Notices
Results 1 to 7 of 7

Thread: Organic Chemistry nomenclature

  1. #1 Organic Chemistry nomenclature 
    Forum Sophomore Stranger's Avatar
    Join Date
    Sep 2005
    Posts
    148
    Hi,

    According to my book, a compound is called iso- if it contains 2 methyl groups joined to one and the same C atom, and is called neo- if it contains 3 methyl groups joined to one and the same C atom.

    Ok, then why is
    .......CH3
    ........|
    H3C-CH
    ........|
    ........CH3

    called "isobutane"? why not "neobutane"?

    Similarly, why is
    .......CH3
    .......|
    H3C-C-SO3H
    ........|
    .......CH3

    called "isobutane sulfonic acid" and not "neobutane sulfonic acid"?

    Either these definitions lack or there is somthing I really don't understand.

    Thanks for help


    Watch what thy eyes can't see... and live it.

    (T.B)
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Senior silkworm's Avatar
    Join Date
    Nov 2005
    Location
    Kansas
    Posts
    337
    Note: Edited because I used some terms inappropriately... I was thinking tert- meant four, but everything else is correct.

    Neo is actually quarterniary, meaning there are 4 carbons attached to the central carbon.

    That is isobutane because there are 4 carbons total. If you were going with IUPAC it would be 2-methylpropane. You can't have a neobutane because the simplest "neo-" you can have is neopentane. You need 5 carbons to have a neo, the central carbon and the 4 bonded to it.

    A common bulky base used to explain organic synthesis is tert-butylalcohol. It isn't neobutyl alcohol because there only 4 carbons total and there is a bond from the central carbon to a hydroxy group. You could however have neopentanol because you'd have the central carbon attached to 4 carbons, with one of them attached to the OH.

    On the second one, that is not a neobutane (which would actually be a neopentane, I'll try to draw you one and post it somewhere when I get back) because all of the attachements to the central carbon are not carbons as well.

    If you know where I can upload a picture I'll draw you one. I just got a new program I'd like to try out, I just don't know where to put things on the net.


    Reply With Quote  
     

  4. #3  
    Forum Sophomore Stranger's Avatar
    Join Date
    Sep 2005
    Posts
    148
    I read the original reply and I was just going to ask you about "neo is tertiary".

    Ok, I think I understand now. I checked other examples and it seems it's ok. Maybe this stupid book could explain it in an easier way. Why not "iso- needs a 3ry C atom and neo- needs a 4ry C atom" instead of all that crap about methyl?

    Well, thank you. I dunno how you can uploads pics; I had the same problem somewhere else. But I do have an isopentane in my book, so it's ok.

    Thanks again. See you.
    Watch what thy eyes can't see... and live it.

    (T.B)
    Reply With Quote  
     

  5. #4  
    Forum Senior silkworm's Avatar
    Join Date
    Nov 2005
    Location
    Kansas
    Posts
    337
    Yeah, sorry about poking that word in there. I'm less drunk now than when I wrote that original message and tertiary sounded like the word I was looking for, but then I realized it totally wasn't.

    What book are you using?
    Reply With Quote  
     

  6. #5  
    Forum Sophomore Stranger's Avatar
    Join Date
    Sep 2005
    Posts
    148
    mmm... maybe "tert" is closer to tetra than tri. This may have been the reason

    The book is called "An introduction to organic chemistry (Chem 102)"
    Watch what thy eyes can't see... and live it.

    (T.B)
    Reply With Quote  
     

  7. #6  
    Forum Senior silkworm's Avatar
    Join Date
    Nov 2005
    Location
    Kansas
    Posts
    337
    It's a 102 class and it's organic chemistry?

    Maybe that means something different where you go to school than it does here.

    Do you know the difference between primary, secondary, and tertiary carbons? Methane would be super primary. Both carbons and ethane would be primary. The carbon attached to the two methyl groups in isopropane is secondary. The carbon attached to the three methyl groups in isobutane is tertiary. If you have 4 methyl groups attached to one central carbon that is neopentane.
    Reply With Quote  
     

  8. #7  
    Forum Sophomore Stranger's Avatar
    Join Date
    Sep 2005
    Posts
    148
    Yes, I understand.

    I actually taught that to a pal who was asking me about the question I posted.
    Watch what thy eyes can't see... and live it.

    (T.B)
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •