Month: January 2023

Deuterium isotope effects on aromatic carbon-13 chemical shifts. V. Nonadditivity of methyl substituent effects on one-bond isotope shifts for methylpyridine N-oxides was written by Nakashima, Yasuki;Fukunaga, Moritaka;Suzuki, Keiko;Takahashi, Kensuke. And the article was included in Bulletin of the Chemical Society of Japan in 1993.Formula: C7H9NO This article mentions the following:

One- and two-bond deuterium isotope effects (¹Δ and ²Δ) on ¹³C chem. shifts for methylpyridines and their N-oxides were investigated. The ¹Δ values for methylpyridines agree with the calculated values, which are based on a simple additive rule of the Me substituent effects. The additive rule was not satisfied for ¹Δ of the N-oxides. This is attributed to a steric interaction between the substituent and the N-oxide group. In the experiment, the researchers used many compounds, for example, 3,5-Dimethylpyridine 1-oxide (cas: 3718-65-8Formula: C7H9NO).

3,5-Dimethylpyridine 1-oxide (cas: 3718-65-8) belongs to pyridine derivatives. In contrast to benzene, Pyridine’s electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom. One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Formula: C7H9NO

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Imidazo[1,5-a]pyridine-Based Fluorescent Probes: A Photophysical Investigation in Liposome Models was written by Renno, Giacomo;Cardano, Francesca;Volpi, Giorgio;Barolo, Claudia;Viscardi, Guido;Fin, Andrea. And the article was included in Molecules in 2022.Name: Phenyl(pyridin-2-yl)methanone This article mentions the following:

In this context, five imidazo[1,5-a]pyridine-based fluorophores were synthesized according to a one-pot cyclization between an aromatic ketone and benzaldehyde in the presence of ammonium acetate and acetic acid. The photophys. features of prepared compounds were investigated in several organic solvents and probes 2-4 exhibited the greatest solvatochromic behavior, resulting in a higher suitability as membrane probes. Their interaction with liposomes as artificial membrane model was tested showing a successful intercalation of the probes in the lipid bilayer. Kinetic experiments were carried out and the lipidic phase influence on the photophys. features was evaluated through temperature-dependent experiments The results herein reported encourage further investigations on the use of imidazo[1,5-a]pyridine scaffold as fluorescent membrane probes. In the experiment, the researchers used many compounds, for example, Phenyl(pyridin-2-yl)methanone (cas: 91-02-1Name: Phenyl(pyridin-2-yl)methanone).

Phenyl(pyridin-2-yl)methanone (cas: 91-02-1) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds. Pyridine derivatives are also useful as small-molecule α-helix mimetics that inhibit protein-protein interactions, as well as functionally selective GABA ligands.Name: Phenyl(pyridin-2-yl)methanone

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Iridium(III)-Catalyzed Intermolecular C(sp³)-H Insertion Reaction of Quinoid Carbene: A Radical Mechanism was written by Wang, Hai-Xu;Richard, Yann;Wan, Qingyun;Zhou, Cong-Ying;Che, Chi-Ming. And the article was included in Angewandte Chemie, International Edition in 2020.Formula: C10H17NO2 This article mentions the following:

In the presence of (octaethylporphyrinato)methyliridium, diazocyclohexadienones such as I underwent regioselective C-H insertion reactions with cyclohexadienes, alkenes, indene, THF, and Boc-pyrrolidine to yield dihydrobiaryls such as II and alkenylarenes and alkylarenes. TEMPO inhibition experiments, kinetic isotope effects, identification of an iridium carbene intermediate, and calculated structure and spin d. for an iridium carbene-derived radical provided evidence for a radical reaction mechanism for the insertion reactions; the insertions are proposed to occur by hydrogen atom transfer to the iridium carbene followed by radical rebound. The regioselectivity of the insertion reactions are determined primarily by steric effects, with insertion into primary C-H bonds favored over insertion into secondary or tertiary C-H bonds. In the experiment, the researchers used many compounds, for example, tert-Butyl 5,6-dihydropyridine-1(2H)-carboxylate (cas: 85838-94-4Formula: C10H17NO2).

tert-Butyl 5,6-dihydropyridine-1(2H)-carboxylate (cas: 85838-94-4) belongs to pyridine derivatives. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Pyridine derivatives are also useful as small-molecule α-helix mimetics that inhibit protein-protein interactions, as well as functionally selective GABA ligands.Formula: C10H17NO2

