What are coordination number (nearest neighbour) in a SCC at distance of it lattice parameter (a) and next nearest neighbour at distance (a√2) and next to next nearest neighbour at distance (a√3) ?.

Coordination Number:

(1) The nearest neighbour distance is just the lattice parameter (a) therefore coordination number for a given atom in SCC unit cell is 6 (six).

(2) The next nearest neighbour are 12 at distancea/root 2 (each face diagonal in x ,y and Z plane).

(3) 3^rd neighbour (Next to Next nearest neighbour) are(8) at distance a root 3 (each corner along body diagonal.

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.