organic 2b Flashcards
the empty orbital on a carbo cation is theeeeee
empty p orbital
bumbbell shaped
what is the shape of a carbocation
its trigonal planar and flat!!
when can hyperconjugation occur
when there is sufficient overlap between the orbitals
what does sufficient overlap mean
it means the orbitals are kinda facing the same way!! they should also have constructive interference but we kinda draw it to make sure it does anyway
whats the word when orbitals dont overlap sufficiently
theyre said to be orthogonal ,, kinda perpendicular to eachother,, not a favourable interaction for hyperconjugation!!
appart from the p orbital ,, what do we kinda say everything else is
either sp3 hybrid,, sp or s
aka we draw the orbitals kinda just overlapping over the bonds with 2 e- in the middle of them where they overlap
constructive overlap is whereeee
they are shaded in the same place,, where there is a bonding interaction - they overlap and allow e- to be shared between them - form a covalent bond - larger e- density between them - lowers energy.
in order for carbocation rearrangements to occur,, what do we need to look for
we need to look at the other bonds around it ,, we need to draw the orbitals and see if there are any ones pointing in the same way as the p orbital!!!
make sure theyre not orthogonal,, make sure they can constructively overlap if theyre pointing in the same way.
when can a tertiary cc+ be rearranged to give a 2CC+
when doing so reduces ring strain: thermodynamic explanation as it releases energy when the more stable structure is made. // when its rearranged to give the more stable structure.
how to draw a cyclohexane chair when its tricky
look for the cyclohexane on the molecule
draw the cyclohexane chair structure
draw the axial and equitorial bonds sticking out
look at the possible wedges and dashes on the acc structure - try add the rest in by looking to see if they would go axially or equatorially!!
see if theres any good overlap!! the p orbital pointing axially + there being an axial bond = good overlap!!
CC+ stability flow chart: most stable to least stable
3 > 2 > 1 > ch3
different types of hyperconjugation + which one is preferred
CH hyperconjugation
CC hyperconjugation
CH hyperconjugation is preferred.
when can a double bond be made
when theres a CC+ with an empty p orbital and the adjacent CC bond can constructively overlap due to pointing the same way.
this will break the bond between them and give a double bond.. the furthest C involved in the CC sigma will have a + charge.
what happens when 2 bonds have good constructive overlap with the 2p orbital
we choose the most stable one due to thermokinetic reasons
if theyre all equally stable,, we get a mixture of different products!!!!
