1. Chemical Structure and Properties

Active Component:

Monomethylamine (MMA)

Molecular Formula:

CH₅N

Structural Formula:

CH₃NH₂ (primary aliphatic amine).

Solvent:

Methanol (MeOH), Molecular Formula: CH₃OH.

Solution Properties:

• Concentration: 25% w/w MMA in methanol.
• Physical State: Clear, colorless liquid with a sharp, ammonia-like odor.
• Boiling Point: ~65°C (dominated by methanol’s volatility).
• Density: ~0.84 g/cm³ at 20°C.
• pH: Strongly alkaline (pH ~12.0 due to MMA).
• Solubility: Miscible with water, ethanol, and polar organic solvents.

Chemical Reactivity:

• Basicity: MMA acts as a weak base (pKa ~10.6), reacting exothermically with acids to form salts.
• Flammability: Highly flammable (flash point: 12°C; autoignition temperature: 385°C).

2. Industrial Applications

Pharmaceutical Industry:

• Intermediate in synthesizing antitussives (e.g., dextromethorphan) and antiviral drugs (e.g., oseltamivir).
• Example: Used to produce N-methyl intermediates for CNS-active compounds.

Agrochemicals:

• Key precursor for glyphosate herbicides and imidacloprid insecticides (reaction with phosphorus trichloride).

Organic Synthesis:

• Alkylation Agent: Quaternizes fatty acids to produce surfactants (e.g., cocamidopropyl betaine).
• Catalyst: Accelerates esterification and transesterification reactions in biodiesel production.

Electronics Manufacturing:

• Cleaning agent for semiconductor wafers to remove organic residues (e.g., TSMC’s wafer fabrication).

3. Safety and Toxicology

Hazards of MMA:

• Inhalation (≥50 ppm): Severe respiratory irritation, pulmonary edema (LC50 rat, 4h: 2,500 ppm).
• Skin Contact: Corrosive burns (rabbit skin LD50: 400 mg/kg); frostbite risk due to rapid evaporation.
• Eye Exposure: Permanent corneal damage.

Acute Exposure:

• Chronic Effects: Potential neurotoxicity (animal studies).

Hazards of Methanol:

• Toxicity: Metabolizes to formaldehyde and formic acid, causing metabolic acidosis, blindness, or death (oral LD50 rat: 5,600 mg/kg).
• Flammability: High vapor pressure increases explosion risk (flammability range: 6–36% vol in air).

Combined Risks:

• Synergistic Toxicity: Co-exposure amplifies CNS depression and metabolic stress.
• Fire Hazard: Flammable liquid with low flash point; requires explosion-proof equipment.

Protection Measures:

• PPE: Neoprene gloves, chemical goggles, and NIOSH-approved respirators with organic vapor cartridges.
• Engineering Controls: Closed systems, local exhaust ventilation, and grounded containers.

4. Environmental and Regulatory Compliance

Environmental Impact:

• MMA reacts with hydroxyl radicals (half-life ~2 days); methanol contributes to ground-level ozone formation.
• MMA: Rapid aerobic degradation (half-life <7 days).
• Methanol: Readily biodegradable (OECD 301F: >90% in 28 days).

Aquatic Toxicity:

• MMA: LC50 (fish, 96h): 120 mg/L; EC50 (daphnia): 85 mg/L.
• Methanol: LC50 (fish, 96h): 1,000 mg/L; EC50 (algae): 500 mg/L.

Regulatory Frameworks:

• GB 13690-2009: Classified as Class 3.2 Flammable Liquid and Class 8.2 Corrosive Substance.
• OSHA PEL: 10 ppm (MMA), 200 ppm (methanol).
• EPA: Listed on the Toxic Release Inventory (TRI); CERCLA RQ = 100 lbs (MMA).
• CLP Regulation: Classified as Flammable Liquid (Category 2), Acute Tox. 2 (H330), and Skin Corr. 1B (H314).
• REACH: Requires SDS with disposal protocols and risk mitigation measures.

EU:
USA:
China:

Transportation:

UN Number: UN 1230 (Methanol solution, flammable).
Hazard Class: 3 (Flammable Liquid), Packing Group II.

5. Case Studies and Application Insights

Case 1: Glyphosate Herbicide Synthesis

Process: MMA/MeOH reacts with phosphorus trichloride to form methylphosphonous acid, a glyphosate precursor (Bayer process).

Efficiency: 25% solution achieves 90% yield at 65°C with reduced side reactions vs. aqueous systems.

Case 2: Semiconductor Wafer Cleaning

Application: Intel uses MMA/MeOH for post-etch residue removal in 7nm chip fabrication.

Advantage: Lower surface tension than pure methanol, enabling better penetration into nanostructures.

Comparative Analysis:

• Pros: Enhanced solubility for hydrophobic reagents; faster reaction kinetics.
• Cons: Higher flammability and methanol toxicity require stringent safety protocols.