Abstract: The invention relates to a process for distillatively purifying crude dimethylacetamide (crude DMAc) comprising DMAc, low boilers and high boilers 5 by removing the low boilers and the high boilers to obtain pure DMAc in one of the column configurations listed hereinbelow: (I) a main column (MC) with sidestream column (SC) or (II) a dividing wall column (DWC), which operating at least the main column (MC) in column configuration (I) and the dividing wall column (DWC) in column configuration (II) at a top pressure in the range from 0.5 to 1.8 bar absolute.

Abstract: The invention relates to a process for distillatively purifying crude dimethylacetamide (crude DMAc) comprising DMAc, low boilers and high boilers 5 by removing the low boilers and the high boilers to obtain pure DMAc in one of the column configurations listed hereinbelow: (I) a main column (MC) with sidestream column (SC) or (II) a dividing wall column (DWC), which comprises operating at least the main column (MC) in column configuration (I) and the dividing wall column (DWC) in column configuration (II) at a top pressure in the range from 0.5 to 1.8 bar absolute.

Abstract: The invention relates to a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds in an evaporator in which the liquid is brought into contact with a heated solid surface for evaporation, by a process in which direct contact between the resulting vapor phase and the heated solid surface is substantially avoided. It also directed to an evaporator composed of a heatable solid surface (16), an apparatus (2, 3) for heating the solid surface and an apparatus (10) for feeding a liquid containing vaporizable compounds to the heatable solid surface, wherein the apparatus for feeding the liquid is designed and arranged in the evaporator in such a way (12, 14, 18) that direct contact between a resulting vapor phase and the heatable solid surface is substantially avoided.