Dehydration of amide with PCl5

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.

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