Isomers Flashcards
What is a constitutional isomer?
Compounds that have the same molecular formula, different atom to atom bonding sequence
What is a double bond equivalent (DBE)?
Rings or pi bonds
What is the DBE formula?
DBEs = 1/2 (2n4 + n3 - n1 + 2)
where n4 = C
n3 = N
n1 = H, halogens
Can constitutional isomers have different functional groups?
Yes
What is a stereoisomer?
Molecules with different arrangement of atoms and groups of atoms in space
What are the two types of stereoisomers?
Conformational and configurational
What are conformational isomers?
Same molecular formula, same atom to atom bonding but the arrangement in space differs by rotation about a single bond
What are configurational isomers?
Molecules that have a different arrangement of atoms or groups of atoms in space that requires bond breaking for interconversion
Are conformational isomers the same compound?
Yes, they interconvert easily via rotation about a single bond and hence can be considered the same molecule
What is a conformer?
A specific shape adopted by the molecule as a result of the rotation about a single bond
What are the two types of conformers?
Staggered and eclipsed
What is an eclipsed conformer?
One in which the groups of adjacent carbon-carbon are lined up - hence least stable
What is a staggered conformer?
One in which the groups of adjacent carbon-carbon are separated furthest apart - hence most stable
How does a conformer go from staggered to eclipsed?
Rotation of 60 degrees about the C-C bond
What are the two types of staggered conformers?
Anti and Gauche
What is an anti conformer?
A type of staggered conformer in which the largest groups of the C-C bond are separated furthest apart
What is a gauche conformer?
A type of staggered conformer in which the largest groups of the C-C bond are 60 degrees apart (close together)