Which of the following nitrogen containing compound does not give Lassaigne's test ?
- Glycine
- Phenyl hydrazine
- Urea
- Hydrazine
Answer
(4) Hydrazine
Solution
Lassaigne's test for N: Na + C + N NaCN → Prussian blue
∵ the compound must contain both C and N
(A): Glycine H2N-CH2-COOH has C and N ⇒ (A) gives the test
(B): Phenyl hydrazine C6H5NHNH2 has C and N ⇒ (B) gives the test
(C): Urea H2N-CO-NH2 has C and N ⇒ (C) gives the test
(D): Hydrazine H2N-NH2 has no carbon ⇒ no NaCN ⇒ (D) does not give the test
Answer: (4)