| 摘要 |
<p>1,132,046. Purification of dimethylformamide. SNIA VISCOSA SOC. NAZIONALE INDUSTRIA APPLICAZIONI VISCOSA S.p.A. 17 Nov., 1965 [26 Nov., 1964], No. 48824/65. Heading C2C. [Also in Division C3] Dimethylformamide which has been recovered in a substantially non-aqueous condition from a process for spinning acrylonitrile polymers and copolymers, is purified for reuse by contact with a mixed bed of a strongly acidic ion-exchange resin belonging to the sulphonated styrenedivinyl benzene copolymer class and a strongly basic ion-exchange resin belonging to the quaternary ammonium hydroxide class, both resins being insoluble in dimethylformamide. It is preferred to effect contact between the dimethylformamide and the resins at ambient temperatures and pressures at a downward flow rate of 5-10 litres per hour per litre of resin. The purified dimethylformamide provides an improved polymerization medium for acrylonitrile (see Division C3).</p> |
