mechanisms and delocalisation, acidity and basicity Flashcards
electrons flow from a ____ to a ______
nucleophile to an electrophile
what must nucleophiles be
molecules with lone pairs or anions
what must electrophiles be
neutral or positively charged
where do inductive effects occur
sigma bonds
what is the inductive effect
the more electronegative the atom, or the more heteroatom in a group, the more electron withdrawing it is
what is hyperconjugation
the donation of electrons from adjacent C-C or C-H sigma bonds to the empty p orbital of a carbocation
when is the only time hyper conjugation can occur
when they are in the same plane
what is the mesomeric effect
the delocalisation of the electron density though pi bonds - both electron donating and withdrawing groups are known
what is the highest energy of 3 combined p orbitals
when all are opposite ways around
more destabilisation =
more stable
the lower the pKa
the stronger the acid
the stronger the acid …
the weaker the conjugate base
the easier it is to break the H-A bond …
the stronger the acid
pKa _____ down a group
decreases (acid strengthens)
what type of hydbridisation is the most acidic and why
sp - more s orbitals held closely to the nucleus which makes it the most stable
what is basicity
a measure of the ability of a species to accept a proton
a negatively charged base is a ____ base then a neutral one
better
if a compound has its neg charge or lone pair delocalised it will be ____ basic then one with a localised charge or lone pair
less
substituents that _____ electron density on N (make lone pair more available) would make a better base
increase