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Catalytic ozonation of organic contaminants in petrochemical wastewater with iron-nickel foam as catalyst was written by Huang, Yuanxing;Luo, Mengyu;Xu, Zhihua;Zhang, Daofang;Li, Liang. And the article was included in Separation and Purification Technology in 2019.Reference of 626-64-2 This article mentions the following:

This work investigated the removal of organic contaminants in actual petrochem. wastewater by catalytic ozonation with iron-nickel foam as catalyst. Under different conditions, the DOC removal percentages ranged from 40% to 61%, the sCOD removals were from 73% to 96% in the reaction time of 120 min. Two thirds of the 66 detected organic compounds disappeared in the treated wastewater. The biodegradability of the petrochem. wastewater was greatly improved after catalytic ozonation. TP, TN, NO₃-N, Cl^– and some heavy metals in the petrochem. wastewater were also removed to some extent. The influence of pH and initial organic matter concentration on the performance of catalytic ozonation was limited. Increase of aqueous ozone concentration and catalyst dosage was advantageous for organic contaminants removal. The probable mechanism of catalytic ozonation was proposed as that the iron-nickel foam was oxidized by ozone into the mixture of oxides, hydroxides, and hydroxyoxides. On one hand, the hydroxyl groups on the catalyst surface motivated the formation of ^·OH. On the other hand, the electrons transferred among different valences of transition metals facilitated the decomposition of ozone. The generated ^·OH diffused into bulk solution, working together with ozone to degrade the organic contaminants. From theor. modeling, the residue ozone in the off gas can be reduced from 98% to 11% by using iron-nickel foam as the catalyst. In the experiment, the researchers used many compounds, for example, Pyridin-4-ol (cas: 626-64-2Reference of 626-64-2).

Pyridin-4-ol (cas: 626-64-2) belongs to pyridine derivatives. Pyridine has a dipole moment and a weaker resonant stabilization than benzene (resonance energy 117 kJ·mol−1 in pyridine vs. 150 kJ·mol−1 in benzene). Pyridine derivatives are also useful as small-molecule α-helix mimetics that inhibit protein-protein interactions, as well as functionally selective GABA ligands.Reference of 626-64-2

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Synthesis and characterization of ionic liquid crystals based on substituted pyridinium cations was written by Santos, Andreia F. M.;Cruz, Carlos;Godinho, Maria H.;Dionisio, Madalena;Figueirinhas, Joao L.;Branco, Luis C.. And the article was included in Liquid Crystals.Formula: C17H30BrN This article mentions the following:

Novel ionic liquid crystals based on pyridinium and methylpyridinium cations with a dodecyl chain and bromide as anion was prepared and characterized. [C₁₂Pyr][Br] and [C₁₂-n-Pic][Br] (n = 2, 3 or 4) were studied in order to understand the influence of the Me group position in the mesomorphic behavior. Neat microwave-assisted reactions were carried out to synthesized [C₁₂Pyr][Br], [C₁₂-3-Pic][Br] and [C₁₂-4-Pic][Br] as a sustainable approach, leading to significantly reduced reaction times (35 min vs. 48 h in conventional method). All prepared compounds were characterized by spectroscopic techniques (¹H and ¹³C-NMR; ATR-FTIR), Elemental Anal., Differential Scanning Calorimetry (DSC), Polarised Optical Microscopy (POM) and X-Ray Powder Diffraction (XRD). It was observed that the presence of water highly influences the phase transformations. Nevertheless, thermotropic smectic phases were detected for all materials with a layer spacing between 20 and 35 Å, compatible with a bilayer interdigitated or tilted lamellar arrangement of the cation′s alkyl chain. This work also indicates new routes for preparing ionic liquid crystals with various functionalities ruled by the synthesis design. In the experiment, the researchers used many compounds, for example, 1-Dodecylpyridin-1-ium bromide (cas: 104-73-4Formula: C17H30BrN).

