Isothiazolinone

Key takeaways

Isothiazolinone belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Isothiazolinone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Isothiazolinone from memory before moving on to harder problems.

Reference excerpt

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 preservatives and antimicrobials.

Synthesis Compared to many other simple heterocycles, the discovery of isothiazolinone is fairly recent, with reports first appearing in the 1960s. Isothiazolinones can be prepared on an industrial scale by the ring-closure of 3-mercaptopropanamides. These in turn are produced from acrylic acid via the 3-mercaptopropionic acid:

Ring-closure of the thiol-amide is typically effected by chlorination or oxidation of the 3-sulfanylpropanamide to the corresponding disulfide.

Many other routes have been developed, including addition of thiocyanate to propargyl amides.

Mechanism of action The antimicrobial activity of isothiazolinones is attributed to their ability to inhibit life-sustaining enzymes, specifically those enzymes with thiols at their active sites. It is established that isothiazolinones form mixed disulfides upon treatment with such species.

Applications The principal isothiazolones are:

Methylisothiazolinone (MIT, MI) Chloromethylisothiazolinone (CMIT, CMI, MCI) Benzisothiazolinone (BIT) Octylisothiazolinone (OIT, OI) Dichlorooctylisothiazolinone (DCOIT, DCOI) Butylbenzisothiazolinone (BBIT) These compounds all exhibit antimicrobial properties. They are used to control bacteria, fungi, and algae in cooling water systems, fuel storage tanks, pulp and paper mill water systems, oil extraction systems, wood preservation, and some paints. They are antifouling agents. They are frequently used in shampoos and other hair care products. Chloromethylisothiazolinone (CMIT) and 2-methyl-4-isothiazolin-3-one (methylisothiazolinone or MIT) are popular derivatives. A 3:1 mixture of CMIT:MIT is sold as Kathon. Kathon is supplied as a concentrated stock solution containing from 1.5 to 15% of CMIT/MIT. For applications the recommended use level is from 6 ppm to 75 ppm active isothiazolones. 4,5-Dichloro-2-n-octyl-4-isothiazolino-3-one (DCOI or Sea-Nine 211) is used especially as an antifouling agent, i.e. paint for ship hulls to prevent the formation of barnacles, etc.

Safety and environmental aspects Together with their wanted function, controlling or killing microorganisms, isothiazolinones also have undesirable effects. Many countries are looking at partial or full bans of the substance due to the known dangers in using the biocide.

Environmental Isothiazolinones have a high aquatic toxicity. DCOI has been detected in both port water and sediment samples in Osaka, Japan, especially in weakly circulating mooring areas. DCOI levels threaten various marine invertebrates. Isothiazolinones also are extremely toxic to fish.

Dermatitis In 2014 the European Commission Scientific Committee on Consumer Safety reported: "The dramatic rise in the rates of reported cases of contact allergy to MI, as detected by diagnostic patch tests, is unprecedented in Europe; there have been repeated warnings about the rise (Gonçalo M, Goossens A. 2013). The increase is primarily caused by increasing consumer exposure to MI from cosmetic products; exposures to MI in household products, paints and in the occupational setting also need to be considered. The delay in re-evaluation of the safety of MI in cosmetic products is of concern to the SCCS; it has adversely affected consumer safety." "It is unknown what proportion of the general population is now sensitized to MI and has not been confirmed as sensitized." In 2014, the European Commission Scientific Committee on Consumer Safety further issued a voluntary ban on "the mixture of Methylchloroisothiazolinone (and) Methylisothiazolinone (MCI/MI) from leave-on products such as body creams. The measure is aimed at reducing the risk from and the incidence of skin allergies. The preservative can still be used in rinse-off products such as shampoos and shower gels at a maximum concentration of 0.0015 % of a mixture in the ratio 3:1 of MCI/MI. The measure will apply for products placed on the market after 16 July 2015." Shortly thereafter, Canada moved to adopt similar measures in its Cosmetic Ingredients Hotlist. Additionally, new research into cross reactivity of MI-sensitized patients to variants benzisothiazolinone and octylisothiazolinone have found that reactions may occur if present in sufficient amounts.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Isothiazolinone

Start with the simplest possible case. Write down what Isothiazolinone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Isothiazolinone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Isothiazolinone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Isothiazolinone

In research: Isothiazolinone appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Isothiazolinone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Isothiazolinone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Isothiazolinones, Preservatives, so understanding it makes those chapters shorter.
In everyday life: Look for Isothiazolinone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Isothiazolinone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Isothiazolinone means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Isothiazolinone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Isothiazolinone in simple terms?

Isothiazolinone (; sometimes isothiazolone) is an organic compound with the formula (CH)2SN(H)CO. A white solid, it is structurally related to isothiazole.

Why does Isothiazolinone matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Isothiazolinone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Isothiazolinone.