Acetonitrile Regeneration from Oligonucleotide Production Waste Streams

A distillation concept is described to process organic and aqueous waste streams from an oligonucleotide process to regenerate 85% of acetonitrile contained in the wastes, for reintroduction back into the oligonucleotide process. Careful selection of the streams to send to regeneration based on their acetonitrile content was shown to simplify the number of processing steps and minimize the size of the equipment required for regeneration. Availability of accurate vapor–liquid equilibrium data was shown to be key to designing the number of processing steps, the operating conditions, and calculating purification performance. A modified classical two-column distillation pressure swing dewatering system with an intermediate-pressure column for the separation of light boilers, was shown to effectively purify and dewater acetonitrile to the required specifications. Aspen Plus software was used to generate vapor–liquid equilibrium (VLE) data and simulate process alternatives.