Day: December 7, 2022

Schlesinger, Arthur H. published the artcilePreliminary evaluation of some quaternary ammonium salts as phytoxic agents, Recommanded Product: 1-(Cyanomethyl)pyridin-1-ium chloride, the publication is Journal of Agricultural and Food Chemistry (1959), 33-4, database is CAplus.

cf. C.A. 46, 491f. Some 60 quaternary ammonium salts RR₁R₂R₃NX were prepared by standard chem. methods. Many of these salts exhibited considerable phytotoxicity in seed-germination tests. In a series of 1-substituted pyridinium bromides, maximum phytotoxicity was noticed when R was C₁₂ to C₁₄. Other active types of similar compounds are also mentioned. Lack of selectivity towards mono- or dicotyledeuous species is evident from these examples.

Journal of Agricultural and Food Chemistry published new progress about 17281-59-3. 17281-59-3 belongs to pyridine-derivatives, auxiliary class Pyridine,Nitrile,Salt, name is 1-(Cyanomethyl)pyridin-1-ium chloride, and the molecular formula is C7H7ClN2, Recommanded Product: 1-(Cyanomethyl)pyridin-1-ium chloride.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Hate, Siddhi S. published the artcileA Mechanistic Study of Drug Mass Transport from Supersaturated Solutions Across PAMPA Membranes, Name: Dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, the publication is Journal of Pharmaceutical Sciences (Philadelphia, PA, United States) (2022), 111(1), 102-115, database is CAplus and MEDLINE.

There is an increasing shift from dissolution testing to dissolution-permeation testing of formulations during formulation development and this has led increasing application of permeability measurements using parallel artificial membrane permeability assay (PAMPA) membranes. However, there is a lack of thorough anal. of the impact of variabilities in the PAMPA setup on the mass flow rate outcomes, particularly for complex solubility-enabling formulations. In this study, we investigated the impact of amorphous drug-rich nanodroplets, formed in supersaturated solutions by liquid-liquid phase separation, on membrane transport by measuring mass flow rate across PAMPA membranes. In addition, we explored the impact of PAMPA variants such as lipid composition, hydrophobicity and pore size of the filter support, as well as receiver sink properties on membrane mass flow rates of solutions containing amorphous nanodroplets. Filter properties and lipid composition did not show a notable influence on the mass flow rates for lipophilic mols., while a marked impact was observed for hydrophilic mols. High sink conditions in the receiver compartment, arising from addition of micellar surfactant, altered the membrane integrity for lipid-impregnated hydrophilic membranes. In contrast, no such effect was observed for a hydrophobic filter support. Membrane integrity tests also suggested that monitoring water transport may be an improved approach over using Lucifer yellow. Furthermore, high sink conditions in the receiver compartment resulted in an increase in the overall mass flow rate. This was due to the effect of asym. conditions, generated across the membrane, on mass transport kinetics. Linearity between mass flow rate and donor concentration was observed until the donor concentration reached the amorphous solubility Above the amorphous solubility, a gradual increase in mass flow rate was observed i.e., with an increasing number of nanodroplets in the solution This was attributed to decrease in the permeability barrier across unstirred water layer due to reduction of the concentration gradient as nanodroplets dissolved to replenish absorbed drug. Observations made in this study provide insights into the mechanisms associated with mass transport of supersaturated solutions across PAMPA membranes, which are critical for improved evaluation of enabling formulations.

Journal of Pharmaceutical Sciences (Philadelphia, PA, United States) published new progress about 21829-25-4. 21829-25-4 belongs to pyridine-derivatives, auxiliary class Membrane Transporter/Ion Channel,Calcium Channel, name is Dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, and the molecular formula is C17H18N2O6, Name: Dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Tolmachova, Kateryna A. published the artcile(Chlorosulfonyl)benzenesulfonyl Fluorides-Versatile Building Blocks for Combinatorial Chemistry: Design, Synthesis and Evaluation of a Covalent Inhibitor Library, Recommanded Product: 2-Bromopyridin-3-amine, the publication is ACS Combinatorial Science (2018), 20(11), 672-680, database is CAplus and MEDLINE.

