Infrared spectra of heterocyclic compounds. VIII. Infrared spectra of substituted pyrazines and their N-oxides was written by Shindo, Hideyo. And the article was included in Chemical & Pharmaceutical Bulletin in 1960.Product Details of 6924-68-1 This article mentions the following:
Previous correlations of infrared spectra and structures of pyridine derivatives (loc. cit.) were extended to the pyrazine (I) ring system to determine the effect of the 2nd ring N. The infrared spectra of I, its H2N (II), Me, Cl (III), Ac (IV), NC (V), HO2C, EtO2C (VI), and H2NOC (VII) derivatives, and their 10 N-oxide derivatives were analyzed. VII dehydrated with POCl3 and submitted to the Hofmann rearrangement gave, resp., V, b31 109-10°, and II, m. 117-18°. POCl3 on the N-oxide of I gave III, b31 62-3°. Ester condensation of VI, m. 52-3°, gave IV, m. 79-80°. Oxidation of I and its derivatives with perhydrol gave their corresponding N-oxides (VIII) (compound oxidized, m.p. of VIII given): I, mono-oxide m. 108°, di-oxide m. 260°; III, 96°; IV, 184°; V, 153°; VI, 147°; VII, 293°. The characteristic N-O stretching frequencies (strong absorption in the region of 1250 and 1350 cm.-1) of all these compounds were correlated to the nature of a substituent present, and the linear relation between the N-O frequency and the σ-value of a substituent in substituted pyridine N-oxides could be extended to that in substituted pyrazine N-oxides by applying the σ-value of ring N (0.93) and the N-oxide group (0.25) toward 4-position of pyridine for N-mono- and N,N’-dioxides, resp. The considerably higher frequency shift of the N-O frequency was shown to be characteristic for the Me group at β-position with respect to the N-oxide group. Ring and ring CH vibrations were discussed on the basis of the correlations found in the pyridine ring system. The splitting of the CO stretching frequency of ester group adjacent to ring N was pointed out and discussed. The infrared spectra of pyrimidine N-oxide, its 4-Me, 4,6-(PhS)Me, 4,6(PhO)Me, 4,6-(EtO)Me, 4,6-(MeO)Me, 4,6-(PhCH3O)Me, 2,6,4-Me2 (PhCH2O), and 4-morpholino-6-methyl derivatives were also examined and discussed in comparison with the above results. In the experiment, the researchers used many compounds, for example, Ethyl pyrazine-2-carboxylate (cas: 6924-68-1Product Details of 6924-68-1).
Ethyl pyrazine-2-carboxylate (cas: 6924-68-1) belongs to pyrazine derivatives. Pyrazinesare six-membered aromatic heterocyclic organic compounds with two nitrogen atoms at 1,4-positions. Pyrazine is a weaker base (pKb = 13.4) than pyridine (pKb = 8.8), pyrimidine (pKb = 12.7). Pyrazine heterocycles and their benzo derivatives possess many interesting properties, including chemical reactivity profiles, and have diverse applications in total synthesis, medicine, chemical biology, materials, dyes, and imaging.Product Details of 6924-68-1