Tag: M.W:100-200

Quality Control of 2-Chloropyridine 1-oxide. Aromatic compounds can be divided into two categories: single heterocycles and fused heterocycles. Compound: 2-Chloropyridine 1-oxide, is researched, Molecular C5H4ClNO, CAS is 2402-95-1, about MO calculations on heterocycles. 21. Interpretation of the photoelectron spectra of substituted pyridine-N-oxides. Author is Scholz, Manfred; Goetze, Raimund; Kluge, Gert; Klasinc, Leo; Novak, Igor.

The He I and He II photoelectron spectra of I (R = H; 2-, 3-, 4-Cl; 2-, 3-, 4-Me) were interpreted by a modified CNDO MO method. With a suitably chosen symmetry anal. an assignment in the MO ionization picture is possible for all mols. up to ∼15 eV.

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Aromatic fluorine compounds. IX. 2-Fluoropyridines》. Authors are Finger, G. C.; Starr, Laurence D..The article about the compound:2-Chloropyridine 1-oxidecas:2402-95-1,SMILESS:ClC1=CC=CC=[N+]1[O-]).Electric Literature of C5H4ClNO. Through the article, more information about this compound (cas:2402-95-1) is conveyed.

cf. C.A. 53, 13090c. Anhydrous KF (I) 9 g., 12.3 g. 2-chloro-3-nitropyridine and 30 ml. HCONMe2 (DMF) was heated 6 hrs. at 150°, cooled, the mixture poured onto crushed ice, saturated with NaCl, steam distilled, the distillate extracted with Et2O, dried and distilled to give 8.4 g. 2-fluoro-3-nitropyridine, b10 109-9.5° n25D 1.5278. I (73.3 g.) added to a stirred solution of 100 g. 2-chloro-5-nitropyridine and 300 ml DMF at 120°, cooled and processed as above gave 70.1 g. 2-fluoro-5-nitropyridine b7 86-7°, n25D 1.5243. NaNO2 (13.3 g.) in 65 ml. H2O added dropwise with stirring at -2° to 0° to 28 g. 2-amino-3-bromo-5-nitropyridine in aqueous H2SO4 (25%, 900 ml.), the mixture boiled, filtered and cooled gave 18.3 g. 3-bromo-5-nitropyridine (II), m. 212° (decomposition) (H2O). II (4.1 g.), 4 g. PCl3 and 1 ml. POCl3 stirred and refluxed 3 hrs., the mixture concentrated in vacuo and poured onto crushed ice gave 4.2 g. 3-bromo-2-chloro-5-nitropyridine (III), m. 67.3-8.0° after sublimation at 60-70° 2 mm. A stirred mixture of 3.8 g. III, 15 ml. DMF and 1.8 g. I was heated 1 hr. at 100° cooled, poured onto ice, steam distilled, the distillate extracted with Et2O, dried and evaporated to give 2.5 g. crude 3-bromo-2-fluoro-5-nitropyridine; this repeatedly vacuum sublimed gave 1.78 g. pure product, m. 60-1.5° Peracetic acid (40%, 137 ml.) was added dropwise to a stirred solution of 50 g. 2-chloropyridine (IV) and 66 ml. glacial AcOH at 45° the mixture heated 5 hrs. at 50° and 17 hrs. at 70°, concentrated in vacuo to 150 ml. on a steam-bath, poured onto crushed ice, made strongly alk. with 40% NaOH, extracted with CHCl3 dried with MgSO4 and a small amount Na2CO3, the extract evaporated and diluted with 10 ml. anhydrous Et2O gave 45.8 g. 2-chloropyridine N-oxide (V), m. 69-9.5° (Et2O-EtOH). To a mixture obtained by adding 10 g. V to 15 ml. concentrated H2SO4 was added with stirring at 1-2° over 45 min. a mixture of 15 ml. concentrated H2SO4 and 27 ml. fuming HNO3 (sp. gr. 1.5), the mixture heated over 1 hr. to 90°, stirred 1 hr. at 90° cooled to 10° poured onto stirred ice-H2O, neutralized with Na2CO3, filtered, the yellow precipitate partially air dried, dissolved in hot CHCl3, the aqueous filtrate extracted with CHCl3 and the combined CHCl3 solutions dried and evaporated to give 11.4 g. crude 2-chloro-4-nitropyridine N-oxide (VI) m. 153-3.5° (EtOH-CHCl3.) 2-Chloro-4-nitropyridine (VII) was obtained in 91% yield by Hamana procedure (C.A. 50, 1817a). VII (5 g.), 3.7 g. I and 10 ml. di-Me sulfoxide gave a good halide test after being heated 1 hr. at 160°; the mixture was cooled, poured onto crushed ice, saturated with NaCl, steam distilled The distillate was extracted repeatedly with CHCl3; the combined extracts dried and evaporated gave no residue, but the pot residue from the steam distillation gave a small portion of solid, unidentified, m. 100.5-5.0° after sublimation. VII and di-Me sulfoxide in the absence of I gave no evidence of reaction. Dry HCl was passed 2.25 hrs. into a stirred solution of 20 g. IV in 200 ml. anhydrous Et2O and the Et2O evaporated in vacuo to leave 23.4 g. hygroscopic needles, 2-chloropyridine-HCl m. 101.5-2.0°, decomposing on standing, darkening on exposure to light.

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Aromatic fluorine compounds. IX. 2-Fluoropyridines》. Authors are Finger, G. C.; Starr, Laurence D..The article about the compound:2-Chloropyridine 1-oxidecas:2402-95-1,SMILESS:ClC1=CC=CC=[N+]1[O-]).HPLC of Formula: 2402-95-1. Through the article, more information about this compound (cas:2402-95-1) is conveyed.

cf. C.A. 53, 13090c. Anhydrous KF (I) 9 g., 12.3 g. 2-chloro-3-nitropyridine and 30 ml. HCONMe2 (DMF) was heated 6 hrs. at 150°, cooled, the mixture poured onto crushed ice, saturated with NaCl, steam distilled, the distillate extracted with Et2O, dried and distilled to give 8.4 g. 2-fluoro-3-nitropyridine, b10 109-9.5° n25D 1.5278. I (73.3 g.) added to a stirred solution of 100 g. 2-chloro-5-nitropyridine and 300 ml DMF at 120°, cooled and processed as above gave 70.1 g. 2-fluoro-5-nitropyridine b7 86-7°, n25D 1.5243. NaNO2 (13.3 g.) in 65 ml. H2O added dropwise with stirring at -2° to 0° to 28 g. 2-amino-3-bromo-5-nitropyridine in aqueous H2SO4 (25%, 900 ml.), the mixture boiled, filtered and cooled gave 18.3 g. 3-bromo-5-nitropyridine (II), m. 212° (decomposition) (H2O). II (4.1 g.), 4 g. PCl3 and 1 ml. POCl3 stirred and refluxed 3 hrs., the mixture concentrated in vacuo and poured onto crushed ice gave 4.2 g. 3-bromo-2-chloro-5-nitropyridine (III), m. 67.3-8.0° after sublimation at 60-70° 2 mm. A stirred mixture of 3.8 g. III, 15 ml. DMF and 1.8 g. I was heated 1 hr. at 100° cooled, poured onto ice, steam distilled, the distillate extracted with Et2O, dried and evaporated to give 2.5 g. crude 3-bromo-2-fluoro-5-nitropyridine; this repeatedly vacuum sublimed gave 1.78 g. pure product, m. 60-1.5° Peracetic acid (40%, 137 ml.) was added dropwise to a stirred solution of 50 g. 2-chloropyridine (IV) and 66 ml. glacial AcOH at 45° the mixture heated 5 hrs. at 50° and 17 hrs. at 70°, concentrated in vacuo to 150 ml. on a steam-bath, poured onto crushed ice, made strongly alk. with 40% NaOH, extracted with CHCl3 dried with MgSO4 and a small amount Na2CO3, the extract evaporated and diluted with 10 ml. anhydrous Et2O gave 45.8 g. 2-chloropyridine N-oxide (V), m. 69-9.5° (Et2O-EtOH). To a mixture obtained by adding 10 g. V to 15 ml. concentrated H2SO4 was added with stirring at 1-2° over 45 min. a mixture of 15 ml. concentrated H2SO4 and 27 ml. fuming HNO3 (sp. gr. 1.5), the mixture heated over 1 hr. to 90°, stirred 1 hr. at 90° cooled to 10° poured onto stirred ice-H2O, neutralized with Na2CO3, filtered, the yellow precipitate partially air dried, dissolved in hot CHCl3, the aqueous filtrate extracted with CHCl3 and the combined CHCl3 solutions dried and evaporated to give 11.4 g. crude 2-chloro-4-nitropyridine N-oxide (VI) m. 153-3.5° (EtOH-CHCl3.) 2-Chloro-4-nitropyridine (VII) was obtained in 91% yield by Hamana procedure (C.A. 50, 1817a). VII (5 g.), 3.7 g. I and 10 ml. di-Me sulfoxide gave a good halide test after being heated 1 hr. at 160°; the mixture was cooled, poured onto crushed ice, saturated with NaCl, steam distilled The distillate was extracted repeatedly with CHCl3; the combined extracts dried and evaporated gave no residue, but the pot residue from the steam distillation gave a small portion of solid, unidentified, m. 100.5-5.0° after sublimation. VII and di-Me sulfoxide in the absence of I gave no evidence of reaction. Dry HCl was passed 2.25 hrs. into a stirred solution of 20 g. IV in 200 ml. anhydrous Et2O and the Et2O evaporated in vacuo to leave 23.4 g. hygroscopic needles, 2-chloropyridine-HCl m. 101.5-2.0°, decomposing on standing, darkening on exposure to light.

