Why is it that benzene diazonium salts don't give the Lassaigne's test for nitrogen. After all they've got both carbon and nitrogen.


1 Answer 1


Benzene diazonium chloride is stable upto 5 degree Celcius, while in Lassaigne's test we need to heat the organic compound with sodium till red hot, before breaking it by plunging into cold water. All the nitrogen will be liberated before it finds a chance to combine with Na and form any NaCN, which is responsible for the test ultimately.

  • $\begingroup$ Is there any method other than the coupling test to test for the presence of benzene diazonium salts? $\endgroup$ Commented Apr 12, 2017 at 5:23
  • $\begingroup$ And in case we use benzene diazonium fluoroborate, will it gie positive result for Lassaigne's test? This is because I read that it is stabler than other diazonium salts at higher temperatures. $\endgroup$ Commented Apr 12, 2017 at 5:28
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    $\begingroup$ It would not be possible because fluoroborates again give of N2 while converting into fluorobenzene upon being HEATed. $\endgroup$
    – Che Mistry
    Commented Apr 13, 2017 at 18:47
  • $\begingroup$ @CheMistry This test also fails for the organic compounds having nitrogen in the ring because sodium cannot extract this nitrogen atom. But what about nitrobenzene? $\endgroup$
    – Apurvium
    Commented Sep 30, 2019 at 5:32

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