2,3-Dimethoxypyridine: Properties, Handling & Lab Use Guide

2,3-Dimethoxypyridine is a methoxy-substituted pyridine heterocycle widely employed as a versatile building block and synthetic intermediate in medicinal chemistry, agrochemical research, and fine chemical synthesis.

CAS Number

23937-26-0

Molecular Formula

C₇H₉NO₂

Molecular Weight

139.15 g/mol

Appearance

Colorless to pale yellow liquid or low-melting solid

Solubility

Soluble in common organic solvents (ethanol, acetone, DCM, THF); limited solubility in water

Storage Condition

Store in a cool, dry, well-ventilated area away from light; seal tightly after use

Chemical Identity and Key Properties

2,3-Dimethoxypyridine (CAS 23937-26-0) is a disubstituted pyridine bearing methoxy groups at the 2- and 3-positions of the aromatic ring. Its molecular formula is C₇H₉NO₂ and its molecular weight is 139.15 g/mol. The presence of two electron-donating methoxy groups modulates the electron density of the pyridine ring, reducing its typical electron-deficient character and influencing reactivity toward electrophilic and nucleophilic transformations.

The compound typically presents as a colorless to pale yellow liquid or low-melting solid and is miscible with most polar aprotic and protic organic solvents. Its moderate lipophilicity makes it amenable to a range of synthetic manipulations including directed metalation, cross-coupling, and nucleophilic substitution reactions. The ring nitrogen retains its coordinating ability, which is relevant in metal-catalyzed reaction design.

Synthetic Applications and Research Uses

2,3-Dimethoxypyridine serves as an important heterocyclic building block in organic and medicinal chemistry. Its substitution pattern makes it a useful precursor for the preparation of more complex pyridine-containing scaffolds found in pharmaceutical candidates, natural product analogs, and functional materials.

Key applications include: (1) Directed ortho-metalation (DoM): The methoxy substituents can act as directed metalation groups (DMGs), enabling regioselective lithiation at specific ring positions followed by quenching with electrophiles to install diverse functional groups. (2) Transition-metal-catalyzed cross-coupling: After appropriate functionalization (e.g., halogenation), the compound serves as a coupling partner in Suzuki–Miyaura, Negishi, or Buchwald–Hartwig reactions to build biaryl and heteroaryl architectures. (3) Nucleophilic aromatic substitution (SNAr): Selective displacement of one methoxy group can be achieved under appropriate nucleophilic conditions, offering a route to mixed-ether or amino-substituted pyridines. (4) Intermediate in pharmaceutical synthesis: The 2,3-dimethoxypyridine motif appears in synthetic routes toward bioactive molecules targeting various enzyme and receptor classes.

Safe Handling and Storage Guidelines

Although 2,3-Dimethoxypyridine is not classified among acutely highly toxic reagents, standard laboratory chemical safety practices must be followed at all times:

• Personal Protective Equipment (PPE): Wear nitrile or neoprene gloves, safety glasses or goggles, and a lab coat. Where vapors may be present, use appropriate respiratory protection in accordance with local regulations.
• Ventilation: Handle in a fume hood or well-ventilated area to minimize inhalation of vapors.
• Skin and eye contact: Avoid direct contact. In case of skin contact, wash thoroughly with soap and water. For eye exposure, irrigate immediately with copious water and seek medical attention.
• Storage: Store in a tightly sealed container in a cool (below 25 °C), dry, and well-ventilated location away from direct sunlight, heat sources, and incompatible materials (strong oxidizers, strong acids).
• Disposal: Dispose of waste material in accordance with applicable local, regional, and national regulations for organic solvent/heterocyclic compound waste.

Always consult the current Safety Data Sheet (SDS) supplied with the product before use. The SDS contains up-to-date hazard classification, first-aid measures, and regulatory information.

Quality, Purity and Specification Considerations

For research and synthesis applications, reagent purity is a critical factor affecting reproducibility and yield. When sourcing 2,3-Dimethoxypyridine, researchers should consider the following specification parameters:

• Purity: High-purity grades (typically ≥97–98% by GC or HPLC) are recommended for sensitive synthetic steps, directed metalation, or catalytic reactions where trace impurities can poison catalysts or distort yields.
• Identity confirmation: Reliable suppliers provide ¹H NMR, ¹³C NMR, and/or GC–MS data to confirm structural identity and purity profile.
• Packaging integrity: The compound should be supplied under inert atmosphere (nitrogen or argon) if moisture-sensitive applications are anticipated; confirm packaging specifications before ordering.
• Lot-to-lot consistency: Request Certificate of Analysis (CoA) data for each lot to ensure reproducibility across experiments.

Aladdin Scientific offers 2,3-Dimethoxypyridine (SKU: D133874) with documented quality specifications. Contact technical support for current CoA data or specific purity requirements for your application.

Frequently asked questions

What is 2,3-Dimethoxypyridine used for in organic synthesis?

2,3-Dimethoxypyridine is primarily used as a heterocyclic building block. Its main synthetic roles include directed ortho-metalation for regioselective functionalization, as a precursor for cross-coupling reactions after halogenation, and as a substrate for selective nucleophilic aromatic substitution to access diversely substituted pyridine derivatives.

How should 2,3-Dimethoxypyridine be stored to maintain stability?

Store 2,3-Dimethoxypyridine in a tightly sealed container in a cool (below 25 °C), dry, and well-ventilated location away from light, heat, and strong oxidizers. Ensuring the container is properly sealed after each use minimizes degradation from moisture and air exposure over time.

Is 2,3-Dimethoxypyridine soluble in water?

2,3-Dimethoxypyridine has limited solubility in water due to its moderate lipophilicity. It dissolves readily in common organic solvents such as ethanol, acetone, dichloromethane (DCM), and tetrahydrofuran (THF), making these the recommended media for most synthetic applications.

What purity grade of 2,3-Dimethoxypyridine is recommended for sensitive catalytic reactions?

For sensitive catalytic and directed metalation reactions, a purity of ≥97% (by GC or HPLC) is generally recommended to minimize catalyst poisoning and ensure reproducible yields. Always request a Certificate of Analysis (CoA) from the supplier to verify the purity and identity of each lot received.

References

1. Snieckus, V. Directed ortho metalation. Tertiary amide and O-carbamate directors in synthetic strategies for polysubstituted aromatics. Chem. Rev. 1990, 90(6), 879–933. doi:10.1021/cr00104a001
2. Clayden, J. Organolithiums: Selectivity for Synthesis. Pergamon, Oxford, 2002.
3. Joule, J. A.; Mills, K. Heterocyclic Chemistry, 5th ed.; Wiley-Blackwell: Chichester, 2010.

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