Organic Syntheses, Coll. Vol. 3, p.463 (1955); Vol. 22, p.63 (1942). 
2-HYDROXY-1-NAPHTHALDEHYDE 
[1-Naphthaldehyde, 2-hydroxy-] 

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 ß-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. 
4. About 175 ml. of hydrochloric acid is required to neutralize the excess sodium hydroxide and to 
liberate the phenolic aldehyde from its sodium salt. 
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.