Y12 Addition reactions to alkenes, stereoisomers

Choose the correct combination.

• LHS:

  • - I is high priority

  • - Br is low priority

  RHS:

  • - Cl is high priority

  • - F is low priority

  Therefore molecule is Z

• LHS:

  • - Br is high priority

  • - I is low priority

  RHS:

  • - Cl is high priority

  • - F is low priority

  Therefore molecule is Z

• LHS:

  • - I is high priority

  • - Br is low priority

  RHS:

  • - F is high priority

  • - Cl is low priority

  Therefore molecule is E

• LHS:

  • - I is high priority

  • - Br is low priority

  RHS:

  • - Cl is high priority

  • - F is low priority

  Therefore molecule is E

Cis always corresponds to Z, and E always corresponds to trans.

True or False?

Choose the (fully) correct statement.

• True.

  trans-but-2-ene and (E)-but-2-ene describe the same molecule

• True.

  Trans means that the high priority groups are on the same side of the molecule

• False.

  Cis corresponds to E and Z corresponds to trans (i.e. the other way round)

• False.

  E/Z isomerism is a separate system to cis/trans.

  e.g. 1,2-dibromo-1-iodoethene

Choose the stereoisomer that is both trans and Z.

• 
• 
• 
• 

What are the conditions for the hydrogenation of ethene to ethane?

H₂ + H₂C=CH₂ → H₃C-CH₃

• Fine nickel catalyst, 150°C

• 300°C

  Phosphoric acid

  60-70 atm

• Sn/HCl

• No special conditions required

What are the conditions for the hydration of ethene to ethanol?

H₂O + ethene --> Ethanol

• Fine nickel catalyst, 150°C

• 300°C

  Phosphoric acid

  60-70 atm

• Sn/HCl

• No special conditions required

Choose the correct prerequisite for cis/trans isomerism

• Each carbon in the C=C bond must have 2 distinct groups.

  At least one group per carbon must be the same.

• Each carbon in the C=C bond must have 2 groups that are the same as each other.

  The groups on one carbon must be different from the groups on the other.

• Each carbon in the C=C bond must have 2 distinct groups. On each carbon, there must be one hydrogen atom.

• Each carbon in the C=C bond must have 2 groups that are the same as each other. This is why 2-methylbut-2-ene has cis/trans isomers.

Name the product from the addition of bromine to pent-2-ene.

(you may wish to draw this out)

• 2,3-dibromopent-2-ene

• 2,3-dibromopentane

• 3-bromopentane + HBr

• 1,2-dibromopentane

For the purposes of assigning stereoisomerism, which atoms are attached to the circled carbon?

• C,C,H

• C,H

• H,CH₂

• C,H,H

Give the possible products of the hydration of ethene.

• ethanal + H₂

• ethanol

• ethan-1-ol and ethan-2-ol

• ethane + O₂

Give the possible products of the hydration of propene.

• propan-1-ol

  propan-2-ol

• propan-1-ol only

• propan-2-ol only

• propanone + H₂