Multigram synthesis of (chlorosulfonyl)benzenesulfonyl fluorides is described. Selective modification of these building blocks at the sulfonyl chloride function under parallel synthesis conditions is achieved. It is shown that the reaction scope includes the use of (hetero)aromatic and electron-poor aliphatic amines (e.g., amino nitriles). Utility of the method is demonstrated by preparation of the sulfonyl fluoride library for potential use as covalent fragments, which is demonstrated by a combination of in silico and in vitro screening against trypsin as a model enzyme. As a result, several inhibitors were identified with activity on par with that of the known inhibitor.

ACS Combinatorial Science published new progress about 39856-58-1. 39856-58-1 belongs to pyridine-derivatives, auxiliary class Pyridine,Bromide,Amine, name is 2-Bromopyridin-3-amine, and the molecular formula is C19H14N2, Recommanded Product: 2-Bromopyridin-3-amine.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Yamashita, Makoto published the artcileA catalytic synthesis of dialkylamines from alkylamines using neopentyl-substituted PNP pincer-iridium complex, Quality Control of 338800-13-8, the publication is Inorganica Chimica Acta (2011), 369(1), 15-18, database is CAplus.

A combination of neopentyl-substituted PNP-iridium complex and NaH could catalyze dimerization of alkylamines to form dialkylamines with the highest activity ever reported. Primary and secondary alkylamines were applicable to the present catalytic reaction. Several mechanistic studies suggested a plausible catalytic cycle. The high activity of catalyst may come from the role of neopentyl groups to make a space around the metal center.

Inorganica Chimica Acta published new progress about 338800-13-8. 338800-13-8 belongs to pyridine-derivatives, auxiliary class Bis-phosphine Ligands, name is 2,6-Bis((di-tert-butylphosphino)methyl)pyridine, and the molecular formula is C15H24BN3O2, Quality Control of 338800-13-8.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Ohmura, Toshimichi published the artcileOrganocatalytic Diboration Involving “Reductive Addition” of a Boron-Boron σ-Bond to 4,4′-Bipyridine, Related Products of pyridine-derivatives, the publication is Journal of the American Chemical Society (2015), 137(8), 2852-2855, database is CAplus and MEDLINE.

A 4,4′-bipyridine-based catalyst system for diboration of pyrazine derivatives was established. The catalyst cycle consists of the following two steps: (1) reductive addition of the boron-boron bond of bis(pinacolato)diboron to 4,4′-bipyridine to form N,N’-diboryl-4,4′-bipyridinylidene and (2) oxidative boryl transfer from the intermediate to pyrazine to give N,N’-diboryl-1,4-dihydropyrazine with regeneration of 4,4′-bipyridine.

Journal of the American Chemical Society published new progress about 1008506-24-8. 1008506-24-8 belongs to pyridine-derivatives, auxiliary class Pyridine,Boronic acid and ester,Ether,Pyridine,Boronic Acids,Boronic acid and ester, name is 3-Methoxypyridine-4-boronic acid, and the molecular formula is C6H8BNO3, Related Products of pyridine-derivatives.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Itabashi, Takayuki published the artcileEffect of substituents on molybdenum triiodide complexes bearing PNP-type pincer ligands toward catalytic nitrogen fixation, Related Products of pyridine-derivatives, the publication is Dalton Transactions (2019), 48(10), 3182-3186, database is CAplus and MEDLINE.

Molybdenum triiodide complexes bearing various substituted pyridine-based PNP-type pincer ligands were prepared and characterized by x-ray anal. Their catalytic activity was studied toward the reduction of nitrogen gas into ammonia under ambient reaction conditions.

