Acetic Anhydride → Acetyl fluoride

Participants

Reaction Steps

A difficultly separable hexafluoroacetone-HF complex mixture containing about 1.01 g-moles hexafluoroacetone and 1.54 g-moles HF was contacted with 2.22 g-moles acetic anhydride at 100 psig. The temperature of the mixture rose from 20° to 31° C within a few minutes. A 411.0 g portion of this mixture was then fractionated at atmospheric pressure using a Freon 11/dry ice cooling bath and a 271/2 inch × 7/16 inch column packed with Helipak Monel. A 135.7 g hexafluoroacetone fraction, an 80.4 g intermediate fraction, and an 85.0 g acetic fluoride fraction were obtained leaving a 147.5 g kettle product of acetic hydride and acetic acid. A gas-liquid chromatographic analysis of the samples showed that the purity of the hexafluoroacetone fraction was 90 area percent. However, to demonstrate that a higher purity hexafluoracetone could be obtained, a portion of the overhead and kettle products were recombined, the mixture was redistilled, and a hexafluoroacetone fraction having a purity of 99.9 area percent was obtained.

Provenance & Evidence