The present invention relates to a process for synthesizing acrolein, coupling the dehydration of glycerol into acrolein with a reaction for aldol condensation of acetaldehyde, produced in the form of an impurity during the dehydration, by means of formaldehyde. The method is based on optimizing process energetics by decoupling of the process energetics from the DRE for target contaminants. A socket has a lip which has a positioning member to be engaged with a notch of the fixing member.