4,5-Dichloro-2-N-octyl-4-isothiazolin-3-one

Synonyms：DCOIT; 4,5-Dichloro-2-N-octyl-3(2H)-isothiazolone; 4,5-Dichloro-2-octyl-2H-isothiazol-3-one
CAS No.：64359-81-5
EINECS No.：264-843-8
Molecular Formula：C₁₁H₁₇Cl₂NOS
Molecular Weight：282.23
Structural Formula：
                                 
Standard：

Properties：It is a white crystalline powder. Slightly soluble in water, soluble in ethanol, acetone and other organic solvents.Melting point: 42.2～42.8℃.
Applications：4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) is a highly effective isothiazolinone-based biocide with broad-spectrum antibacterial, antifungal, and anti-algal activity. It is widely used as a non-oxidizing microbiocide and industrial preservative in antifouling and material-protection systems. Due to its fast-acting mechanism against bacteria, fungi, and algae, DCOIT is formulated into various industrial products. Its major application fields include:

2. Mold and Mildew Protection for Paints and Coatings

DCOIT is used in architectural coatings, industrial paints, and wood coatings to prevent mold, algae, and microbial degradation, especially in high-humidity environments. Many interior and exterior coating formulations include DCOIT to inhibit surface staining fungi and extend the durability of paint films.

3. Preservation of Plastics, Polymers, and Polymer Emulsions

DCOIT serves as a long-term antimicrobial and anti-mold additive for plastics and polymer systems—particularly polyethylene, polyurethane, rubber materials, and polymer emulsions used in outdoor or humid environments.
It helps prevent microbial discoloration, mold growth, material degradation, and surface biofouling.

4. Industrial Water Treatment (Cooling Water and Marine Water Systems)

In industrial water systems such as cooling towers, heat exchangers, and seawater cooling applications, DCOIT is used as a non-oxidizing biocide and algaecide. It effectively controls biofilm formation, algae growth, and bacterial contamination, helping maintain heat-exchange efficiency and reducing corrosion, clogging, and fouling risks.

5. Wood and Wood Products Preservation

DCOIT is used in wood protection to inhibit mold, fungi, and other wood-degrading microorganisms. It is applied in outdoor wooden structures, furniture, and composite wood products to improve durability. Some countries include DCOIT within their registered wood preservatives.

6. Antimicrobial and Anti-Mold Treatments for Textiles, Leather, Printing, and Paper

DCOIT is used to impart long-lasting antimicrobial properties to textiles, functional fabrics, sportswear, leather products, dyed materials, and paper coatings. 

7. Preservation of Adhesives, Inks, Hydraulic Fluids, and Construction Additives

DCOIT is formulated into adhesives, printing inks, emulsions, hydraulic fluids, and concrete additives to prevent microbial spoilage, unpleasant odors, viscosity changes, and degradation during storage and use.

8. Replacement for Organotin Antifouling Agents

Following global restrictions on toxic organotin antifouling compounds (such as TBTO), DCOIT was developed and widely adopted as a more environmentally acceptable antifouling alternative. It offers strong antifouling performance and is more readily biodegradable compared with traditional organotin systems, though environmental risk management is still required.

Storage：Keep in a well-closed and light-resistant container, and store in a cool, dry and ventilated place. Do not contact with reductive metals (Fe, Al etc.), nor with Oxidative materials.
Packing：25kg cardboard drum