Thiazoles. XI. The preparation of 2-amino-5-(phenylazo)thiazoles and the reductive scission of 2,2′-azothiazoles and 2-(phenylazo)thiazoles with phenylhydrazine was written by Beyer, Hans;Wolter, Gerhard. And the article was included in Chemische Berichte in 1952.Product Details of 6318-74-7 This article mentions the following:
A diazonium solution from 9.3 g. PhNH2 buffered with AcONa added at 0° to 11.4 g. 2-amino-4-methylthiazole (I) gives 90.6% 2-amino-4-methyl-5-(phenylazo)thiazole (II), p-RC6H4N:N.C:CR’.N:C(NH2).S (IIa, R = H, R’ = Me), orange needles, m. 184° (di-Ac derivative, prepared by heating 1.09 g. II with 3 cc. Ac2O 1 h. on a water bath, fine yellow needles, m. 254-5°). 5-p-Tolylazo homolog (IIa, R = R’ = Me), 90.5%, long dark red columns from AcOEt-Me2CO, m. 189-90°, or rhombic sepia leaflets from EtOH, m. 190-1° (di-Ac derivative, yellow needles, m. 251°); 5-p-nitrophenyl analog (IIa, R = NO2, R’ = Me), 93.5%, fine dull red needles, m. 192° (di-Ac derivative, dark red leaflets, m. 206°). Coupling the diazonium compound from 17.2 g. p-H2NC6H4SO2NH2 (III) with I gives 75% p-(2-amino-4-methyl-5-thiazolylazo)benzenesulfonamide (IIa R = SO2NH2, R’ = Me), m. 202° (di-Ac derivative, cubelike orange-yellow crystals, m. 223°). Coupling the diazonium salt from 9.3 g. PhNH2 with 17.6 g. 2-amino-4-phenylthiazole gives 87.8% 2-amino-4-phenyl-5-(phenylazo)thiazole (IIa, R = H, R’ = Ph), fine felted cinnabar needles, m. 195° (di-Ac derivative, felted yellow needles, m. 214°); 5-p-tolylazo homolog (IIa, R = Me, R’ = Ph), 71.4%, fine felted red-orange needles, m. 200° (di-Ac derivative, long felted yellow needles, m. 217°); 5-p-nitrophenyl analog (IIa, R = NO2, R’ = Ph), 90.8%, fine moss-green needles, m. 254° (Ac derivative, shiny dark green crystals, m. 293°); p-(2-amino-4-phenyl-5-thiazolylazo)benzenesulfonamide (IIa R = SO2NH2, R’ = Ph) 75%, bright red needles with a green surface sheen, m. 255° (di-Ac derivative, small cinnabar-red needles, m. 293°). Coupling the diazonium salt from 10.7 g. p-toluidine with 10 g. 2-aminothiazole (IV) gives 72% 2-amino-5-(p-tolylazo)thiazole (IIa, R = Me, R’ = H), small fine red needles, sintering 180°, m. 205° (di-Ac derivative, dark brown powder, m. 243°); coupling the diazonium salt from 17.2 g. III with 10 g. IV gives 75% p-(2-amino-5-thiazolylazo)benzene sulfonamide (IIa, R = SO2NH2, R’ = H), microcrystalline brown-yellow powder, m. 223° (di-Ac derivative, yellow-brown amorphous powder, m. 235°). Azothiazoles are reductively split by PhNHNH2 to the corresponding NH2 compounds Heating 3.7 g. di-Et 2,2′-azobis(4-methyl-5-thiazolecarboxylate) and 10.8 g. PhNHNH2 (V) slowly to 180° and keeping the mixture 5 min. at 180° and overnight at 20° give 78% Et 2-amino-4-methyl-5-thiazolecarboxylate, needles, m. 175-6°. Similarly, Et 2-phenylazo-4-methyl-5-thiazolecarboxylate and V give 90% of the 2-phenylhydrazino analog, rhombic leaflets, m. 194°, which, on further heating with V at 200° gives 72% 2-amino analog; in the same way, 2-phenylazo-4,5-diphenylthiazole gives the 2-amino compound, m. 186°. Heating 2,2′-azobis(4-phenylthiazole) or 2-phenylazo-4-phenylthiazole with V at 180° gives the corresponding hydrazo compounds which, on further heating at 220°, give 18 and 14% 2-amino-4-phenylthiazole, m. 147°. In the experiment, the researchers used many compounds, for example, 4,5-Diphenylthiazol-2-amine (cas: 6318-74-7Product Details of 6318-74-7).
4,5-Diphenylthiazol-2-amine (cas: 6318-74-7) belongs to thiazole derivatives. Thiazole rings are planar and aromatic. Thiazoles are characterized by larger pi-electron delocalization than the corresponding oxazoles and have therefore greater aromaticity. The pyridine-type nitrogen in the thiazole ring deactivates the ring for electrophilic substitution reactions, which is further reduced in acid due to protonation of the thiazole ring.Product Details of 6318-74-7
Referemce:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica