Alkenes and Alkynes

Question 1

Elimination Reactions (Dehydrohalgenation of Alky Halides)
NaOH or C2H5O-, DMF

Answer 1

• E2 is preferred over E1
• E1 and SN1 occur at the same time

Question 2

Dehydration of Alcohols
H2SO4

Answer 2

• Forming Alkene

Question 3

Dehydrohalgenation of vic-dibromides

Answer 3

• Creating Alkenes or Alkynes

Question 4

Hydrogenation
H2/Pt, Pd or Ni

Answer 4

• Strips all the pi bonds
• Syn addition

Question 5

1) OsO4 2) H2O/NaHSO3

Answer 5

• Syn addition of -OH groups to the pi bonds

Question 6

RCO3H (mCPBA) to Alkene

Answer 6

• Syn addition
• Formation of an epoxide

Question 7

Hydroboration-Oxidation
1) BH3:THF 2) H2O2, HO-

Answer 7

• Syn addition
• Anti-Markovnikov
• Breaks pi bond to form an alcohol

Question 8

X2 to Alkene
(X: Br or Cl)

Answer 8

• Anti addition
• Forms a di-halogenated carbon structure

Question 9

X2, H2O
(X:Br or Cl)

Answer 9

• Anti addition
• Forms a halogenated structure with an alcohol group

Question 10

1) RCO3H 2) H3O+, OH-

Answer 10

• Anti addition
• Instead of an epoxide, it breaks the double bond to add two OH groups

Question 11

1) X2 2) Nucleophile (e.g., Ro-, RMgX)

Answer 11

• Make an ether or add another side group.
• Nucleophiles are not the same as the mechanism provide
• Anti-Addition

Question 12

Hydration
H2O, HA

Answer 12

• Markovnikov
• Adding alcohol group to a double bond

Question 13

1) Hg(OAc)2, H2O, THF 2) NaBH4, OH-

Answer 13

• Markovnikov
• Adding one alcohol to the pi bond

Question 14

HX
- HBr, ROOR (Peroxides)

Answer 14

• HBr, ROOR (Peroxides): Anti-Markovnikov
• HX: Markovnikov
• Halogenate pi bonds

Question 15

Hydrogenation
H2, Ni2B (P-2) (Syn)
Li, EtNH2 (Anti)

Answer 15

• Only one pi bond is broken