Methylchloroisothiazolinone, commonly abbreviated as MCI, MCIT or CMIT, is a synthetic isothiazolinone compound used primarily for its preservative and antimicrobial functionality. Its INCI name is METHYLCHLOROISOTHIAZOLINONE, and COSMILE Europe identifies it as a preservative used in various rinse-off cosmetic products, generally in combination with methylisothiazolinone (MI).
Methylchloroisothiazolinone is particularly associated with preservation systems designed to protect water-containing formulations from microbial spoilage. Because microorganisms can proliferate in aqueous cosmetic products, preservation is an important formulation consideration for products such as shampoos, cleansers and other rinse-off personal-care preparations.
Methylchloroisothiazolinone has the chemical name 5-Chloro-2-methyl-2H-isothiazol-3-one, with CAS Number 26172-55-4 and EC Number 247-500-7. Its molecular formula is C₄H₄ClNOS and molecular weight is approximately 149.60 g/mol.
The material is also known as 5-Chloro-2-methyl-4-isothiazolin-3-one, Chloromethylisothiazolinone, Chloromethylisothiazolone, MCI, MCIT and CMIT. Published physicochemical data report a melting point around 52°C, although the physical characteristics of commercial preparations can differ according to concentration, solvent system and formulation grade.
Commercial Methylchloroisothiazolinone materials may be supplied as solutions or as part of preservative systems rather than as a neat crystalline raw material. Therefore, the actual concentration, appearance, pH and other quality parameters should be established from the specific supplier specification or Certificate of Analysis.
Methylchloroisothiazolinone functions primarily as a preservative. Its role is to help control microbial growth and protect susceptible cosmetic formulations against deterioration. COSMILE Europe also identifies a fragrance-functional use, describing it as a functional ingredient of perfume oils and/or flavours.
MCI is commonly encountered together with methylisothiazolinone in preservative systems. The combination has historically been used because the two isothiazolinones provide complementary antimicrobial activity. However, formulation use requires careful attention to applicable concentration limits and regulatory requirements.
Methylchloroisothiazolinone also has recognized sensitising potential. Consequently, regulatory authorities have placed significant restrictions on its cosmetic use.
Methylchloroisothiazolinone is principally associated with rinse-off cosmetic and personal-care formulations. Potential formulation categories include shampoos, rinse-off hair-care products, body washes, liquid cleansers and other aqueous preparations where microbial preservation is required.
In the European Union, the current Annex V framework permits the Methylchloroisothiazolinone/Methylisothiazolinone mixture in rinse-off products at a maximum concentration of 0.0015%, expressed for the specified 3:1 mixture. The EU regulatory entry identifies CAS numbers 26172-55-4 and 2682-20-4 for the components and CAS 55965-84-9 for the mixture.
The EU framework therefore needs to be considered when developing products intended for European markets. Regulatory requirements in India and other markets may differ.
The use level of Methylchloroisothiazolinone must be determined according to the finished-product formulation, regulatory requirements, preservative system and the specification of the supplied material. The concentration of active MCI in a commercial solution should not be confused with the permitted concentration of the substance in the finished cosmetic.
Compatibility, pH, packaging, preservative interactions and microbiological performance should be evaluated during formulation development. Because MCI and MI have sensitising potential, appropriate regulatory review and safety assessment are important before commercial use. COSMILE Europe specifically notes their sensitising potential and the strong restrictions applying to cosmetic use.
As a Methylchloroisothiazolinone Cosmetic Ingredient Manufacturer in India, Swapnroop can position this material for B2B cosmetic and personal-care ingredient requirements, subject to the actual commercial grade and regulatory suitability. Buyers evaluating Methylchloroisothiazolinone should review identity, concentration, physical characteristics, analytical method, impurity profile and applicable regulatory documentation before incorporation into a finished formulation.
For manufacturers seeking a Methylchloroisothiazolinone supplier in India, technical documentation and batch-specific quality information are important for formulation development, quality control and regulatory review. Bulk cosmetic ingredient supply should always correspond to the agreed product specification and intended application.
| Parameter | Specification |
|---|---|
| Appearance | White or colourless crystals / white powder |