side cut stream and a high boiling point component containing the ester is removed from the bottom of the column for the single column for this purpose a plate column or a packed column having 7 or more theoretical plates is used a column having 7 to 15 theoretical plates is preferable the column is operated at 30 to 40 torr and 150 u00b0 to 230 u00b0 c it is desirable that the feed be charged at a lower part of the column to allocate at least one theoretical plate for the stripping section and that crude o toluic acid be drawn at an upper point higher than the middle portion and lower than 1 5 of the column length from the top of the column in the operation using only one distillation column in usual cases a sufficient reflux ratio may be obtained automatically a preferable amount of reflux is between 0 1 and 1 times based on the total amount of the light component recovered at the top and the crude o toluic acid withdrawn as the side cut stream crude o toluic acid which is drawn from the column as the side cut stream may be subjected to a stripping operation the difference in boiling points of the ester and o toluic acid is great enough to separate the two compounds almost completely recovery of o toluic acid in this operation is about 99 8 for the treatment with ammonia any kinds of ammonia containing gas such as gaseous ammonia or liquefied ammonia and ammonia containing solution such as aqueous ammonia or aqueous solution of ammonium carbonate can be employed the treatment is carried out at a temperature of 95 u00b0 to 240 u00b0 c preferably 110 u00b0 to 240 u00b0.