Isolable Adducts of Tertiary Amines and Dinitrogen Trioxide

Abstract

Anhydrous dinitrogen trioxide, N 2 O 3 , dissolved in toluene or dichloromethane rapidly forms stable adducts with tertiary amines such triethyl-, tribenzyl-, or trihexyl-amine. With DABCO, 1,4-diazabicyclo[2.2.2]octane it forms a free flowing orange solid. The analytical and spectroscopic data for the DABCO adduct indicate a formula of DABCO(N 2 O 3 ) 2 which has been characterized by IR, Raman, and UV/Vis spectroscopy. The R 3 N-N 2 O 3 adducts are hydrolytically sensitive oils or solids which rapidly react quantitatively with thiols to give RSNO. The reac- [a]

Preparation of Dinitrogen Trioxide for Organic Synthesis: A Phase Equilibrium Approach

“…As N 2 O 3 can be stabilized by solvation (Scheme 2), its solutions (up to 1 M N 2 O 3 ) can be stable at 0 °C under p(NO) � 1700 mbar and used for reactions at room temperature. [11,79,80] Comparing with the preparation of pure N 2 O 3 (Section 3.1), the requirement on condition control is attenuated, making N 2 O 3 solution relatively accessible for synthetic chemists.…”

“…Even though, this method is still handy to prepare a few milliliter of N 2 O 3 solution for qualitative experiments. [79,80] In continuous flow reactors (Scheme 7c), where there is no head space, the gases can be completely dissolved (V g = 0, P = 1) when the ratio of flow rates of NO and O 2 lies between 2 (NO 2.0 ) and 4 (NO 1.5 ). When the ratio of flow rates NO/O 2 = 4, the concentration of N 2 O 3 (c l ) in the homogeneous liquid flow is an independent variable that can be precisely controlled by setting the flow rates of the solvent (V l ) and the gases (n) on pumps and mass flow controllers (MFC) respectively.…”

“…Because of the limited specific g/l interface for the mass transport, the operation is slow and cumbersome. Even though, this method is still handy to prepare a few milliliter of N 2 O 3 solution for qualitative experiments [79,80] …”

“…Weak Lewis bases like aromatic donors (toluene, m ‐xylene, mesitylene, and anisole) [122] form 1 : 1 adducts with N 2 O 3 in the solid phase; the stoichiometry was identified by the l/s phase diagrams. The adduct with strong Lewis bases like some tertiary amines (DABCO) [79] is stable at room temperature.…”

“…These solvents are generally anhydrous non‐reductive aprotic solvents; N 2 O 3 is more prone to dissociate in apolar solvents than in polar aprotic solvents [9] (e. g. CCl 4 and MeCN in Scheme 2). As N 2 O 3 can be stabilized by solvation (Scheme 2), its solutions (up to 1 M N 2 O 3 ) can be stable at 0 °C under p (NO)≈1700 mbar and used for reactions at room temperature [11,79,80] . Comparing with the preparation of pure N 2 O 3 (Section 3.1), the requirement on condition control is attenuated, making N 2 O 3 solution relatively accessible for synthetic chemists.…”