An organic compound X with the molecular formula C_3H_9N reacts with cold nitrous acid (HN… — JAMB UTME

An organic compound $X$ with the molecular formula $C_3H_9N$ reacts with cold nitrous acid ( $HNO_2$ ) at $0-5^\circ\text{C}$ to produce a yellow, oily liquid without the evolution of nitrogen gas. Which of the following is the IUPAC name of compound $X$ ?

A
Propan-1-amine
$N$ -methylethanamineCevap
C
Propan-2-amine
D
$N,N$ -dimethylmethanamine

Cevap

The correct compound is

N

-methylethanamine because secondary aliphatic amines react with nitrous acid (

HNO_2

) at low temperatures to produce insoluble, yellow oily

N

-nitrosamines without liberating nitrogen gas.

Secondary aliphatic amines such as

N

-methylethanamine react with cold nitrous acid (

HNO_2

) to form

N

-nitrosamines. These compounds are insoluble in water and appear as yellow oily liquids. Because no aliphatic diazonium intermediate breaks down to release gas, no nitrogen gas effervescence is observed.

Adım Adım Çözüm

Classify the given structural isomers of

C_3H_9N

by amine degree.

Propan-1-amine and propan-2-amine are primary (

1^\circ

) amines;

N

-methylethanamine is a secondary (

2^\circ

) amine;

N,N

-dimethylmethanamine is a tertiary (

3^\circ

) amine.

Amine classification determines the distinct reaction pathway and observable products with nitrous acid.

Analyze the reaction behavior of each amine class with nitrous acid (

HNO_2

) at

0-5^\circ\text{C}

Primary amines evolve

N_2

gas and form alcohols; secondary amines form yellow oily

N

-nitrosamines without gas evolution; tertiary amines form soluble nitrite salts.

Nitrous acid is used as a qualitative reagent to distinguish between

1^\circ

2^\circ

, and

3^\circ

amines.

Match the observation (yellow oily liquid, no nitrogen gas) to the correct compound.

The observation corresponds uniquely to a secondary amine, which is

N

-methylethanamine.

Only secondary amines undergo nitrosation at the nitrogen atom to form neutral, oily

N

-nitrosamine layers.

Anahtar Kavram

Distinction tests for primary, secondary, and tertiary amines using nitrous acid (

HNO_2

)

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

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