Addition Reactions with Alkenes

Question 1

(Catalytic Hydrogenation of Alkenes); Syn or Anti?

Answer 1

Syn Addition

Question 2

(Hydrogen Halides + Alkenes) form what?

Answer 2

Alkyl Halides

Question 3

(Hydrogen Halides + Alkenes); Markonikov or Anti Markonikov? Regioselective or not?

Answer 3

Markonikov, regioselective

Question 4

Definition of Regioselectivity

Answer 4

Preference of one bond to break over all others

Question 5

(Hydrogen Halides + Alkenes); Mechanism steps

Answer 5

Step 1: Protonation to form most stable carbocation

Step 2: Halide reacts with e- deficient carbon

Question 6

(Acid Catalyzed Hydration of Alkenes); reactant?

Answer 6

H3O+ (H+ and H2O)

Question 7

(Catalytic Hydrogenation of Alkenes); reactant?

Answer 7

Catalyst, sometimes Pt

Question 8

(Acid Catalyzed Hydration of Alkenes); Markonikov or Anti Markonikov? Regioselective or not?

Answer 8

Markonikov, regioselective

Question 9

(Acid Catalyzed Hydration of Alkenes); slow step?

Answer 9

protonation

Question 10

(Acid Catalyzed Hydration of Alkenes); special feature?

Answer 10

can rearrange to obtain more stable carbocation

Question 11

(Acid Catalyzed Hydration of Alkenes); Mechanism steps

Answer 11

Step 1: Protonation to form most stable carbocation
Step 2: Possible rearrangement
Step 3: Water attacks the carbocation
Step 4: Another water takes away one of the hydrogens from previous water, creating an alcohol group.

Question 12

(Viscinal Dihalides); reagent?

Answer 12

CCl4

Question 13

(Bromination); Trans gives ___ product(s). Cis gives ___product(s).

Answer 13

1, 2 enantiomers

Question 14

(Bromination); Mechanism Steps

Answer 14

Step 1: Double bond attacks one bromine and bromide molecule splits
Step 2: Bromine atom creates a bromonium ion
Step 3: Other bromine attacks backside

Question 15

(Halohydrins); Solution contains a lot of ___.

Answer 15

H2O

Question 16

(Halohydrins); Which is the nucleophile? Halide or Water?

Answer 16

Water

Question 17

(Halohydrins); Mechanism Steps

Answer 17

Step 1: Double bond attacks one Halide
Step 2: Halide molecule splits
Step 3: Halide forms a triangular molecule (e.g. bromonium ion)
Step 4: Water attacks backside
Step 5: Another water molecule attacks one of the hydrogens on previous connected water molecule creating an alcohol group

Question 18

(Oxymercuration & Reduction); Main reason

Answer 18

Can prevent rearrangement, and create a secondary alcohol

Question 19

(Oxymercuration & Reduction); reagent?

Answer 19

HgX2 in H2O

Question 20

(Oxymercuration & Reduction); Mechanism steps

Answer 20

Step 1: Double bond splits and creates mercuridium ion
Step 2: Water attacks more substituted bond in cyclopropane ring.
Step 3: Another water molecule attacks a hydrogen from previous connected water to create alcohol group
Step 4: Molecule is treated with NaBH4 to convert C-Hg bond to C-H bond

Question 21

Stereospecific

Answer 21

Can only produce one product

Question 22

(Hydroboration); Stereoselective or Stereospecific? Syn or Anti? Markovnikov or Anti Markovnikov?

Answer 22

Stereospecific, Syn, net Anti Markovnikov.

Question 23

(Hydroboration); Nucleophile? Electrophile? More or less substituted?

Answer 23

Hydrogen is nucleophile, Boron is electrophile, meaning it goes to the side of alkene that is less substituted.

Question 24

(Hydroboration); Reaction with three alkenes with BH3 forms what?

Answer 24

Trialkylborane

Question 25

(Hydroboration); Mechanism Steps (General)

Answer 25

Step 1: BH3 lewis base attaches to alkenes making trialkylborane
Step 2: Reaction of borane with O-OH
Step 3: 1,2 Shift
Step 4: Hydrolysis of each bond to gain 3 alcohol molecules

Question 26

(Ozonolysis); Mechanism Steps (General)

Answer 26

Alkene->Molozonide->Ozonide->Dimethyl sulfide->Aldehyde or ketone ((OR Ozonide->H2O2->carboxylic acid and ketone or aldehyde))

Question 27

(Ozonolysis); How many [3+2] cycloadditions, and how many [3+2] reverses?

Answer 27

2, 1

Question 28

(Free Radical Hydrogen Bromide); Markovnikov or Anti Markovnikov?

Answer 28

Anti Markovnikov

Question 29

(Free Radical Hydrogen Bromide); Mechanism Steps: Initiation

Answer 29

Step 1: RO-OR -> 2RO radicals
Step 2: RO radical and H-Br react by H and radical both donating one electron, and H-Br bond donating one electron to Br. This makes ROH and Br radical

Question 30

(Free Radical Hydrogen Bromide); Mechanism Steps: Propagation

Answer 30

Step 1: Alkene double bond donates one electron to another bond to create a radical in the molecule, and one electron to combine with Br radical. This forms a radical molecule with the new Br attached
Step 2: Radical combines with another H.
Step 3: End result, H on the more substituted, Br on least sub.