ORGANIC CHEM - ISOMERISM

Question 1

What is an isomer of a molecule?

Answer 1

a molecule with the same molecular formula but the atoms are arranged differently

Question 2

What are structural isomers?

Answer 2

isomers in which the atoms are connected in different ways

Question 3

What are stereoisomers?

Answer 3

isomers with the same structural formula but a different arrangement of atoms in space

Question 4

What are the 3 types of structural isomers?

Answer 4

• chain isomers (caused by having a diff carbon chain (eg: butane and methylpropane))
• position isomerism (caused by the functional group being in a different position (eg: propan-1-ol and propan-2-ol))
• functional group isomerism (caused by having a different functional group (eg: cyclohexane and hex-1-ene))

Question 5

What are the 2 types of stereoisomers?

Answer 5

• E-Z isomers/geometric isomers (caused by molecules with a C=C bond with 2 different groups attached to each of the C atoms in the C=C bond)
• optical isomers (caused by C atoms having 4 different groups attached leading to molecules that are superimposable mirror images of each other)

Question 6

Why do E/Z isomers exist?

Answer 6

no rotation in alkenes due to C=C double bond which causes geometric isomerism

Question 7

What are the Cahn-Ingold-Prelog priority rules?

Answer 7

• rules that allow us to figure out how to assign priority in order to decide if a molecule is an E isomer or a Z isomer
• look at atoms directly bonded to each of the C atoms
• higher atomic no. = higher priority
• if higher priority groups are on the same side its a Z isomer
• if higher priority groups are across from each other its an E isomer