Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: NeedHelp3 on April 23, 2011, 12:27:08 PM

Title: Free-Radical Chlorination of 2,2,4-trimethylpentand
Post by: NeedHelp3 on April 23, 2011, 12:27:08 PM

How many constitutionally isomeric monochlorides can be formed in the free-radical chlorination of 2,2,4-trimethylpentane?

a. 1
b. 2
c. 3
d. 4
e. 5

The answer is d. 4, but I don't understand why.  Whenever I work through the steps I always get 5 (1-chloro-2,2,4-trimethylpentane; 3-chloro-2,2,4-trimethylpentane [forms a stereogenic carbon]; 2-chloro-2,4,4-trimethylpentane; 1-chloro-2,4,4-trimethylpentane).  Does the stereogenic molecule only count as 1?  I have been counting it as 2 isomers.  Is 1-chloro-2,2,4-trimethylpentane considered exactly the same as 1-chloro-2,4,4-trimethylpentane?  Thank you for the time!

Title: Re: Free-Radical Chlorination of 2,2,4-trimethylpentand
Post by: Schrödinger on April 24, 2011, 05:19:26 AM

1-chloro-2,2,4-trimethylpentane and 1-chloro-2,4,4-trimethylpentane are different compounds.

The question is : How many constitutionally isomeric compounds.. You shouldn't be counting the stereoisomers.