ADA Paid # 89

[tokyoman]

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Bromination of this structure. with Br2/Fe
ADA Called it naphthalene, but it's actually anthracene.

How many monosubstituded isomers do they have?

Ans = 2

How? is there any rule for this? can someone please help me with explaining how to tackle these fused aramatic ring?
my testbook only covers Disubstitued with different reagent.

 

[flyingforever]

Its 2 because of cis/trans isomers. I don't know the other explanation.

 

[CANgnome]

I think the question was really asking about napthalene

Like benzene, naphthalene can undergo electrophilic aromatic substitution. For many electrophilic aromatic substitution reactions, naphthalene reacts under milder conditions than does benzene. For example, whereas both benzene and naphthalene react with chlorine in the presence of a ferric chloride or aluminium chloride catalyst, naphthalene and chlorine can react to form 1-chloronaphthalene even without a catalyst. Similarly, whereas both benzene and naphthalene can be alkylated using Friedel-Crafts reactions, naphthalene can also be alkylated by reaction with alkenes or alcohols, with sulfuric or phosphoric acid as the catalyst.

from wiki.

it is just that they posted the wrong picture, i think.


If you think about it, and it really is napthalene, although you can attack in many places along the outside of the 2 rings, if you monosubstitute it, you will only get 2 products, I don't know if this is clear or not.

http://en.wikipedia.org/wiki/1-Chloronaphthalene

It can add to the 2 position too. but if it is mono substituted, even if you add to the 3 position, since the carbon is sp2, adding to the 3 position will equal to adding to the 2 position and adding to the 4 position will equal to adding to the 1 position. Which is why i suspect there is no such thing as 3-chloronapthalene.

if it is anthracene I guess it is upped to 3.

 

[RCT PC CRN]

I think with the structure shown in a image you will get 3 different monobromination product. If it is naphthalene which is not shown here then you will get 2 product.

 

[CANgnome]

I am personally planning to do about 5 math destroyer tests the day before my DAT to really get it fresh in my head.

 

[RING12]

I think becuase Br can go ortha and para since the molcule has symmetry if you look at from any side then your answer should be two. becuase it's just says needs to be monosubsitued each time.