Question

The following labels were found on bottles of liquid hydrocarbons in the laboratory of Dr. Ima Turkey following his disappearance under mysterious circumstances. Although each name defines a structure unambiguously, some are not correct IUPAC substitutive names. Give the correct name for any compounds that are not named correctly.

(a) 2-ethyl-2,4,6-trimethylheptane
(b) 5-neopentyldecane
(c) 1-cyclopropyl-3,4-dimethylcyclohexane
(d) 3-butyl-2,2-dimethylhexane

Answer 1

(a) 2,4,6,6-tetramethyloctane; (b) 5-(2,2-dimethylpropyl)decane; (d) 4-tert-butyloctane

Step-by-step explanation:

(a) 2-Ethyl-2,4,6-trimethylheptane

They haven't picked the longest chain.

The correct name is 2,4,6,6-tetramethyloctane.

There are no spaces in the name.

Commas join numbers to numbers, and hyphens join numbers to letters.

(b) 5-Neopentyldecane

They correctly identified the main chain.

However, the side chain cannot be called neopentyl.

The preferred IUPAC name (PIN) for the group is 2,2-dimethylpropyl.

The name of the compound is 5-(2,2-dimethylpropyl)decane.

(c) 1-Cyclopropyl-3,4-dimethylcyclohexane

This compound is named correctly.

(d) 3-Butyl-2,2-dimethylhexane

They didn't pick the longest chain.

The new side chain is a tert-butyl group (the prefix is in italics).

The old systematic name for the group was 1,1-dimethylethyl, but tert-butyl is now the PIN.

The correct name for the compound is 4-tert-butyloctane.