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The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《5-Chloro- and 5,6-dichloronicotinic acids》. Authors are Graf, Roderich; Lederer-Ponzer, Ernst; Kopetz, Viktor; Purkert, Renato; Laszlo, Paul.The article about the compound:5-Hydroxynicotinic acidcas:27828-71-3,SMILESS:O=C(O)C1=CN=CC(O)=C1).Recommanded Product: 5-Hydroxynicotinic acid. Through the article, more information about this compound (cas:27828-71-3) is conveyed.

Nicotinic acid HCl salt (100 g.) and 180 g. SOCl2, gently boiled 5 days and then heated in tubes 12 hrs. at 180°, give 50-60% of a mixture of the 5-Cl and 5,6-di-Cl derivatives (I), in about equal amounts; more SOCl2 increases the proportion of the di-Cl acid. 5-Aminopyridine-3-carboxylic acid (II), m. 288-90° (decomposition). II through the diazo reaction gives the 5-Br derivative, m. 182-3°; chloride, m. 74-5°; Me ester, m. 98-9°; Ph ester, m. 86-7°. The chloride and N2H4.H2O in C6H6 give sym-bis(5-bromo-3-pyridoyl)hydrazine, m. 308° (decomposition). The Me ester gives 5-bromopyridine-3-carbonyl hydrazide, m. 193-4° (benzal derivative, m. 191-3°); the azide m. 88-9° (decomposition) and with absolute EtOH gives 5-bromo-3-carbethoxyaminopyridine, m. 150-1°; Me ester, m. 169-70°; heating the Et ester with 30% NaOH gives 5-bromo-3-aminopyridine (III), b12 149-50°, m. 66-7°; the intermediate Na 5-bromo-3-pyridylcarbamate was also analyzed; Ac derivative of III, m. 127-8° (dihydrate, m. 76-8°); picrate of III, deep yellow, m. 212-3°; chloroaurate, red-orange, m. 185-7°. 5-Iodopyridine-3-carboxylic acid, m. 220°; Ph ester, m. 100-1° Me ester, m. 121°; Et ester, m. 86-7°; amide, m. 221-2°. 5-Hydroxypyridine-3-carboxylic acid, m. 299° (decomposition). The Et ester of I and N2H4.H2O give Et 5-chloro-6-hydrazinopyridine-3-carboxylate (IV), m. 137-8°; the hydrazide, gray, m. 238-40°; the free acid m. 248-9° and was also obtained directly from I. IV on diazotizing yields Et 5-chlorobenzotetrazole-3-carboxylate, m. 95-6°; the free acid m. 195-6°; heating with HCO2H gives 5-chlorobenzotriazole-3-carboxylic acid, m. above 300°. I and concentrated NH4OH at 180-90° give 6-amino-5-chloropyridine-3-carboxylic acid, m. 323° (decomposition); Me ester, m. 163-5°; the Me ester of the 6-HO derivative m. 218°.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

Most of the natural products isolated at present are heterocyclic compounds, so heterocyclic compounds occupy an important position in the research of organic chemistry. A compound: 7651-82-3, is researched, SMILESS is OC1=CC2=C(C=NC=C2)C=C1, Molecular C9H7NOJournal, Article, Research Support, Non-U.S. Gov’t, Angewandte Chemie, International Edition called RadH: A Versatile Halogenase for Integration into Synthetic Pathways, Author is Menon, Binuraj R. K.; Brandenburger, Eileen; Sharif, Humera H.; Klemstein, Ulrike; Shepherd, Sarah A.; Greaney, Michael F.; Micklefield, Jason, the main research direction is RadH halogenase halogenation; biocatalysis; directed evolution; enzyme mechanisms; halogenases; pathway engineering.Product Details of 7651-82-3.

Flavin-dependent halogenases are useful enzymes for providing halogenated mols. with improved biol. activity, or intermediates for synthetic derivatization. We demonstrate how the fungal halogenase RadH can be used to regioselectively halogenate a range of bioactive aromatic scaffolds. Site-directed mutagenesis of RadH was used to identify catalytic residues and provide insight into the mechanism of fungal halogenases. A high-throughput fluorescence screen was also developed, which enabled a RadH mutant to be evolved with improved properties. Finally we demonstrate how biosynthetic genes from fungi, bacteria, and plants can be combined to encode a new pathway to generate a novel chlorinated coumarin “”non-natural”” product in E. coli.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Nicotinic Acid Adenine Dinucleotide Phosphate Analogues Substituted on the Nicotinic Acid and Adenine Ribosides. Effects on Receptor Mediated Ca2+ Release》. Authors are Trabbic, Christopher J.; Zhang, Fan; Walseth, Timothy F.; Slama, James T..The article about the compound:5-Hydroxynicotinic acidcas:27828-71-3,SMILESS:O=C(O)C1=CN=CC(O)=C1).COA of Formula: C6H5NO3. Through the article, more information about this compound (cas:27828-71-3) is conveyed.

