The common name

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The common name

Postby JuliaPark2H » Sat Feb 27, 2016 10:11 am

If a question tells you to identify the molecular formula, structural formula, and line structure of a certain organic molecule, the IUPAC name of the structure gives away the basis of how to figure out everything else. Does the common name give away any information? (the configuration, order of substituents, which structure to go about using...)

this question was based on:
2-methyl-1,3butadiene has the common name isoprene. Give its molecular formula, structural formula, and draw its line structure.

Also, how do does the common name nomenclature process work? I don't understand how the iso-/neo concept can bring about a very different name from the IUPAC name:
5-isobutyl-4methylnonane vs 4-methl-5-(2-methylpropyl)nonane

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Re: The common name

Postby Chem_Mod » Sat Feb 27, 2016 1:51 pm

Hi Julia,

The common name does not really give any additional information, it is just shorter to write. Everything you need to know about a molecule's structure is relayed in both the IUPAC and common name.

And for your second question, in short the common name encapsulates all carbons in a particular arrangement, rather than systematically naming them from a parent chain. That is why you see isobutyl vs methylpropyl, etc... It is incorporating all four carbons in that particular arrangement into a name, rather than naming the parent chain and a methyl substituent. It is useful to learn the common names for the sake of writing less lol, but IUPAC will definitely get you to the correct answer always.

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