Hydrocarbons

Which of the following reaction is correct?

1. C2H5CONH2 + Br2 + NaOH C2H5CH2NH2 + Na2CO3 + NaBr + H2O
2. [figure]
3. [figure]
4. CH3CH2CH2NH2 [H2O]HNO2, 0 C CH3CH2OH + N2 + HCl

Answer

(3) [figure]

Solution

(1): Hofmann bromamide gives an amine with one C less ⇒ C2H5CONH2 C2H5NH2 ⇒ (1) is wrong

(2): Br2/UV light on an alkene ⇒ allylic substitution (3-bromocyclohexene), not 1,2-dibromide ⇒ (2) is wrong

(3): Markovnikov addition through the more stable 3° carbocation:

[figure]

⇒ (3) is correct

(4): 1° amine + HNO2 keeps the C chain ⇒ CH3CH2CH2OH (not ethanol) ⇒ (4) is wrong

Answer: (3)