News

IUPAC Name: 5-Methylpyrazine-2-carboxylic acid
CAS Number: 5521-55-1
Molecular Formula: C₆H₆N₂O₂
Molecular Weight: 138.13 g/mol

Physical Properties

• Appearance: Light yellow to off-white crystalline powder.
• Melting Point: 166–169°C (reported as 167–171°C in some sources).
• Boiling Point: 316.5°C at 760 mmHg.
• Flash Point: 145.2°C.
• Density: 1.319 g/cm³.
• Solubility: Insoluble in water; solubility in organic solvents (e.g., DMSO, ethanol) may vary.

Chemical Properties

• Functional Groups: Pyrazine ring with a methyl substituent at the 5-position and a carboxylic acid group at the 2-position.
• pKa: Approximately 2.5 (carboxylic acid group).
• Stability: Stable under normal conditions but may decompose upon prolonged exposure to heat or light.

Synthesis

• General Method: Prepared via oxidation of 2,5-dimethylpyrazine or related derivatives using electrolytic oxidation or chemical oxidants (e.g., permanganate).
• Alternative Routes: Reaction of 5-methylpyrazine with carboxylic acid derivatives (e.g., COCl₂) or via metal-catalyzed coupling reactions.

Applications

1. Pharmaceutical Intermediates:
   • Used in the synthesis of glipizide (a second-generation sulfonylurea antidiabetic drug) and acipimox (a lipid-lowering agent).
   • Serves as a key intermediate in the preparation of pyrazine-based pharmaceuticals and agrochemicals.
2. Coordination Chemistry:
   • Reacts with metal salts (e.g., Ln(NO₃)₃·6H₂O, K₄[W(CN)₈]·2H₂O) to form coordination complexes with unique 3D network structures.
3. Materials Science:
   • Employed in the synthesis of metal-organic frameworks (MOFs) and europium(III) complexes for luminescent applications.

Safety & Handling

• Hazards:
  • GHS Classification: Eye Damage/Irritation (Category 1).
  • Hazard Statements: H318 (Causes serious eye damage).
• Protective Measures:
  • Wear appropriate PPE (goggles, gloves, lab coat).
  • Avoid inhalation of dust; work in a fume hood.
• Storage: Store in a cool, dry place in a tightly sealed container.

Analytical Data

• NMR Spectroscopy: Characteristic signals for pyrazine protons and carboxylic acid protons.
• IR Spectroscopy: Strong absorption bands for C=O (carboxylic acid) and pyrazine ring vibrations.
• Mass Spectrometry: Molecular ion peak at m/z 138.04 (M⁺).

Regulatory & Environmental Information

• EINECS Number: 413-260-9.
• WGK Germany: 1 (slightly water-endangering).
• Disposal: Dispose of in accordance with local regulations for chemical waste.