Summary of Reactions CHEM2341 (1)

Page 1: Alkene Addition Reactions

  • Markovnikov Addition:

    • Uses H2SO4 to form a Markovnikov carbocation intermediate.

    • Reaction with BH3:THF leads to Syn addition of H and OH.

    • Hg(OAc)2 and H2O leads to Markovnikov carbocation intermediate.

    • Products include alcohols (ROH) with Markovnikov orientation.

  • Anti-Markovnikov Addition:

    • Treatment with H2O2/OH- leads to Anti-Markovnikov product.

    • NaBH4 provides a method for reducing ketones or aldehydes without rearrangement.

  • Cyclic Intermediates:

    • Reaction with X2 results in Anti addition, and no rearrangement occurs.

    • Water (H2O) adds Markovnikov, leading to OH groups positioned correctly versus hydrogen.

Page 2: Oxidation and Reduction Reactions

  • Oxidation Reactions:

    • OsO4 results in syn addition forming diols (HO–OH) across double bonds.

    • O3 cleaves pi bonds to produce aldehyde and ketone products.

    • KMnO4 also cleaves pi bonds and can form carboxylic acids, especially from terminal carbons.

  • Reduction Reactions:

    • H2 with Pt (platinum) allows syn addition to convert alkenes to alkanes.

    • Complete hydrogenation may utilize H2 with Lindlar's catalyst to produce cis-alkenes from alkynes.

Page 3: Alkyne Addition and Free Radical Reactions

  • Alkyne Addition:

    • 1: HX leads to double Markovnikov addition.

    • 2: X2 results in trans (anti) addition.

    • Addition of 2: HX demonstrates Markovnikov addition with H and X added in a trans manner.

  • Free Radical Reactions:

    • Cl2 with hv promotes radical formation.

    • Low specificity of bromine with hv.

    • HBr in the presence of peroxides yields Anti-Markovnikov addition.

    • Benefits from resonance-stabilized radical intermediates.

Page 4: Continued Free Radical Reactions and Alcohol Reactions

  • Free Radical Reactions Continued:

    • NBS adds bromine adjacent to alkene through a radical mechanism.

  • Alcohol Reactions:

    • Alcohol elimination can occur via dehydration in the presence of H2SO4, favoring Zaitsev elimination.

    • Stereospecific reactions:

      • SOCl2 and PBr3 allow substitution of OH groups with Cl or Br in SN2 fashion.

      • PCl3 offers similar stereospecific outcomes by converting alcohols to more reactive halides.

Page 5: Ether Synthesis and Reactions

  • Ether Synthesis:

    • 2 OH can react with H2SO4 to yield ethers via acid-catalyzed dehydration.

    • Williamson Ether Synthesis involves NaH or NaNH2 to prepare ethers from primary alkyl halides.

    • Peroxyacid example: MCPBA introduces epoxide formation across alkene carbons.

  • Reactions of Ethers:

    • Ether cleavage with HX can yield various products depending on conditions.

    • Reaction with HI under cold conditions produces only one product due to regioselective attack at the most substituted carbon.

    • SN2 attack implications for reaction pathways involve stereochemistry, leading to anti configurations.