US3365500A   Hydroxybenzaldehyde process 1964  Current Assignee  Dow Chemical Co

Example 1 
A solution of 240 g. of sodium hydroxide and 282,3 g. of phenol in a solvent consisting of 240 g. of water and 60 g. of methanol was prepared in a reaction flask and its temperature was adjusted at 55 C.

 To the stirred solution there was added 119.5 g. of chloroform over a two hour period. 
 
 The temperature of the reaction mixture was maintained at 55 C. during this period by moderate external cooling. 
 
 After addition of the chloroform, stirring at 55 C. was continued for an additional 1.5 hours.
 
 The resulting reaction mixture was diluted by addition of about half its volume of process water and then was acidified to pH with dilute sulfuric acid to form an oil layer and an aqueous layer.
 
 The oil layer was washer once with water and then was steam distilled, using the combined aqueous layers, after recovery of methanol therefrom, to supply the steam. 
 
 The steam distillate oil layer consisted essentially of salicylaldehyde and unreacted phenol which were separated by fractional distillation. 
 
 The organic residue from the steam distillation was extracted with aqueous sodium hydroxide. p-Hydroxybenzaldehyde was recovered from the extract; the extracted residue was a causticinsoluble tar. 
 
 The recovered products, based on the average of eight such preparations, were: 45.5 g. of salicylaldehyde, 21.1 g. of p-hydroxylbenzaldehyde, and 12.8 g. of insoluble tar. 
 
 Based on the phenol disappearing in the process, an 83.9% yield of combined aldehydes was obtained (57.4% yield of salicylaldehyde plus 26.5% yield of p-hydroxybenzaldehyde).