Methylchloroisothiazolinone, also referred to as MCI, is the

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

with the formula S(C₂HCl)C(O)N(CH₃). It is a white solid that melts near room temperature. The compound is an

isothiazolinone Isothiazolinone (sometimes isothiazolone) is an organic compound with the formula (CH)2SN(H)CO. A white solid, it is structurally related to isothiazole. Isothiazolone itself is of limited interest, but several of its derivatives are widely used ...

, a class of

heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

s used as biocides. These compounds have an active sulphur moiety that is able to oxidize thiol-containing residues, thereby effectively killing most aerobic and anaerobic bacteria. MCI is often used in combination with

methylisothiazolinone Methylisothiazolinone, MIT, or MI, is the organic compound with the formula S(CH)2C(O)NCH3. It is a white solid. Isothiazolinones, a class of heterocycles, are used as biocides in numerous personal care products and other industrial applications ...

, a mixture known as Kathon. The isothiazolinones have attracted attention because they can cause contact dermatitis. Methylchloroisothiazolinone is effective against

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

and

gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...

, and

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

Application

Methylchloroisothiazolinone is found in many water-based personal care products and cosmetics. Methylchloroisothiazolinone was first used in cosmetics in the 1970s. It is also used in glue production, detergents, paints, fuels, and other industrial processes. Methylchloroisothiazolinone is known by the registered tradename ''Kathon'' CG when used in combination with

. Methylchloroisothiazolinone may be used in combination with other preservatives including

ethylparaben Ethylparaben (ethyl ''para''-hydroxybenzoate) is the ethyl ester of ''p''-hydroxybenzoic acid. Its formula is HO-C6H4-CO-O-CH2CH3. It is a member of the class of compounds known as parabens. It is used as an antifungal preservative. As a fo ...

benzalkonium chloride Benzalkonium chloride (BZK, BKC, BAK, BAC), also known as alkyldimethylbenzylammonium chloride (ADBAC) and by the trade name Zephiran, is a type of cationic surfactant. It is an organic salt classified as a quaternary ammonium compound. ADBACs ha ...

bronopol Bronopol ( INN; chemical name 2-bromo-2-nitropropane-1,3-diol) is an organic compound that is used as an antimicrobial. It is a white solid although commercial samples appear yellow. The first reported synthesis of bronopol was in 1897. Bronopol ...

and

phenoxyethanol Phenoxyethanol is the organic compound with the formula C6H5OC2H4OH. It is a colorless oily liquid. It can be classified as a glycol ether and a phenol ether. It is a common preservative in vaccine formulations. Use Phenoxyethanol has germic ...

Hazards

Methylchloroisothiazolinone can cause allergic reactions in some people. The first publication of the preservative as a contact allergen was in 1988. Cases of photoaggravated allergic contact dermatitis, i.e. worsening of skin lesions after sun exposure, have also been reported. In pure form or in high concentrations, methylchloroisothiazolinone is a skin and membrane irritant and causes chemical burns. In the United States, maximum authorized concentrations are 15 ppm in rinse-offs (of a mixture in the ratio 3:1 of 5-chloro-2-methylisothiazol 3(2H)-one and 2-methylisothiazol-3 (2H)-one). In Canada, methylchloroisothiazolinone may only be used in rinse-off products in combination with methylisothiazolinone, the total concentration of the combination may not exceed 15 ppm.

References

External links

CMIT/MIT Assessment
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Methylchloroisothiazolinone at the National Library of Medicine
{{Use dmy dates, date=February 2021 Preservatives Isothiazolidinones Chloroarenes