Dehydration of amide with PCl5
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 $\ce{HCl}$.

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

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.