 5) in
900 ml. of dry ether. The mixture is stirred for 3 hours in the cold, and the
triethylamine hydrochloride, removed by filtration, is washed twice with
30–50 ml. portions of dry ether (Note 6). The
ether is removed from the combined filtrate and washings on a
rotary evaporator. The yellow solid residue is dissolved in
75 ml. of dry ether, and the solution is cooled with an acetone–dry-ice mixture. The solid deposited is collected by filtration on a
glass fritted-disk funnel, and the adhering
ether is removed under reduced pressure as the temperature is allowed to reach room temperature, giving
26.6–28.8 g. (
85–92%) of yellow
1-(diazoacetyl)naphthalene, m.p.
52–53° (Note 7) and
(Note 8).
B. Ethyl 1-naphthylacetate. A solution of 15.7 g. (0.0801 mole) of 1-(diazoacetyl)naphthalene in 50 ml. of absolute ethanol is placed in a 100-ml., two-necked flask equipped with a Teflon-coated magnetic stirring bar, a serum stopper cap, and a reflux condenser connected to a gas-collecting device. The solution is heated to reflux, and 1 ml. of a freshly prepared catalyst solution made by dissolving 1 g. of silver benzoate (Note 9) in 10 ml. of triethylamine is added by injection through the serum cap. Evolution of nitrogen occurs and the mixture turns black. Addition of a second milliliter of catalyst solution is made when the evolution of nitrogen almost stops. This procedure is continued until further additions cause no further evolution of nitrogen (Note 10). The reaction mixture is refluxed for 1 hour, cooled, and filtered. The solvents are removed from the filtrate on a rotary evaporator. The residue is taken up in 75 ml. of ether, and the solution is washed twice in turn with aqueous 10% sodium carbonate, water, and saturated brine. Each aqueous extract is extracted with ether, and the combined ethereal extracts and solution are dried by filtration through anhydrous magnesium sulfate. After removal of the ether, distillation affords 14.4–15.8 g. (84–92%) of colorless ethyl 1-naphthylacetate, b.p. 100–105° (0.1–0.2 mm.) (Note 11).
2. Notes
1.
The submitters prepared pure
1-naphthoyl chloride, b.p.
95–96° (0.2 mm.), from pure
1-naphthoic acid in
95% yield by treatment with
thionyl chloride or
phosphorus pentachloride. The
1-naphthoic acid used was prepared by carbonation of
1-naphthylmagnesium bromide. As commercial
1-bromonaphthalene is impure, fractionation through a
17 × 600 mm. column is needed to obtain pure
1-bromonaphthalene, b.p.
105–108° (0.1–0.2 mm.), as indicated by GC.
2.
The checkers prepared
1-naphthoyl chloride by treatment of
1-naphthoic acid, m.p. 157–161°, obtained from Aldrich Chemical Co., with
phosphorus pentachloride.
3.
All dry
ether used was freshly distilled from
ethylmagnesium bromide.
4.
Solutions of
diazomethane in
ether were titrated with
benzoic acid.
5.
Triethylamine was dried by storage over anhydrous
barium oxide.
6.
About 90% of the theoretical yield of
triethylamine hydrochloride is obtained.
7.
This compound is a severe skin irritant; hence, great care should be exercised to avoid any contact. For best yields this crystallization is recommended, since the yield of
ethyl 1-naphthylacetate is reduced by about 20% if the crude product is used in the rearrangement step. A sample of crystallized
1-(diazoacetyl) naphthalene, m.p.
52–53°, that had been stored in a screw-top bottle in a refrigerator for about 2 weeks afforded the same yield of
ethyl 1-naphthylacetate as a freshly prepared sample.
8.
The checkers obtained
26.1–26.5 g. (
83–84.5%) of
1-(diazoacetyl) naphthalene, m.p.
47–49.5°, when
1-naphthoyl chloride prepared from commercial
1-naphthoic acid was used (cf.
(Note 1) and
(Note 2)). Recrystallization from
hexane gave
24.6 g. (
78%) of
1-(diazoacetyl)naphthalene, m.p.
49.5–52°, that was used in Part B.
9.
The
silver benzoate was made by reaction of
silver nitrate with
sodium benzoate in water. The submitters dried the
silver benzoate and recrystallized it from
N-methylpyrrolidone or
N,N-dimethylformamide. The checkers dried it in an
oven at 130° for 1 hour immediately before use, but did not recrystallize it. Any precipitate present after dissolving the
silver benzoate in
triethylamine is removed by filtration or centrifugation.
10.
Usually 3–4 additions are required. The total time of reaction should not be more than 45 minutes. The checkers added the catalyst solution in 0.5-ml. portions;
nitrogen evolution was initially very vigorous, and only four such additions were required.
11.
When
propanol is used instead of
ethanol, comparable results are obtained:
propyl 1-naphthylacetate, b.p.
115–118° (0.1–0.2 mm.).
3. Discussion
Ethyl 1-naphthylacetate has been prepared by ethanolysis of
1-naphthylacetonitrile under acidic conditions
2 and by the Arndt-Eistert reaction of
1-(diazoacetyl)naphthalene with
ethanol and
silver oxide.
3
The method described here represents a modified Arndt-Eistert reaction as developed by Newman and Beal,
4 gives results that are more reproducible than those of the original Arndt-Eistert reaction and, in general, allows the rearrangement to be carried out successfully on larger-scale runs. The use of
triethylamine in the formation of diazo ketones makes possible the use of only one equivalent of
diazomethane.
5This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
brine
ethanol (64-17-5)
ether,
diethyl ether (60-29-7)
phosphorus pentachloride (10026-13-8)
thionyl chloride (7719-09-7)
silver oxide (20667-12-3)
silver nitrate (7761-88-8)
sodium carbonate (497-19-8)
barium oxide
nitrogen (7727-37-9)
Benzoic acid (65-85-0)
sodium benzoate (532-32-1)
1-bromonaphthalene (90-11-9)
propanol (71-23-8)
Triethylamine hydrochloride (554-68-7)
ethylmagnesium bromide (925-90-6)
magnesium sulfate (7487-88-9)
Diazomethane (334-88-3)
1-Naphthoic acid (86-55-5)
1-naphthoyl chloride (879-18-5)
N,N-dimethylformamide (68-12-2)
hexane (110-54-3)
triethylamine (121-44-8)
N-methylpyrrolidone (872-50-4)
Ethyl 1-naphthylacetate (3121-70-8)
1-Naphthaleneacetic acid, ethyl ester (2122-70-5)
1-(diazoacetyl) naphthalene,
1-(Diazoacetyl)naphthalene (4372-76-3)
silver benzoate (532-31-0)
1-naphthylmagnesium bromide
propyl 1-naphthylacetate
1-naphthylacetonitrile (132-75-2)
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved