Organic Syntheses, CV 3, 60
Submitted by George H. Coleman and Herbert L. Johnson.
Checked by Reynold C. Fuson and E. A. Cleveland.
1. Procedure
The reduction is carried out in four cells of the type shown in
f.htmig. 2. Each cell consists of a
1-l. beaker (
B), a
porous cup (
P), a
mechanical stirrer, and
sheet lead electrodes (
E1 and
E2) each having a total surface area of 100 sq. cm. (Note
1). In the cathode space of each cell are placed
25 g. (0.18 mole) of anthranilic acid (Note
2) and
400 ml. of 15% sulfuric acid. In each porous cup is placed
200 ml. of 15% sulfuric acid. The cells are connected in series as shown in
Fig. 5 with an
ammeter (
A) and suitable
resistance (
R) (Note
3) also in the circuit.
Fig. 2.
The stirrers are started, the current (110 volt d.c.) is turned on, and the resistance is so adjusted that the ammeter records 10–12 amperes. The temperature of the solution in the cells is maintained at 20–30° by surrounding them with a bath of cool water (Note
4). The reduction is complete after 60–70 ampere-hours. This fact is indicated by the increased evolution of
hydrogen and the complete solution of the
anthranilic acid.
The cathode liquid is removed from the cells and neutralized with solid
ammonium carbonate or concentrated aqueous
ammonia. The solution is filtered to remove any resinous material, then saturated with
ammonium sulfate and extracted with five
80-ml. portions of chloroform (Note
5). The
chloroform solution is dried with
20 g. of anhydrous sodium or magnesium sulfate and filtered, and the
chloroform is removed by evaporation on a
steam bath (Note
6). The yield of
o-aminobenzyl alcohol obtained from the four cells is
62–70 g. (
69–78%).
This product is light brown and melts at
75–80°. After one recrystallization from
petroleum ether the melting point is
80–81° (Note
7).
2. Notes
1. Ordinary sheet lead of 99.9% purity is satisfactory.
3. A resistance of 10–12 ohms is required for the apparatus described. It may be necessary to adjust the rheostat several times during the course of the reaction.
4. The checkers found it necessary to cool the cells by frequent addition of ice to the
water bath surrounding them.
5.
Ethyl ether may be used in place of
chloroform but is not so satisfactory since several more extractions are necessary to remove the same amount of product from the aqueous solution.
6. The evaporation may be carried out in an apparatus that permits recovery of the solvent.
7.
Petroleum ether boiling at
65–75° is used for recrystallization. The product has a limited solubility even in the hot solvent, and a relatively large volume is therefore required.
3. Discussion
This preparation is referenced from:
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