Preparation of unsaturated aldehydes

Claim 1

IN THE PROCESS OF PRODUCING AN UNSATURATED ALDEHYDE BY THE REACTION OF FORMALDEHYDE, ANOTHER ALDEHYDE OF AT LEAST THREE CARBON ATOMS AND A SALT OF A SECONDARY AMINE AND WHEREIN A MANNICH BASE SALT IS FORMED BY REACTION OF SAID ALDEHYDES AND SAID AMINE SALT WITH SPLITTING OUT OF WATER, AND IN WHICH SAID MANNICH BASE SALT IS DECOMPOSED TO FROM THE DESIRED UNSATURATED ALDEHYDE, THE IMPROVEMENT WHICH COMPRISES CONTINUOUSLY FEEDING SAID ALDEHYDES IN ABOUT EQUIMOLECULAR PROPORTIONS TOGETHER WITH SAID AMINE SALT AND WATER TO A REACTION ZONE MAINTAINED UNDER SUPERATMOSPHERIC PRESSURE AND AT A TEMPERATURE OF ABOUT 90 TO 120*C., MAINTAINING THE RESULTING MIXTURE IN SAID REACTION ZONE FOR A PERIOD OF TIME SUFFICIENT TO CONVERT MORE THAN 90% OF SAID ALDEHYDE OF AT LEAST 3 CARBON ATOMS TO THE MANNICH BASE SALT, THEN PASSING SAID MIXTURE CONTINUOUSLY INTO A SECOND REACTION ZONE MAINTAINED AT AN ELEVATED TEMPERATURE SUFFICIENTLY HIGH TO DECOMPOSE SAID MANNICH BASE SALT TO FORM BY SAID DECOMPOSITION AN UNSATURATED ALDEHYDE AND AN AQUEOUS SOLUTION OF SAID AMINE SALT, BOILING THE MIXTURE IN SAID SECOND ZONE TO DRIVE OFF SAID UNSATURATED ALDEHYDE CONTINUOUSLY, AND CONTINUOUSLY RECYCLING SAID AQUEOUS SOLUTION TO SAID FIRST REACTION ZONE.