Hydrocarbons Question 74
Question: An unknown compound A has a molecular formula $ C_4H_6. $ When A is treated with an excess of $ Br_2 $ a new substance B with formula $ C_4H_6Br_4 $ is formed. A forms a white precipitate with ammoniacal silver nitrate solution. A may be [MP PET/PMT 1998]
Options:
A) Butyne-1
B) Butyne-2
C) Butene-1
D) Butene-2
Show Answer
Answer:
Correct Answer: A
Solution:
$ \underset{1-Butyne}{\mathop{CH_3-CH_2-C}}\equiv CH+2Br_2\to CH_3-CH_2-\underset{\underset{Br}{\mathop{|}}}{\overset{\overset{Br}{\mathop{|}}}{\mathop{C}}}-\underset{\underset{Br}{\mathop{|}}}{\overset{\overset{Br}{\mathop{|}}}{\mathop{C}}}-H $ Since the molecule takes 2 moles of $ Br_2 $ .
Therefore it is alkyne.
Also it gives white ppt with Tollen’s reagent therefore acidic H is present.
Hence it is 1-Butyne.
BETA
