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Overview of CMIT/MIT( isothiazolone biocide)

CMIT/MIT( isothiazolone biocidepreservatives are 2-methyl-4-isothiazolin-3-one (MI) and 2-methyl-5-chloro-4-isothiazolin-3-one (CMI) and inorganic salt stabilizers mixture, usually CMI:MI = 3:1. CMIT/MIT( isothiazolone biocide) is an excellent fungicide commonly used in finished cosmetic products, shampoos and conditioners, and is a preservative that inhibits the growth of microorganisms. It has a good inhibitory effect on yeast, fungi, gram bacteria, heteroxic bacteria, algae, etc. It is widely used in textile, papermaking, oil refining, cosmetics, cleaning agents, oil field water injection, sewage treatment and other fields of sterilization and antiseptic treatment. .

Basic concept of CMIT/MIT( isothiazolone biocide)

CMIT/MIT( isothiazolone biocide) is a series of isothiazolinone compounds produced by Rohmand & Hass Company in the United States, also known as ketamine. CMIT/MIT( isothiazolone biocide) is a mixture of 2-methyl-4-isothiazolin-3-one (MI) and 2-methyl-5-chloro-4-isothiazolin-3-one (CMI) and an inorganic salt stabilizer, Usually CMI:MI = 3:1. CMIT/MIT( isothiazolone biocide) is an excellent fungicide commonly used in finished cosmetic products, shampoos and conditioners, and is a preservative that inhibits the growth of microorganisms. This strain is an internationally recognized safe, efficient, broad-spectrum preservative, does not contain any heavy metals , can effectively inhibit and kill bacteria and various microorganisms, and has a remarkable antiseptic effect. It can completely inhibit bacterial growth at a concentration of 150ppm. At 125ppm, it completely inhibits yeast and mold growth.

CMIT/MIT( isothiazolone biocide) is composed of two active components: 2-methyl-4-isothiazolin-3-one (MIT) and 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) The mixture is a highly effective broad-spectrum bacteriostatic agent. CMIT/MIT( isothiazolone biocide) has strong biological activity , which can inhibit bacteria and sterilize. It can solve the problems of product fermentation, mildew, deterioration and excessive bacteria caused by fungal infection, and because of its penetrating effect on mucus, not only It can be used in cosmetics, detergents, industrial sterilization ring water, machine tool coolants, paints, etc. It is a kind of environmentally friendly “green product” bactericide with a wide range of uses. high added value.

Isothiazolinones are a novel, broad-spectrum, and highly efficient non-oxidizing bactericide , and one of the most cost -effective antiseptic bactericides . Algae have good inhibitory effect and are widely used in sterilization and antiseptic treatment in textile, papermaking, oil refining, cosmetics, cleaning agents, oil field water injection, sewage treatment and other fields.

Nature of CMIT/MIT (Isothiazolinones)

Pure CMIT/MIT( isothiazolone biocide) is a colorless and transparent liquid, and industrial CMIT/MIT( isothiazolone biocide) is usually an aqueous solution. Due to the different impurities, the appearance is light yellow to amber, and the odor is mild. The relative density (20/4) is 1.19, and the viscosity (23) 5.0 MPa .s, freezing point -18~21.5℃, pH3.5~5.0, it is easily soluble in water, low carbon alcohol and ethylene glycol. The optimum pH value is 4-8. When pH > 8, the stability will decrease. If it is stored at room temperature for one year or 50 ℃ for half a year, the activity will decrease very little. The activity will decrease when stored at high temperature. Compatible with various ionic emulsifiers and proteins. [31]

Antibacterial mechanism of Isothiazolinones (CMIT/MIT)

Due to the NS bond in the molecule, CMIT/MIT( isothiazolone biocide) plays a bactericidal effect by breaking the bond between bacterial and algal proteins. After contacting with microorganisms, it can quickly inhibit its growth. This inhibition process is irreversible, resulting in microorganisms. cell death. Before cell death, the microorganisms treated with CMIT/MIT( isothiazolone biocide) can no longer synthesize enzymes and secrete adhesive biofilm substances. By penetrating the biofilm adhered to the surface of the cold water system equipment, the microorganisms under the biofilm can be destroyed. effective control. 

As an isothiazolinone derivative, the relationship between CMIT/MIT( isothiazolone biocide) and various fungi has been extensively studied. As a heterocyclic compound, its bactericidal mechanism is mainly non-oxidative bactericidal effect, relying on the active part of the heterocyclic ring to form hydrogen bonds with the bases of DNA in proteins in bacteria, and adsorb on the cells of bacteria, thereby destroying the structure of DNA in cells. It loses its ability to replicate, resulting in cell death. Morley JO et al. further proved this sterilization mechanism by studying the electronic structure characteristics.

