Aromatic amines are lesser basic than aliphatic amines.why ? Why is the aliphatic amine a stronger base than the aromatic amide? Primary aliphatic amines are stronger bases than ammonia which is a stronger base than aromatic amines. Why are aliphatic amines stronger bases than aromatic amines? Aromatic amines due to resonance effect and lower stability of aryl ammonium ion than aryl amine, e- density on N is less. In the following table, pK a again refers to the conjugate acid of the base drawn above it. This explains why aliphatic amines are stronger bases than aromatic amines. On the other hand, aromatic amines are weaker bases than ammonia due to the electron withdrawing nature of the aryl group. Since alcohols are much stronger acids than amines, their conjugate bases are weaker than amide bases, and fill the gap in base strength between amines and amide salts. More Resources for CBSE Class 12: R-OH --> R- O- + H + Alcohol Alkoxide ion. R-NH 2 --> R – N-H + H + Amide ion. (iii) Due to the −R effect of the benzene ring, the electrons on the N- atom are less available in case of aromatic amines. (b) Aromatic amines arS more stable than corresponding protonated ion; Hence, they hag very less tendency to combine with a proton to form corresponding protonated ion, and thus they are less basic. Similarly, alcohol loses a proton to give alkoxide ion. Therefore, the electrons on the N-atom in aromatic amines cannot be donated easily. Structure-basicity relationship of amines Their pK b values lie in the range of 3 to 4.22. 1 See answer HIRESHYADAV6671 is waiting for your help. Therefore, aromatic amines are weaker bases than ammonia and aliphatic amines. o … Answer: Amines undergo protonation to give amide ion. HIRESHYADAV6671 HIRESHYADAV6671 13.01.2019 Chemistry Secondary School Why are aliphatic amines stronger bases than aromatic amines? Aliphatic amines are more basic in nature than aromatic amines because In aliphatic amines the electron density around N atom increases due to - I effect of alky group and thus chance for proton attack also Increases.
(iii) Why are aliphatic amines stronger bases than aromatic amines? (iii) Due to the −R effect of the benzene ring, the electrons on the N- atom are less available in case of aromatic amines. The benzene ring draws electrons towards itself and the nitrogen lone pair gets partially delocalised onto the benzene ring. Answer: Alkyl amines has positive I effect/electron donating effect, so high electron density on N and stable alkyl ammonium ion formation. NCERT Solutions for Class 12 Chemistry All Chapters
(ii) Why do primary amines have higher boiling point than tertiary amines? (b, Aromatic amines such as aniline in general are weaker bases than aliphatic amines such as cyclohexan amine. (iii) Why are aliphatic amines stronger bases than aromatic amines? In aromatic amines, lone pair of nitrogen is in resonance and hence not available to nitrogen atom itself and hence it acts as a weak base. This explains why aliphatic amines are stronger bases than aromatic amines. The more available the lone pair of electrons, the stronger the base. Explain why. Give plausible explanation for each of the following:
(i) Why are amines less acidic than alcohols of comparable molecular masses? Most base reagents are alkoxide salts, amines or amide salts. Therefore, the electrons on the N-atom in aromatic amines cannot be donated easily. 3. Aliphatic amines are stronger bases than ammonia due to +I effect of alkyl groups leading to high electron density on the nitrogen atom. Aliphatic amines are stronger bases than inorganic bases such as NaOH and KOH. All aliphatic amines are strong bases than NH 3 while aromatic amines are weaker bases than NH 3 due to the electron withdrawing nature of the aryl group. (a, Aqueous solutions of amines are basic. Water-insoluble amines react with strong aqueous acids such as HC1 to form water- soluble salts. -- > R – N-H + H + amide ion ii ) why are aliphatic amines are weaker bases ammonia! Amines have higher boiling point than tertiary amines and lower stability of aryl ammonium ion than aryl amine, density! 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