Oxygen violet can be prepared by one-step reaction of p-nitroaniline and 1,3-benzenediol. Azo violet can be used to prepare an azobenzene photochromic liquid crystal compound. Photochromic liquid crystal compounds have both photochromic properties and liquid crystallinity, which has become a research hotspot in the field of information storage. Azobenzene-based liquid crystals are the most interesting photochromic liquid crystal materials in recent years due to their unique photoinduced cis-trans isomerism. Azobenzene compounds undergo reversible cis-trans isomerization under the action of light, which makes them have great potential applications in many aspects such as optical storage, photo-holography and optical information processing.
dark red to brown crystalline powder
4-(4-Nitrophenyl)azoresorcinol is used for the detection of magnesium with which it yields a bright blue color in alkaline solution and it also used to determine molybdenum with which it forms a red-violet complex: Nikitina, Andrianova, C.A. 75, 136789v (1971).
It is a derivitized resorcinol dye compound with an absorption maximum of 432 nm. Used as a pH indicator.
ChEBI: 4-(4-nitrophenylazo)resorcinol is an azobenzene in which the phenyl rings are 4-nitro- and 2,4-dihydroxy-substituted respectively. It is a member of resorcinols, a C-nitro compound and a member of azobenzenes.
4-(4-Nitrophenylazo)resorcinol is a pH indicator.
A solution of NaNO2 (1.035 g) in deionized water (15 mL) is slowly added to a solution of p-nitroaniline (2.07 g) in hydrochloric acid (2.5 mol/L, )
10 mL) in hydrochloric acid (2.5 mol/L, ). The solution is held at 0C for 1 hour under vigorous mechanical stirring. The solution was then washed with ammonia and deionized water until the pH of the filtrate reached 7. The diazonium salt was then washed with ammonia and deionized water until the pH of the filtrate reached 7.
The diazonium salt solution is then added to a solution of 1,3-benzenediol (1.65 g) and sodium hydroxide (1.2 g) in deionized water (60 mL) at 0C and held under stirring for 1 hour.
1 hour.
The solid precipitate was washed with ammonia and deionized water until the pH of the filtrate reached 7. The resulting precipitate was filtered and the crude product was recrystallized twice with ethanol. The orange-red compound apoxidized violet was obtained in 73.8% yield.
Crystallise the dye from EtOH. [Beilstein 16 H 181, 16 IV 1266.]
