introduction to organic chem exam qs

Question 1

What is the general formula for aldehydes, ketones and alcohols

Answer 1

ketones - CnH2nO

aldehyes - CnH2n+1 CHO

alcohols - CnH2n + 1OH

carboxylic acid - CnH2n+1 COOH

Question 2

Define stereoisomer

Answer 2

Two (or more) compounds have the same structural formula
But have their atoms/bonds/groups arranged differently in space

Question 3

How does a compound display stereoisomerism?

Answer 3

has restricted rotation around a planar carbon-carbon double bond

Question 4

What are the conditions for cis- trans isomerism and E- Z isomerism ?

Answer 4

• the carbon atoms in the double bond must each be attached to two different groups
• at least one of these groups must be the same for both carbons in the double bond

Question 5

When can E-Z isomerism be used instead of cis trans

Answer 5

when the carbon atoms in double bond are attached to 4 different groups ( no common group for both carbons)

Question 6

What are the CIP priority rules for E-Z isomerism

Answer 6

• establish the highest priority group on each carbon in the double bond
• this can be done using the atomic number ( number of protons)
  -if the two highest priority groups are on the same side of the molecule, isomer is Z. if they are on opposite sides of the molecule, isomer is E