N-Oxides of the quinoxaline series. I. N-Oxides of quinoxaline-2-carboxylic acid was written by Elina, A. S.;Magidson, O. Yu.. And the article was included in Zhurnal Obshchei Khimii in 1955.Quality Control of Ethyl 3-chloroquinoxaline-2-carboxylate This article mentions the following:
2-(m-Nitrostyryl)quinoxaline (6.3 g.) heated to boiling in 200 ml. Me2CO, cooled and treated with 5% aqueous KMnO4, filtered (when colorless, the filtrate concentrated and acidified gave mixed acids which treated with 30 ml. 10% NaHCO3 followed by 10 ml. EtOH gave Na quinoxaline-2-carboxylate, which with dilute HCl gave the free acid (I), m. 210-11°, in 56.4% yield; Et ester, m. 83-4°. To 20 g. 2-methylquinoxaline in MePh (240 ml.) was slowly added 18 g. SeO2, the mixture refluxed 1.5 hrs., filtered, the filtrate steam distilled, and the distillate salted out gave quinoxaline-2-carboxaldehyde, which is extracted with Et2O; the pure aldehyde, 56.6%, m. 110° (from petr. ether); the precipitate from the reaction yielded 19.8% I. The aldehyde with thiosemicarbazide in EtOH gave the thiosemicarbazone, decompose 238-9°. The aldehyde treated with KMnO4 in Me2CO gave 72.7% I. I Et ester (4.75 g.) added over 3 hrs. at 45° to 25 ml. AcOH, 19.2 ml. Ac2O, and 23 ml. 30% H2O2 and kept 16 hrs. at 50° gave on neutralization with NaHCO3, 80.1% yellow I 4-oxide Et ester (II), m. 156-7° (from MeOH); similar treatment of I gave I 4-oxide, 80%, m. 180-2° (from EtOH), this substance also being formed in good yield on stirring its Et ester 20 min. with 7.5% NaOH. II and alc. NH3 kept 12 hrs. at room temperature gave I 4-oxide amide, m. 230-30.5° (from EtOH). II in EtOH with 85% N2H4 after 12 hrs. at room temperature gave 90% I 4-oxide hydrazide, m. 216-17° (from 50% EtOH). NH2OH.HCl (1.64 g.) in 9 ml. MeOH treated with 1.97 g. KOH in 29 ml. MeOH, followed, at 40°, by 2 g. II and kept 20 hrs. gave K quinoxaline-2-hydroxamate 4-oxide, yellowish, m. 185-6° (from H2O). To I 4-oxide (0.3 g.) in 3.5 ml. 15% NaOH and 22 ml. H2O was slowly added 0.5 g. Na2S2O4 and after 1 hr. at room temperature the mixture was acidified to Congo red, yielding 83.9% I. II (1 g.) and 10 ml. POCl3 refluxed 1.5 hrs., concentrated, quenched in ice and neutralized, gave Et 3-chloroquinoxaline-2-carboxylate, m. 41.5-2° (cf. Gowenlock, et al., C.A. 40, 341.3), which heated 1.5 hrs. with Na2CO3 in 70% MeOH gave the corresponding free acid, m. 146-7° (decomposition); passage of NH3 in EtOH solution of the Et ester at 0° gave 3-chloroquinoxaline-2-carboxamide, m. 214-15°. To 3 g. 2-methylquinoxaline 1,4-dioxide in C6H6 at reflux was added 3.5 g. SeO2 and after 2 hrs. refluxing, the filtrate yielded 2.02 g. quinoxaline-2-carboxaldehyde 1,4-dioxide, decompose 189-90°, which gives typical aldehyde reactions and liberates iodine from acidic KI solution This on oxidation with 30% H2O2 in AcOH-Ac2O at 50° 1 hr. gave I 1,4-dioxide, yellow, m. 208-9° (from AcOH); this reduced with Na2S2O4 in 5% NaOH at 20-5° to I 1-oxide, colorless, m. 180-1°; this reduced with Na2S2O4 in 3% NaOH to I. In the experiment, the researchers used many compounds, for example, Ethyl 3-chloroquinoxaline-2-carboxylate (cas: 49679-45-0Quality Control of Ethyl 3-chloroquinoxaline-2-carboxylate).
Ethyl 3-chloroquinoxaline-2-carboxylate (cas: 49679-45-0) belongs to quinoxaline derivatives. Quinoxaline derivatives are important constituents of pharmacologically active compounds, including as well as for RNA synthesis inhibition, reactive dyes and pigments, azo dyes, flurox Cylin Dyes, Corrosion Inhibitors and Photovoltaic Polymers. They are well-known for application in organic light emitting devices, polymers and pharmaceutical agents. The quinoxaline-containing polymers are applicable in optical devices due to their thermal stability and low band gap.Quality Control of Ethyl 3-chloroquinoxaline-2-carboxylate
Referemce:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider