A process for purifying and recycling a solvent stream

A process comprises:a) Recovering a crude recycle solvent stream comprising a tertiary formalmide (TF; e.g. DMF) and a tertiary acetamide (TA; e.g. DMAC) from a mixture comprising at least one substance less volatile than the TF and the TA; b) Reducing the concentration of TA in the crude recycle solvent stream to provide a purified recycle solvent stream (e.g. via distillation); andc) Recycling the purified recycle solvent stream for use as a reaction vehicle. Alternatively, a method comprises contacting a contaminated TF containing a TA with a chlorinating agent (e.g. N,N-dilmethylchloroformiminium chloride formed from DMF and phosgene) to react the TA with the chlorinating reagent.Alternatively, a method comprises:a) Forming a mixture of sucrose-6-acylate, reaction vehicle, TF and TA; b) Analyzing the mixture to determine the amount of TA; andc) Contacting the mixture with a quantity of chlorinating agent to react the TA and the sucrose-6-acylate with the chlorinating agent, wherein the amount of chlorinat