Dalton Transactions published new progress about 338800-13-8. 338800-13-8 belongs to pyridine-derivatives, auxiliary class Bis-phosphine Ligands, name is 2,6-Bis((di-tert-butylphosphino)methyl)pyridine, and the molecular formula is C23H43NP2, Related Products of pyridine-derivatives.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Walker, Gordon N. published the artcileApplication of sodium borohydride reduction to synthesis of substituted aminopiperidines, aminopiperazines, aminopyridines, and hydrazines, Safety of 4-Amino-2-picoline, the publication is Journal of Organic Chemistry (1961), 2740-7, database is CAplus.

Quaternization of 4-aminopyridine (I) with alkyl and arylalkyl halides gave 4-aminopyridinium salts, which were reduced with NaBH₄ to 1-(alkyl or arylalkyl)-4-aminopiperidines. Both 1-alkyl-4-aminopiperidines and 1-alkyl-4-aminopiperazines could be converted to Schiff bases, which were reduced with NaBH₄ to the corresponding secondary amines. Similar reduction of appropriate Schiff bases as a means of preparing substituted 3-aminopiperidines, aminopyridines, and aminomethylpyridines, as well as reduction of dialkylhydrazones to the corresponding trisubstituted hydrazines were also described. Anhydrous HBr was passed through a cold solution of 33.6 g. veratryl alc. in 500 mL. C₆H₆ 10 min., the lower layer separated, the C₆H₆ treated with Na₂CO₃, stirred, the solution of veratryl bromide (II) filtered, and used in the following step without purification To the C₆H₆ solution of II was added 19 g. I; the mixture refluxed 1.5 h., filtered, and the product crystallized gave 54 g. 1-(3,4-dimethoxybenzyl)-4-aminopyridinium bromide (IIa), m. 248-50° (decomposition), (alc.). A simple two-step synthesis was used in the preparation of the 1,2-diphenylethyl- and 3,4-dimethoxyphenacyl-substituted compounds The remaining substances were prepared from the com. available bromo (in one case, iodo) compounds by the same procedure with a few modifications in solvents used and reaction times. In reactions involving α,ω-dibromoalkanes, a mixture of the compound, 2 equivalents I, and a suitable amount of PhMe was refluxed. The product often settled as an oil. In this case the supernatant was decanted, and the oil crystallized 2-Methyl-4-aminopyridine (III) was most conveniently synthesized by a 2-step reduction of 4-nitro-2-picoline N-oxide as follows. (A) The oxide (45 g.) in 200 mL. alc. containing 4 g. 10% Pd-C shaken under H at 45 lb./sq. in. gave 33 g. 2-methyl-4-aminopyridine N-oxide (IV), yellow crystals, m. 181-3° (alc.). IV (30 g.) in 300 mL. 1:1 AcOH-H₂O treated with excess Zn dust, the mixture warmed 1 h., cooled, covered with Et₂O, treated with a 40% solution of 500 g. NaOH, and the Et₂O solution evaporated gave 16.8 g. III, m. 95° (cyclohexane). The following (4-H₂NC₅H₄N)RBr were obtained (R, solvent prepared in, reflux time in