Antibacterial properties of Isothiazolinones (CMIT/MIT)

The bactericidal properties of Isothiazolinones (CMIT/MIT) have broad spectrum, can kill algae, fungi, bacteria, and at the same time have a penetrating effect on mucus, so that the microorganisms treated by Kasson cannot synthesize enzymes and secrete substances with adhesion and biofilm formation before cell death, and the sterilization is more thorough. ; Kathon is also effective at low concentrations. Generally, when the effective concentration is 0.5 mg/L, the growth of bacteria can be well controlled, which is unmatched by other agents; It can achieve physical compatibility with chlorine, corrosion inhibitor, scale inhibitor and dispersant and most anionic, cationic and nonionic surfactants. ~16:1, the product has a synergistic and spectral bactericidal effect; CMIT/MIT( isothiazolone biocide) can effectively organize the formation of slime, which can easily pass through the surface of the slime, thereby effectively killing the microorganisms in the slime, when the When the agent is put into a cleaning system, it can effectively prevent the growth of the slime layer; it is harmless to the environment, and the agent degrades quickly in the aqueous solution. Environmental pollution; it has a wide range of application to pH value, and can maintain high stability even in alkaline systems. Generally, the pH value can be applied in the range of 5.5-9.5; low toxicity, long dosing interval, and due to its No surface activity, the agent does not produce foam during use.

Research on Stabilizers of Isothiazolinones (CMIT/MIT)

  1. Inorganic stabilizer

Substances that can be used as inorganic stabilizers for CMIT/MIT( isothiazolone biocide) mainly include metal nitrites or nitrates and metal salt complexes. Among them, there are many reports on metal nitrite or nitrate stabilizers. The metal salt complex can increase the thermal stability of the CMIT/MIT( isothiazolone biocide) solution while maintaining its biological activity . When sodium cupric citrate is selected as the stabilizer, the sodium cupric citrate itself also has a killing effect.

  1. Organic stabilizer

Organic stabilizers are further divided into carbonyl compounds, halogen-containing organic compounds and other organic stabilizers.

What’s application of Isothiazolinones (CMIT/MIT)?


CMIT/MIT( isothiazolone biocide) is used as an industrial fungicide

CMIT/MIT( isothiazolone biocide) has high bactericidal activity against both Gram-positive and negative bacteria, and has a good inhibitory effect on Streptococcus and yeast. It is widely used in cosmetics, personal care products, coatings, water-based polymers, metal cutting fluids, adhesives, inks, dyes, paraffin fluids, wood, leather, water treatment, industrial circulating water, swimming pool water treatment, pulp and paper, etc. The industry’s sterilization and antiseptic. CMIT/MIT( isothiazolone biocide) products are mainly used for cosmetic preservation. Because of low toxicity, wide antibacterial effect, strong effect, good compatibility with cosmetic raw materials, and can be dissolved in water, it is easy to use, so it can be directly added to cosmetics for use. CMIT/MIT( isothiazolone biocide) is mainly used as an industrial bactericidal preservative in China, and is used in industrial open circulation systems, air scrubbers, breweries, oilfield water injection, synthetic fiber oils, papermaking and other industries. There have been a lot of reports and patents in this area. Has been put into production, and domestic products have reached the international level. [6]

CMIT/MIT( isothiazolone biocide) is used as marine antifouling agent

In the early 1990s, Rohm & Haas Company of the United States first successfully developed 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOI), a derivative of Isothiazolinones, and used Sea-Nine 211 as the product. The trademark was put on the market, and relevant research proved that: DCOI is an environmentally friendly marine antifouling agent. It won the PresidentialGreen Ghemistry Challenge Award in 1996 and the Chemical Environment Excellence Award in 1997. Its value has been recognized and it is called a green antifouling agent. It meets the challenges faced by the ban of organotin and cuprous oxide antifouling agents, and has been widely recognized by chemists at this stage.

CMIT/MIT( isothiazolone biocide) is used in other applications

CMIT/MIT( isothiazolone biocide) is also widely used in chemical sensitizers for photography, indoor air fresheners, raw materials for audio tapes and plant growth regulators.

What’s advantage of isothiazolinones (CMIT/MIT)?

