CR gas

**CR gas**
Names
	Preferred IUPAC name Dibenzo[b,f][1,4]oxazepine
Identifiers
CAS Number	257-07-8 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL1085100 ;
ChemSpider	8858 ;
ECHA InfoCard	100.114.990
IUPHAR/BPS	6472;
PubChem CID	9213;
UNII	C1Q77A87V1 ;
CompTox Dashboard (EPA)	DTXSID8059764 ;
	InChI InChI=1S/C13H9NO/c1-3-7-12-10(5-1)9-14-11-6-2-4-8-13(11)15-12/h1-9H Key: NPUACKRELIJTFM-UHFFFAOYSA-N ; InChI=1/C13H9NO/c1-3-7-12-10(5-1)9-14-11-6-2-4-8-13(11)15-12/h1-9H Key: NPUACKRELIJTFM-UHFFFAOYAI;
	SMILES N\1=C\c3c(Oc2c/1cccc2)cccc3;
Properties
Chemical formula	C13H9NO
Molar mass	195.221 g·mol−1
Density	1.160±0.10 g/cm3
Melting point	73 °C (163 °F; 346 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

CR gas or dibenzoxazepine (chemical name dibenz[b,f][1,4]oxazepine, is an incapacitating agent and a lachrymatory agent. CR was developed by the British Ministry of Defence as a riot control agent in the late 1950s and early 1960s. A report from the Porton Down laboratories described exposure as "like being thrown blindfolded into a bed of stinging nettles", and it earned the nickname "firegas".

In its effects, CR gas is very similar to CS gas (o-chlorobenzylidene malononitrile), but twice as potent, even though there is little structural resemblance between the two. For example, 2 mg of dry CR causes skin redness in 10 min, 5 mg causes burning and erythremia, and 20 mg‍—‍strong pain. Water usually amplifies the pain effect of CR on skin. CR aerosols cause irritation at concentrations of 0.2 mcg/L, becoming intolerable at 3 mcg/L. The LD₅₀ of CR through air inhalation 350 mg·min/L.