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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: orgo814 on June 29, 2012, 05:12:46 PM

Title: isomer question
Post by: orgo814 on June 29, 2012, 05:12:46 PM
Hi Everyone,

I have a question regarding isomers. For C8H18 (octane), it is possible to have two methyl branches from the 3rd carbon in (3,3 dimethylhexane) but it is not possible to have the two methyl branches on the second carbon in (2,2 dimethylhexane). I'll leave the link to a picture of all the isomers of C8H18. I just don't get it... since if you attach the two methyl branches on the second carbon it'll still have the same number of hydrogen atoms and it is a different structural formula so I don't see why it is not a valid isomer. Please explain this to me.

image link (http://www.google.com/imgres?q=C8H18+isomers&um=1&hl=en&sa=N&biw=1600&bih=775&tbm=isch&tbnid=bAFzKWCOBgl4rM:&imgrefurl=http://commons.wikimedia.org/wiki/File:C8H18_(R,S)isomer.jpg&docid=NqrxSOUn5lLFlM&imgurl=http://upload.wikimedia.org/wikipedia/commons/8/88/C8H18_(R,S)isomer.jpg&w=1200&h=1180&ei=HhnuT_bCDoKK8QTUwOmGAg&zoom=1&iact=hc&vpx=167&vpy=163&dur=463&hovh=223&hovw=226&tx=86&ty=156&sig=101081754886280972516&page=1&tbnh=121&tbnw=123&start=0&ndsp=35&ved=1t:429,r:0,s:0,i:89)

Edit: link edited
Title: Re: isomer question
Post by: sjb on June 29, 2012, 05:21:19 PM
Hi Everyone,

I have a question regarding isomers. For C8H18 (octane), it is possible to have two methyl branches from the 3rd carbon in (3,3 dimethylhexane) but it is not possible to have the two methyl branches on the second carbon in (2,2 dimethylhexane). I'll leave the link to a picture of all the isomers of C8H18. I just don't get it... since if you attach the two methyl branches on the second carbon it'll still have the same number of hydrogen atoms and it is a different structural formula so I don't see why it is not a valid isomer. Please explain this to me.

image link (http://commons.wikimedia.org/wiki/File:C8H18_%28R,S%29isomer.jpg)

Edit: link edited

What do you see as the 1st column, 3rd row?
Title: Re: isomer question
Post by: orgo814 on June 29, 2012, 05:56:19 PM
Oh, well that's embarassing. Thank you for your help.