Patent ID: 6946060

Claim:
A method of separating N,N-dimethylacetamide (DMAC) from an aqueous DMAc solution containing acetic acid comprising (a) providing said solution to a first distillation column, said column having a feed port and an exit port, and having top and bottom portions, said bottom portion having upper, mid, and lower bottom portions, at a temperature sufficient to render the lower bottom portion of the column substantially dry and the upper bottom portion of the column substantially wet, and to partition acetic acid between an overhead stream and a bottom stream of the first column, (b) providing the bottom stream of the first column to an entry port of a second distillation column to partition purified DMAc into an overhead stream and a mixture of DMAc and acetic acid into a bottom stream, and (c) partitioning an additional portion of the acetic acid from the mixture of DMAc and acetic acid to the overhead stream of the first column.