Editing Isocyanate (section)

=== With nucleophiles ===
Isocyanates are [[electrophiles]], and as such they are reactive toward a variety of [[nucleophiles]] including [[alcohols]], [[amines]], and even water having a higher reactivity compared to structurally analogous [[isothiocyanates]].<ref>{{Cite journal|last1=Li|first1=Zhen|last2=Mayer|first2=Robert J.|last3=Ofial|first3=Armin R.| last4=Mayr|first4=Herbert|date=2020-04-27|title= From Carbodiimides to Carbon Dioxide: Quantification of the Electrophilic Reactivities of Heteroallenes|journal=Journal of the American Chemical Society|volume=142|issue=18|pages=8383–8402|doi=10.1021/jacs.0c01960|pmid=32338511|bibcode=2020JAChS.142.8383L |s2cid=216557447 }}</ref>

Upon treatment with an alcohol, an isocyanate forms a [[carbamate|urethane]] linkage:
: {{chem2 | ROH + R'NCO -> ROC(O)N(H)R' }}

where R and R' are [[alkyl]] or [[aryl]] groups.
If a diisocyanate is treated with a compound containing two or more hydroxyl groups, such as a [[diol]] or a [[polyol]], polymer chains are formed, which are known as [[polyurethane]]s.

:[[File:Polyurethane synthesis.tif|thumb|left|700px|Synthesis of polyurethane from a diisocyanate and a diol]]{{clear-left}}

Isocyanates react with water to form [[carbon dioxide]]:
: {{Chem2 | RNCO + H2O -> RNH2 + CO2 }}
This reaction is exploited in tandem with the production of polyurethane to give polyurethane foams.  The carbon dioxide functions as a [[blowing agent]].<ref name="Coleman2019">{{cite book | last1=Coleman | first1=M.M. |last2=Painter |first2=P. | title=Fundamentals of Polymer Science: An Introductory Text, Second Edition | publisher=CRC Press | year=2019 | isbn=978-1-351-44639-6 | url=https://books.google.com/books?id=VvSDDwAAQBAJ | page=39}}</ref>

Isocyanates also react with amines to give [[urea]]s:
:{{chem2 | R2NH + R'NCO -> R2NC(O)N(H)R' }}
The addition of an isocyanate to a urea gives a [[biuret]]:
:{{chem2 | R2NC(O)N(H)R' + R'\'NCO -> R2NC(O)NR'C(O)NHR'\' }}
Reaction between a di-isocyanate and a compound containing two or more amine groups produces long polymer chains known as [[polyurea]]s.

[[Carbodiimide]]s are produced by the decarboxylation of alkyl and aryl isocyanate using phosphine oxides as a catalyst:<ref>{{cite journal |doi=10.15227/orgsyn.043.0031|title=Diphenylcarbodiimide|journal=Organic Syntheses|year=1963|volume=43|page=31|first1=T. W.|last1=Campbell|first2=J. J.|last2=Monagle}}</ref>
:{{chem2 | C6H11NCO -> (C6H11N)2C  +  CO2 }}