Thermal decomposition of o-azidoazobenzenes. II. Synthesis of 2-substituted benzotriazoles

Abstract

Found: C, 70.42; H, 4.60; N, -1,3a,4,6a-tetraazapentalene (IV).-2-(2-Azido-4-methylphenyl)benzotriazole (0.91 g 0.00364 mol) was placed in 10 ml of decalin and the solution was heated to 165-175' for 15 min, followed by 15 min of refluxing at 195'. On cooling, needles separated, which were filtered and washed with petroleum ether: yield 0.68 g (94%) of IV; mp 198'. Recrystallization from methanol and acetone gave an analytical sample.Anal. Calcd for C13HloNa: C, 70.27; H, 4.50; N, 25.23. Found: C, 70.48; H, 4.56; N, 24.89.Thermal Decomposition of 2-(2-Azidophenyl)-5-methylbenzo-triazo1e.-In 50 ml of decalin was placed 4.74 g (0.0189 mol) of the azide and the solution was heated to 165-175" for 40 min. After standing overnight a t room temperature, the mixture of I11 and IV was filtered and washed with petroleum ether: yield 3.36 g (80%); mp 184185". Recrystallization did not raise the melting point. Attempts to separate the mixture by chromatography on alumina were unsuccessful.

Reactivity-Based Detection of Copper(II) Ion in Water: Oxidative Cyclization of Azoaromatics as Fluorescence Turn-On Signaling Mechanism

“…The thermal decomposition of o -azidoazobenzene 3 is one of the oldest known synthetic routes to benzotriazole 2 and its analogues (Scheme ), , which was reported as early as in 1887 . More conveniently, 2 is prepared by the oxidation of azoaniline 1 (Scheme ), a synthetically more accessible precursor that can be subjected to large-scale laboratory manipulations.…”

Anions Containing Tripoid Conjugated N4− System: Salts of 5-(Substituted Amino)-[1,2,3]triazolo[4,5-c][1,2,5]oxadiazol-5-ium-4-ides, as well as Their Synthesis, Structure, and Thermal Stability

“…at 80 °C for several hours. Related cyclization of the adjacent azido and triazene groups took place in more drastic conditions at temperatures ≥ 130 °C in order to give N -substituted 2-aminobenzotriazoles [ 16 , 17 ].…”

Synthesis of 2-Aryl-2H-benzotrizoles from Azobenzenes and N-Sulfonyl Azides through Sequential Rhodium-Catalyzed Amidation and Oxidation in One Pot

“…Although a variety of synthetic methods for N 1 -arylation of benzotriazole have been reported, a selective N 2 -arylation of benzotriazole is still needed. To date, thermal decomposition of o -azidoazobenzenes, reduction of 2-[(2-nitro­phenyl)­azo]­phenols with thiourea S , S -dioxide, SmI 2 , or Zn and Cu-catalyzed oxidative cyclization of azoanilines were reported for N 2 -arylation of benzotriazoles. However, these methods required prefunctionalized azobenzenes having an azido, nitro, or amino group on the aryl ring before cyclization.…”