Patent ID: 7531066

Claim:
A continuous process for the manufacture of 3-(methylthio)propionaldehyde, the process comprising: (a) subjecting propylene to vapor-phase oxidation using a catalyst, to obtain a crude acrolein-based product; (b) removing acids present in the crude acrolein-based product; (c) absorbing the crude acrolein-based product with water to obtain an aqueous acrolein solution; (d) purifying the aqueous acrolein solution to obtain purified gaseous acrolein by a process comprising: introducing the aqueous acrolein solution into a distillation column equipped at its base with at least one boiler and at its top with at least one condenser, withdrawing a liquid mixture essentially comprising water at the base of the distillation column, withdrawing a gas mixture essentially comprising acrolein and water at the top of the distillation column, cooling the gas mixture withdrawn at the top of the distillation column in the condenser, to a temperature which makes it possible to obtain, on the one hand, an aqueous condensate and, on the other hand, an acrolein-rich gas mixture, and withdrawing the acrolein-rich gas mixture; and (e) reacting the purified gaseous acrolein with methyl mercaptan, to obtain 3-(methylthio)propionaldehyde; wherein: noncondensable gases produced in step (a) are separated from the acrolein prior to step (e).