Lecture 7: Chemistry of Alkenes

Question 1

general formula of alkenes

Answer 1

CnH2n

Question 2

hybridization of C double bonded with C

Answer 2

sp2

Question 3

what bonds does 1 double bond consist of?

Answer 3

sigma+pi

Question 4

which is stronger: sigma or pi?

Answer 4

1. sigma because head-on overlap
2. pi weaker cz side to side overlap
3. sigma weaker than double bond because double bond had more area overlapping orbitals

Question 5

hydrogen halide reaction with alkene

Answer 5

alkene is nucleophile
reactant: HX
product: haloalkane formed

Question 6

halogenation reaction with alkene

Answer 6

alkene is nucleophile
reactant: X2
product: dihaloalkane

Question 7

hydrogenation reaction with alkene

Answer 7

alkene is a nucleophile
reactant: H2 + Pd/C
product: alkane

Question 8

why are alkenes more reactive?

Answer 8

1. higher electron density
2. electrons are above and below the c double bond c (easily accessible)
3. weaker bond

Question 9

what do alkenes act as in presence of a electrophile?

Answer 9

nucleophile

Question 10

most type of reactions of alkenes

Answer 10

addition reactions

Question 11

different types of reactions of alkenes

Answer 11

1. halogenation (X2)
2. hydrogen halide (HX)
3. hydrogenation (Paladium[Pd]/Carbon[C])

Question 12

mechanism of electrophilic addition

Answer 12

1. C_C bond to H delta+
2. H-Br bond to Br delta -
3. Br- to carbocation

Question 13

major product is from where in electrophilic addition?

Answer 13

major product formed by favored pathway which is from the most stable, tertiary carbocation

Question 14

electrophilic addition of halogens

Answer 14

1. C_C bond to Cl delta +
2. Cl delta + bond to Cl delta -
3. Cl- to carbocation

Question 15

bromination with alkenes

Answer 15

turns colorless