DE4104835A1  (1991)    BASF SE   Salicylaldehyde prodn. - by ozonisation of o-propenyl-phenol

example

In a stirring flask with a high-speed gassing stirrer was provided, 134 g (1 mol) of o-propenylphenol in 1370 ml of methanol solved. At -60 ° C was a gas stream of 200 l of oxygen, the 28 g of ozone delivered per hour, initiated for 100 min. 110 ml (1.5 Mol) added dimethyl sulfide. After warming to room temperature and For one hour under reflux, the peroxide content was 0.035 mol like. At this point it was worked up by distillation. First you got the excess dimethyl sulfide, then methanol, then a fraction of 181 g was obtained, the 68% salicylaldehyde and the rest Contained dimethyl sulfoxide.

This distillate was mixed with 200 ml of toluene and four times with 100 ml each Extracted water to remove the dimethyl sulfoxide. In the repeated fractional distillation, 109 g of salicylaldehyde receive. This corresponds to a yield of 89.3%.