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How is the superacid CH5+ made?

  1. Apr 30, 2004 #1
    Could someone please tell me how CH5 is made? I learned in class that is a superacid, but i am having a hard time seeing how something like could be made. Carbon does not contain a 'd' orbital so in theory CH5+ should not be able to be created.

    I have search online for the anwser, but have not found it.

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  3. Apr 30, 2004 #2
    maybe its CH4H and one of the hydrogens is bonded to another hydrogen
    not sure though
    though if its a super acid meaning the H would leave readily and hydrogen bonds dissolve little in solution so that would make it a weak acid. So it seems that we are back in the same place. And hydrogen only has one electron pair so it couldn't bond to C and H.

    I know a man that would know, his name is Adrian Dingle, he teaches at a very prestigous school in Georgia i think. Search for the name and you might find it.
  4. Apr 30, 2004 #3


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    "Chemical ionization mass spectrometry." See also, papers by Burnaby Munson.
  5. Apr 30, 2004 #4
    Carbon can't expand its octet, so how could it hold another hydrogen?

    And I've neevr heard of hydrogen expanding its octet in the case of of a hydrogen bonded to another hydrogen AND a carbon.

    I don't know how this would work.
  6. Apr 30, 2004 #5


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    The QM crowd may have more up-to-date thoughts/theories/solutions on this, but mid- to late- 70s, the party line was that you're looking at a trigonal bi-pyramidal configuration. Sorta frozen nucleophilic attack of H+ on methane --- reaction being H+ + CH4 = same, so no net enthalpy or free energy change --- it just sits there in the CH5+ configuration, picking its nose and wondering what to do next. Call it sp2 with a pair of half ionized Hs associated with the un-hybridized p.

    At that time, the only identifiable production occurred in the source of a mass spectrometer --- ionize hydrogen in the source, let it mingle with a "high" pressure of methane in the region surrounding the source, and the CH5+ then served as the agent/reagent for ionization of whatever sample was in the mass spec --- a "kinder, gentler" ionization of the sample --- less fragmentation.
  7. May 1, 2004 #6
    Thanks for the anwser but im still confused

    Thank you all for the answers, but im still confused on how it works or is possible. I am still in G-Chem (taking O-chem next year), so my understandings of lewis acids/bases/nucleopliphic attact is limited.

    I read a few artical on superacids form physical review but did not fully understand them. I know they react methane with CH4+ to make CH5+ CH3. I am not sure how they make CH4= (the artical said they bombarded with a 150eV electrons (does this enegy need to be negative).

    If any ones has any links to this topic i would greatly appreate it.
  8. May 1, 2004 #7


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    Olah's was one of the first to introduce this concept; go to the nobel prize site and download his nobel lecture in pdf. It is essentially a 2 electron 3 nuclear bond; in the case of CH5, one of the local C-H sigma orbital is actually shared with another proton. A proper organometallic catalyst can be used to faciliate this reaction, it requires a strong electrophile.

    C-----------H, the sigma bond local serves as somewhat of a pi locality (although no pi bonds are involved), a nucleophilic site.

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    Last edited by a moderator: May 1, 2017
  9. May 1, 2004 #8
    Thank you

    Thank you, i will do that. LOL, before i posted this went to the noble prize site and looked at every link but his lecture ( figured it would be an "i would like to thank 'x', 'y','z'" speach
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