Optical isomerism Flashcards
what property must a carbon have for the molecule to display optical isomerism about that carbon atom
4 different substituents attached to one carbon atom
what are the similarities and differences between two optical isomers
same atoms and bonds, but they are not superimposable mirror images of one another. not identical in chemical properties necessarily.
differ in the way they rotate plane polarised light- rotate plane of polarisation by the same angle but in different directions.
what word is used to describe optically active molecules
chiral
what are the pair of isomers called
enantiomers
what is the chiral centre
the carbon that has four different substituents attached to it
how is the chiral centre denoted
C*
How is light polarised
by passing it through a polarised filter, so oscillations are only in one plane
what effect does the racemix mixture have on plane polarised light
none
what effect does the + isomer have on plane polarised light
rotates plane of polarisation by X’ clockwise
what is the structure of a polarimeter
light source
polarising filter
polarised light passes through compartment containing sample
detector determines the angle of rotation of the plane polarised light
what are polarimeters used fore
to identify which enantiomer is present
the purity of the sample
the concentration of the sample
first reaction of the synthesis of lactic acid from ethanal
CH3CHO + HCN -> CH3CH(OH)CN
second reaction of the synthesis of lactic acid from ethanal
CH3CH(OH)CN + HCL + 2H2O -> CH3CH(OH)COOH + NH4CL
are racemic mixtures formed in nature
not often, as enzyme mechanisms are 3D so only form one enantiomer
why is optical isomerism a problem for the drug industry
sometimes, only one enantiomer is effective due to enzyme’s active/cell receptors being 3D
