3. Stereochemistry Flashcards
what are isomers in terms of type and number of atoms
same type of atoms
same number of atoms
what are the 2 types of isomers
stereoisomers
constitutional isomers
what are constitutional isomers in terms of molecular formula and connectivity of atoms
same molecular formula
different connectivity of atoms
what are stereoisomers in terms of molecular formula and connectivity of atoms
same molecular formula
different spatial orientation of atoms
how does geometric isomerism occur for alkenes and cyclic compounds
cis and trans compounds
what are cis isomers
when substituents are on the same side of the ring or double bond
what is a trans isomer
when substituents are on opposite sides of the ring or double bond
is the cis or trans isomer more stable and why
trans more stable
substituents are further apart and there are less steric repulsions
what are chiral objects
objects that are not superimposable on their mirror images
what are chiral centres
carbon that is connected to 4 different groups
how many ways are there to arrange 4 groups around a chiral centre
only 2
how do the 2 chiral arrangements differ from each other
differ in spatial arrangement
what is an enantiomer
when a compound that is chiral, it will have one non superimposable mirror image
what is R/S configuration assigned to
assigned for each chiral centre
what are the 3 steps to determining R/S configuration for chiral centres
- assign priorities to each of the 4 groups connected to chiral center according to atomic # (highest atomic # = highest priority)
- rotate molecule so 4th priority atom is on the dash (facing backwards)
- count other 3 atoms and determine if its clockwise or anticlockwise
if the atoms around a chiral carbon are ordered in priority and go clockwise is it R or S configuration
R
if the atoms around a chiral carbon are ordered in priority and go anticlockwise is it R or S configuration
S
do enantiomers have similar physical properties to each other
yes
do diastereomers have similar physical properties to each other and why
no as they arent mirror images of each other
what is the equation for finding the maximum number of stereoisomers
max # of stereoisomers = 2^n
n = # of chiral centres
any compound with 1 chiral center must be ___ compound
chiral compound
any compound with 2 chiral center must be ___ compound
chiral or achiral
any compound has a plane of symmetry it must be ___ compound
achiral
any compound lacks a plane of symmetry it must be ___ compound
most likely chiral - chiral for GAMSAT
what are meso compounds
achiral compound if it has chiral centres and a plane of summetry
if a group of stereoisomers contains a meso compound what happens to the maximum number of stereoisomers
there will be less than 2^n stereisomers
for fischer projections what do the horizontal lines mean
they are coming out of the pages towards you
for fischer projections what do the vertical lines mean
they are going into the page away from you
