Epoxides

Question 1

Nucleophilic Substitution: Acidic Conditions

Answer 1

Reactant: Epoxide

Reagents: any base like HX, H₂O, or an alcohol

Products: Vary (will be an alcohol) but something else may be added on

Mechanism: Partially SN1 and partially SN2

Nucleophile attacks most substituted carbon

Question 2

Nucleophilic Substitution: Basic or Neutral Conditions

Answer 2

Reactant: Epoxide

Reagents: any base, HX, alcohol, H₂O

Product: will vary but it will be an alcohol and something else attached

Mechanism: SN2

Nucleophile will attack the least substituted carbon

Question 3

Alkene to an alcohol w/o carbocation rearrangement

Answer 3

Reactant: Alkene

Reagents: 1.MCPBA, 2.LAH (hydrogen donor) 3.HCL (an acid that can protonate the oxygen)

Product: Alcohol

The hydrogen will attack the least substituted side in step 2.

Question 4

Formation of a Trans 1,2-diol

Answer 4

Reactant: Epoxide

Reagent: 1. strong base or a good nucleophile

2. HCl or a proton donating alcohol

Product: Trans 1,2-diols (get both stereoisomers)

Mechanism: SN2

Stereochemistry: Anti

Question 5

Formation of a Cis 1,2-diol

Answer 5

Reactant: Alkene

Reagents:

1. OsO₄
2. H₂O₂. H₂O

Product: Cis 1,2-diol or Cis-glycol

Stereochemistry: Syn

Question 6

Arene Oxide Rearrangement

Answer 6

Reactant: Arene Oxide

Reagents: An acid like HX

Product: Phenol

When forming the carbocation, there is usually 2 ways you can go, the major product and the one you want to form is the one that leads to the most stable product. That would be the carbocation that does not have a chance of interrupting an aromatic ring (like a benzene) and the carbocation that is most stable. A carbocation near an electron donating group is more stable than a carbocation without anything attached which is more stable than a carbocation near an electron withdrawing group.