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Homework Help: Dihydro Benzene is more polar than Dichloro benzene

  1. Aug 16, 2006 #1
    Can someone explain why this is so or atleast nudge me in the right direction?
  2. jcsd
  3. Aug 16, 2006 #2


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    Your thoughts (whether in favor or opposing)?
  4. Aug 20, 2006 #3
    well i have just now started learning chemical bonding so I am not very sure about the answer but anyway..
    para-dichlorobenzene most probably doesnt have a dipole moment because of the oppositely positioned Chlorine atoms. Ortho and meta dichlorobenzene would definitely have a dipole moment(greater in the case of ortho). But I have no clue about dihydro-benzene. I dont even have any idea about its strucutre... Can you please help?:confused:
  5. Aug 22, 2006 #4
    dihydrobenzene doesn't really contain benzene

    NOTE: The post previously had 1,3 cyclohexadiene mislabeled as 1,2 cyclohexadiene. Mistake noted by Cesium.

    dihydrobenzene comes in two forms. These are also known as:
    1) 1,3 cyclohexadiene
    2) 1,4 cyclohexadiene
    (or if you wanted you could do the ortho,para naming)
    but the key difference between these compounds and dichlorobenzene is that these, while still a derivative of benzene, do not have 3 alternating double bonds and are not aromatic.
    If you are confused of the exact structure I found them at sigmaaldrich.com searching for dihydrobenzene.
    The dipole moment of the 1,3 cyclohexadiene form makes sense considering the molecule is no longer symetrical (as in the para-dichlorobenzene or the 1,4 cyclohexadiene). As for the dipole moment of the 1,4 cyclohexadiene I really have no idea, it shouldn't have much, if any dipole moment.
    Last edited: Aug 22, 2006
  6. Aug 22, 2006 #5
    What about 1,3-cyclohexadiene? It should have a dipole moment.
  7. Aug 22, 2006 #6
  8. Aug 22, 2006 #7
    you are correct, It was my mistake, I mislabeled my first post. The 1,2 cyclohexadiene should read as 1,3 cyclohexadiene. When I was working the nomenclature out by hand (in attempt to answer your question) I had mistakenly used the numbers as the carbon positions where the hydrogen is attached, not the bond position. So YES, 1,3 cyclohexadiene has a dipole moment, I don't think 1,4 cyclohexadiene does. And I'll probably be corrected again, but I don't think 1,2 cyclohexadiene exists. Good call.
  9. Aug 22, 2006 #8
    I agree with you. A quick search online (not the ultimate authority) does not show much for 1,2-cylcohexadiene. It seems as if it is only a reactive intermediate.
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