It has high-efficiency, broad-spectrum bactericidal properties, good compatibility, can maintain activity in a large pH value range, small addition amount, fast onset, strong bactericidal power, convenient use and low price. More importantly, the fungicides such as CMIT/MIT( isothiazolone biocide) are environmentally friendly “green products”, so they have been widely used in developed countries. CMIT/MIT( isothiazolone biocide) has strong biological activity, which can inhibit bacteria and sterilize. It can solve the problems of product fermentation, mildew, deterioration and excessive bacteria caused by bacterial infection. It can not only be used in cosmetics and detergents, but also can be used in In industrial sterilization ring water, machine tool coolant, paint, paper, daily chemical, paint, cosmetics, petroleum and other industries and oil field water injection, sewage treatment and many other projects and industries. Internationally, it is mainly used in sterilization and mildew prevention of cosmetics, and it is more common in facial cleanser, hair fix conditioner, washing shampoo, etc. Its trade name is Kathon CG. (CMIT/MIT CG)

Synthesis of isothiazolinones (CMIT/MIT)

There are three main steps in the synthesis of CMIT/MIT( isothiazolone biocide):

First, by reacting methyl acrylate with sodium bicarbonate and sodium polysulfide to generate dimethyl dithiodipropionate;

Subsequently, dimethyl dithiodipropionate reacts with methylamine to generate N,N’-dimethyldithiodipropionamide;

Finally, N,N’-dimethyldithiodipropionamide reacts with sulfuryl chloride in the presence of dichloroethane as a solvent to form a mixture of MIT and CMIT, namely CMIT/MIT( isothiazolone biocide).

High-quality water-colored isothiazolinone fungicides can be achieved by:

①Select high-purity amide (N,N’-dimethyldithiodipropionamide) to reduce the generation of nitrous amines;

②Add a halogenating agent reasonably, and control the cyclization temperature at 5 ~ 20 ℃;

③The filter cake is washed at the same time by the combination of centrifugation and suction filtration to reduce the residue of solvent, hydrochloric acid and amine impurities;

④The isothiazolinone hydrochloride after vacuum drying should be prepared into liquid storage in time;

⑤ When making magnesium nitrate protective solution, pay attention to pH value adjustment and long enough clarification time to precipitate and remove iron ions and heavy metal ions;

⑥ The pH adjuster should choose the varieties with low content of iron and other chromophoric metal ions, in which the iron can be removed by physical and chemical methods. 

Quality Standard of CMIT/MIT

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Exteriorlight yellow transparent liquid
Active ingredient(%)14
Density 25℃1.10-1.20
pH value2-5

use standard

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  1. The dosage of ordinary daily cosmetics is 0.2-0.3‰
  2. The dosage of high-grade cosmetics is 0.3-0.5‰
  3. The dosage of washing supplies is 0.5-1.0‰


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Generally, high performance liquid chromatography and gas chromatography are used for identification.

In order to confirm that the unknown sample is a Kathon preservative and its purity, the vector calculation method in Millennium2010 software was used in this experiment to compare 2-methyl-4-isothiazolin-3-one and 2-methyl-5 in carson preservative. – The spectral difference between the two components of chloro-4-isothiazolin-3-one, that is, the chromatographic peak is scanned with the full wavelength, that is, when each point (or any time) of the chromatogram is scanned, the ultraviolet spectrum The angle of a vector direction can be obtained, thereby obtaining a multi-dimensional space angle, which is called the purity angle. The purity angle reflects the singleness of the chromatographic peak (that is, the purity of the chromatographic peak). The range of the purity angle is from 0° to 90°. The lower the value, the higher the purity of the chromatographic peak, and the lower the purity of the peak. In , the intersection of the purity curve and the chromatographic peak indicates that the spectrum before and after the retention time is quite different from the spectrum at the peak of the chromatographic peak, the purity angle is larger, and there may be impurities. The purity angle can be obtained quantitatively by calculating each wavelength of each point of the chromatographic peak (the actual calculation is a complex formula, which is automatically completed by the Millennium2101 chromatographic management system and 996 software), and then each spectrum is calculated. Compare. [8]

According to the principle of spectral comparison, the standard sample database is searched , which makes the determination and quality analysis of CMIT/MIT( isothiazolone biocide) preservatives simple and reliable.


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CMIT/MIT( isothiazolone biocide) preservative is a second-class corrosive product . Pay attention to safety protection during operation and avoid contact with skin and mucous membranes . Once in contact, rinse with running water immediately and repeatedly.

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