Organic Chemistry: Alkenes and Alkynes
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Questions and Answers

What suffix is commonly used in the nomenclature of alkenes?

  • -yne
  • -ane
  • -ene (correct)
  • -ol

    • Electrophilic addition of H2O to alkenes is always anti-addition.

    False

    What is the regioselectivity when adding HBr to an alkene?

    Markovnikov

    In the bromination of alkenes, a ______ ion is formed as an intermediate.

    <p>bromonium</p> Signup and view all the answers

    Match the reagents with their resulting products in electrophilic addition to alkenes:

    <p>HBr = H+ and Br- Br2/CCl4 = Br+ and Br- H3O+ = H+ and OH- H2/catalyst = H and H</p> Signup and view all the answers

    Which reaction leads to syn addition?

    <p>H2/catalyst</p> Signup and view all the answers

    Electrophilic addition reactions can involve carbocation rearrangement.

    <p>True</p> Signup and view all the answers

    What is the result of the hydroboration-oxidation reaction on an alkene?

    <p>Anti-Markovnikov addition of alcohol</p> Signup and view all the answers

    Using ______ as a reagent provides an anti addition mechanism.

    <p>Br2/CCl4</p> Signup and view all the answers

    Match the reagent with its type of selectivity:

    <p>H2/catalyst = Syn addition HBr = Markovnikov Br2/H2O = Markovnikov BH3.THF = Anti-Markovnikov</p> Signup and view all the answers

    What is the condition required for oxidative cleavage of alkenes using ozonolysis?

    <p>O3 at -78°C</p> Signup and view all the answers

    Anti-Markovnikov addition occurs with the presence of a radical initiator.

    <p>True</p> Signup and view all the answers

    What is the product formation for syn addition using RCO3H (MCPBA)?

    <p>OH and OH</p> Signup and view all the answers

    Under reducing conditions, the products formed from oxidative cleavage yield ___ chiral centers.

    <p>none</p> Signup and view all the answers

    Match the oxidative conditions with their appropriate method:

    <p>Ozone = Ozonolysis KMnO4 (hot, concentrated) = Oxidative cleavage KMnO4 (cold, dilute) = Hydroxylation H2O2 = Oxidation</p> Signup and view all the answers

    Which reagent is used in syn hydroxylation of alkenes?

    <p>KMnO4 (cold, dilute)</p> Signup and view all the answers

    Both syn and anti addition products from alkene reactions are chiral.

    <p>False</p> Signup and view all the answers

    What is the typical number of chiral centers when using OsO4 for syn addition?

    <p>2</p> Signup and view all the answers

    In anti-addition reactions, the usual number of products formed is ___.

    <p>2</p> Signup and view all the answers

    What is the result of oxidative cleavage under reducing conditions?

    <p>No chiral centers</p> Signup and view all the answers

    Match the electrophilic addition reagents to their added components:

    <p>HBr (or HCl, HI) = H+ and Br- H3O+ = H+ and OH- Br2/CCl4 = Br+ and Br- (1) BH3.THF = H+ and OH-</p> Signup and view all the answers

    Match the reagents with their regioselectivity:

    <p>HBr (or HCl, HI) = Markovnikov Br2/H2O = Markovnikov (1) Hg(OAc)2, H2O = Markovnikov (1) BH3.THF = Anti-Markovnikov</p> Signup and view all the answers

    Match the reagents with their intermediate types:

    <p>Br2/CCl4 = bromonium ion (1) Hg(OAc)2, H2O = mercurinium ion H2/catalyst = - H3O+ = carbocation</p> Signup and view all the answers

    Match the reagent with its type of stereochemistry:

    <p>Br2/CCl4 = Anti (1) BH3.THF = Syn (1) Hg(OAc)2, ROH = Anti H2/catalyst = Syn</p> Signup and view all the answers

    Match the reagents with potential rearrangements:

    <p>HBr (or HCl, HI) = Possible (1) Hg(OAc)2, H2O = No H2/catalyst = No (1) BH3.THF = No</p> Signup and view all the answers

    Match the reagent to its product nature:

    <p>Br2/H2O = H+ and OH- HBr/ROOR (peroxide) = H and Br (2) NaBH4 = Reducing agent H3O+ = Hydration product</p> Signup and view all the answers

