Preparation of Alcohol
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Questions and Answers

What is the main role of pyridine in the conversion of alcohols to tosylates?

  • It is not involved in the reaction
  • It acts as a strong acid
  • It acts as a catalyst to speed up the reaction
  • It acts as a base to neutralize the acid formed (correct)
  • What is the abbreviation for the tosyl group?

  • TOs
  • Ts (correct)
  • Tos
  • TsO
  • What is the pKa value of p-toluenesulfonic acid (TsOH)?

  • -5
  • -9
  • -10
  • -7 (correct)
  • What type of mechanism occurs when alkyl tosylates are treated with strong nucleophiles and bases?

    <p>SN2</p> Signup and view all the answers

    What happens to the configuration of the stereogenic center when the leaving group is bonded to it during substitution?

    <p>Inversion of configuration</p> Signup and view all the answers

    What is the purpose of converting alcohols to tosylates?

    <p>To convert a poor leaving group to a good one</p> Signup and view all the answers

    What reaction occurs when alkyl tosylates are treated with strong bases?

    <p>Both nucleophilic substitution and β elimination</p> Signup and view all the answers

    What is required for ethers to undergo substitution or elimination reactions?

    <p>Conversion of poor leaving group into a good leaving group by reaction with strong acid</p> Signup and view all the answers

    What type of mechanism is involved in the cleavage of the C-O bond when 2° or 3° alkyl groups are bonded to the ether oxygen?

    <p>SN1 mechanism</p> Signup and view all the answers

    What is the result of the reaction between ethers and HBr or HI?

    <p>Two alkyl halides are formed as products</p> Signup and view all the answers

    What is the characteristic of the three-membered ring in epoxides that makes nucleophilic attack favorable?

    <p>It is a strained ring</p> Signup and view all the answers

    What is the necessary condition for nucleophilic addition to epoxides to occur?

    <p>The presence of a strong nucleophile</p> Signup and view all the answers

    Why do epoxides not contain a good leaving group?

    <p>Because they contain a strained three-membered ring</p> Signup and view all the answers

    What is the type of mechanism involved in the cleavage of the C-O bond when methyl or 1° R groups are bonded to the ether oxygen?

    <p>SN2 mechanism</p> Signup and view all the answers

    What is the mechanism of attack by a nucleophile on an electron-deficient carbon in an epoxide ring?

    <p>SN2</p> Signup and view all the answers

    What is the product of the protonation of the alkoxide in the second step of the epoxide ring opening reaction?

    <p>A neutral product with Mo functional groups</p> Signup and view all the answers

    Which of the following is NOT a common nucleophile that opens an epoxide ring?

    <p>—NO2</p> Signup and view all the answers

    What is the role of acid in the epoxide ring opening reaction with H2O or ROH?

    <p>To act as a catalyst</p> Signup and view all the answers

    What is the characteristic of the epoxide ring opening reaction with either a strong nucleophile or an acid HZ?

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

    What is the difference in site selectivity between the epoxide ring opening reactions with a strong nucleophile and an acid HZ?

    <p>They are opposite</p> Signup and view all the answers

    What is the driving force behind the epoxide ring opening reaction?

    <p>Relief of steric strain</p> Signup and view all the answers

    What is the role of HCI, HBr, and HI in the epoxide ring opening reaction?

    <p>Act as acids to open the epoxide ring</p> Signup and view all the answers

    What is the product of the reaction of an epoxide with an acid HZ?

    <p>A neutral product with Mo functional groups</p> Signup and view all the answers

    What is the role of the nucleophile in the first step of the epoxide ring opening reaction?

    <p>To attack an electron-deficient carbon</p> Signup and view all the answers

    Which of the following is a common nucleophile that opens an epoxide ring?

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

    What is the result of the protonation of the alkoxide in the second step of the epoxide ring opening reaction?

    <p>A neutral product with Mo functional groups on adjacent atoms</p> Signup and view all the answers

    What is the characteristic of the epoxide ring opening reaction with either a strong nucleophile or an acid HZ?

    <p>It is a regioselective reaction</p> Signup and view all the answers

    What is the difference between the site selectivity of the epoxide ring opening reactions with a strong nucleophile and an acid HZ?

    <p>The site selectivity is opposite for both reactions</p> Signup and view all the answers

    Which of the following acids can open an epoxide ring?

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

    What is the role of water in the epoxide ring opening reaction with an acid HZ?

    <p>To protonate the alkoxide</p> Signup and view all the answers

    Why do strong nucleophiles open an epoxide ring?

    <p>Because the ring is strained</p> Signup and view all the answers

    What is the mechanism of the first step of the epoxide ring opening reaction?

    <p>SN2</p> Signup and view all the answers

    What is the driving force behind the relief of the strain of the three-membered ring?

    <p>The formation of a more stable product</p> Signup and view all the answers

    The epoxide ring opening reaction with a strong nucleophile is a one-step reaction.

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

    Acids such as HCl, HBr, and HI can open an epoxide ring.

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

    The site selectivity of the epoxide ring opening reactions with a strong nucleophile and an acid HZ is the same.

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

    NH3 is a common nucleophile that opens an epoxide ring.

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

    The epoxide ring opening reaction is non-regioselective.

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

    The three-membered ring in epoxides is strain-free.

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

    Water is not involved in the epoxide ring opening reaction with an acid HZ.

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

    The alkoxide is not protonated in the second step of the epoxide ring opening reaction.

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

    The epoxide ring opening reaction with a strong nucleophile is a reversible reaction.

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

    ROH can open an epoxide ring in the presence of acid.

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

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