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Gabriel Synthesis quiz

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  • What is the main purpose of the Gabriel synthesis in organic chemistry?
    The Gabriel synthesis is used to efficiently produce primary amines, avoiding issues like polyalkylation and unwanted by-products.
  • Which molecule is central to the Gabriel synthesis method?
    Potassium thalidomide is the key molecule used in the Gabriel synthesis.
  • What are the three main reagents required for the Gabriel synthesis?
    The three main reagents are KOH, a primary alkyl halide (RX), and hydrazine (N2H4).
  • What role does KOH play in the Gabriel synthesis?
    KOH deprotonates the nitrogen in thalidomide, forming potassium thalidomide, a strong nucleophile.
  • Why is potassium thalidomide considered a strong nucleophile?
    Potassium thalidomide has a negatively charged nitrogen, making it a strong base and nucleophile.
  • What type of reaction occurs between potassium thalidomide and the alkyl halide?
    An SN2 backside attack occurs, where potassium thalidomide attacks the alkyl halide.
  • Why is a primary alkyl halide used in the Gabriel synthesis?
    A primary alkyl halide is used to ensure efficient SN2 reaction and avoid side reactions.
  • What is the product after the SN2 reaction in Gabriel synthesis?
    The product is a nitrogen atom attached to the alkyl group (R), still linked to thalidomide.
  • What reagent is used to cleave the nitrogen from thalidomide in the final step?
    Hydrazine (N2H4) is used to cleave the nitrogen from thalidomide.
  • What mechanism does hydrazine follow to release the primary amine?
    Hydrazine follows a nucleophilic substitution (NAS) mechanism, forming a tetrahedral intermediate.
  • What happens during the NAS mechanism in the Gabriel synthesis?
    A proton transfer occurs, and the nitrogen with the R group is expelled, yielding the primary amine.
  • What is the final product of the Gabriel synthesis?
    The final product is a primary amine (NRH), where R is the desired alkyl group.
  • How does Gabriel synthesis avoid polyalkylation?
    Gabriel synthesis uses a controlled mechanism that releases only the desired primary amine, preventing multiple alkylations.
  • Why is Gabriel synthesis preferred over amine alkylation for making primary amines?
    Gabriel synthesis is more efficient and avoids unwanted by-products compared to amine alkylation.
  • What is the significance of the proton transfer step in the NAS mechanism?
    The proton transfer helps to neutralize charges and facilitates the expulsion of the nitrogen with the R group, completing the formation of the primary amine.