Can $\ce{PCl5}$, phosphorus pentachloride, react with an amide?

I saw a reaction where the corresponding cyanide was formed in this process. What other reagents could do the same?


There's a couple of newer methods, using

  • zinc + N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA)
  • copper + N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA)
  • diethyl chlorophosphate $\ce{(EtO)2POCl}$
  • $\ce{PdCl2}$ in $\ce{CH3CN/H2O}$
  • $\ce{(COCl)2}$ with DMSO at -78 °C (Swern-type conditions)

Thionyl chloride, $\ce{SOCl2}$ is almost a classic here.

Under these conditions, the side products of the amide dehydration are $\ce{SO2}$ and $\ce{HCl}$.

$\ce{R-CONH2 + SOCl2 -> R-C#N + SO2 ^ + 2 HCl ^}$

On the first view, $\ce{PCl5}$ looks like leave quite a mess. Thinking in the workup, that's probably the last thing I would try.

  • $\begingroup$ Thanks a lot sir.!!...btw pcl5 is considered as a dehydrating reagent ,right? $\endgroup$ – Piyush Kumar Jan 7 '17 at 14:29
  • $\begingroup$ Yes, it is. But it can be used to convert carboxylic acids to their chlorides too. $\endgroup$ – Klaus-Dieter Warzecha Jan 7 '17 at 14:32

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