How can we easily obtain 2-bromoacetophenone from bromobenzene?

  • Thread starter Raghav Gupta
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In summary, in order to get 2-bromoacetophenone from bromobenzene, one would need to do the following: iodide in NaOH (iodoform reaction), Schmidt reaction using N3H, diazotization, and H3PO2.
  • #1
Raghav Gupta
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By which reagent we would get 2-bromoacetophenone in one step from bromobenzene?
 
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  • #2
You can do this:
1)iodine in NaOH (iodoform reaction) to get ph-COOH
2)Schmidt reaction using N3H to get ph-NH2
3)Diazotization
4)H3PO2
 
  • #3
Will this work?#Aditya
By Dow's process.. get phenol, then reduce to benzene using Zn.
then by acylation.. you'll get acetophenone, then by bromination, α hydrogen of the substituent group gets replaced by Br?
#Raghav.. i still kept my word.. it was already out of the unanswered section.
 
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  • #4
I'm sorry, I gave the answer for bromobenzene from 2-bromoacetophenone.
For the conversion, the answer is CH3Cl in anhydrous AlCl3 (acylation)
 
  • #5
AdityaDev said:
I'm sorry, I gave the answer for bromobenzene from 2-bromoacetophenone.
For the conversion, the answer is CH3Cl in anhydrous AlCl3 (acylation)
But that will give 2-bromo toluene or 4-bromotoluene.
I'm asking 2-bromoacetophenone from bromobenzene.
See structure of 2-bromoacetophenone.
 
  • #6
You can get 2'-bromoacetophenone (with the acetyl unit in the ortho position on the benzene ring) by a Friedel-Crafts acylation of bromobenzene with acetyl chloride. To get the compound you linked to (benzene with a 2-bromoacetyl group) directly from bromobenzene, I think you're going to need more than one step. Maybe a Pd-catalyzed coupling of some kind, but you'll get competition with the Br on the acetyl group.
 
  • #7
Raghav Gupta said:
But that will give 2-bromo toluene or 4-bromotoluene.
I'm asking 2-bromoacetophenone from bromobenzene.
See structure of 2-bromoacetophenone.
No. I am talking about acylation. It will give the required product. Check NCERT book.
 
  • #8
AdityaDev said:
No. I am talking about acylation. It will give the required product. Check NCERT book.
As TeethWhitener said it will give acetyl group in the para position of bromobenzene.
And I'm not wanting that. See again the structure in the link given above in post.
For reference: It was a recent cbse board exam question.
 
  • #9
Raghav Gupta said:
See again the structure in the link given above in post.
Raghav, my teacher said, that the link thing is wrong, 2-bromoacetophenone is bromine attached at ortho position on the benzene ring. the compound in the link is
1-phenyl-2-bromoethanone because acetophenone is nothing but 1-phenylethanone.
 
  • #10
Suraj M said:
Raghav, my teacher said, that the link thing is wrong, 2-bromoacetophenone is bromine attached at ortho position on the benzene ring. the compound in the link is
1-phenyl-2-bromoethanone because acetophenone is nothing but 1-phenylethanone.
Ya, I think you are right. Don't know why the wikipedia a famous site was showing that.
Now acylation will give para thing. How ortho?
 
  • #11
Bromine is ortho-para directing, so Friedel-Crafts will give you a mixture of ortho and para isomers. Bonus question: how would you get meta-bromoacetophenone (starting from benzene)?
 
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  • #12
TeethWhitener said:
Bromine is ortho-para directing, so Friedel-Crafts will give you a mixture of ortho and para isomers. Bonus question: how would you get meta-bromoacetophenone (starting from benzene)?
Easy.
First friedel crafts acylation to get acetophenone.
Then bromination in presence of FeBr3 to get meta brominated product.
this conversion is even better: benzene to benzene-(1,3)-dicarboxylic acid. Try it.
 
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  • #13
AdityaDev said:
this conversion is even better: benzene to benzene-(1,3)-dicarboxylic acid. Try it.
We'll probably get the thread locked for being off-topic, but it's fun regardless. Friedel-Crafts alkylation of benzene with a methyl halide to get toluene, then oxidize with permanganate to benzoic acid (now it's meta-directing), then repeat the process to get the 1,3-dicarboxyl compound.
 
  • #14
TeethWhitener said:
Bromine is ortho-para directing, so Friedel-Crafts will give you a mixture of ortho and para isomers.
But para one would be in majority because of steric hindrance by ortho group.
So now what?
 
  • #15
I don't know if there's really a good way to get ortho-bromoacetophenone in one step from bromobenzene with high regioselectivity. Typically, regioselective ortho-directed reactions require some sort of directing group. Look up "ortho-directed metalation" for more info. The general idea is that you have a benzene ring with a directing group (usually an acyl or amide group) which allows substitution of the ortho hydrogen with lithium. That ortho-lithiated product can be subsequently functionalized.
 
  • #16
TeethWhitener said:
We'll probably get the thread locked for being off-topic, but it's fun regardless. Friedel-Crafts alkylation of benzene with a methyl halide to get toluene, then oxidize with permanganate to benzoic acid (now it's meta-directing), then repeat the process to get the 1,3-dicarboxyl compound.
Correct. It is interesting indeed.
 
  • #17
Anyways, I think acylation would be fine enough for 1 step, no matter what the amount of ortho product would be.
Thanks to you all.
 

FAQ: How can we easily obtain 2-bromoacetophenone from bromobenzene?

What is a reagent?

A reagent is a substance or compound that is used to cause or promote a specific chemical reaction. It is typically added in small amounts to a reaction mixture and is consumed during the reaction.

What is bromobenzene?

Bromobenzene is a compound with the chemical formula C6H5Br. It is a colorless liquid that is commonly used as a solvent in organic chemistry reactions. It is also used in the production of pharmaceuticals, pesticides, and other chemicals.

How is reagent on bromobenzene used in organic synthesis?

Reagent on bromobenzene, also known as bromobenzene Grignard reagent, is used in organic synthesis as a nucleophilic source of the benzene ring. It is formed by reacting bromobenzene with magnesium in the presence of an ether solvent. This reagent is commonly used in the synthesis of various organic compounds, such as alcohols, ketones, and carboxylic acids.

What are the safety precautions when working with reagent on bromobenzene?

Reagent on bromobenzene is a flammable and toxic compound. It should be handled in a well-ventilated fume hood, and appropriate personal protective equipment, such as gloves and safety glasses, should be worn. It should also be stored in a tightly sealed container away from heat and sources of ignition.

Can reagent on bromobenzene be substituted in a chemical reaction?

Yes, reagent on bromobenzene can be substituted with other Grignard reagents or nucleophilic sources of the benzene ring in a chemical reaction. However, the specific properties and reactivity of bromobenzene may make it the most suitable choice for certain reactions. It is important to carefully consider the reaction conditions and desired products before substituting this reagent.

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