Naming isopropyl substituent: Question 2.48

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Justin Le 2I
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Naming isopropyl substituent: Question 2.48

Postby Justin Le 2I » Mon Mar 09, 2015 9:07 pm

I don't understand why the numbering wouldn't start at the isopropyl group and then go counterclockwise. The numbers would then be 1,2,and then 4. The answer starts at the OH and goes clockwise so the numbers are 1,2,5.

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Re: Naming isopropyl substituent: Question 2.48

Postby Chem_Mod » Mon Mar 09, 2015 9:14 pm

Hi Justin, because -OH is a suffix group (the molecule will take the ending "-ol" ), the -OH receives the lowest number possible, before we even consider the other groups.

Justin Le 2I
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Re: Naming isopropyl substituent: Question 2.48

Postby Justin Le 2I » Mon Mar 09, 2015 9:16 pm

Thanks. Is isopropyl considered a functional group though?

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Re: Naming isopropyl substituent: Question 2.48

Postby Chem_Mod » Mon Mar 09, 2015 9:19 pm

No, isopropyl is an alkyl substituent, which can only take prefixes.

Prefix groups have the last priority when trying to assign low numbers (behind suffix group and also behind double/triple bonds).

martha-1I
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Re: Naming isopropyl substituent: Question 2.48

Postby martha-1I » Tue Mar 10, 2015 10:28 am

Just thought I'd post this as a reminder of highest to lowest priority when it comes to numbering.
1) Functional groups (ex. carboxylic acid, alcohol, amine, aldehyde, ketone)
2) Double or triple bonds
3) Substituents

Justin Le 2I
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Re: Naming isopropyl substituent: Question 2.48

Postby Justin Le 2I » Wed Mar 11, 2015 10:00 pm

Thank you!

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Re: Naming isopropyl substituent: Question 2.48

Postby Chem_Mod » Wed Mar 11, 2015 11:30 pm

yeah Martha is correct..you can follow that ordering for preferential numbering


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