Patent ID: 6187971
Filing Date: 2001-02-13
Classification: C07C,Y02P

Abstract:
A process for the preparation of a methylolalkanal of the formula II ##STR11##wherein R is a methylol group or an alkyl group of from 1 to 22 carbon atoms or an aryl of aralkyl group of from 6 to 22 carbon atoms, by condensation of aldehyde having from 2 to 24 carbon atoms with formaldehyde and a tertiary amine catalyst, which process is carried out step-wise and comprisesa) in a first step, reacting the aldehyde with 2 to 8 times the molar amount of formaldehyde in the presence of the tertiary amine,b) in a second step, separating the reaction mixturei) into a bottom fraction comprising, in addition to the compounds of formula II, an incompletely methylolated compound of the formula III ##STR12##and a distillate stream comprising unconverted or partially converted starting materials, orii) into an aqueous phase and an organic phase, by means of a phase-separating equipment,and recycling the distillate stream or the organic phase to the first stage, andc) in a third stage, subjecting the bottom fraction or the aqueous phasei) to a catalytic reaction or thermal reaction, to convert the compound of the formula III to the compound of formula II and to a corresponding methylene compound of formula IV ##STR13##wherein R' is hydrogen or the radical R, andii) distilling the reaction product, wherein an overhead stream comprising the compound of the formula IV and unconverted formaldehyde is recycled to the first stage, andthe compound of the formula II is isolated from the bottom fraction.