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

Recommanded Product: 3,5-Dimethyl-4-nitropyridine 1-oxide. So far, in addition to halogen atoms, other non-metallic atoms can become part of the aromatic heterocycle, and the target ring system is still aromatic. Compound: 3,5-Dimethyl-4-nitropyridine 1-oxide, is researched, Molecular C7H8N2O3, CAS is 14248-66-9, about Electrostatic potentials mapped on Hirshfeld surfaces provide direct insight into intermolecular interactions in crystals.

Ab initio electrostatic potentials for mols. can readily be mapped onto their Hirshfeld surfaces and displayed within a crystal packing diagram. In this manner the close mol. contacts in the crystal can be rationalized and discussed in terms of the electrostatic complementarity of touching surface patches in adjacent mols. By way of example a detailed discussion is given of mol. electrostatic potentials for a large number of small, sym., cyclic mols. that crystallize in space groups P41212 or P43212, with a focus on the qual. insight that can be obtained and the ways in which this complements the intermol. electrostatic energies recently reported for some of these materials.

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

Application of 2402-95-1. The protonation of heteroatoms in aromatic heterocycles can be divided into two categories: lone pairs of electrons are in the aromatic ring conjugated system; and lone pairs of electrons do not participate. Compound: 2-Chloropyridine 1-oxide, is researched, Molecular C5H4ClNO, CAS is 2402-95-1, about Study on synthesis of 2-chloropyridine-4-amine. Author is Zhu, Kongjie; Li, Xiuqin; Zhuang, Wenming.

2-chloropyridine-4-amine is an important intermediate of synthesizing many fine chem. products. It was synthesized from 2-chloropyridine via oxidation with H2O2 , nitration and reduction of iron powder, the structure was confirmed by 1HNMR. The affecting factors including the ratio of the raw materials , the reaction time and the temperature were investigated. Synthesis method is simple and the overall yield was 74.4% with a purity of 98. 28%.

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

Shiro, Motoo; Yamakawa, Masumi; Kubota, Tanekazu published an article about the compound: 3,5-Dimethyl-4-nitropyridine 1-oxide( cas:14248-66-9,SMILESS:O=[N+](C1=C(C)C=[N+]([O-])C=C1C)[O-] ).Formula: C7H8N2O3. Aromatic heterocyclic compounds can be classified according to the number of heteroatoms or the size of the ring. The authors also want to convey more information about this compound (cas:14248-66-9) through the article.

