Question

What are the names of the following branched alkane molecules?

My teacher hasn't explained how to name branched alkanes and now I'm having trouble with this homework. Can someone please help me with this?

Answer 1

I will do the first of your problems.......

Explanation:

With all these problems, you should draw the compound as symmetrically as possible, and (i) identify the LONGEST carbon chain:

We have `H_3C-CH_2CH(CH_3)CH_2CH_2CH_2CH_3`, i.e. a seven carbon chain is the longest chain,

number the longest carbon chain:

`H_3stackrel1Cstackrel2CH_2stackrel3CH(CH_3)stackrel4CH_2stackrel5CH_2stackrel6CH_2stackrel7CH_3`.

Note that I COULD have numbered from the other end, the right hand end, but in that case the substituent would have been at `stackrel5C` not `stackrel3C`, and the numbering scheme demands that these substituent numbers be MINIMIZED.

And thus we have a 7-carbon alkyl chain, an alkane, i.e. `"3-methylheptane"`.

Try the other examples according to this scheme and the one in your text, and if in doubt, ask again........