What is the structure of an organic species that has a formula of #C_9H_18# in which ALL the hydrogens are equivalent?

Question

Ellie Andrews · Accepted Answer

#"Hexamethylcyclopropane..........?"# I could not find a picture of this, and for all I know the molecule is unknown. A cyclopropyl ring, however, substituted with 6 methyl groups, fits your requirement. There are 6 methyl carbons attached to the three-membered ring, and all of them are #CH_3# groups.

Mateo Aguilar · Answer

Anor277 is correct! hexamethylcyclopropane!

To solve this, one must first recognize that the only way to get all primary hydrogens is to have all the hydrogens on methyl groups, #CH_3#.

There are 18 hydrogens.

That means there are 18/3 methyl groups.

That means we will need 6 carbons for the methyl groups.

That leaves 3 carbons to make up the support structure.

You could put them in a straight chain, but when you do that you end up with too many hydrogens and two of those hydrogens are tertiary:

This is the same problem you have with alkanes: two too many hydrogens for a linear alkane. You solve that by making it a cycloalkane!

And there you have it! At least, that's how I reasoned through it.

Xavier Avery · Answer

undefined The structure of an organic species with the formula C₉H₁₈, where all hydrogens are equivalent, is a linear alkane molecule called nonane.