| 摘要 |
<p>N-Dialkylated acid amides or N-alkyl-N-b -cyanoalkyl acid amides which have been contaminated by being used as solvents in a spinning process are purified by passing in admixture with at least 10% of water either over a strongly acid ion exchanger in the H-ion form and then over a strongly basic ion exchanger in the carbonate ion form or, alternatively, over a mixture of the above two ion exchangers and thereafter in both cases freeing the acid amides from water by fractional distillation. Specified N-dialkylated amides are dimethyl formamide, dimethyl cetamide, dimethyl methoxyacetamide and N-methyl-N-b -cyanoethyl formamide. It is preferred to use 30-35% water in the mixture. The preferred acid ion exchanger is the sulphonation product of a cross-linked polystyrene and the preferred base ion exchanger is a quaternary ammonium compound of a cross-linked polystyrene.</p> |
