Carbonyls - conjugation and acetals

Topic 5

double bonds are conjugated when:

separated by a single bond, pi-MOs overlap

hard nucleophiles

react in a 1,2 manner

small and highly polarised (i.e. OH- and F-)

soft nucleophiles

react in a 1,4 manner

larger

type of nucleophile is grignards

hard

type of nucleophile is organo copper and zinc

soft

acetals

sp3 carbon bonded to 2 Os attached to carbons

acetal formation

formed from a ketone in acidic conditions, huge equilibrium → requires excess alcohol and dehydrating agent to remove H2O

acetals can be used as

protecting groups!

imine formation

primary amine + aldehyde / ketone, acid catalyst

imine is less reactive than ______ so requires stronger conditions like _________.

aldehydes/ketones, protonation

the more substituted the amine the _________________.

more nucleophilic

to prevent over alkylation of an amine you

protonate it to an immonium ion and use chemoselective reducing agent like [Na(OAc)3NH]

ester → amide

must activate ester in situ by using thionyl chloride, DCC or Coenzyme A