Preparation of Dinitrogen Trioxidefor Organic Synthesis: A Phase Equilibrium Approach.

Dinitrogen trioxide (N 2 O 3 ) is a potent nitrosating agent featured with high reactivity and appealing atom economy. Because of its instability and the entanglement of chemical and phase equilibria, N 2 O 3 has rarely been utilized in organic synthesis as a stock reagent with well-defined composition. In this review,the preparations of pure N 2 O 3 and its concentrated solution (>0.1 M) are discussed from the aspect of phase equilibrium. Understanding the physical and chemical characteristics of N 2 O 3 , along with how reaction parameters (temperature, pressure, molar ratio) interact, plays a crucial role in managing the concentration of N 2 O 3 in the liquid phase. This control holds practical significance in achieving quantitative reactions.