C1: Isomers Flashcards
what makes a molecule chiral?
NOT having a plane of symmetry and having 4 different substituents at chiral center(s)
for constitutional isomers,
- how many compounds?
- same/different formula?
- same/ different connectivity of atoms?
- same/ different chemical and physical properties?
- can also be called 2 other names which are…?
- have the same ____
- 2 or more
- same
- different
- different
- regioisomers, structural isomers
- degree of unsaturation
what does the degree of unsaturation tell you?
- what is the formula?
- what do you do if there are N atoms?
- the # of pi bonds and rings in a molecule
- d= (2n+2)-x/2
where,
n= # of C atoms
x= # of H atoms+ # of X atoms - replace each N atom with 1 C atom and 1 H atom
a tautomer is a special kind of ____
- what are its 2 forms?
- how do these 2 forms differ?
- a tautomer is ____
- constitutional isomer
- keto and enol
- differ by the position of the double bond
- in equilibrium
for conformational isomers,
- how many compounds?
- same/different formula?
- same/ different connectivity of atoms?
- same/ different chemical and physical properties?
- can also be called 3 other names which are…?
- 1 compound with different rotation of bonds
- same
- same
- identical
- rotational isomers, rotamers, conformers
for steroisomers,
- how many compounds?
- same/different formula?
- same/different connectivity of atoms?
- same/different orientation in 3D space? what are the 3 kinds of orientations?
- same/ different chemical and physical properties?
- can also be called 1 other name which is…?
- 1 or more compounds
- same
- same
- different; chiral center, ring, double bond
- similar
- configurational isomers
what are the CIP priority rules?
step 1: compare atomic #s first
step 2: compare atomic masses if atomic #s are the same
step 3: if atomic #s and atomic masses are the same, move out an additional layer of atoms and start again
step 4: multiple bonds count as multiple atoms (ex: double bonded O counts as 2 O’s)
what are the steps for assigning R/S configuration?
step 1: find chiral centers (C or N with 4 different groups)
step 2: assign priority of the 4 groups by following CIP priority rules
step 3: check that the lowest priority group is on a dash
- if the arrangement from 1-4 is clockwise (to the right), it is R. if the arrangement from 1-4 is counterclockwise (to the left), it is S.
what does it mean when a molecule is achiral?
- does it have a chiral center?
- when it does not exhibit optical activity
- it can
when assigning R/S configurations,
what do you do if the lowest priority group is not on the dash?
step 1: switch any 2 groups so that it is
step 2: determine R/S configuration
step 3: switch decided configuration to the opposite (if it is R, switch it to S and vice versa)
describe a fischer projection
all groups on either side are coming toward you and all groups on top and bottom are going away from you
for enantiomers,
- they are a type of ____
- how many compounds?
- how many chiral centers?
- all chiral centers are ____
- same/ different chemical and physical properties?
- equal/ unequal and same/opposite optical activities?
- are ____ images
- optical isomer
- 2 compounds
- 1 or more chiral centers
- opposite
- identical
- equal and opposite
- non-superimposable mirror images
for diasteromers,
- they are a type of ____
- how many compounds?
- how many chiral centers? what is there to point out about these chiral centers?
- same/ different chemical and physical properties?
- describe their optical activities?
- are ____ images
- optical isomer
- 2 compounds
- 2 or more chiral centers, some are opposite
- similar but different
- unrelated
- non-superimposable non-mirror images
for epimers,
- they are a type of ____
- how many chiral centers?
- opposite/same chiral centers?
- diastereomers
- 2 or more
- only 1 is opposite
for geometric isomers,
- they are a type of ____ that has a different ____ arrangement around a ring or ____
- what does a cis/trans assignment describe? what do each of these mean?
- what does an E/Z assignment describe? what do each of these mean?
- stereoisomer; 3D; double bond
- the relative position of 2 groups; cis= same sides, trans= opposite sides
- assign priority using CIP rules, look at 2 groups on each C atom separately (means there will be 2 sets of priorities); Z= highest priorities on zame zides, E= highest priorities on opposite sides