The crystal structures of 3-methyl-4-nitropyridine N-oxide (I), tetragonal 3,5-dimethyl-4-nitropyridine N-oxide (II) and orthorhombic 3,5-dimethyl-4-nitropyridine N-oxide (III) determined I is orthorhombic, space group P212121, with a 21.359(2), b 6.111(1), and c 5.132(1) Å; Z = 4. II is tetragonal, space group P41212, with a 7.443(1), and c 13.447(1) Å; Z = 4. III is orthorhombic, space group Pbca, with a 7.329(1), b 14.912(2), and c 13.852(2) Å; Z = 8. The intensity data were collected on a 4-circle diffractometer by use of Zr-filtered Mo Kα radiation. The structures were refined by a block-diagonal least-squares method to R = 0.062 for I (661 reflections), 0.051 for II (472) and 0.085 for III (941). The twist angles of the nitro group out of the mol. plane are 16.7, 49.4 and 51.1.degree., and the N-O distances of the N-oxide group are 1.292 (1.299 after libration corrections), 1.289 (1.293) and 1.302 (1.306) Å, resp. The contribution of the quinoid structure to the resonance forms is significant in the 2 mols., as in 4-nitropyridine N-oxide. The intramol. charge transfer from the N-oxide group O atom to the nitro group plays an important role in stabilizing these mols. in less-twisted conformations than those of their related compounds

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Structure and reactivity of 2-aminopyridine 1-oxide》. Authors are Katritzky, A. R..The article about the compound:2-Chloropyridine 1-oxidecas:2402-95-1,SMILESS:ClC1=CC=CC=[N+]1[O-]).HPLC of Formula: 2402-95-1. Through the article, more information about this compound (cas:2402-95-1) is conveyed.