1-Dodecylpyridin-1-ium bromide (cas: 104-73-4) belongs to pyridine derivatives. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Reduced pyridines, namely tetrahydropyridines, dihydropyridines and piperidines, are found in numerous natural and synthetic compounds. The synthesis and reactivity of these compounds have often been driven by the fact many of these compounds have interesting and unique pharmacological properties. Formula: C17H30BrN

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Transient Imine as a Directing Group for the Metal-Free o-C-H Borylation of Benzaldehydes was written by Rej, Supriya;Chatani, Naoto. And the article was included in Journal of the American Chemical Society in 2021.Product Details of 4783-68-0 This article mentions the following:

Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chem. The selective borylation strategies that are currently in use largely rely on the use of transition-metal catalysts. Hence, identifying much milder conditions for transition-metal-free borylation would be highly desirable. The authors herein present a unified strategy for the selective C-H borylation of electron-deficient benzaldehyde derivatives using a simple metal-free approach, using an imine transient directing group. The strategy covers a wide spectrum of reactions and (i) even highly sterically hindered C-H bonds can be borylated smoothly, (ii) despite the presence of other potential directing groups, the reaction selectively occurs at the o-C-H bond of the benzaldehyde moiety, and (iii) natural products appended to benzaldehyde derivatives can also give the appropriate borylated products. Also, the efficacy of the protocol was confirmed by the fact that the reaction proceeds even in the presence of external impurities. In the experiment, the researchers used many compounds, for example, 2-Phenoxypyridine (cas: 4783-68-0Product Details of 4783-68-0).

2-Phenoxypyridine (cas: 4783-68-0) belongs to pyridine derivatives. Pyridines are an important class of heterocycles and occur in polysubstituted forms in many naturally occurring biologically active compounds, drug molecules and chiral ligands. Many analogues of pyridine are known where N is replaced by other heteroatoms . Substitution of one C–H in pyridine with a second N gives rise to the diazine heterocycles (C4H4N2), with the names pyridazine, pyrimidine, and pyrazine.Product Details of 4783-68-0

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Efficient regioselective preparation of monobromo- and bromoiodo-hydroxypyridines from dibromo derivatives via bromine-lithium exchange was written by Meana, Angela;Rodriguez, Justo F.;Sanz-Tejedor, Ma Ascension;Garcia-Ruano, Jose L.. And the article was included in Synlett in 2003.Related Products of 13472-81-6 This article mentions the following:

Annular dibromination of hydroxypyridines with NBS followed by bromine-lithium exchange with alkyllithium and subsequent trapping with H₂O or I₂ afforded bromo(hydroxy)- and bromo(iodo)hydroxypyridines, e.g., I, in a completely regioselective way. Iodination of bromohydroxypyridines with NIS is totally regioselective. In the experiment, the researchers used many compounds, for example, 3,5-Dibromo-2-hydroxypyridine (cas: 13472-81-6Related Products of 13472-81-6).

3,5-Dibromo-2-hydroxypyridine (cas: 13472-81-6) belongs to pyridine derivatives. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Pyridine groups exist in countless molecules, and their applications include catalysis, drug design, molecular recognition, and natural product synthesis.Related Products of 13472-81-6

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Directed lithiation of 4-halopyridines: chemoselectivity, regioselectivity and application to synthesis was written by Marsais, F.;Trecourt, F.;Breant, P.;Queguiner, G.. And the article was included in Journal of Heterocyclic Chemistry in 1988.Product Details of 116922-60-2 This article mentions the following:

The title pyridines I (R = Cl, F, R¹ = H) were ortho-lithiated with BuLi-N,N,N‘,N‘-tetramethylethylenediamine or LiN(CHMe₂)₂ and treated with electrophiles, e.g. MeI, Me₃SiCl, and PhCHO, to give 3,4-disubstituted pyridines I [R = Cl, F, R¹ = Me, Me₃Si, Ph(OH)CH], resp. Oxidation of I [R = F, R¹ = Ph(HO)CH] with MnO₂ followed by ammonolysis with NH₃-EtOH gave ketone II. Annulation of II with cyclohexanone gave 1,6-naphthyridine III. Lithiation of I (R = F, R¹ = H) at low temperature followed by warming gave 3,4-pyridyne which was trapped by cycloaddition with furan to give adduct IV. In the experiment, the researchers used many compounds, for example, 3-Bromo-4-fluoropyridine (cas: 116922-60-2Product Details of 116922-60-2).

