Diazomethane

Definition

Diazomethane is a highly reactive organic compound with the chemical formula CH2N2. It is a key reagent used in organic synthesis, particularly in the addition of carbenes to alkenes and the preparation of ethers.

5 Must Know Facts For Your Next Test

1. Diazomethane is a highly reactive and explosive compound that must be handled with extreme caution.
2. Diazomethane can undergo addition reactions with alkenes to form cyclopropanes, a process known as cyclopropanation.
3. In the preparation of ethers, diazomethane can be used to alkylate alcohols, forming the desired ether product.
4. The reactivity of diazomethane stems from the presence of the diazo group (-N=N-), which acts as a carbene precursor.
5. Diazomethane is commonly generated in situ from precursor compounds, such as N-methyl-N-nitroso-p-toluenesulfonamide (Diazald), to avoid the hazards of handling pure diazomethane.

Review Questions

• Explain the role of diazomethane in the addition of carbenes to alkenes to form cyclopropanes.
  • Diazomethane is a key reagent used in the addition of carbenes to alkenes, a process known as cyclopropanation. The diazo group (-N=N-) in diazomethane acts as a carbene precursor, generating a highly reactive carbene species upon thermal or photochemical decomposition. This carbene can then undergo a [2+1] cycloaddition with an alkene, forming a cyclopropane ring. The cyclopropane products are useful synthetic intermediates in organic chemistry due to their strained and reactive nature.
• Describe how diazomethane is utilized in the preparation of ethers.
  • Diazomethane can be employed in the synthesis of ethers through the alkylation of alcohols. In this reaction, the diazo group of diazomethane acts as a methylating agent, transferring the methyl group to the oxygen atom of the alcohol. This process generates the desired ether product, with the alkyl group from the diazomethane now bonded to the oxygen. The use of diazomethane in ether synthesis is a valuable tool in organic chemistry, as ethers are important structural motifs found in many natural and synthetic compounds.
• Analyze the reactivity and safety considerations associated with the use of diazomethane in organic synthesis.
  • Diazomethane is a highly reactive and potentially explosive compound, requiring extreme caution during its handling and use in organic synthesis. The diazo group (-N=N-) is responsible for the compound's reactivity, as it can undergo thermal or photochemical decomposition to generate a reactive carbene species. This carbene can then participate in a variety of addition and insertion reactions, making diazomethane a valuable reagent. However, the inherent hazards associated with diazomethane necessitate the use of specialized equipment and procedures, such as in situ generation from safer precursor compounds, to minimize the risks of handling the pure compound. Careful consideration of the reaction conditions and appropriate safety protocols are essential when utilizing diazomethane in organic chemistry laboratories.

Related terms

Carbene: A highly reactive neutral carbon-based species with a divalent carbon atom and two nonbonded valence electrons.

Cyclopropane: A cyclic organic compound with a three-membered ring consisting of three carbon atoms and six hydrogen atoms.

Ether: A class of organic compounds containing an oxygen atom connected to two alkyl or aryl groups.