Methylchloroisothiazolinone

Names
Preferred IUPAC name 5-Chloro-2-methyl-1,2-thiazol-3(2H)-one
Other names 5-Chloro-2-methylisothiazol-3(2H)-one 5-Chloro-2-methyl-4-isothiazolin-3-one Chloromethylisothiazolinone Chloromethylisothiazolone Methylchloroisothiazolinone Methylchloroisothiazolone CMI CMIT MCI MCIT CIT
Identifiers
CAS Number	26172-55-4 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1210149
ChEBI	CHEBI:53621 Y
ChemSpider	30800 Y
DrugBank	DB14197
ECHA InfoCard	100.043.167
EC Number	247-500-7
PubChem CID	33344
UNII	DEL7T5QRPN Y
CompTox Dashboard (EPA)	DTXSID9034286
InChI InChI=1S/C4H4ClNOS/c1-6-4(7)2-3(5)8-6/h2H,1H3 Y Key: DHNRXBZYEKSXIM-UHFFFAOYSA-N Y InChI=1/C4H4ClNOS/c1-6-4(7)2-3(5)8-6/h2H,1H3 Key: DHNRXBZYEKSXIM-UHFFFAOYAV
SMILES ClC=1SN(C(=O)C=1)C
Properties
Chemical formula	C4H4ClNOS
Molar mass	149.59 g·mol−1
Appearance	white solid
Density	1.02 g/cm3
Melting point	52 °C (126 °F; 325 K)
Solubility in water	Miscible
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H300, H301, H310, H311, H314, H317, H330, H331, H335, H410
Precautionary statements	P260, P261, P262, P264, P270, P271, P272, P273, P280, P284, P301+P310, P301+P330+P331, P302+P350, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P312, P320, P321, P322, P330, P333+P313, P361, P363, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Methylchloroisothiazolinone, also referred to as MCI, is the organic compound with the formula S(C₂HCl)C(O)N(CH₃). It is a white solid that melts near room temperature. The compound is an isothiazolinone, a class of heterocycles 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, a mixture known as Kathon. The isothiazolinones have attracted attention because they can cause contact dermatitis.^[1][2][3] Methylchloroisothiazolinone is effective against gram-positive and gram-negative bacteria, yeast, and fungi.

Application

Methylchloroisothiazolinone is found in many water-based personal care products and cosmetics.^[2] 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 methylisothiazolinone.^[3]

Methylchloroisothiazolinone may be used in combination with other preservatives including ethylparaben, benzalkonium chloride, bronopol and phenoxyethanol.

Hazards

Methylchloroisothiazolinone can cause allergic reactions in some people.^[4] The first publication of the preservative as a contact allergen was in 1988.^[5] Cases of photoaggravated allergic contact dermatitis, i.e. worsening of skin lesions after sun exposure, have also been reported.^[4]

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).^[6] 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.^[7]