17a - chirality Flashcards
what is a chiral carbon?
carbon with 4 different groups attached, no plane of symmetry & non-superimposable mirror images
what are enantiomers?
2 compounds that are optical isomers of each other
what are racemate / racemic mixtures?
mixture containing 50:50 of 2 enantiomers -> no effect on plane-polarised light
what is optical isomerism?
same structural formula but different arrangement of atoms in space
what is plane-polarised light?
light oscillate in 1 direction only
how is plane-polarised light produced?
standard light (which oscillate in all directions) is passed through a polaroid filter
what effect would optically active compounds have on plane polarised light?
rotation
how would different enantiomers affect plane polarised light?
1 enantiomer rotates light clockwise & the other rotates anticlockwise
describe the effect of plane-polarised light on racemates.
no effect; 2 enantiomers cancel out
which type of halogenoalkanes react through SN1 mechanisms? what would be formed? draw the mechanism.
3’ halogenoalkanes; produces intermediate
which type of halogenoalkanes react though SN2 mechanisms?
primary
which SN mechanism would produce a racemic mixture? why?
- SN1
- Y could attack from both sides resulting in equal chances of either enantiomers forming
- C+ carbocation is planar
what would be different to the reactant through an SN2 mechanism? why?
- nucleophile attack opposite group -> formed enantiomer will rotate light differently
