Organic Nitrogen Compounds

Question 1

Amines

Answer 1

Amines the derivatives of ammonia in which one or more hydrogen atoms have been replaced by alkyl or aryl groups
Amines are classified as
Ammonia
Primary amine 1° RNH2, CH3NH2, C6H5NH2
Secondary amine 2° CH3NHCH2CH3, C6H5NHCH3
Tertiary amine 3° (CH3)3N, (C6H5)2NCH3

Question 2

Hofmann reaction

Answer 2

NH3+R-X —> RNH3+X- —NaOH–>RNH2+ NaX+H2O
Alkyl halide with aqueous alcoholic ammonia gives salt of primary amine
Proceed by SN2 mechanism.
This method is of very limited synthetic application because of multiple alkylation
Multiple alkylation can be minimise by using large excess of ammonia

Question 3

Reductive amination

Answer 3

Reaction in which aldehyde and keton can be converted to amine through catalytic reduction in the presence of ammonia. Initially formed amine is reduced when amine
RCHO + NH3 <===> [RCH=NH] –H2/Ni—> RCH2NH2
RR’C=O +NH3 <====> [RR’C=NH] —H2/Ni–> RR’CH-NH2 1°amine
C6H5CHO+NH3 <===> [C6H5CH=NH] –H2/Ni–> C6H5CH2NH2 Benzyl amine

Question 4

Acylation reduction

Answer 4

Acylation reduction of ammonia within acid chloride or acid anhydride followed by the reduction of amide or substituted amide
In the reduction(H2/Ni, LiAlH4) of amide CO group is reduced to CH2 group
RCHOCl+ NH3–> R-CONH2–H2/Ni-> RCH2NH2

Question 5

Gabriel synthesis

Answer 5

Treatment of phthalimide with potassium hydroxide to form potassium phthalimide and phthalimide anion is a strong nucleophile it react with alkyl halide to give an alkyl phthalimide which on hydrolysis with aqueous acid or base gives primary amine
C6H5(CO)2NH —> C6H5(CO)2NK —> C6H5(CO)2NR —>C6H5(COo-)2 +RNH2

They hadrolysis of an alkyl phthalimide with aqueous acid or base is often difficult it is more convenient to treat th an alkylamine with hydrogen is reflection ethanol to give primary amine and phthalazine,-14-dione