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Halogen priority for naming compounds (TPR OChem workbook passage #17)

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ModerateMouse

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Hello,

(I searched for this couldn't find anything similar)

Is 1-bromo-2-iodobenzene a correct or incorrect name for benzene with two adjacent halogen substituents (a bromine and an iodine)?

I have always thought that all halogens are clumped together for priority rules for nomenclature.

Since they are clumped together, bromine would get the number "1" because of the alphabetical order.

Here is just one link.

But, TPR says that the correct name is

"2-bromo-1-iodobenzene" because "the higher-priority group should be given the first position.

[ The only other rule for this that I learned (guideline) is that the more a functional group oxidizes the carbon that it's attached to, the higher the priority should be. TPR doesn't seem to be following this either. ]

Thanks for your help. :xf:
 

orgohacks

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Hello,

(I searched for this couldn't find anything similar)

Is 1-bromo-2-iodobenzene a correct or incorrect name for benzene with two adjacent halogen substituents (a bromine and an iodine)?

I have always thought that all halogens are clumped together for priority rules for nomenclature.

Since they are clumped together, bromine would get the number "1" because of the alphabetical order.

Here is just one link.

But, TPR says that the correct name is

"2-bromo-1-iodobenzene" because "the higher-priority group should be given the first position.

[ The only other rule for this that I learned (guideline) is that the more a functional group oxidizes the carbon that it's attached to, the higher the priority should be. TPR doesn't seem to be following this either. ]

Thanks for your help. :xf:

Your instincts were right, TPR is wrong. It's 1-bromo-2-iodobenzene. For halogens nomenclature is alphabetical.
 

ModerateMouse

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Thank you all for your comments.

I've always put such great stock in TPR, and have always assumed that they are right.

Now I am wondering if I've been forced to accept other wrong answers, and have changed my way of thinking because of them.
 
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