2-Aminopyridine 1-oxide (I) was prepared Comparison of its ultraviolet spectrum with those of 2-methylimino- and 2-imino-1-methoxy-1,4-dihydropyridine (II) showed that I does not exist mainly in the tautomeric imino form. Et 2-pyridinecarbamate (III), 72 cc. AcOH, and 43 cc. 30% aqueous H2O2 kept overnight at 70°, the solid (IV) filtered off, volatile material removed from the filtrate in vacuo, the residue and IV refluxed overnight with 40 cc. concentrated HCl, volatile material removed in vacuo, 50 cc. EtOH and alc. NaOEt (from 6 g. Na in 150 cc. EtOH) added followed by small pieces of solid CO2 until the solution was no longer alk., the mixture filtered, the filtrate evaporated, and the residue crystallized from EtOH-EtOAc gave 16.1 g. I, m. 157-62°, and when further recrystallized m. 163-4°, λ0.1N HCl 231, 301 mμ (ε 8080, 5230), λ0.1N NaOH 221,310 mμ (ε 23,300, 3900), inflection 239 mμ (ε 6900), λEtOH 227,251,321 mμ (ε 25,000, 5740, 4610). 2-Chloropyridine (22.6 g.), 150 cc. AcOH, and 50 cc. 30% aqueous H2O2 heated overnight at 80°, volatile material removed in vacuo, 140 cc. CHCl3 added, the mixture digested with 17 g. K2CO3 5 min. at 65°, the precipitate filtered off, washed with 60 cc. CHCl3, and filtrate and washings evaporated gave 19.75 g. 2-chloropyridine 1-oxide (V), m. 67-8.5° (from EtOAc). V (7 g.) and 40 cc. 25% aqueous MeNH2 heated 12 hrs. at 140°, 4 g. K2CO3 added, the whole evaporated to dryness in vacuo, the residue extracted with EtOH, the extracts evaporated, and the residue crystallized from EtOAc gave 5.5 g. 2-methylaminopyridine 1-oxide (VI), needles, m. 103-5°, or prisms, m. 68-70°, giving a dark blue color with FeCl3, λ0.1N HCl 236, 314 mμ (ε 7950, 4250), λ0.1N NaOH 226, 324 mμ (ε 18,700, 3640), inflection 246 mμ (ε 5500) [picrate (VII), needles, m. 155.5-7.0° (from EtOH); picrolonate (VIII), yellow needles, m. 201-3° (from EtOH); HCl salt, needles, m. 203-4° (from EtOH)]. To 0.3 g. VI was added 0.5 cc. Ac2O, the whole left overnight at 18°, EtOH added, the mixture evaporated in vacuo, treated with CHCl3 and K2CO3, filtered, and evaporated to give 0.28 g. Ac derivative, hygroscopic prisms, m. 95-7° (from EtOAc), giving no color with FeCl3. Prepared like VI in about 80% yield, 2-dimethylaminopyridine 1-oxide, b0.25 143-5° (bath temperature), nD20 1.6117, giving no color with FeCl3, λ0.1N HCl 243, 320 mμ (ε 7370, 4470), λ0.1N NaOH 236, 319 mμ (ε 16,500, 2690), inflection 261 mμ (ε 5400) [picrate, plates, m. 142.5-4.0° (from EtOH); picrolonate, orange-yellow prisms, m. 180-1° (decomposition) (from EtOH)]. Attempted preparation of II: I (5.5 g.) heated overnight at 100° with 9.3 g. p-MeC6H4SO3Me (IX) and the product crystallized from EtOH-EtOAc gave 12.66 g. 2-amino-1-methoxypyridinium p-toluenesulfonate (X), prisms, m. 127-9°, giving no color with FeCl3. X (0.6 g.) in EtOH treated with 5.5 cc. 0.4N NaOEt, the solid filtered off, and 0.46 g. picric acid in EtOH added gave 0.40 g. 2-amino-1-methoxypyridinium (XI) picrate (XII), yellow needles, m. 169.5-71° (from EtOH), its infrared spectrum quite distinct from those of VII and 2-aminopyridinium picrate, needles, m. 222-3° (from EtOH). Similarly to XI was prepared XI picrolonate, yellow prisms, m. 245-7° (decomposition), its infrared spectrum distinct from those of VIII and 2-aminopyridinium picrolonate, yellow prisms, m. 269-71° (decomposition) (from EtOH). X (1.48 g.) in 3 cc. EtOH treated with 0.8 cc. 60% HClO4 gave 0.95 g. perchlorate, laths, m. 182-4° (from EtOH), λ0.1N HCl 230, 299 mμ (ε 7670, 5870), λ0.1N NaOH 230, 291 mμ (ε 8890, 4400). X (0.6 g.) in 3 cc. pyridine and 0.4 g. 3,5-(O2N)2C6H3COCl (XIII) kept overnight at room temperature and treated with aqueous NaOH gave 2-(3,5-dinitrobenzoylimino)-1,2-dihydro-1-methoxypyridine, pale yellow needles, m. 219-20° (from EtOH). VI (1.24 g.) and 1.86 g. IX heated 24 hrs. at 100° gave 2.33 g. 1-methoxy-2-methylaminopyridinium p-toluenesulfonate, prisms, m. 98-100° (from MeCN-EtOAc), λ0.1N NaOH 237, 297, 302 mμ (ε 9400, 3390, 3370), inflection 236 mμ (ε 9650), λ0.1N HCl 235, 314 mμ (ε 10,900, 6590). I (1 g.), 6 cc. pyridine, and 2.4 cc. BzCl kept overnight, and H2O added, gave 1.57 g. 2-benzamidopyridine 1-oxide (XIV) benzoate (XV), needles, m. 94-5° (from C6H6-petr. ether). XV (0.75 g.) treated in CHCl3, with 1 g. K2CO3, the mixture filtered, and the filtrate evaporated gave 0.47 g. XIV, m. 122-4° (from EtOH), giving a red color with FeCl3. BzCl (0.6 cc.) and 0.55 g. I in 5 cc. hot MeCN kept overnight at room temperature gave 0.43 g. 1-benzoyloxy-1,2-dihydro-2-iminopyridine (XVI), needles, m. 158-9° (from EtOH), giving no color with FeCl3. XVI recrystallized from EtOH and left in the mother liquor for 4 days gave XIV. 2-Benzamidopyridine (0.32 g.), 6 cc. AcOH, and 0.2 cc. 30% aqueous H2O2 kept overnight at 70° and worked up gave XIV. I (0.55 g.) in 10 cc. hot MeCN treated with 0.5 cc. EtO2CCl and kept 2 days gave a low yield of Et 2-pyridinecarbamate 1-oxide. I (1.1 g.), 10 cc. MeCN, and 1 cc. Ac2O kept overnight gave 0.82 g. 2-acetamidopyridine 1-oxide, rods, m. and mixed m.p. 140.5-1.0°. I (1 g.) and 3 cc. (CO2Et)2 boiled 10 min. and EtOH added to the cooled solution gave 0.2 g. N,N’-di-2-pyridyloxamide 1,1′- dioxide, which separated from AcOH as the diacetate, plates, m. and mixed m.p. 270° (deompn.) (varying with rate of heating). PhNCO (0.6 g.) and 0.55 g. I in 10 cc. hot MeCN kept 2 days at room temperature gave 0.52 g. 2-N-phenylureidopyridine 1-oxide, needles, m. and mixed m.p. 212-13° to 220-0.5° (varying with the rate of heating). XIII (1.15 g.) added to 0.55 g. I in 10 cc. hot MeCN and worked up after 30 hrs. at room temperature gave 0.98 g. 2-(3,5-dinitrobenzamido)-pyridine 1-oxide, separating from AcOH as the acetate, needles, m. 216-17°. I did not react smoothly with (EtO)2CO, o-C6H4(CO)2O, α-naphthyl thiocyanate, or CS2. III (1.66 g. and 0.9 cc. morpholine refluxed 18 hrs., cooled, and recrystallized from C6H6-petr. ether gave 1.05 g. 2-morpholinocarbonylaminopyridine, needles, m. 91-2.5°. To 1.1 g. I in 2 cc. concentrated HCl was added 4 g. ice followed by dropwise addition of 0.9 g. KNO2 in 5 cc. H2O and the mixture gradually added to 1.44 g. β-naphthol in 12 cc. 10% aqueous NaOH and 6 g. ice gave 1.15 g. 2-(2-hydroxy-1-naphthylazo)pyridine 1-oxide, crimson plates, m. 215-16° (decomposition)(from EtOH), λEtOH 225, 292, 466 mμ (ε 12,100, 5800, 5600).

