N,N,2,6-Tetramethyl aniline is more basic than N,N-Dimethyl aniline.Why ?

In case of N,N-Dimethyl aniline its dialkyl derivatives the NMe₂group is coplanar with benzene ring.  So p-electron (lone pair) on N atom and pi orbitals are remain in the same plane. For this the p-electron on N-atom can delocalized via pi orbital in the benzene ring and its result the electron availability in para position is high and less available at nitrogen atom and hence less basic.

On the other hand , in case of N,N,2,6 tetramethyl aniline(2,6-dimethyl N,N-dimethyl aniline) having two bulky methyl group in ortho position of the benzene ring , the NMe₂ group can not remain in the same plane. That is why the p-electron on N-atom cannot delocalized through pi orbital in para position. (due to steric inhibition of resonance)  It is localized at nitrogen atom Thus 2,6-Dimethyl aniline  derivative is more basic.

Related Questions:

1. What is relative basic strength order 1° amines , 2°amines and 3° amines ? 
2. Explain:Arrange the following in the increasing order of their acid strength : Methyl amine, Dimethyl amine, Aniline, N-methyl aniline (I.I.T, 1988).
3. What is Carbylamine test or Isocyanide test ?
4. What is Hinsberg's reagent and where Hinsberg's test use?
5. Can we prepare aniline by Gabriel – phthalimide reaction?
6. N-Ethyl-N-methyl propanamine does not show optical activity why?
7. What is relative basic strength order 1° amines , 2°amines and 3° amines ? Explain:
8. Amines are more basic than ammonia why?
9. Give an explanation for the fact that Guanidine NH=C(CH3)2 is a stronger base than most of amines?
10. Arrange in correct order of basic Character of aniline, pyrrol, pyridine and piperidine?
11. What is correct basicity order of pyridine, pyridazine, pyrimidine and pyrazine ?
12. Give an explanation for the fact that Guanidine NH=C(CH3)2 is a stronger base than most of amines?
13. Arrange in correct order of basic Character of aniline, pyrrol, pyridine and piperidine?
14. What is correct basicity order of pyridine, pyridazine, pyrimidine and pyrazine ?
15. Why pyridine is more basic than Pyrrole?
16. Why pyrimidine is less basic than pyridine?
17. Imidazole is more basic than pyridine? Why?
18. Biological Important of Imidazole and structure:
19. Pyridine is almost 1 million times less basic than piperidine? Why?
20. Cyclohexylamine amine is the stronger base than Aniline? Why?
21. Tetrahydroquinoline amine is the stronger base than Tetrahydroisoquinoline? Why?

pH of a 0.1 M monobasic acid is found to be 2. Hence its osmotic pressure at a given temp. TK is:

Lower aliphatic acids having 1 to 5 carbons are soluble in water but higher fatty acids having six or more than six carbon are insoluble in water but soluble in alcohol. Explain.

SOLUTION: Lower fatty acids dissolve because H of COOH group can farm hydrogen bond with water in two ways:

The alkyl group of these acids is nonpolar and hydrophobic and this effect predominates when alkyl group has more than five carbons, thereby diminishing the solubility of the acid. Alcohols are less polar than water hence higher members are soluble in alcohol.

Explain why the free radical chlorination of methane occurs nearly twelve times faster than CD4.

SOLUTION: Although C-H and C-D bonds are chemically identical But C-D bonds are slightly stronger than C-H honds. Therefore,∆H for abstraction of D is slightly greater than for H. Since, abstraction is the slow step, removal of H will be faster.

Explain Why maleic acid is stronger acid than fumaric acid.

Acidity, depends upon the stability of acid anion. Hence , maleic acid is more acidic than fumaric acid because anion of maleic acid is more stable due to intramolecular H-bond.

Related questions;

What is Steric Inhibition in Resonance of SIR effect ?

What is the Inversion of Amines ?

Which is more stable? CH3-CH2+ (Ethyl carbocation) or CH2=CH+ (Vinyl carbocation)? And why?

Why The phenoxide ion is more stable than phenol ?

What happens if two deactivating and one activating group is present on a benzene ring?

Among orthochlorophenol and orthofluorophenol, which will be a stronger acid and why?

Why benzyl carbonium ion is more stable than ethyl carbonium ion?

Explain why aniline is less basic than ammonia?

4- nitrophenol is more acidic than 3,5 - dimethyl –4-nitro-phenol. Explain.

What are the difference between Tautomerism & Resonance ?

Though enol form is less stable than keto form, phenol exists in enol form, why?

What is the nucleophilicity of halides?

What is correct acidic strengths order of the haloforms acids ? Give correct explanation.

Why are bridge head carbocations unstable?

Why is cyclopropyl methyl carbocation exceptionally stable?

Azabicyclo[2,2,1]heptane is more basic thantriethylamine why?.

Which carbocation is more stable : Benzyl or Tertiary?

Which is more stable ,vinyl carbocation or allyl carbocation?

Which carbocation is more stable : Benzyl or Tertiary?