Diazomethane

Diazomethane is a chemical compound with the formula CH₂N₂. It is a yellow, toxic, and volatile liquid that is a derivative of nitrogen in the diazo group, which consists of two nitrogen atoms connected by a double bond. Diazomethane is used primarily in organic chemistry as a methylating agent for the transfer of a methyl group to oxygen, nitrogen, and sulfur containing compounds. It is also employed in the preparation of methyl esters from carboxylic acids.

Properties

Diazomethane is characterized by its explosive nature, especially when concentrated or in contact with sharp edges. It is highly sensitive to light, heat, and shock, necessitating careful handling and storage. Despite its hazards, it is a valuable tool in organic synthesis due to its reactivity and versatility.

Synthesis

The most common method for preparing diazomethane involves the reaction of N-methyl-N-nitroso-p-toluenesulfonamide (also known as Diazald) with a base, typically potassium hydroxide (KOH), in an ether solvent. This process generates diazomethane gas, which can be condensed or used in situ for reactions.

Applications

In organic synthesis, diazomethane is used for the methylation of acids, alcohols, phenols, and carboxylic acid derivatives. It is particularly useful for the preparation of methyl esters, a critical step in the analysis of fatty acids in lipids. Additionally, diazomethane can be employed in the Wolff rearrangement, where it serves as a precursor to carbenes, which are used to insert into hydrogen-hydrogen bonds and carbon-hydrogen bonds.

Safety

Due to its explosive nature, diazomethane must be handled with extreme caution. Protective equipment, including safety glasses and gloves, is mandatory when working with this compound. It is also advisable to perform reactions involving diazomethane in a well-ventilated area or under a fume hood to avoid inhalation of its toxic fumes.

See also

• Methylating agent
• Organic synthesis
• Wolff rearrangement
• Carbene