    Match the reagents with their used solvents or catalysts:

    <p>Br2/CCl4 = Non-polar solvent H2/catalyst = Pd/C, Pt/C, or Ni H3O+ = Water (1) Hg(OAc)2, ROH = Alcohol</p> Signup and view all the answers

    Match the reagents with their final product specificity:

    <p>HBr (or HCl, HI) = Add H and halogen (1) Hg(OAc)2, ROH = Markovnikov product H2/catalyst = Alkane product (1) BH3.THF = Anti-Markovnikov alcohol</p> Signup and view all the answers

    Match the reaction conditions with the type of addition they produce:

    <p>RCO3H (MCPBA) = Syn addition (1) OsO4, (2) H2O2 = Syn addition KMnO4 (cold, dilute)/ OH- = Syn addition (1) O3, (2) (CH3)2S = Reductive cleavage</p> Signup and view all the answers

    Match the reagents with their respective outcomes in oxidative cleavage of alkenes:

    <p>O3, -78°C = Produces carbonyl compounds KMnO4 (hot, concentrated)/OH- = Oxidative cleavage H2O2 = Oxidative cleavage Zn/H2O = Reductive cleavage</p> Signup and view all the answers

    Match the type of mechanism with its characteristic addition:

    <p>Anti-Markovnikov = Radical addition Syn addition = Bicyclic intermediates Anti addition = Non-superimposable products Syn addition with OsO4 = Formation of 2 chiral centers</p> Signup and view all the answers

    Match the products with the usual number of chiral centers formed:

    <p>0 chiral centers = None 1 chiral center = 2 products 2 chiral centers = Syn addition 4 products = None</p> Signup and view all the answers

    Match the reagents with their specific types of addition:

    <p>RCO3H (MCPBA) = Anti addition OsO4 = Syn addition KMnO4 (cold, dilute) = Syn addition H3O+ = Acidic hydration</p> Signup and view all the answers

    Match the oxidative cleavage conditions with their type:

    <p>O3 followed by H2O2 = Oxidizing conditions KMnO4 (hot, concentrated) = Oxidizing conditions Zn in acid = Reducing conditions (1) O3, (2) (CH3)2S = Reducing conditions</p> Signup and view all the answers

    Match the addition mechanism with their reagent:

    <p>Radical = HBr with peroxide Syn addition = OsO4 Anti addition = RCO3H Hydration = H3O+</p> Signup and view all the answers

    Study Notes

    Alkenes Nomenclature

    • Alkenes are identified by the suffix "-ene."
    • Configuration designated as E/Z specifies the relative positioning of substituents around the double bond.

    Electrophilic Addition Reactions

    • Various reagents can add to alkenes via electrophilic addition, with each reaction having different characteristics.

    Reagent Types and Characteristics

    • HBr, HCl, HI

      • Adds H+ and Br-.
      • Follows Markovnikov's rule for regioselectivity.
      • Possible carbocation rearrangement.

    • H3O+

      • Produces H+ and OH-.
      • Also follows Markovnikov's rule with rearrangement possible.

    • H2 and ROH

      • Adds H+ and OR- conforming to Markovnikov's rule with possible rearrangement.

    • Br2/CCl4 or Cl2

      • Adds Br+ and Br- or Cl+ and Cl-.
      • Anti addition (trans) through formation of a bromonium or chloronium ion.
      • No rearrangement possible.

    • Br2/H2O and Cl2/H2O

      • Adds Br+ and OH- or Cl+ and OH-.
      • Markovnikov's rule applies, with anti addition.

    • Br2/ROH and Cl2/ROH

      • Produces Br+ and OR- or Cl+ and OR-.
      • Follows Markovnikov's rule with anti addition.

    • (1) Hg(OAc)2, H2O / (2) NaBH4

      • Introduces H+ and OH-.
      • Adheres to Markovnikov's rule with anti addition.

    • (1) BH3.THF / (2) H2O2, OH-, H2O

      • Forms H+ and OH-.
      • Anti-Markovnikov addition resulting in syn stereochemistry.

