Industrial-Scale Bulk Synthesis Process of 1-Methyl-3-Phenylthiourea
- High-yield, scalable synthesis route using phenyl isothiocyanate and methylamine under controlled conditions.
- Industrial purity ≥99% with full COA documentation for agrochemical and pharmaceutical intermediate applications.
- NINGBO INNO PHARMCHEM CO.,LTD. offers competitive bulk pricing and reliable global supply of 1-Methyl-3-phenylthiourea.
1-Methyl-3-phenylthiourea (CAS 2724-69-8), also known as 1-phenyl-3-methylthiourea or 1-methyl-3-phenyl-2-thiourea, is a critical sulfur-containing heterocyclic intermediate widely used in the synthesis of herbicides, fungicides, and specialty pharmaceuticals. Its structural motif—featuring a thiourea core substituted with a phenyl and a methyl group—imparts unique reactivity and stability, making it indispensable in modern crop protection chemistry. When sourcing high-purity 1-Methyl-3-phenylthiourea, buyers should prioritize suppliers with validated synthesis routes, stringent quality control, and scalable production capacity.
Industrial Synthesis Route and Reaction Mechanism
The most efficient and commercially viable synthesis route for 1-Methyl-3-phenylthiourea involves the nucleophilic addition of methylamine to phenyl isothiocyanate in an anhydrous polar solvent such as ethanol or methanol. This one-step condensation proceeds under mild conditions with excellent atom economy:
Reaction Equation:
C₆H₅–N=C=S + CH₃NH₂ → C₆H₅–NH–C(S)–NHCH₃
This method avoids hazardous reagents like phosgene or dimethyl sulfate, which are common in urea-based syntheses but pose significant safety and environmental challenges. The reaction is typically conducted at 0–25°C to suppress side products such as dithiocarbamates or bis-adducts. After completion (monitored by HPLC or TLC), the crude product is isolated via crystallization, yielding a white to off-white solid with >98% purity. Final purification through recrystallization from ethanol achieves industrial-grade purity of ≥99%, suitable for regulated applications.
Alternative routes—such as alkylation of 1-phenylthiourea with methyl iodide or dimethyl sulfate—have been reported but suffer from lower selectivity, over-alkylation risks, and higher waste generation. Consequently, the direct condensation method remains the industry standard for bulk manufacturing process due to its simplicity, safety, and cost-effectiveness.
Key Process Parameters and Yield Optimization
To maximize yield and ensure batch-to-batch consistency in bulk production, several critical parameters must be tightly controlled:
- Molar Ratio: A slight excess of methylamine (1.05–1.10 eq) ensures complete consumption of phenyl isothiocyanate while minimizing unreacted amine residues.
- Solvent Choice: Absolute ethanol provides optimal solubility and facilitates easy crystallization. Water content must be <0.1% to prevent hydrolysis of the isothiocyanate.
- Temperature Control: Addition at 5–10°C followed by stirring at 20–25°C for 2–4 hours balances reaction rate and selectivity.
- pH and Workup: Neutral to slightly basic conditions during workup prevent decomposition. The product is recovered by filtration, washed with cold solvent, and vacuum-dried at 40–50°C.
Under optimized conditions, this process consistently delivers yields of 92–95% on multi-hundred-kilogram scale. NINGBO INNO PHARMCHEM CO.,LTD. has refined this protocol to achieve >99% HPLC purity with residual solvents and heavy metals well below ICH Q3 guidelines, supported by comprehensive Certificate of Analysis (COA) for every batch.
Bulk Supply, Purity, and Commercial Considerations
As a premier global manufacturer of fine chemical intermediates, NINGBO INNO PHARMCHEM CO.,LTD. specializes in the large-scale production of high-value thiourea derivatives. The company’s facility in China is equipped with dedicated reactors, advanced analytical instrumentation (including GC-MS, HPLC, and Karl Fischer titration), and ISO-compliant quality systems to guarantee consistent industrial purity and regulatory compliance.
For commercial procurement, 1-Methyl-3-phenylthiourea is available in 25 kg fiber drums or custom packaging, with typical lead times of 2–4 weeks. The compound is stable under ambient storage conditions and shipped with full documentation, including SDS, COA, and spectral data. Competitive bulk price structures are offered based on annual volume commitments, making it accessible for both agrochemical formulators and API developers.
| Parameter | Specification |
|---|---|
| CAS Number | 2724-69-8 |
| Molecular Formula | C₈H₁₀N₂S |
| Molecular Weight | 166.24 g/mol |
| Appearance | White to off-white crystalline powder |
| Purity (HPLC) | ≥99.0% |
| Residual Solvents | Complies with ICH Q3C |
| Heavy Metals | <10 ppm |
| Packaging | 25 kg drums (custom options available) |
In summary, the bulk synthesis of 1-Methyl-3-phenylthiocarbamide is a mature yet precisely engineered process that balances efficiency, safety, and quality. With decades of expertise in heterocyclic chemistry, NINGBO INNO PHARMCHEM CO.,LTD. stands as a trusted partner for global clients requiring reliable access to this essential building block in agrochemical innovation.