sodium azide reaction

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A base wash still keeps the azide intact in the aqueous layer.
Best way is to treat the separated aqueous layer with sodium nitrite and HCl to give laughing gas and nitrogen.

Ironically I ran the my scale up of this reaction yesterday.  Using a NEt3HCl and NaN3 in toluene system to make the tetrazole,  I was able to filter the bulk of the excess sodium azide out of the solution after the reaction was complete.  Then used an acid/nitrite aqueous solution in my wash/extraction workup to destroy what azide was left.

Mild wash with aqueous base. Avoid the formation of volatile/dangerous HN3 by keeping the residual azide basic.