    • H2/catalyst (Pd/C, Pt/C, Ni)

      • Hydrogenation resulting in syn addition of H and H.

    • HBr/ROOR (peroxide)

      • Produces anti-Markovnikov addition of H and Br.
      • Involves a radical mechanism.

    • RCO3H (MCPBA)

      • Creates O via syn addition.

    • (1) RCO3H (MCPBA) / (2) H3O+

      • Yields OH and OH through anti addition.

    • (1) OsO4 / (2) H2O2

      • Generates OH and OH through syn addition.

    • KMnO4 (cold, dilute)/OH-

      • Adds OH and OH in syn fashion.

    Chiral Centers and Products

    • No chiral centers lead to 1 product.
    • One chiral center generates 2 products.
    • Two chiral centers can create 2 syn products or 2 anti products, leading to a total of 4 products in syn or anti scenarios.

    Oxidative Cleavage of Alkenes

    • Reducing Conditions:

      • O3 followed by (CH3)2S or Zn/H2O cleaves alkenes.

    • Oxidizing Conditions:

      • O3 followed by H2O2 or KMnO4 (hot, concentrated)/OH- or with H3O+ achieves oxidative cleavage.

    Alkenes Nomenclature

    • Alkenes are identified by the suffix "-ene."
    • Configuration designated as E/Z specifies the relative positioning of substituents around the double bond.

    Electrophilic Addition Reactions

    • Various reagents can add to alkenes via electrophilic addition, with each reaction having different characteristics.

    Reagent Types and Characteristics

    • HBr, HCl, HI

      • Adds H+ and Br-.
      • Follows Markovnikov's rule for regioselectivity.
      • Possible carbocation rearrangement.

    • H3O+

      • Produces H+ and OH-.
      • Also follows Markovnikov's rule with rearrangement possible.

    • H2 and ROH

      • Adds H+ and OR- conforming to Markovnikov's rule with possible rearrangement.

    • Br2/CCl4 or Cl2

      • Adds Br+ and Br- or Cl+ and Cl-.
      • Anti addition (trans) through formation of a bromonium or chloronium ion.
      • No rearrangement possible.

    • Br2/H2O and Cl2/H2O

      • Adds Br+ and OH- or Cl+ and OH-.
      • Markovnikov's rule applies, with anti addition.

    • Br2/ROH and Cl2/ROH

      • Produces Br+ and OR- or Cl+ and OR-.
      • Follows Markovnikov's rule with anti addition.

    • (1) Hg(OAc)2, H2O / (2) NaBH4

      • Introduces H+ and OH-.
      • Adheres to Markovnikov's rule with anti addition.

    • (1) BH3.THF / (2) H2O2, OH-, H2O

      • Forms H+ and OH-.
      • Anti-Markovnikov addition resulting in syn stereochemistry.

    • H2/catalyst (Pd/C, Pt/C, Ni)

      • Hydrogenation resulting in syn addition of H and H.

    • HBr/ROOR (peroxide)

      • Produces anti-Markovnikov addition of H and Br.
      • Involves a radical mechanism.

    • RCO3H (MCPBA)

      • Creates O via syn addition.

    • (1) RCO3H (MCPBA) / (2) H3O+

      • Yields OH and OH through anti addition.

    • (1) OsO4 / (2) H2O2

      • Generates OH and OH through syn addition.

    • KMnO4 (cold, dilute)/OH-

      • Adds OH and OH in syn fashion.

    Chiral Centers and Products

    • No chiral centers lead to 1 product.
    • One chiral center generates 2 products.
    • Two chiral centers can create 2 syn products or 2 anti products, leading to a total of 4 products in syn or anti scenarios.

    Oxidative Cleavage of Alkenes

    • Reducing Conditions:

      • O3 followed by (CH3)2S or Zn/H2O cleaves alkenes.

    • Oxidizing Conditions:

      • O3 followed by H2O2 or KMnO4 (hot, concentrated)/OH- or with H3O+ achieves oxidative cleavage.

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    Alkenes & Alkynes PDF

    Description

    Test your knowledge on alkenes and alkynes, focusing on nomenclature and electrophilic addition reactions. Learn about the different reagents, regioselectivity, and intermediates involved in these important organic reactions.

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