Iso and Neo Prefixes

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keyanabogan 2J
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Joined: Wed Sep 21, 2016 2:56 pm

Iso and Neo Prefixes

Postby keyanabogan 2J » Mon Mar 06, 2017 4:50 pm

I don't understand what purpose iso- serves in naming molecules nor for neo-. I only understand that neo is used or molecules with more than 5 carbon atoms. Can someone explain what these prefixes are used for?

Allison Suzuki 2B
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Re: Iso and Neo Prefixes

Postby Allison Suzuki 2B » Mon Mar 06, 2017 6:51 pm

The prefixes 'iso-' and 'neo-' are used for common naming instead of IUPAC naming; 'iso-' being used when there are 4 or less carbons, and 'neo-' when there are five or more. Common naming doesn't follow the rule of numbering the longest carbon chain, but instead counts all of the carbons. Using common names is primarily just a way to shorten the IUPAC name.

Preston_Dang_1B
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Re: Iso and Neo Prefixes

Postby Preston_Dang_1B » Mon Mar 06, 2017 6:52 pm

Iso- is used to name a substituent chain that has a specific orientation of carbon and hydrogen atoms, (CH3)2CH-. You would then determine the name of the whole substituent based on how many total carbon atoms there are in the entire structure. Neo- is the same as Iso- with respect to naming a specific orientation of carbon and hydrogen atoms, (CH3)3C- and you would again determine the name of the entire substituent based on how many total carbon atoms there are in the entire structure.

Hope this helps!

Amber_Candelaria_1D
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Re: Iso and Neo Prefixes

Postby Amber_Candelaria_1D » Tue Mar 07, 2017 10:13 pm

Allison Suzuki 2B wrote:The prefixes 'iso-' and 'neo-' are used for common naming instead of IUPAC naming; 'iso-' being used when there are 4 or less carbons, and 'neo-' when there are five or more. Common naming doesn't follow the rule of numbering the longest carbon chain, but instead counts all of the carbons. Using common names is primarily just a way to shorten the IUPAC name.


Hi sorry I'm confused by this explanation...if 'iso-' is used when there are 4 or less carbons and 'neo-' when there are five or more, why does 2-Methylbutane have the common name of isopentane when it has 5 carbons? and 2-Methylpentane is isohexane when it has 6 carbons?

Katherine_Zhuo_3B
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Re: Iso and Neo Prefixes

Postby Katherine_Zhuo_3B » Wed Mar 08, 2017 10:36 am

I believe the prefix iso- is not restricted to 4 or less carbons, and you can tell when it is used when the line structure has a branch of CH(CH3)2

Chem_Mod
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Re: Iso and Neo Prefixes

Postby Chem_Mod » Wed Mar 08, 2017 11:19 am

Iso- and neo- refer to a specific number and orientation of carbons. See the attached document for examples.
Iso and Neo.pdf
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