How many pi and sigma bonds in caffeine?

Discussion in 'Plant biotechnology' started by mansell32, Nov 14, 2009.

  1. mansell32

    mansell32 Guest

    How many pi and sigma bonds are in caffeine: http://www.mhhe.com/biosci/pae/botany/botany_map/images/caffine.gif

    What kinds of orbitals do the lone pairs occupy?
    only sp^2, only sp^3, sp^2 and sp^3, or only sp

    THANK YOU!!!
  2. attleigh

    attleigh Guest

    All of the double bonds are a pi and sigma and all of the single bonds are just sigma bonds. Don't forget that in the CH3 groups, there are three additional single/sigma bonds not shown.

    So we have 4 pi and 25 sigma.

    As far as the lone pairs, just look at where they are and if there are two lone pairs and a double bond, it would be sp^3 and if there is 1 LP and a double bond, sp^2, 1 LP and single bond, sp,2 LP and double bond is sp^2....just count!
  3. beavan81

    beavan81 Guest

    I count 4 double bonds, so the number of pi bonds is 4.

    Count up all the single bonds, don't forget the 3 Hydrogens in each Methyl group or that each double bond also has a sigma bond in it. If you count all these up, you will get the number of sigma bonds.

    Their are lone pair(s) on both heteroatoms Oxygen and Nitrogen. If their are only single bonds to the heteroatoms, then the lone pair(s) are in sp3 orbitals. If the heteroatom is involved in a double bond, the lone pair(s) are in sp2 hybridized orbitals.

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