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca2+ releasing intracellular second messenger in both mammals and echinoderms. The authors report that large functionalized substituents introduced at the nicotinic acid 5-position are recognized by the sea urchin receptor, albeit with a 20-500-fold loss in agonist potency. 5-(3-Azidopropyl)-NAADP was shown to release Ca2+ with an EC50 of 31 μM and to compete with NAADP for receptor binding with an IC50 of 56 nM. Attachment of charged groups to the nicotinic acid of NAADP is associated with loss of activity, suggesting that the nicotinate riboside moiety is recognized as a neutral zwitterion. Substituents (Br and N3) can be introduced at the 8-adenosyl position of NAADP while preserving high potency and agonist efficacy and an NAADP derivative substituted at both the 5-position of the nicotinic acid and at the 8-adenosyl position was also recognized although the agonist potency was significantly reduced.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《The tautomerism of N-heteroaromatic hydroxy compounds. I. Infrared spectra》. Authors are Mason, S. F..The article about the compound:Isoquinolin-6-olcas:7651-82-3,SMILESS:OC1=CC2=C(C=NC=C2)C=C1).Recommanded Product: Isoquinolin-6-ol. Through the article, more information about this compound (cas:7651-82-3) is conveyed.

cf. Gibson, et al., C.A. 50, 3899h. The IR spectra of 37 N-heterocyclic hydroxy compounds have been measured in the O-H, N-H, and double-bond stretching-vibration regions by use of a Perkin-Elmer model 12C spectrometer with a LiF or NaCl prism. The compounds were examined at concentrations of 10-2 to 10-3M in cells of 5 cm. (CCl4) or 1 cm. (CHCl3) thickness in the O-H and N-H regions, and 1 mm. in the double-bond region, and as solids included in pressed KBr disks. The compounds with a OH group α or γ to a ring-N atom absorb in the N-H and C:O stretching vibration regions both in the solid state and in CHCl3 solution, and so possess principally amide structures under these conditions. The remaining compounds have mainly enolic structures in solution, showing absorption due to a free or an intramolecularly H-bonded O-H group. The IR evidence for the zwitterionic structure of the latter group of compounds in the solid state is discussed. The compounds which tautomerize to an amide with a quasi ο-quinonoid structure show an N-H stretching vibration absorption in the range 3360-3420 cm.-1, while their quasi p-quinonoid isomers absorb in the range 3415-45 cm.-1, and their analogs with 5-membered rings in the range 3440-85 cm.-1 The position of the C:O band of such compounds depends upon the structural type and the number of N atoms in the ring carrying the potentially tautomeric OH group. For nuclei similarly substituted, the C:O band of the quasiο-quinonoid amides lies at a higher frequency than that of the quasi p-quinonoid isomers. The structures of some dihydroxy and polyaza compounds are elucidated by means of these correlations.

There is still a lot of research devoted to this compound(SMILES：OC1=CC2=C(C=NC=C2)C=C1)Recommanded Product: Isoquinolin-6-ol, and with the development of science, more effects of this compound(7651-82-3) can be discovered.

Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

Epoxy compounds usually have stronger nucleophilic ability, because the alkyl group on the oxygen atom makes the bond angle smaller, which makes the lone pair of electrons react more dissimilarly with the electron-deficient system. Compound: 5-Hydroxynicotinic acid, is researched, Molecular C6H5NO3, CAS is 27828-71-3, about NMR study of acid-base reactions of 3-hydroxypyridine, 3-hydroxypyridine N-oxide, and β-hydroxypyridinecarboxylic acids.Quality Control of 5-Hydroxynicotinic acid.

An NMR method was used to determine the protonation and ionization constants of 3-hydroxypyridine (I) and its N-oxide (II); 5-hydroxynicotinic acid, 3-hydroxyisonicotinic acid (III), and their Et esters; and 5-hydroxypicolinic acid. Introduction of the CO2H group at different positions of the β-hydroxypyridine ring generally had a deshielding effect on the ring protons. The ionization of the CO2H group in nicotinic and picolinic acid was not appreciably affected by introduction of the OH group. Ionization of III was hindered by intramol. H bonding between the OH and CO2H groups. The acidity of II was much greater than that of I.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: 5-Hydroxynicotinic acid( cas:27828-71-3 ) is researched.Reference of 5-Hydroxynicotinic acid.Deady, L. W.; Shanks, R. A.; Campbell, Arthur Derek; Chooi, S. Y. published the article 《Synthesis of some substituted methyl pyridinecarboxylates. II. Methyl 4-substituted picolinates, methyl 5-substituted picolinates, and methyl 5-substituted nicotinates》 about this compound( cas:27828-71-3 ) in Australian Journal of Chemistry. Keywords: nicotinates picolinates pyridines; picolinates pyridines nicotinates; pyridines picolinates nicotinates; amino pyridines; bromo pyridines; picoline oxide. Let’s learn more about this compound (cas:27828-71-3).

The preparation of substituted Me pyridinecarboxylates is described. Me 4-X-substituted picolinates and methyl 5-X-substituted picolinates (X = NO2, Br, MeO, Me2N) are prepared from 2-picoline via 4-nitro-2-picoline N-oxide and 2-amino-5-nitropyridine, resp. Me 5-X-substituted nicotinates (X = Br, MeO, Me2N) are prepared from 5-bromonicotinic acid. Preparations of Me 4-methylpicolinate and Me 5-methylnicotinate from the corresponding lutidines and Me 5-methylpicolinate from 2-amino-5-methylpyridine are described.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

Alvarez, M.; Joule, J. A. published the article 《Product class 5: isoquinolines》. Keywords: review isoquinoline preparation; isoquinoline oxide preparation review; isoquinolinium salt preparation review.They researched the compound: Isoquinolin-6-ol( cas:7651-82-3 ).HPLC of Formula: 7651-82-3. Aromatic heterocyclic compounds can be divided into two categories: single heterocyclic and fused heterocyclic. In addition, there is a lot of other information about this compound (cas:7651-82-3) here.

A review primarily covering methods of preparation of isoquinolines via cyclization, ring transformations or substituent modification. Isoquinoline 2-oxides and isoquinolinium salts are also included.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

Epoxy compounds usually have stronger nucleophilic ability, because the alkyl group on the oxygen atom makes the bond angle smaller, which makes the lone pair of electrons react more dissimilarly with the electron-deficient system. Compound: 5-Hydroxynicotinic acid, is researched, Molecular C6H5NO3, CAS is 27828-71-3, about Six-Coordinate Lanthanide Complexes: Slow Relaxation of Magnetization in the Dysprosium(III) Complex.Formula: C6H5NO3.

A series of six-coordinate lanthanide complexes {(H3O)[Ln(NA)2]·H2O}n (H2NA = 5-hydroxynicotinic acid; Ln = GdIII (1·Gd); TbIII (2·Tb); DyIII (3·Dy); HoIII (4·Ho)) have been synthesized from aqueous solution and fully characterized. Slow relaxation of the magnetization was observed in 3·Dy. To suppress the quantum tunneling of the magnetization, 3·Dy diluted by diamagnetic YIII ions was also synthesized and magnetically studied. Interesting butterfly-like hysteresis loops and an enhanced energy barrier for the slow relaxation of magnetization were observed in diluted 3·Dy. The energy barrier (Δτ) and pre-exponential factor (τ0) of the diluted 3·Dy are 75 K and 4.21 × 10-5 s, resp. This work illustrates a successful way to obtain low-coordination-number lanthanide complexes by a framework approach to show single-ion-magnet-like behavior.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: 5-Hydroxynicotinic acid( cas:27828-71-3 ) is researched.HPLC of Formula: 27828-71-3.Liu, Yongjuan; Yu, Haijing; Zhao, Lingzhou; Zhang, Huabei published the article 《Design and synthesis of new agents for neuronal nicotinic acetylcholine receptor (nAChRs) imaging》 about this compound( cas:27828-71-3 ) in Nuclear Medicine and Biology. Keywords: iodine 125 radiotracer single photon emission computed tomog nAChR. Let’s learn more about this compound (cas:27828-71-3).

The most abundant subtype of cerebral nicotinic acetylcholine receptors (nAChR), α4β2, plays a critical role in various brain functions and pathol. states. Due to rapid technol. progress in chem., bioinformatics, structural biol. and computer technol., computer aided drug design (CADD) plays a more and more important role in today’s drug discovery. Two novel 3-pyridyl ether nicotinic ligands-3-((pyridine-2-yl)methoxy)-5-iodopyridine, and 3-(((S)-pyrrolidin-2-yl)methoxy)-5-((4-iodobenzyloxy)-methyl)pyridine were designed and synthesized and radiolabeled with I-125 based on our 3D-QSAR models reported previously. Their ability to label high-affinity brain nicotinic acetylcholine receptors (nAChRs) was evaluated.[125I]3-((pyridin-2-yl)methoxy)-5-iodopyridine shows rapid accumulation and elimination with peak (1.86%ID/g) at 5 min post injection, but has high blood uptake. [125I]3-(((S)-pyrrolidin-2-yl)methoxy)-5-((4-iodobenzyloxy)methyl)pyridine entered the brain with maximal uptake value 3.01%ID/g at 15 min after injection, and showed approx. 27% inhibition of radioactivity uptake in thalamus in mice pretreated with nicotine.The results of this preliminary study show that [125I]3-(((S)-pyrrolidin-2-yl)methoxy)-5-((4-iodobenzyloxy)methyl)pyridine shows relatively high uptake to the brain, however, since the in vivo selectivity for α4β2 nAChRs was not enough, [125I]3-(((S)-pyrrolidin-2-yl)methoxy)-5-((4-iodobenzyloxy)methyl)pyridine does not have the required properties for imaging nAChRs using SPECT. Structure optimization is needed for specific visualization of brain α4β2 nAChRs in vivo.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method

Most of the compounds have physiologically active properties, and their biological properties are often attributed to the heteroatoms contained in their molecules, and most of these heteroatoms also appear in cyclic structures. A Journal, Journal of the American Chemical Society called Effect of structure on kinetics and mechanism of the alkaline hydrolysis of anilides, Author is Biechler, Sydney S.; Taft, Robert W. Jr., which mentions a compound: 22426-30-8, SMILESS is CC(C)(C#N)C(O)=O, Molecular C5H7NO2, Recommanded Product: 2-Cyano-2-methylpropanoic acid.

The rates of the aqueous alk. hydrolysis of CF3CONHPh (I) and a series of N-methylanilides, RCONMePh (II), were determined at 2.55° spectrophotometrically. I (3.5 g.) in 60 cc. dry Me2CO treated with 3.7 g. powd. KOH and 1.7 cc. MeI in 10 cc. dry Me2CO, refluxed 0.5 hr., and filtered, the filtrate evaporated, the residual oil diluted with H2O and extracted with Et2O, and the extract worked up gave MePhNCOCF3, m. 25-6°. PhNHMe, 6.4 g. HCO2H, and 20 cc. PhMe refluxed with the azeotropic removal of H2O and distilled gave MePhNCHO, b15 130°, n25D 1.552. PhNH2 (5 g.), a pinch of powd. KOH, and 4 g. CHF2CO2Et refluxed 2 days gave PhNHCOCHF2, m. 58° (aqueous EtOH). PhOCH2COCl (5 g.) in 25 cc. dry Et2O treated dropwise with MeNHPh until the reaction ceased and filtered, and the filtrate washed and worked up gave PhOCH2CONMePh, m. 92-3° (aqueous EtOH). In the same manner was prepared ClCH2CONMePh (III), m. 68-9° (aqueous EtOH). III (7.7 g.) and 10 cc. Me3N heated 3 hrs. in 20 cc. absolute EtOH and the resulting viscous liquid dried over refluxing xylene in a drying pistol gave betaine-N-methylanilide, hygroscopic solid. NCCH2CO2Et (20 g.) added to 10 g. Na in 100 g. absolute EtOH, the mixture treated with cooling with 50 cc. MeI in 20 cc. EtOH, refluxed 4 hrs., and evaporated, the residue diluted with H2O and extracted with Et2O, and the extract worked up gave NCCMe2CO2Et, b15 75°, n25D 1.4098; the ester saponified, the acid, m. 54-5°, converted to the acid chloride, b13 58°, and this dissolved in Et2O and treated dropwise with PhNHMe gave Me2C(CN)CONMePh, m. 55-6° (aqueous EtOH). I (0.328 g.) and 0.679M NaOH in aqueous dioxane kept 2 days and extracted with Et2O, and the extract dried and treated with dry HCl yielded 54.4% PhNH2.HCl; the aqueous layer treated with 10 cc. concentrated HCl and extracted with Et2O, the Et2O removed at 33°, and the residue titrated with NaOH showed 59.6% recovery of CF3CO2H. The rate constants, k1 × 103 min.-1 for the alk. hydrolysis of I in 50% aqueous dioxane at a constant ionic strength (0.500M) and in H2O at 25°, were determined at various concentrations of hydroxyl ion (M concentration of OH- given); the hydrolysis proceeded by 1st-order kinetics, and proceeded by the rate law k1 = k2(OH-)/1 + (OH-)K. The rate constants, k1 min.-1, for the II (R = CF3, CHF2, CH2Cl, CH2N+Me3, CMe2CN, CH2OPh, H) were determined in H2O at 25.5° in the presence and absence of Na2SO4 at varying hydroxyl ion and added salt concentrations The rate law followed by the II is k1 = k2(OH-) + k3(OH-)2. The ratio k3/k2 for the hydrolysis in H2O at 25.5° and an ionic strength of 0.6M was determined for the various II (R and ratio given): CF3 190, CHF2 34, CMe2CN 0.5, CH2OPh 0.7, H 3.4, CH2Cl 2.0, CH2N+Me3 5.6. The mechanism of the hydrolysis of I and II is discussed and correlated with the exptl. data.

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Reference:
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method