NO2NO3

NO2NO3 is the condensed notation used for dinitrogen pentoxide, the chemical compound with formula N2O5. It is the anhydride of nitric acid and a very strong nitrating agent used in organic synthesis. In pure form it is a white to colorless solid that is highly reactive with water.

Structure and properties

Dinitrogen pentoxide comprises two nitro-like units connected through an oxygen bridge, commonly represented as O2N–O–NO2. The molecule is best described as a highly oxidizing species, with the tendency to hydrolyze readily in the presence of moisture to yield nitric acid. It is typically prepared and stored under strictly dry conditions, as contact with water leads to rapid decomposition.

Preparation and handling

N2O5 is usually produced by dehydration of nitric acid using drying agents or by in situ generation from nitrogen oxides under controlled conditions. Because it hydrolyzes upon exposure to moisture, it is handled and stored under anhydrous, inert or dry atmospheres and in compatible, moisture-impermeable containers. It is often generated and used immediately in situ for nitration reactions to minimize handling hazards.

Reactions and applications

As a strong nitrating agent, N2O5 can introduce nitro groups into organic substrates, typically via formation of the nitronium ion or through direct nitration pathways. It also reacts with water to form 2 equivalents of nitric acid (N2O5 + H2O → 2 HNO3). In atmospheric chemistry, N2O5 forms from reactions of nitrogen oxides and contributes to nitrate aerosol formation, especially under humid conditions.

Safety

N2O5 is a powerful oxidizer and corrosive compound. It reacts violently with water and many organic materials, and its vapors can be harmful if inhaled. Proper laboratory precautions include dry handling, appropriate containment, and protection against moisture and incompatible materials.