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

SDS of cas: 14248-66-9. Aromatic compounds can be divided into two categories: single heterocycles and fused heterocycles. Compound: 3,5-Dimethyl-4-nitropyridine 1-oxide, is researched, Molecular C7H8N2O3, CAS is 14248-66-9, about Single-Step versus Stepwise Two-Electron Reduction of Polyarylpyridiniums: Insights from the Steric Switching of Redox Potential Compression. Author is Fortage, Jerome; Peltier, Cyril; Perruchot, Christian; Takemoto, Yohei; Teki, Yoshio; Bedioui, Fethi; Marvaud, Valerie; Dupeyre, Gregory; Pospisil, Lubomir; Adamo, Carlo; Hromadova, Magdalena; Ciofini, Ilaria; Laine, Philippe P.; M.

Contrary to 4,4′-dipyridinium (i.e., archetypal Me viologen), which is reduced by two single-electron transfers (stepwise reduction), the 4,1′-dipyridinium isomer (so-called “”head-to-tail”” isomer) undergoes two electron transfers at apparently the same potential (single-step reduction). A combined theor. and exptl. study has been undertaken to establish that the latter electrochem. behavior, also observed for other polyarylpyridinium electrophores, is due to potential compression originating in a large structural rearrangement. Three series of branched expanded pyridiniums (EPs) were prepared: N-aryl-2,4,6-triphenylpyridiniums (Ar-TP), N-aryl-2,3,4,5,6-pentaphenylpyridiniums (Ar-XP), and N-aryl-3,5-dimethyl-2,4,6-triphenylpyridinium (Ar-DMTP). The intramol. steric strain was tuned via N-pyridinio aryl group (Ar) Ph (Ph), 4-pyridyl (Py), and 4-pyridylium (qPy) and their bulky 3,5-di-Me counterparts, xylyl (Xy), lutidyl (Lu), and lutidylium (qLu), resp. Ferrocenyl subunits as internal redox references were covalently appended to representative electrophores in order to count the electrons involved in EP-centered reduction processes. Depending on the steric constraint around the N-pyridinio site, the two-electron reduction is single-step (Ar = Ph, Py, qPy) or stepwise (Ar = Xy, Lu, qLu). This steric switching of the potential compression is accurately accounted for by ab initio modeling (D. Functional Theory, DFT) that proposes a mechanism for pyramidalization of the Npyridinio atom coupled with reduction When the hybridization change of this atom is hindered (Ar = Xy, Lu, qLu), the first reduction is a one-electron process. Theory also reveals that the single-step two-electron reduction involves couples of redox isomers (electromers) displaying both the axial geometry of native EPs and the pyramidalized geometry of doubly reduced EPs. This picture is confirmed by a combined UV-vis-NIR spectroelectrochem. and time-dependent DFT study: comparison of in situ spectroelectrochem. data with the calculated electronic transitions makes it possible to both evidence the distortion and identify the predicted electromers, which play decisive roles in the electron-transfer mechanism. Last, this mechanism is further supported by in-depth anal. of the electronic structures of electrophores in their various reduction states (including electromeric forms).

