Alkenes

Question 1

How does the double bond in alkenes affect rotation?

Answer 1

Restricts rotation

Question 2

Pi bond definition

Answer 2

The sideways overlap of 2 atomic orbitals above and below the two bonded atoms

Question 3

Stereoisomer definition

Answer 3

Compounds with the same structural formula but with a different arrangement of the atom in space

Question 4

What are the 2 types of stereoisomerism?

Answer 4

1. E/Z isomerism

2. Optical isomerism

Question 5

What is the criteria for E/Z isomerism?

Answer 5

1. Molecule must contain a double bond which restricts movement
2. Both carbons attached in the double bond must have 2 different groups attached to them

Question 6

How are priority groups determined?

Answer 6

The atom with the highest atomic number is the priority group

Question 7

What is an E isomer?

Answer 7

Where the priority groups are on different sides of the C=C double bond

Question 8

What is a Z isomer?

Answer 8

Where the priority groups are on the same side of the C=C double bond

Question 9

What is cis-trans isomerism?

Answer 9

Where one group on each carbon in the double bond is the same

Question 10

When do you have cis isomerism?

Answer 10

When the same group is on the same side

Question 11

When do you have trans isomerism?

Answer 11

When the same group is on the opposite side

Question 12

What is the conversion of hydrogenation?

Answer 12

Alkene –> alkane

Question 13

What is the reagent for hydrogenation?

Answer 13

H2

Question 14

What are the conditions for hydrogenation?

Answer 14

Nickel catalyst

Question 15

What is the conversion for hydration?

Answer 15

Alkene –> alcohol

Question 16

What is the reagent for hydration?

Answer 16

Steam

Question 17

What are the conditions for hydration?

Answer 17

H3PO4 catalyst

Question 18

What is the conversion for addition halogenation?

Answer 18

Alkene –> haloalkane

Question 19

What is the reagent for addition halogenation?

Answer 19

Halogen/hydrogen halide (HCl)

Question 20

What are the conditions for addition halogenation?

Answer 20

Room temperature

Question 21

What are the 3 reactions for alkenes?

Answer 21

Hydrogenation, hydration and addition halogenation

Question 22

What is the test for alkenes?

Answer 22

Add bromine water, the solution will change from orange to colourless

Question 23

What does a curly arrow represent?

Answer 23

The movement of a pair of electrons

Question 24

What is an electrophile?

Answer 24

An electron pair acceptor

Question 25

What are the first 4 steps in electrophilic addition?

Answer 25

1. The slightly positive H in polar HBr is attracted to the the electron-rich pi bond 2. Pi bond breaks and it's electron pair is donated to H atom in HBr 3. Covalent bond forms between a C from the double bond and the H 4. H-Br bond breaks by heterolytic fission

Question 26

What does the addition of a hydrogen halide/water to an ASYMMETRIC alkene make?

Answer 26

Two isomeric products

Question 27

What is an asymmetric alkene?

Answer 27

Where the 2 sides of the double bond are different (e.g. one carbon gas 2 H groups, the other carbon has CH3 and H)

Question 28

What is a carbocation?

Answer 28

Positive carbon

Question 29

What are primary, secondary and tertiary carbocations?

Answer 29

Primary - 0 or 1 alkyl group attached to carbocation Secondary - 2 alkyl groups attached Tertiary - 3 alkyl groups attached

Question 30

What changes from primary to tertiary carbocations?

Answer 30

Stability increases

Question 31

What is a major product?

Answer 31

The major product (the one that's made more) forms via the most stable carbocation intermediate