hrs., % yield, and m.p. given): EtO₂CCH₂, C₆H₆-alc., 1.5, 92, 197°; EtO₂CCH₂CH₂, PhMe, 5, 73, 159°; HOCH₂CH₂, PhMe, 3.5, 80, 131°; PhCH₂, C₆H₆, 0.5, 90, 196°; Ph₂CH, PhMe, 3, 56, 263°; PhCH₂CH₂, PhMe, 2, 77, 260°; PhCH₂CHPh, C₆H₆, 9, 53, 245°; PhOCH₂CH₂, PhMe, 4.5, 75, 184°; BzCH₂, C₆H₆, 2, 96, 308°; 3,4-(MeO)₂C₆H₃COCH₂, C₆H₆-alc., 0.3, 64, 271°; p-O₂NC₆H₄CH₂, PhMe, 5.5, 66, 266°; 2,4-(O₂N)₂C₆H₃, PhMe, 1, 56, 294°. The following [4-H₂NC₅H₄N(CH₂)_nNC₅H₄-4]Br₂ were similarly obtained (n, solvent, reflux time, % yield, and m.p. of product given): 4, PhMe, 2, 87, 273°; 6, PhMe, 14, 91, 303°; 8, PhMe, 5.5, 84, 300°; 9, PhMe, 5, 14, 221°; 10, PhMe, 5, 88, 247°; 11, PhMe, 7.5, 48, 216°; 12, PhMe, 13, 29, 209°; 16, PhMe (prepared from alkyl iodide), 11, 94, 185°. The following [2,4-Me(H₂N)C₅H₄N(CH₂)_nNC₅H₄(NH₂)Me- 4,2]Br₂ were obtained (n, solvent, reflux time in hrs., % yield, and m.p. given): 8, PhMe, 8, 60, 304°; 9, PhMe, 9, 17, 275°. IIa (30 g.) in 700 mL. MeOH treated in 1 h. with 250 g. NaBH₄, the mixture heated on a steam bath, cooled, treated with 500 mL. H₂O, covered with 2 l. Et₂O, the 2 phases treated with anhydrous K₂CO₃ to convert the lower layer to a paste, the Et₂O separated, evaporated, the 20 g. oil dissolved in 30 mL. alc., and treated with dry HCl gave 12.2 g. 1-(3,4-dimethoxybenzyl)-4-aminopiperidine-2HCl, m. 223-5° (decomposition) (MeOH-Et₂O). Other 4-aminopiperidines were obtained from the resp. quaternary salts by the same procedure. The free bases were hygroscopic oils. The amines had to be salted out with NaCl. When 4-aminopiperidines, as free bases, were required for further work, they were used directly in the crude state. 1-Methyl-4-aminopiperidine and 1-(β-hydroxyethyl)-4-aminopiperidine, both formed hygroscopic salts with HCl. The following 4-(N-substituted-amino)piperidine-2HCl were thus obtained (R, % yield, and m.p. given): EtO₂CCH₂, 17, 169°; PhCH₂, 41, 255°; PhCH₂CH₂, 88, 321°; PhCH₂CHPh, 40, 237° (decomposition); PhOCH₂CH₂, 44, 220°; PhCH(OH)CH₂, 90, 248° (decomposition); 3,4-(MeO)₂C₆H₃CH(OH)CH₂, 56, 220° (decomposition); p-O₂NC₆H₄CH₂, 10, 265° (decomposition). The following 4-H₂NC₅H₄N(CH₂)_nNC₅H₄NH₂-4.4HCl were similarly obtained (n, % yield, and m.p. given): 6, 22, 204°; 10, 16, 295°; 12, 34, 311°; 16, 20, 315°. 1,10-Bis(4-amino-1-piperidyl)decane was also characterized by preparation of the bis(dichloroacetate)-2HCl, m. 227-30° (decomposition) (alc.). 1-Methyl-4-aminopiperazine (8.1 g.) and 11.2 g. veratraldehyde in 200 mL. PhMe refluxed 1.5 h., evaporated, the residue dissolved in 150 mL. MeOH, the solution reduced with 40 g. NaBH₄, heated 0.5 h. on the steam bath, and the 20.5 g. yellow oil treated with alc. HCl gave 10 g. 1-methyl-4-(3,4-dimethoxybenzylamine)piperazine, m. 199-202° (decomposition). Other secondary aminopiperidines and aminopiperazines were given in a table. Attempts to reduce imines derived from 1-phenyl-2-propanone and 1-substituted 4-aminopiperidines with NaBH₄ did not lead to desired products, probably because of cleavage of the unstable imines. 