Unit 5 - Stereochemistry Flashcards
(27 cards)
What are Constitutional Isomers?
Isomers that have the same molecular formula but are connected differently
What are Stereoisomers?
Isomers that have atoms connected in the same sequence but they differ in their 3 D arrangements
What is Configuration?
The 3D arrangement of the bonds that connect atoms
What are Enantiomers?
Molecules that are not superimposable as mirror images
What kind of Compounds are Enantiomers?
Chiral Compounds
What is Chirality?
The ability of objects to exist as no superimposable mirror images of one another
What are Achiral molecules?
Objects that are superposable on their mirror images
How can you determine if a molecule is Chiral?
Look for a mirror plane in the image itself, if it has a mirror plane it is not chiral. You may also have to perform a reflection and do it the old fashioned way
What are Chirality centers?
Atoms connected to four DIFFERENT groups
Why can Nitrogen not be considered a Chrial center?
Because of the rapid inversion around the N-pyramidal atom. The only exception is nitrogen in a ring
How do you choose Cahn-Inghold Priorities?
The one with the highest atomic number goes first the then the next ones down. But Lowest priority always has to be in the back, if it’s not do it normally and switch your answer
What does CCW Cahn-Inghold give us?
S
What does CW Cahn-Inghold give us?
R
How are the Cahn-Inghold priorities related in Enantiomers?
One will always be S and one will always be R
What should you do in Cahn-Inghold if the two substitutents are the same atomic number?
Walk along the chain and find the next highest substitutents
How do you name compounds with 2 Stereocenters?
Put the number of the stereocenter and its classification separated by commas in brackets
What are Diasteromers?
Stereoisomers that are not mirror images/Enantiomers. Basically connected in the same way but the 3D is different and they are not mirror
How can you estimate the number of stereoisomers?
2^n
What are Mesocompounds?
They contain more than 1 Stereocenter
Have superimposable mirror images
Have an internal plane of symmetry
What is the E/Z system?
When classifying whether an object is Cis or Trans we use E or Z to describe it
What does Z mean?
When the two highest priority substitutents are on different sides
What does Z mean?
When the two highest priority substitutents are on the same side
When are Enantiomers no Physically and chemically identical?
When they interact with Chiral molecules and when they interact with polarized light
How do Enantiomers affect polarized light?
They rotate them in opposite directions
