Organic Syntheses, CV 3, 463
Submitted by Alfred Russell and Luther B. Lockhart.
Checked by W. E. Bachmann and Charles E. Maxwell.
1. Procedure
In a
2-l. three-necked round-bottomed flask (Note
1) fitted with a
40-in. reflux condenser, a
mercury-sealed stirrer, and a
dropping funnel are placed
100 g. (0.69 mole) of β-naphthol and
300 g. of 95% ethanol. The stirrer is started, and a solution of
200 g. (5 moles) of sodium hydroxide in 415 g. of water is rapidly added.
The resulting solution is heated to 70–80° on a
steam bath, and the dropwise addition of
chloroform is started. After the reaction begins (Note
2), further heating is unnecessary. A total of
131 g. (1.1 moles) of chloroform is added at such a rate that gentle refluxing is maintained (Note
3). Near the end of the addition the
sodium salt of the phenolic aldehyde separates. Stirring is continued for 1 hour after all the
chloroform has been added.
The
ethanol and excess
chloroform are removed by distillation from a steam bath.
Hydrochloric acid (sp. gr. 1.18) is added dropwise to the residue, with good stirring, until the contents of the flask are acid to Congo red paper (Note
4). The dark oil that separates is mixed with a considerable amount of
sodium chloride. Sufficient water to dissolve the salt is added, and the oil is separated and washed several times with hot water. By distillation of the oil under reduced pressure there is obtained
87.5–93.7 g. of a slightly colored distillate which boils at
163–166° at 8 mm. (Note
5) and which solidifies on cooling. Recrystallization of the solid from
75 ml. of ethanol yields
45.2–57.5 g. (
38–48%) of pure
2-hydroxy-1-naphthaldehyde, melting at
79–80°.
2. Notes
1. The submitters employed a
5-l. flask for a run four times this size. They obtained the same percentage yield of product.
2. The beginning of the reaction is indicated by the formation of a deep blue color.
3. The
chloroform is added over a period of 1 to 1.5 hours.
5. The boiling range of the aldehyde is
177–180°/20 mm. The lower pressure is preferable to avoid decomposition. The checkers found a boiling point of
139–142°/4 mm. The color of the distillate varies in different runs; it may be green, pink, or amber.
3. Discussion
Copyright © 1921-2002, Organic Syntheses, Inc. All Rights Reserved