3-Bromo-4-fluoropyridine (cas: 116922-60-2) belongs to pyridine derivatives. Pyridine has a conjugated system of six π electrons that are delocalized over the ring. The molecule is planar and, thus, follows the Hückel criteria for aromatic systems. Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Product Details of 116922-60-2

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Infrared absorption band due to nitrile stretching vibration of cyanopyridine derivatives was written by Tani, Hideo;Fukushima, Kunio. And the article was included in Yakugaku Zasshi in 1961.Electric Literature of C7H6N2 This article mentions the following:

Infrared spectra of NCC₅H₄N derivatives having various substituents were examined The CN stretching absorption of the CN bonded directly to the ring appears at 2239 ± 4 cm.^-1, while that of cyanomethylpyridine derivatives appears at 2257 ± 4 cm.^-1 Introduction of an electron-attracting group into the ring shifts the CN stretching absorption to a higher wave-number region, with marked decrease in its intensity. The absorption band splits into two 2- and 3-NCC₅H₄N(O), appearing, resp., at 2237 and 2245 cm.^-1, and at 2241 and 2249 cm.^-1 The CN stretching absorption in 4-NCC₅H₄N(O) derivatives shifts to a lower wave number than those of 4-NCC₅H₄N derivatives, with marked increase in their intensity. The relation between Hammet’s σ value and wave number, mol. extinction coefficient, and integrated absorption intensity is generally linear. The wave number and intensity of CN stretching absorption in 2-and 4-NCC₅H₄N(O) are markedly different from those of 2- and 4-NCC₅H₄N, indicating that the electron-donating property of the NO bond in 4-NCC₅H₄N(O) is considerable. This is also suggested by the result of nitration of C₅H₅N(O). In the experiment, the researchers used many compounds, for example, 4-Methylpicolinonitrile (cas: 1620-76-4Electric Literature of C7H6N2).

4-Methylpicolinonitrile (cas: 1620-76-4) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds. Halopyridines are particularly attractive synthetic building blocks in a variety of cross-coupling methods, including the Suzuki-Miyaura cross-coupling reaction.Electric Literature of C7H6N2

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Pyridine dicarboxylic-2,4-acid N-oxide synthesis and hydrogen bond was written by Szafran, Miroslaw;Sarbak, Zenon. And the article was included in Roczniki Chemii in 1969.Related Products of 1620-76-4 This article mentions the following:

A solution of 13.8 g. 4-picoline N-oxide in 45 g. MeI was refluxed 2 hrs. to give 30.9 g. N-methoxy-4-picoline iodide (I), m. 90-2° (MeOH). A mixture of 2.4 g. KCN in 12 ml. H2O and 3 g. I was shaken until the whole became clear, kept 2 hrs. and extracted with Et2O to give 0.8 g. 2-cyano-4-picoline (II), m. 89° (anhydrous alc.). When refluxed, 6 hrs., and worked up a solution of 14.5 g. II in 110 ml. concentrated HCl and 150 ml. H2O afforded 6.6 g. 4-methylpicolinic acid (III), m. 139°. A mixture of 6 g. II in 50 ml. AcOH and 35 ml. 30% H2O2 refluxed 5 hrs., concentrated, and worked up twice with water, gave 9.5 g. crude 2-cyano-4-picoline N-oxide (IV), which, refluxed 7 hrs. in 18 ml. concentrated HCl and 28 ml. H2O and worked up, afforded 2.6 g. 4-methylpicolinic acid N-oxide (V), m. 169° (alc.). V was also prepared in 72% yield from III, AcOH, and 30% H2O2 refluxed and worked up as described above for IV. A solution of 5 g. V in 250 ml. H2O and 2.3 g. K2CO3, was bubbled, at 70°, with CO2, treated portionwise with 13.5 g. KMnO4, filtered, acidified with HNO3 to pH 6 and treated with Pb(OAc)2. The precipitate formed was suspended at 90° in 200 ml. H2O, saturated with H2S, and concentrated, to give 2 g. pyridine-2,4-dicarboxylic acid N-oxide (VI), m. 262° (decomposition). Ir spectra of V and VI and their deuterated analogs were examined In the experiment, the researchers used many compounds, for example, 4-Methylpicolinonitrile (cas: 1620-76-4Related Products of 1620-76-4).

4-Methylpicolinonitrile (cas: 1620-76-4) belongs to pyridine derivatives. In contrast to benzene, Pyridine’s electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom. One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Related Products of 1620-76-4

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem