This compound belongs to the class of organic compounds known as pyridinium derivatives. These are compounds containing a pyridinium ring, which is the cationic form of pyridine.
External Descriptors
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1. Djoumbou Feunang Y, Eisner R, Knox C, Chepelev L, Hastings J, Owen G, Fahy E, Steinbeck C, Subramanian S, Bolton E, Greiner R, and Wishart DS. ClassyFire: Automated Chemical Classification With A Comprehensive, Computable Taxonomy. Journal of Cheminformatics, 2016, 8:61.
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Recensioni
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Application Protocols
No vendor-validated bioassay protocols (WB, IHC, IF, FC) apply to this small-molecule reagent. For synthetic or analytical use, consider the following general, non-validated workflow outlines:
Cross-coupling screening (general):
Set up under inert atmosphere. Charge aryl boronic acid (1.5 equiv), base (3 equiv), catalyst/ligand (1 mol% Pd, 2 mol% ligand), and 3-chloropyridine N‑oxide (1.0 equiv) in toluene/H2O (or MeCN). Heat 80–100 °C, monitor by LC/MS. Work up with aqueous quench and extract; purify by chromatography with basic modifiers as needed.
N–O reduction (general):
Cool dry CH2Cl2 to 0 °C, add PCl3 dropwise to a solution of the N‑oxide. Stir to completion (TLC/LC). Quench cautiously, neutralize, and isolate 3‑chloropyridine. Alternatively, employ Zn/AcOH at reflux for metal-mediated reduction.
These outlines are illustrative only. Optimize and validate for your specific substrate set, scale, and equipment. Always consult the primary literature and your organization’s SOPs before execution.
Biological Roles
This product is intended strictly for research use; no clinical or diagnostic use is implied.
General biochemistry perspective (literature):
Pyridine N‑oxides are often encountered as metabolic oxidation products of pyridines in biological systems and can modulate polarity, solubility, and transport compared to the parent heteroarene.
The N‑oxide function acts as a strong hydrogen-bond acceptor and can coordinate metal centers, influencing enzyme inhibition/activation studies or metalloprotein binding models in vitro.
The 3-chloro substituent is a common handle in medicinal chemistry for structure–activity relationship (SAR) exploration via cross-coupling diversification (e.g., installing aryl/alkyl/amine fragments after deoxygenation or directly when compatible).
As a heteroaromatic scaffold, substituted pyridine N‑oxides can serve as reference compounds or probes in physicochemical property studies (pKa shifts, logD modulation, permeability) without implying any therapeutic role.
Caveat: Any statements here are general and literature-based. Specific biological behavior of 3-chloropyridine N‑oxide (binding, metabolism, transport) should be established empirically for your system and is not specified for this catalog item.
Buffer Applications
Not typically applicable. 3-Chloropyridine N-oxide is a heteroaromatic building block rather than a buffering agent. It does not form a standard conjugate acid/base pair used for biological or analytical buffers with defined pKa ranges.
For experiments requiring controlled pH, select an appropriate buffer system (e.g., phosphate, HEPES, MOPS) compatible with your reaction or assay matrix, and consider the compound’s stability in that buffer if it will be present during the procedure.
Green Alternatives
Although this product is a solid reagent rather than a solvent, greener chemistry considerations apply to its use in synthesis.
Role of N‑oxides in greener strategies (literature perspective):
Temporary directing group: Using the built-in N‑oxide to direct C–H activation can avoid installing/removing external directing auxiliaries, reducing steps and waste.
Milder oxidant footprint: Some transformations leverage N‑oxide functionality to obviate stoichiometric external oxidants in specific catalytic cycles.
Solvent choices for reactions using this reagent:
Prefer greener polar aprotics where feasible (MeCN, 2-MeTHF, CPME, dimethyl carbonate) over high-toxicity solvents (DMF, NMP). Water/ethanol co-solvent systems may work for certain cross-couplings with appropriate catalysts.
Coupling chemistry sustainability:
Use ligand/catalyst systems active for aryl chlorides to avoid converting to bromides/iodides (reduces halogen waste and upstream E-factor).
Heterogeneous catalysts (e.g., Pd/C under flow) or low-Pd systems can reduce metal usage; consider catalyst recovery.
Comparison snapshot (general):
DMF/NMP: strong solvating power but reproductive-tox concerns; replace with MeCN, 2-MeTHF, or propylene carbonate when compatible.
Toluene/dioxane: effective for C–Cl activation; CPME or cyclohexyl methyl ether may offer lower peroxide tendency and better safety (still verify for your route).
Balance green choices with performance and safety. Validate any substitution by small-scale trials and analytical comparability.
Pharmaceutical Uses
No therapeutic or clinical applications are claimed. For research use only.
General formulation/manufacturing context (literature):
Intermediate/Building block: 3-Chloropyridine N-oxide can serve as a masked, polarity-enhanced analog of 3-chloropyridine in medicinal chemistry routes. The N‑oxide can facilitate late-stage C–H functionalization or change solubility profiles during purification, then be deoxygenated to the pyridine.
Impurity/Metabolite reference: Pyridine N‑oxides may arise as oxidative impurities or metabolites; standards can support analytical method development, stress testing, and impurity profiling.
Salt formation: Protonated N‑oxide salts (e.g., with mineral or organic acids) can be prepared for crystallization studies or property tuning in preformulation experiments, without implying use in human/animal dosing.
Regulatory note: If used in a regulated setting, obtain full characterization and impurity data from the CoA/Spec Sheet and qualify suppliers under your quality system. There is no pharmacopeial monograph specific to this compound to our knowledge; compendial status is not specified for this item.
Physical Properties
Item-specific specs
Appearance: Not specified for this item; refer to CoA/Spec Sheet.
Storage/Shipping (from Product Data)
Storage: 2–8 °C, argon charged (inert atmosphere)
Shipped: on wet ice
Literature/General physical data (reference only; not item-specific)
Molecular formula: C5H4ClNO (literature)
Molecular weight: ~129.55 g/mol (literature)
Physical state: many pyridine N-oxides are low-melting solids or viscous liquids; exact MP/BP for 3-chloropyridine N-oxide is not specified here.
Polarity: significantly more polar than the parent chloropyridine due to the N‑oxide; capable of strong dipolar interactions and hydrogen-bond acceptance via the N–O group.
Solubility (qualitative, literature insight): N‑oxides often show good solubility in polar organic solvents (e.g., MeOH, EtOH, MeCN, DMF, DMSO) and variable solubility in water depending on substitution; specific solubility values for this compound are not provided here.
pKa/logP: Not specified for this item; refer to literature or computational estimates as needed for method development.
Refractive index/density/UV cutoff: Not specified for this item; refer to CoA/Spec Sheet.
Practical note: Because N‑oxides are hygroscopic in some cases and can engage in strong hydrogen bonding, drying prior to moisture-sensitive transformations may be beneficial. Verify actual properties for this item on the CoA before process scale-up.
Quality and Grades
Item-specific grade/purity
Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
How to interpret grades (general guidance)
Research/technical grade: Suitable for most synthetic and exploratory R&D work. Impurity profiles (e.g., residual solvents, inorganic salts) are controlled but not necessarily at trace-analytical levels.
Analytical/HPLC grade (if offered): Tailored for low UV background and minimal non-volatile residue, beneficial for chromatography or analytical reference use.
High-purity/selective grades (if offered): May feature tighter specs on related pyridine impurities, water content (KF), and halide content, which are important for moisture- or base-sensitive cross-couplings.
Stabilizers and additives
Stabilizer: Not specified for this item; refer to CoA/Spec Sheet. Many N-oxides are stable without added stabilizers; however, an inert gas headspace (argon) is provided for this item per Product Data.
What to check on the CoA for this compound type
Identity confirmation: 1H/13C NMR, HRMS, and IR bands characteristic of N→O stretching (~1260–1310 cm⁻¹; literature) and aryl C–Cl stretches.
Purity metrics: HPLC/GC area %, residual solvents, and water by KF (if reported).
Inorganic residues: halides/metals if the route involved chlorination or metal-catalyzed steps.
Always use the lot-specific CoA/Spec Sheet for definitive specifications in regulated or validated workflows.
Reaction and Applications
3-Chloropyridine N-oxide is a versatile heteroaromatic building block. The N‑oxide functionality profoundly alters ring electronics, enabling transformations that are difficult on the parent pyridine.
Key application families (literature):
Directed C–H Functionalization: The N‑oxide serves as an intrinsic directing group, enabling ortho (C2) activation under Pd, Rh, or Ru catalysis. Subsequent removal of the N‑oxide regenerates the pyridine framework after installation of the desired substituent.
Cross-Coupling at C–Cl: The aryl chloride supports Suzuki–Miyaura, Negishi, Kumada, and Buchwald–Hartwig (amine coupling) reactions. The N‑oxide can modulate oxidative addition rates and regioselectivity; ligand choice (e.g., dialkylbiaryl phosphines) helps activate the C–Cl bond.
N–O Bond Transformations: Reduction to 3-chloropyridine via PCl3, Zn/AcOH, TiCl3, or PPh3-based systems; or activation with acylating agents (Ac2O) to trigger rearrangements (e.g., Boekelheide), furnishing 2‑functionalized pyridines after hydrolysis.
SNAr Pathways: The electron-withdrawing influence of the N‑oxide can facilitate nucleophilic aromatic substitution at activated ring positions under strong nucleophiles/bases; site-selectivity depends on substitution pattern and reaction conditions.
Oxidation/oxygen-transfer chemistry: While not a strong oxidant per se, activated N‑oxides can participate in oxygen delivery or serve as internal oxidants in tailored sequences.
Practical tips:
If the N‑oxide is used as a temporary directing group, plan a mild deoxygenation step at the end of the sequence to avoid damaging newly installed functionalities.
For couplings, pre-screen ligands optimized for aryl chlorides; dry, degassed solvents and rigorous exclusion of water/air improve performance.
Monitor for potential N‑oxide coordination to catalysts, which can be beneficial or inhibitory; additives (e.g., halide salts) or ligand tuning can mitigate issues.
Reaction Conditions
Generalized conditions from literature for transformations of pyridine N‑oxides and aryl chlorides (illustrative; optimize for your system):
Suzuki–Miyaura coupling at C–Cl:
Catalyst/ligand: Pd2(dba)3 (0.5–1 mol% Pd) with SPhos/XPhos (1–2 mol%).
Base: K3PO4 or K2CO3 (2–3 equiv).
Solvent: Toluene/H2O, 1,4-dioxane, MeCN, or CPME; 60–100 °C.
Notes: Degas solvents; monitor for potential coordination of the N‑oxide—ligand choice can offset deactivation.
Buchwald–Hartwig amination:
Catalyst: Pd(OAc)2 (1–2 mol%) with BrettPhos or RuPhos; NaOtBu or Cs2CO3 base.
Solvent: Toluene, dioxane, or tAmOH; 80–110 °C.
Notes: Strong bases can be compatible, but verify N‑oxide stability under conditions.
Directed C2-arylation/alkenylation via N‑oxide:
Catalyst: Pd(OAc)2 (5–10 mol%) with ancillary ligand (e.g., pyridone ligands) and Ag(I) or Cu(II) salts as oxidants.
Solvent/Temp: MeCN, DCE, or AcOH; 50–100 °C.
Notes: The N‑oxide chelates to the metal enabling ortho activation; subsequent deoxygenation restores pyridine.
N–O reduction to 3-chloropyridine:
Reagents: PCl3 (or PBr3) in CH2Cl2 at 0–25 °C; or Zn/AcOH at rt–reflux; or PPh3 with acylating agent (Staudinger-type).
Notes: Choose conditions compatible with other functionalities introduced.
Boekelheide rearrangement (N‑oxide acylation):
Reagents: Ac2O (excess) ± catalytic acid.
Solvent/Temp: Neat or in anhydrous aprotic solvent; 25–80 °C.
Outcome: 2‑acyloxypyridine derivatives after rearrangement; hydrolysis affords 2‑hydroxymethyl products.
These are representative conditions from literature; adjust scale, stoichiometry, and temperature based on pilot experiments.
Safety and Handling
GHS and hazard details (item-specific)
Signal word: Not specified for this item; refer to SDS.
Hazard statements (H-phrases): Not specified for this item; refer to SDS.
GHS classification and pictograms: Not specified for this item; refer to SDS.
General safety guidance (professional laboratory practice; defer to SDS as authoritative)
Likely hazards: Aromatic N-oxides and chloropyridines may cause irritation to skin, eyes, and respiratory tract upon contact or inhalation. Avoid dust or aerosol formation.
PPE: Wear lab coat, safety glasses or chemical splash goggles, and appropriate chemical-resistant gloves (e.g., nitrile). Use in a fume hood to control vapors/particulates.
Incompatibilities: Strong reducing agents (may reduce N–O bond); strong acids/bases may alter reactivity or lead to decomposition; potent oxidizers should be segregated unless used in controlled protocols. Avoid prolonged exposure to moisture if purity is critical for downstream reactions.
First aid (overview): In case of skin contact, wash with soap and water. If in eyes, rinse cautiously with water for several minutes and seek medical attention if irritation persists. If inhaled, move to fresh air. If ingested, rinse mouth and seek medical advice. Always follow the site-specific EHS procedures.
Fire safety: Not known to be highly flammable; however, treat as an organic combustible. Use CO2, dry chemical, or foam. Thermal decomposition may release nitrogen oxides, HCl, and other irritants.
Handling tips: Minimize exposure to air if instructed (argon blanket per product data). Reseal promptly after use; consider storing in septum-sealed or crimped containers for air-sensitive workflows.
Solvent Selection
This product is a heteroaromatic solid reagent, not a solvent. Solvent selection pertains to using 3-chloropyridine N-oxide in reactions, purifications, or analyses.
Polarity considerations (general): The N‑oxide raises polarity relative to 3-chloropyridine, favoring dissolution in polar organics (MeOH, EtOH, MeCN, acetone, DMF, DMSO). Solubility in nonpolar solvents (hexanes, toluene) may be limited unless heated or co-solvents are used.
Acid/base behavior: The N‑oxide is a strong H‑bond acceptor and a weak base; avoid strongly acidic media when preserving the N‑oxide, unless protonation is intentional (to form pyridine N‑oxide salts).
Synthetic workups: For extractions, water miscibility can vary; salting-out with brine and selecting EtOAc or DCM as organic phases can aid partitioning. When very polar, switch to n‑butanol or MTBE as required.
Chromatography: Normal-phase silica may retain N‑oxides strongly. Additives (0.1–1% Et3N) or switching to basic alumina/reverse phase can improve elution and prevent tailing.
Drying solvents: If performing moisture-sensitive couplings or rearrangements, dry solvents (molecular sieves, solvent purification systems) are advisable.
Comparison to parent heteroarene:
3-Chloropyridine: Less polar; better in nonpolar solvents but poorer solubility in protic polar media.
3-Chloropyridine N-oxide: More polar; enhanced solubility in polar/aprotic solvents and often cleaner behavior in polar chromatographic systems.
Choose solvents based on the downstream transformation (e.g., Pd-catalyzed coupling often uses toluene/DMF/MeCN; Boekelheide conditions use acyl anhydrides in aprotic media).
Storage and Reconstitution
Item-specific storage/shipping
Storage conditions: Store at 2–8 °C, under argon (inert atmosphere) as provided in the Product Data.
Shipping: Supplied on wet ice.
Handling and aliquoting
Keep container tightly closed. Purge headspace with argon after each use to maintain the inert atmosphere.
Minimize extended exposure to air and ambient humidity to preserve quality, especially before moisture- or air-sensitive transformations.
If frequent small-scale use is anticipated, consider preparing argon-purged aliquots in compatible vials to reduce repeated air exposure.
Reconstitution/solubilization
Solubility data are not specified for this item; typical solvents for pyridine N‑oxides include MeCN, MeOH, EtOH, acetone, DMF, and DMSO (literature). Start with dry, oxygen-free solvent if required by your application.
For analytical stock solutions, prepare at known concentration (e.g., 10–100 mM) in a suitable solvent and store in sealed, inerted containers at 2–8 °C or colder as stability dictates. Verify stability by LC over time.