3-Aminopyridine (16.8 g.) and 30 g. veratraldehyde in 500 mL. xylene refluxed 24 h. and the 45.5 g. residual oily imine in MeOH reduced with NaBH₄ gave 33 g. 3-(3,4-dimethoxybenzylamino)pyridino (V), m. 123-5° (MeOH). The other pyridines were similarly prepared The following RNHR’ were thus obtained (R, R’, % yield, and m.p. given): 3,4- dimethoxybenzyl, 1-methyl-4-piperidyl, 60, 254-6° (decomposition); 3,4,5-trimethoxybenzyl, 1-methyl-4-piperidyl, 37, 264-5° (decomposition); 3,4-dimethoxybenzyl, 1-(β-hydroxyethyl)-4-piperidyl, 12, 255-6° (decomposition); 4-methoxybenzyl, 1-(3,4-dimethoxybenzyl)-4-piperidyl, 46, 274-5° (decomposition); 3,4,5-trimethoxybenzyl, 1-methyl-4-piperazyl, 56, 135-7°; p-dimethylaminobenzyl, 1-methyl-4-piperazyl, 40, 125-7° (157-60°); 3-pyridylmethyl, 1-methyl-4-piperazyl, 95, 201-2° (220-6° with 0.5H₂O); 1-hydroxy-1-phenyl-2-Pr, 1-methyl-4-piperazyl, 25, 219-21° (decomposition); 3,4-dimethoxybenzyl, 2-pyridyl, 65, 102-3°; 3,4,5-trimethoxybenzyl, 2-pyridyl, 45, 167-8°; p-dimethylaminobenzyl, 2-pyridyl, 52, 125-6°; 3,4,5-trimethoxybenzyl, 3-pyridyl, 63, 109-10°; 3,4,5-trimethoxybenzyl, 3-pyridylmethyl, 90, 205-7°; p-dimethylaminobenzyl, 3-pyridylmethyl, 96, 185-6° (decomposition); 3,4-dimethoxybenzyl, 4-pyridylmethyl, 22, 200° (decomposition); 3,4,5-trimethoxyhenzyl, 4-pyridylmethyl, 43, 214-16°; p-dimethylaminobenzyl, 4-pyridylmethyl, 45, 195-6°; 1-phenyl-2-Pr, 3-pyridylmethyl, 55, 205-7°; 1-phenyl-2-Pr, 4-pyridylmethyl, 80, 181-3°; 3,4,5-trimethoxybenzyl, NMe₂, 45, 81-3; p-dimethylaminobenzyl, NMe₂, 7, 158-61° (decomposition); 1-phenyl-2-Pr, NMe₂, 70, 123-5°; 1,2-diphenylethyl, NMe₂, 23, 183-5°; PhCH:CHCHMe, NMe₂, 5, 117-20° (decomposition). V (14.1 g.) converted rapidly to the MeI salt, evaporated, the crystals suspended in 200 mL. MeOH, reduced with 125 g. NaBH₄, and the residual oil treated with HCl gave 14.6 g. 1-methyl-3-(3,4-dimethoxybenzylamino)piperidine-2HCl, m. 233-5° (decomposition). 3-Aminopiperidine (7.6 g.), 12.7 g. veratraldehyde, and 250 mL. PhMe refluxed 3.5 h., the crude imine reduced with NaBH₄ in alc., and crystallized gave 20.6 g. V.2HCl, m. 229-31° (alc.). Reduction of p-dimethylaminobenzylidene derivative and isolation gave 76% 3-(4-dimethylaminobenzylamino)piperidine, no definite m.p. 3-(3-Pyridylmethylamino)piperidine was obtained in 79% yield by reduction of the 3-pyridylidene derivative and isolated as the tri-HCl salt. Veratraldehyde (16.3 g.) and 6.5 g. N,N-dimethylhydrazine mixed, the oil taken up in 200 mL. C₆H₆, the solution refluxed 4 h., evaporated, and the hydrazone reduced in MeOH with NaBH₄ gave 13.9 g. N,N-dimethyl-N-(3,4-dimethoxybenzyl)hydrazine-HCl, m. 172-4.5°. The other hydrazine derivatives above were prepared by the same method.

