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EAS question

Discussion in 'DAT Discussions' started by Fariba, Jul 19, 2006.

  1. Fariba

    Fariba Member
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    I am hoping someone will clarify a few things for me:

    1. Wouldn't -CH2X (halomethyl) on a benzene make it meta directing? My reasoning is that the more electronegative X would cause C to have a slight + charge? My book is listing it under O/P directing. Could someone explain?

    2. I understand why NR1 and NR2 are O/P directors, but why wouldn't NR3 also be O/P directing? N is more electronegative than the carbons... so it would have a slight negative charge making it O/P. What is the 3rd R group doing to change it?

    Thanks!
     
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  3. dat_student

    dat_student Junior Member
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    halomethyls are o-, p-directing & deactivating because of the halogen part....

    In -NR3, N is positively charged & doesn't have a lone pair of electrons.
     
  4. Fariba

    Fariba Member
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    I completely understand the NR3 part. I dont know why I didnt see that. But I still do not understand why the halogen makes it o/p? I understand why a halogen DIRECTLY attached to the benzene is o/p deactivating... but wouldnt the halogen NEXT TO the carbon attached to the benzene pull carbon's electrons away, so that carbon gets a slight positive charge?

    Thanks for the quick response, by the way! ;)
     
  5. tom_servo_dds

    tom_servo_dds Senior Member
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    In my O-Chem textbook it has -CH2X as being even more deactivating (but still O-P directing) than a straight -X would.
     
  6. Fariba

    Fariba Member
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    I am just having a mental block on this. I cannot understand how the C in -CH2X would not have a slight positive charge to it.

    Oh well! I guess I really shouldn't worry about it because A)I don't think I will EVER forget that it is o-p directing and B) I have probably annoyed a few of you with my cluelessness.

    Thanks for your patience! :p
     

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