Isomer Question Organic Chemistry

Question

I was studying orgo and I realized something weird. My answer to the question was wrong yet I couldn't find out why.

Question

What are all the alkyl constitutional isomers of C5H11. I drew one and the I named it.......it came out as

2,2 dimethyl propyl..............yet this was not an answer........why is that so? They don't go against the rules of being a constitutional isomer of C5H11.

Answer 1

Somehow, this question seems incomplete. C5H11 is only part of the question. What is the other part? Are you asking about alcohols, benzene derivatives, bromides or what? If you were asking about alkanes, then the MF would be C5H12, so I presume you are asking about something different.

2,2-dimethylpropyl should be an answer. Was it there in another form, such as neopentyl? What book is this question from?

Answer 2

Should it have been 2, 2 dimethylpropane?

Propyl is a group, not a molecule.

Answer 3

the compound you proposed, 2,2-dimethyl propyl (which should be called 2,2-dimethylpropane) would have the stucture (CH3)4C, for tetramethyl methane. It's molecular formula is C5H12, not C5H11...

Hope this helps!!!

Answer 4

If you are talking about an alkyl group then C5H11 is a group called Pentyl which had an old common name of Amyl.

What you called "2,2 dimethyl propyl-" would have the structure of

CH3-C(CH3)2-CH2-

This would be called Neopentyl-

The corresponding alkane (C5H12) would be called Neopentane or 2,2-Dimethylpropane