Aminobenzothiazoles. III. Tautomerism and unsaturation of the aminothiazole system was written by Hunter, R. F.. And the article was included in Journal of the Chemical Society in 1926.Application of 40172-65-4 This article mentions the following:
1-Aminobenzothiazole (I) and MeI at 100° for 5 hrs. give 1-imino-2-methyl-1,2-dihydrobenzothiazole (II), m. 123°, whose constitution was established by its synthesis from the dibromide, orange-red, sinters and softens at 125° (prepared from PhNMeC(:S)NH2 and Br in CHCl3). There is also probably formed some 1-methylaminobenzothiazole (III), m. 138°, which was prepared from the tetrabromide (IV), scarlet, m. 65-7° (decomposition) (prepared from PhNHC(:S)NHMe and Br in CHCl3). Ethylation of I gave the 2-Et derivative corresponding to II, pale yellow, m. 85°, likewise prepared from its tetrabromide, vermilion-orange, m. 160-1° (decomposition). Acetylation of I gives almost quant. the 1-Ac derivative, m. 186°, also obtained by the reduction of its tetrabromide, orange-red, m. 137-9°; the isomer could not be obtained pure. II in CHCl3, treated with excess of 20% Br in CHCl3, gives a tribromide, orange, becomes white without melting at 245°. IV, exposed to the air for 20 hrs., loses Br and forms the orange-yellow dibromide, sinters 136°, chars at 191°; it loses more Br on further exposure. IV in absolute EtOH, after dilution with H2O and concentration, gives a mixture of Br- and Br2-substitution products, which could not be separated 1-Imino-2-acetyl-1,2-dihydrobenzothiazole (V), m. 118-20°, results by the reduction with H2SO3 of the dibromide (VI), orange, m. 130-2° (from the labile form of PhNHC(:S)NH2); a 2nd form, purplish red, sinters 160°, m. 173° (decomposition), which is very stable in air and is more slowly reduced by SO2, was also isolated. The HBr salt, dark chocolate prisms, turns orange 178° and m. 180° (decomposition). Hydrolysis of V gives I. 1-Benzoylaminobenzothiazole tetrabromide, orange-yellow, becomes colorless and loses Br at about 185°; boiling in EtOH gives 5-bromo-1-benzoylaminobenzothiazole, m. 226°. I, diazotized and treated with β-C10H7OH, gives benzothiazole-1-azo-β-naphthol, deep purple-red, m. 146°; it dyes cotton a fugitive shade of yellow; reduction gives I. 1-Aminoazobenzothiazole, cream-white, m. 135°; HCl salt, yellow, m. 232° (decomposition). With NaOCl this gives a dark purple compound, m. 156-8°. EtNO2 in EtOH gives ψ-aminobenzothiazole, pale yellow, m. about 127°, isolated as the HCl salt, ruby-red or deep orange, m. 239-40°. ψ-Amino-3-toluthiazole HCl salt, ruby-red, sinters 145°, changes color at 145°; the corresponding 5-derivative, red, sinters 130°, softens about 150°. These facts establish the mobility of I. 5-Bromo-1-amino-benzothiazole dibromide (VII), orange-red, softens 80-2°, from p-BrC6H4NHC(:S)NH2 and Br in CHCl3; H2SO3 and NH3 convert it into the free thiazole, m. 211°. 1-Acetylaminobenzothiazole hexabromide, orange-red, turns yellow at 130°, loses Br at 140° and becomes colorless at about 160°; in EtOH it gives 5-bromo-1-acetylaminobenzothiazole, m. 223°. VI in EtOH gives 5-bromo-1-imino-2-acetyl-1,2-dihydrobenzothiazole, m. 199-200°. Hydrolysis of each of these gives 5-bromo-1-aminobenzothiazole. 1-Amino-3-methylbenzothiazole, m. 136°, results by reduction of the dibromide, orange, m. 110° (decomposition), which in turn is formed from o-MeC6H4NHC(:S)NH2 and Br in CHCl3; the latter is unstable and loses Br in the air; in EtOH it gives the HBr salt, turns yellow at 260°, chars about 290°, of bromo-1-amino-3-methylbenzothiazole, m. 212°. 1-Amino-5-methylbenzothiazole, m. 142°, is formed from the dibromide-HBr, orange-red, m. 134° (decomposition); with EtOH the latter yields a Br substitution product, m. 210°. 1-Amino-4-methylbenzothiazole, m. 145°, from the tetrabromide, orange-red, m. about 250° (decomposition) after undergoing a series of color changes. The 3,5-di-Me derivative, m. 116°; its tetrabromide, red, does not m. 250° and is very unstable, losing Br and becoming colorless on exposure to the air for 0.5 hr. 2-Amino-β-naphthothiazole, sinters 220°, m. 235-7°; tetrabromide, orange, does not m. 260°; the corresponding α-derivative, sinters 230°, m. 249-51°; tetrabromide, yellow, m. 165° (decomposes). I dibromide in nearly boiling H2O gives VII. In the experiment, the researchers used many compounds, for example, Naphtho[1,2-d]thiazol-2-amine (cas: 40172-65-4Application of 40172-65-4).
Naphtho[1,2-d]thiazol-2-amine (cas: 40172-65-4) belongs to thiazole derivatives. The thiazole ring has been identified as a central feature of numerous natural products, perhaps the most famous example of which is epothilone. There are numerous natural products that possess a thiazole ring with broad pharmacological activities. Thiamine, also known as vitamin B1, possesses a thiazole ring linked with 2-methylpyrimidine-4-amine as hydrochloride salt.Application of 40172-65-4
Referemce:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica