Isocyanate

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Isocyanate

Isocyanate is the functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
of atoms –N=C=O (1 nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
, 1 carbon

Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
, 1 oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
), not to be confused with the cyanate

Cyanate

The cyanate ion is an anion consisting of one oxygen atom, one carbon atom, and one nitrogen atom, [OCN]-, in that order, and possesses 1 unit of negative electric charge, borne mainly by the nitrogen atom....
functional group which is arranged as –O–C=N. Any organic compound

Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
which contains an isocyanate group may also be referred to in brief as an isocyanate. An isocyanate may have more than one isocyanate group. An isocyanate that has two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for reaction with polyol

Polyol

The name polyols refers to alcohols containing multiple hydroxyl groups. In two technological disciplines polyols have special meaning: food science and polymer chemistry....
s in the production of polyurethane

Polyurethane

A polyurethane, commonly abbreviated PU, is any polymer consisting of a chain of organic chemistry units joined by carbamate links. Polyurethane polymers are formed by reacting a monomer containing at least two isocyanate functional groups with another monomer containing at least two alcohol groups in the presence of a catalyst....
s.

isocyanate group reacts with the hydroxyl

Hydroxyl

Hydroxyl in chemistry stands for a molecule consisting of an oxygen atom and a hydrogen atom connected by a covalent bond. The neutral form is a hydroxyl Radical and the hydroxyl anion is called a hydroxide....
functional group to form a urethane

Carbamate

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Encyclopedia

Isocyanate is the functional group

Functional group

Nitrogen

Carbon

Oxygen

Cyanate

Organic compound

Polyol

Polyurethane

Chemistry

The isocyanate group reacts with the hydroxyl

Hydroxyl

Carbamate

Carbamates, or urethanes, are a group of organic compounds sharing a common functional group with the general structure -NHO-. Carbamates are esters of carbamic acid, NH2COOH, an unstable compound....
linkage. If a diisocyanate is reacted with a compound containing two or more hydroxyl groups (a polyol), long polymer chains are formed, known as polyurethane

Polyurethane

Polyurea

Polyurea is a type elastomer that is derived from the reaction product of an isocyanate component and a synthetic resin blend component. The isocyanate can be aromatic or aliphatic in nature....
s.

The isocyanate group can react with itself. Aliphatic

Aliphatic compound

In organic chemistry, compounds composed of carbon and hydrogen are divided into two classes: aromatic compounds, which contain benzene rings or similar rings of atoms, and aliphatic compounds , which do not contain aromatic rings....
diisocyanates can form trimer

Trimer (chemistry)

In chemistry a trimer is a chemical reaction of three identical molecules. Trimers are typically encountered as cyclic trimers. Chemical compounds that very easily form trimers are aliphatic isocyanates and cyanic acids as an early intermediate in a polymerisation process, see also oligomers....
s, known as biuret

Biuret

Biuret is a condensation compound of urea, equivalent to two molecules of urea less one of ammonia. It is a white solid soluble in hot water and decomposes at 186?189 Celsius....
s.

The isocyanate group reacts with water to form carbon dioxide

Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
(CO₂). Carbon dioxide is used as a blowing agent (in situ) in order to produce polyurethane foams. (See Fundamentals to Polymer Science, An Introductory Text, p. 39, by Paul Painter and Michael Coleman, Second Edition, for more information).

Common compounds

A monofunctional isocyanate of industrial significance is methyl isocyanate

Methyl isocyanate

Methyl isocyanate is an organic compound with the molecular formula C2H3NO, arranged as H3C-N=C=O. Synonyms are isocyanatomethane, methyl carbylamine, and MIC....
(MIC), which is used in the manufacture of pesticides.

The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate

Methylene diphenyl diisocyanate

Methylene diphenyl diisocyanate, most often abbreviated as MDI, is an aromaticity isocyanate. It exists in three isomers, 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI....
(MDI), 34.1% was toluene diisocyanate

Toluene diisocyanate

Toluene diisocyanate is an Aromaticity isocyanate. It is produced for reaction with polyols to form polyurethanes. It exists in two isomers, 2,4-TDI and 2,6-TDI ....
(TDI), 3.4% was the total for hexamethylene diisocyanate

Hexamethylene diisocyanate

Hexamethylene diisocyanate is an organic compound in the class known as isocyanates. More specifically, it is an Aliphatic compound diisocyanate....
(HDI) and isophorone diisocyanate

Isophorone diisocyanate

Isophorone diisocyanate is an organic compound in the class known as isocyanates. More specifically, it is an Aliphatic compound diisocyanate. It is produced in relatively small quantities, accounting for only 3.4% of the global diisocyanate market in the year 2000....
(IPDI), and 1.2% was the total for various others.

Hazards

The reactivity of isocyanates makes them harmful to living tissue. They are toxic

Toxicity

Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver ....
and are known to cause asthma

Asthma

Asthma is a common chronic obstructive pulmonary disease, in which the Lung constrict, become inflammation, and are lined with excessive amounts of thickened mucus, often in response to one or more triggers....
in humans, both through inhalation exposure and dermal contact. Exposure to isocyanates and their vapors should be avoided. For the safe handling of isocyanates,information is available from ISOPA, the European Diisocyanate and Polyol Producers Association.

External links

, from the website of the National Institute for Occupational Safety and Health (NIOSH)
, website of the UK Health and Safety Executive, useful search terms on this site — isocyanates, MVR, asthma

Isocyanate

Chemistry

Common compounds

Hazards

See also

External links