Cyclopentane Naming

[Blake_Katsev_2E]

In question 1.16 there is a pentane ring with a isopropyl and dimethyl substituent. Shouldn't the isopropyl be 1 and dimethyl be on Carbon two? They are both either 1 or 2 so i thought you would go alphabetically

[Jenny2G]

Its hard to explain but I think its because you want the smaller numbers. The other way you would have 2,2-dimethyl rather than 1,1-dimethyl. But it's confusing.

[Alice Gonzalez 2F]

Smaller numbers do not have to correspond to names in alphabetical order. I believe we use 1,1 instead of 2,2 because 2,2 > 1,1 and we want the lowest numbers possible.

[Namaste246]

The isopropyl should be 2 because it would give the lowest number combination. 1,1,2 is less than 1,2,2.

[Chem_Mod]

If you only had one methyl group, you would name it 1-isopropyl-2-methylcyclopentane. But in this case you have two methyl groups so your numbering options are either 1-isopropyl-2,2-dimethyl or 2-isopropyl-1,1-dimethyl. Repeating the 1 is better than repeating the 2 so the name of this molecule is 2-isopropyl-1,1-dimethylcyclopentane.