Preservatives & Biocides
REACH
Methylchloroisothiazolinone
CAS Number
26172-55-4
EC Number
247-500-7
Abbreviation
CMIT
What is Methylchloroisothiazolinone?
Methylchloroisothiazolinone (CAS 26172-55-4), known as CMIT or MCI, is a broad-spectrum biocide that controls microbial growth in water-based systems and industrial formulations.
Where is Methylchloroisothiazolinone used?
- Personal care and cosmetics: preservative in rinse-off shampoos, conditioners and liquid soaps, typically blended with MIT
- Industrial water treatment: prevents biofouling in cooling towers, process water circuits and paper mill white water loops
- Coatings and adhesives: extends in-can shelf life of water-based paints, emulsions and sealants
- Oilfield and metalworking: controls sulfate-reducing bacteria in injection water and cutting fluids
- It is most effective against bacteria, fungi and algae.
Good to know: Rarely handled as a pure substance due to specific stability requirements.
Commercial specifications
- Aqueous solution, commonly 1.5% or 14% active concentrate
- Supply governed by ISO or in-house specifications
- Packaging from drums to IBC containers
Other Names (Synonyms)
CMIT|2,3-dihydro-2-methyl-3-oxo-5-chloroisothiazole|MCI|5-chloro-2-methyl-2H-isothiazol-3-one|5-Chloro-2-methyl-4-isothiazolin-3-one|5-Chloro-2-methyl-3(2H)-isothiazolone|5-Chloro-2-methyl-3-isothiazolone|Kathon CG 5243
What are the physical properties of Methylchloroisothiazolinone?
Melting Point 52 °C
Boiling Point 109.7°C
Density 1.25 (14% aq.)
Appearance Liquid
Color White
Odor Pungent aromatic odor
Form Liquid
Refractive Index n 20/D 1.378
Log P 0.240 (est)
How is Methylchloroisothiazolinone classified and handled safely? Learn More
Danger
GHS05· Corrosive GHS06· Toxic GHS07· Irritant GHS09· Environmental Hazard
Hazard Statements
H300 Fatal if swallowed
H301 Toxic if swallowed
H310 Fatal in contact with skin
H311 Toxic in contact with skin
Precautionary Statements
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P262 Do not get in eyes, on skin, or on clothing.
P264 Wash … thoroughly after handling.
Which trade and regulatory codes apply to Methylchloroisothiazolinone?
HS Code 3808929090
UN Number 1760
ADR Class 8
Packing Group II
Storage Class 12 - Non Combustible Liquids
WGK (Germany) 1