Journal of Organic Chemistry published new progress about 18437-58-6. 18437-58-6 belongs to pyridine-derivatives, auxiliary class Pyridine,Amine, name is 4-Amino-2-picoline, and the molecular formula is C12H9NO, Safety of 4-Amino-2-picoline.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Laserna, J. J. published the artcileKinetic determination of cobalt by complexation with pyridine-2-aldehyde 2-pyridylhydrazone and ligand oxidation with bromate, Category: pyridine-derivatives, the publication is Mikrochimica Acta (1985), 2(5-6), 457-67, database is CAplus.

Optimum conditions are outlined for the kinetic determination of Co. The rate of disappearance of pyridine-2-aldehyde 2-pyridylhydrazone (PAPH) in acidic medium is monitored spectrophotometrically at 372 nm. The method is based on the modification of the oxidation rate by complexation of PAPH with Co ions. The detection limit was 0.25 μg/mL. Beer’s law was obeyed for 0.40-1.50 μg/mL.

Mikrochimica Acta published new progress about 2215-33-0. 2215-33-0 belongs to pyridine-derivatives, auxiliary class Pyridine,Amine, name is 2-((2-(Pyridin-2-yl)hydrazono)methyl)pyridine, and the molecular formula is C11H10N4, Category: pyridine-derivatives.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Hidalgo, M. published the artcileSurface-enhanced resonance Raman spectroscopy of 2-pyridylhydrazone and 1,10-phenanthroline chelate complexes with metal ions on colloidal silver, Name: 2-((2-(Pyridin-2-yl)hydrazono)methyl)pyridine, the publication is Analytica Chimica Acta (1996), 318(2), 229-37, database is CAplus.

Surface-enhanced resonance Raman spectra (SERRS) of the complexes PAPH-Co(II), PAPH-Ni(II), PAPH-Fe(II), and PHEN-Fe(II) (PAPH = 2-pyridine carboxyaldehyde 2-pyridylhydrazone and PHEN = 1,10-phenanthroline) adsorbed on silver colloid have been studied. Differences among SERS spectra of ligands and SERRS spectra of complexes have been investigated. Ultra-sensitive methods for metal determination with limits of detection at the ng mL^-1 level are presented.

Analytica Chimica Acta published new progress about 2215-33-0. 2215-33-0 belongs to pyridine-derivatives, auxiliary class Pyridine,Amine, name is 2-((2-(Pyridin-2-yl)hydrazono)methyl)pyridine, and the molecular formula is C11H10N4, Name: 2-((2-(Pyridin-2-yl)hydrazono)methyl)pyridine.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Iribarren, Inigo published the artcileCations brought together by hydrogen bonds: the protonated pyridine-boronic acid dimer explained, Name: 2-Pyridinylboronic acid, the publication is Physical Chemistry Chemical Physics (2019), 21(10), 5796-5802, database is CAplus and MEDLINE.

According to the Cambridge Structural Database, protonated pyridine-boronic acid dimers exist in the solid phase, apparently defying repulsive coulombic forces. In order to understand why these cation-cation systems are stable, we carried out M06-2X/6-311++G(3df,2pd) electronic structure calculations and used a set of computational tools (energy partitioning, topol. of the electron d. and elec. field maps). The behavior of the charged dimers was compared with the corresponding neutral systems, and the effect of counterions (Br^– and BF₄^–) and the solvent (PCM model) on the binding energies has been considered. In the gas-phase, the charged dimers present pos. binding energies but are local min., with a barrier (16-19 kJ mol^-1) preventing dissociation Once the environment is included via solvent effects or counterions, the binding energies become neg.; remarkably, the strength of the interaction is very similar in both neutral and charged systems when a polar solvent is considered. Essentially, all methods used evidence that the intermol. region where the HBs take place is very similar for both neutral and charged dimers. The energy partitioning explains that repulsion and electrostatic terms are compensated by the desolvation and exchange terms in polar solvents, thus giving stability to the charged dimer.

Physical Chemistry Chemical Physics published new progress about 197958-29-5. 197958-29-5 belongs to pyridine-derivatives, auxiliary class Pyridine,Boronic acid and ester, name is 2-Pyridinylboronic acid, and the molecular formula is C5H6BNO2, Name: 2-Pyridinylboronic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem