Iso and Neo Prefixes

[keyanabogan 2J]

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]

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]

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]

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]

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]

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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