Stability notes
Long-term stability and assay/purity limits are not specified for this item; refer to the CoA/Spec Sheet and SDS. Avoid strong reducing agents or acids/bases during storage.
Always follow your institution’s chemical hygiene plan. For authoritative safety and stability information, consult the SDS for this product.
Structure and Identity
Item-specific identifiers (from Product Data)
SKU: C340348
Product name: 3-Chloropyridine N-Oxide
CAS: 1851-22-5
InChIKey: Not specified for this item; refer to CoA/Spec Sheet.
SMILES: Not specified for this item; refer to CoA/Spec Sheet.
Literature/Computed identity data (for reference only; not item-specific specs)
Structural features (general chemistry description)
Core scaffold: a six-membered aromatic heteroaromatic ring (pyridine) bearing an N→O oxide function (pyridine N-oxide) and a chlorine substituent at the 3-position (meta to the N).
Functional groups: aromatic N-oxide ([N⁺→O⁻]) and aryl chloride (C–Cl) on a pyridine ring.
Charge distribution: formal positive charge on N and negative charge on O in the N‑oxide resonance description; overall neutral molecule.
2D description: Starting at the ring nitrogen (oxidized to N-oxide), the ring positions 2 and 4 are unsubstituted carbons; position 3 bears chlorine; positions 5 and 6 are unsubstituted carbons. The N–O bond is exocyclic to the ring and is shorter than a typical N–O single bond due to partial double-bond character.
Note: All structural/literature identifiers above are provided for context; consult the product’s CoA/Spec Sheet for the definitive identifiers of this specific lot.
Synthetic Utility
Functional elements and their reactivity (literature):
Aryl chloride (C–Cl): Gateway to Pd-catalyzed cross-couplings (Suzuki–Miyaura, Buchwald–Hartwig, Negishi, Kumada). Oxidative addition into C–Cl can be promoted by electron-deficient rings and advanced ligands (e.g., SPhos, XPhos, BrettPhos families).
Pyridine N‑oxide: Powerful directing group for ortho C–H activation (C2 of pyridine). Temporary nature allows install–modify–remove strategies. The N‑oxide also tunes ring electronics, enhancing SNAr propensity at specific positions.
N–O bond chemistry: Reduction to the parent pyridine preserves installed substituents; activation with acylating agents (Ac2O or mixed anhydrides) enables Boekelheide rearrangement to yield 2‑functionalized derivatives (e.g., 2‑hydroxymethyl analogs after hydrolysis), complementing cross-coupling approaches.
Retrosynthetic value:
Use the N‑oxide as a handle to introduce ortho functionality, then deoxygenate to access 2,X‑disubstituted 3-chloropyridines that might otherwise require multi-step halogen dance or directed metallation.
Alternatively, first exploit C–Cl for diversification (aryl/alkyl/amine), then leverage the N‑oxide for further C–H elaboration, giving orthogonal late-stage diversification pathways.
Practical workflow:
Sequence planning should consider compatibility of the N‑oxide with bases and catalysts; protect or reduce the N‑oxide only after its directing utility is exhausted.
Purification can be optimized using basic stationary phases or eluent modifiers to mitigate strong adsorption due to the N‑oxide.
Target Specificity
Not applicable. This product is a small-molecule heteroaromatic reagent, not an antibody, enzyme, or affinity reagent. No antigen/epitope specificity, clone, or isotype information applies.
Domande frequenti
What is the purity of this product?
This product is supplied at ≥98% purity (chemical assay). Lot-specific values are stated on the Certificate of Analysis.
How should this product be stored?
Store at 2–8 °C under argon. It is supplied under an argon blanket; reseal under inert gas after each use.
How is this product shipped?
This product ships chilled on wet ice. Unpack on arrival and transfer it to the storage condition stated above.
What are the CAS number, molecular formula and molecular weight?
The CAS Number is 1851-22-5, the molecular formula is C5H4ClNO, and the molecular weight is 129.54 g/mol. InChIKey NEXUNCTUUDERGR-UHFFFAOYSA-N.
What documentation is provided?
Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.
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