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Activated nucleophilic substitution in aromatic compounds. V. Reactivity of 2-, 3-, and 4-chloropyridine N-oxides with piper[dine in methanol》. Authors are Coppens, G.; Declerck, F.; Gillet, C.; Nasielski, J..The article about the compound:2-Chloropyridine 1-oxidecas:2402-95-1,SMILESS:ClC1=CC=CC=[N+]1[O-]).Name: 2-Chloropyridine 1-oxide. Through the article, more information about this compound (cas:2402-95-1) is conveyed.

cf. CA 50, 11260f. The conductimetrically-measured rates of reaction of 2-, 3-, and 4-chloropyridine N-oxides with piperidine in MeOH solution gave, at 80°, the apparent unimol. rate constants 3.70 ×10-4, 1.04 × 10-7, and 1.02 × 10-4 sec.-1, resp. The reactivity sequence 2 > 4 ≫ 3 was discussed in terms of competing inductive and internal solvation effects.

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Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Activated nucleophilic substitution of aromatic compounds. VI. Ortho-para relation. Reactivity of 2- and 4-chloropyridines, chloropyridine oxides, and chloronitrobenzenes with piperidine in methanol》. Authors are Coppens, G.; Declerck, F.; Gillet, C.; Nasielski, J..The article about the compound:2-Chloropyridine 1-oxidecas:2402-95-1,SMILESS:ClC1=CC=CC=[N+]1[O-]).Safety of 2-Chloropyridine 1-oxide. Through the article, more information about this compound (cas:2402-95-1) is conveyed.

cf. CA 57, 5881a. The effect of the groups NO2, cyclic, aromatic -N=, and N → O on the reactivity of the halogens of the chloronitrobenzenes, chloropyridines, and chloropyridine oxides with piperidine in methanol was studied. The reactivity sequence is N → O > NO2 -N=. The results are (compound, temperature, concentration of the halogen derivative, and second order constant in mole-1 sec.-1 = 107 given): 2-chloronitrobenzene (I), 80°, 0.00998, 144; I, 90°, 0.00985, 274; I, 100°, 0.00972, 537; I, 110°, 0.00959, 1090; 4-chloronitrobenzene (II), 70°, 0.00942, 28.8; II, 70°, 0.00942, 27.4; II, 80°, 0.0263, 61.4; II, 90°, 0.0259, 116; II, 90°, 0.0259, 122; II, 100°, 0.0256, 31; II, 110°, 0.0252, 442; 2-chloropyridine (III), 90°, 0.0482, 3.66; III, 100°, 0.0476, 8.60; III, 110°, 0.0469, 20.3; III, 120°, 0.0463, 40.7; 4-chloropyridine (IV), 70°, 0.0891, 8.37; IV, 80°, 0.0879, 16.4; IV, 90°, 0.0868, 32.3; IV, 100°, 0.0857, 67.2. Because of the low reactivity of the meta derivatives, a 50:50 piperidine-H2O mixture was used. These facts are in accordance with the hypothesis of internal solvation as the ex-planation of the high reactivity of the halogen in the meta position in 2,4-dinitrochlorobenzene with piperidine.

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Reference:
Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem