of alkyl ketene dimer by the removal of the solvent and the remaining tertiary amine conventional techniques for removing volatile substances from relatively non volatile substances are appropriate including distillation or vacuum distillation preferably the distillation process is performed under an inert atmosphere and the solvent is recovered for re use this example shows the production of an alkyl ketene dimer using n methylpyrrolidine in methylcyclohexane 140 parts by weight of n methylpyrrolidine in 460 parts of methylcyclohexane was placed in an oven dried 1 l 5 necked flask equipped with nitrogen inlet outlet ptfe paddle stirrer condenser and dropping funnel 410 parts of palmitoyl chloride was then added dropwise over a period of 50 minutes with stirring during which the temperature rose to 35 u00b0 u02dc 45 u00b0 c from room temperature after the addition was completed the fluid reaction mixture was heated and maintained at 60 u00b0 c for 90 minutes the tertiary amine hydrochloride precipitate was separated from the alkyl ketene dimer solution in methylcyclohexane by suction filtration follow by wash the tertiary amine hydrochloride salt cake with 100 parts of hot u02dc 70 u00b0 c methylcyclohexane the filtrate containing the alkyl ketene dimer was then stripped off the solvent and the excess n methylpyrrolidine under reduced pressure using a rotary evaporator at 55 u00b0 c to obtain the alkyl ketene dimer analysis of the product showed that it contains an alkyl ketene dimer assay of 91 3 and a non volatile content of 99 8 this example shows the preparation of an alkyl ketene dimer using n methylpyrrolidine in cyclohexane alkyl ketene dimer was prepared using n methylpyrrolidine in the cyclohexane dimerization solvent and following the same procedure as.