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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: tissueagenda on July 29, 2020, 05:45:59 AM

Title: Nomenclature for 1,1-dimethylethyl cyclopentane
Post by: tissueagenda on July 29, 2020, 05:45:59 AM

Hi everyone, studying chemistry again after a really long time.

I was going through Khan Academy videos, in the end there was a cyclopentane with a tertbutyl. For the systematic naming, why is the longest chain not a propyl? My brain also can't wrap around the 1,1 dimethyl ethyl, could someone explain it please?

Thank you

Title: Re: Nomenclature for 1,1-dimethylethyl cyclopentane
Post by: Babcock_Hall on July 29, 2020, 10:34:47 AM

Which has more carbon atoms, the tertiary-butyl group or the ring?

Title: Re: Nomenclature for 1,1-dimethylethyl cyclopentane
Post by: Enthalpy on July 30, 2020, 05:12:19 PM

You need to name the tert-butyl keeping in mind which carbon makes a link with the cyclopentane.

I naming it methylpropyl, a different carbon would link to the cyclopentane. That would mean an isobutyl, not a tert-butyl.

So if you must call it ethyl, the branches can only be dimethyl. And because the name is long, normally you write t-butyl.