Patent ID: 7491838

Claim:
A process of producing highly purified acetonitrile having no more than about 0.3 milligrams of acetamide per liter of acetonitrile comprising (1) distilling crude acetonitrile in a first distillation column affixed with a first overhead reflux loop at a first pressure of at least 1 atmosphere to remove HCN, producing a first acetonitrile/water azeotrope and a first bottom product containing water, (2) distilling the first azeotrope in a second distillation column affixed with a second overhead reflux loop at a second pressure less than 1 atmosphere to separate the first azeotrope into a second bottoms product containing water and a second acetonitrile/water azeotrope having a greater acetonitrile concentration than that the first azeotrope, (3) distilling the second acetonitrile/water azeotrope in a third distillation column affixed with a third overhead reflux loop at a third pressure above 1 atmosphere to produce a third acetonitrile/water azeotrope containing substantially all of the water from the second azeotrope, a third bottoms product comprising acetonitrile and heavy organics and a side stream comprising highly pure acetonitrile, and (4) passing the highly pure acetonitrile side stream through an acidic ion exchange resin to further purify said highly pure acetonitrile producing highly purified acetonitrile having a UV cutoff for impurities of <190 nm wherein the reflux ratios in Steps 1, 2 and 3 are kept at greater than 3 to 1, greater than 3.4 to 1 and greater than 6.4 to 1, respectively.