Synthesis and structures of 3-hydroxy-6-(R-phenylazo)-7,8-benzo-1,2,3,4-tetrahydroquinolines as products of analytical test reactions for nitrite and nitrate anions

Abstract

An improved procedure was proposed for the synthesis of 3 hydroxy 7,8 benzo 1,2,3,4 tetrahydroquinoline, which is used as a reagent for the analytical test reaction for nitrate and nitrite anions based on azo coupling with diazo compounds. 3 Hydroxy 6 (R phenylazo) 7,8 benzo 1,2,3,4 tetrahydroquinolines (R = 2 COOH, 4 COOH, or 4 SO 3 H) were synthesized by azo coupling reactions in 65-70% yields. The structures of these compounds were con firmed by elemental analysis, 1 H NMR and IR spectroscopy, and X ray diffraction. Based on the X ray data, the bathochromic shift in the UV spectrum of the o carboxy isomer compared to the p carboxy isomer (∆λ max = 50 nm) is attributed to a strong intramolecular hydro gen bond.

Para-Selective Dehydrogenative Phenothiazination of Hydroquinolines and Indolines

“…Indeed, those N-containing heterocycles also have enormous medicinal and biological relevance (Scheme ). Several of the latter bioactive scaffolds possess moreover a para N-functional group. ,− However, to the best of our knowledge, there is still no simple oxidative method for the dehydrogenative phenothiazination of the very important bioactive indolines and hydroquinoline scaffolds.…”

Advances in the Chemistry of Tetrahydroquinolines

“…The tetrahydroquinoline derivative 99 and related compounds were studied as sensitizers for alkali-developable photopolymerization systems . Other families of dyes containing a tetrahydroquinoline structural fragment include monoazo dyes 100 , 101 , , and 102 (Figure ). The tetrahydroquinoline derivatives 103 were prepared as molecular glasses and their thermal and photochemical properties were studied …”

Advances in the reduction of quinolines to 1,2,3,4‐tetrahydroquinolines

“…Besides the above applications, 1,2,3,4‐tetrahydroquinolines have been reported as dyes [232,233] (Figure 10) and also in the synthesis of chiral dyes with interesting optical properties as a corrosion inhibitor [234].…”