[annu]

 
 How can i convert m-chloroaniline to 3-chloro-6-nitro aniline

What I thought was :-
       1.protect aniline gr. by acetylation as NHCOCH₃,
       2.consecutive 2 nitrations, using conc. H₂SO₄ & conc. HNO₃ to introduce NO₂ at pos. 4 & 6
       3.selectiv red. using Na₂S, NO₂ at pos. 4 --------> NH₂
       4.diazotization of NH₂ at pos. 4
       5.removal of N₂Cl, by tretment with H₃PO₂,
       6.hydrolysis to convert NHCOCH₃ -------->NH₂
 
Am I correct ?

[swati]

I am doubtful about the nitration at pos 6 because of the steric hindrance of NHCOCH₃ group.

[PRIYA1022]

I agree with Swati.

[swati]

How can i convert m-chloroaniline to 3-chloro-6-nitro aniline

If someone knows the correct answer, then please answer this question 

[enahs]

How can i convert m-chloroaniline to 3-chloro-6-nitro aniline

You can not, as that is not a valid name.
Do you mean 5-chloro-2-nitroaniline?

[swati]

  Oh I am sorry

So tell me
 How can i convert m-chloroaniline to 5-chloro-2-nitro aniline

[enahs]

m-chloroAnilin + CH3COCl /base -> 3-chloroAcetanilide
3-chloroAcetanilide + sulfonation  -> 3-chloro-4-sulfonicacetanilide (major) + others (minor), separate
3-Chloro-4-sulfonicAcetanilide + nitration -> 5-chloro-2-nitro-4-sulfonicacetanilide) (major) +  others, separate (the Cl position is not changing, you are just now counting from the other direction, which is what I think you are forgetting you can do and are getting lost)
Careful desulfination of 5-chloro-2-nitro-4-sulfonicacetanilide leaves you 5-chloro-2-nitroacetanilide. Then just converting it back to ##aniline by Water, H2SO4 and heat, then OH-

[swati]

3-Chloro-4-sulfonicAcetanilide + nitration -> 5-chloro-2-nitro-4-sulfonicacetanilide) (major) + others, separate (the Cl position is not changing, you are just now counting from the other direction, which is what I think you are forgetting you can do and are getting lost)

Are you sure that on nitration NO₂ will be attached to position 2 i.e ortho to NHCOCH₃ . There will be so much steric hindrance. Also what is the use of protecting NH₂ group here.

[enahs]

Are you sure that on nitration NO2 will be attached to position 2 i.e ortho to NHCOCH3 . There will be so much steric hindrance. Also what is the use of protecting NH2 group here.

Yes I am surel. The SO3H group is meta directing, the Cl is ortho-para directing (and one of the o is now taken by the SO3H). They are both demanding it go their.

I am not making it acetamido to protect it, NH2 is o-p directing, while acetamido in many reactions is almost purely para directing (as in this case, so we get more SO3H in the para position instead of meta (this is just to increase yield in the second step, and it is easy to do and undo).

It also helps with the nitration. Yes there is steric hindrance at that carbon (we want to to nitrate), but the Cl and the SO3H are both directing it to either carbon adjacent to the acetamido group. By making it bulkier it makes it harder to attach to the adjacent carbon that is adjacent to the Cl (due to the combined steric hindrance), and so that carbon is the easiest to attack.

 

[enahs]

And I meant to say “get more SO3H in the para position instead of ortho”