METHOD OF TREATING CRUDE ACETONITRILE AND METHOD OF PREPARING OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY-GRADE ACETONITRILE Russian patent published in 2004 - IPC

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to a method of treating crude acetonitrile containing acrylonitrile as impurity, which method comprises feeding crude acetonitrile containing acrylonitrile as impurity and water into top section of distillation column, distilling crude acetonitrile in presence of water over a period of time long enough to vaporize essentially acrylonitrile impurities in presence of water and removing them with column top stream, while crude acetonitrile essentially free of acrylonitrile impurities is recovered from bottom section of column. Method of preparing of high performance liquid chromatography-grade acetonitrile comprises (1) feeding crude acetonitrile containing acrylonitrile as impurity into first distillation column at pressure at least 1 atm to remove all or essentially all acrylonitrile impurities and to remove them together with HCN impurities present in crude acetonitrile with top stream coming out of the first distillation column and forming first acetonitrile/water azeotrope essentially free of acrylonitrile impurities and first water-containing sedimentary product; (2) optionally passing the first azeotrope through autoclave to remove remaining acrylonitrile and HCN by treating with aqueous base solution and optionally with formaldehyde solution; (3) distillation of the first azeotrope in second distillation column at second pressure below 1 atm to separated the first azeotrope into second water-containing sedimentary product and second acetonitrile/water azeotrope having higher acetonitrile concentration than the first azeotrope; (4) distillation of the second acetonitrile/water azeotrope in third distillation column at third pressure above 1 atm to produce third acetonitrile/water azeotrope containing essentially all water from the second azeotrope, third sedimentary product containing acetonitrile and heavy organics and side stream containing high-purity acetonitrile. According to invention, in step (1), water is fed into the top section of the first distillation column along with crude acetonitrile and distillation of crude acetonitrile is effected in presence of water over a period of time long enough to absorb by water essentially all acrylonitrile impurities and, in this case, top sections of all there distillation columns are linked to upper dephlegmation loop and, after step (4) side stream consisting of high-purity acetonitrile is passed through acid ion-exchange resin to further refine high-purity acetonitrile formed in step (3) and produce high performance liquid chromatography-grade acetonitrile, wherein reflux-to-product ratios in steps 1, 2, and 3 are maintained above 2.7:1, above 2.2:1, and above 3.0:1, respectively.

EFFECT: simplified refining operation and reduced expenses.

15 cl, 1 dwg