Acetone cyanohydrin

Acetone cyanohydrin
Ball and stick model of acetone cyanohydrin	Spacefill model of acetone cyanohydrin
Names
	Preferred IUPAC name 2-Hydroxy-2-methylpropanenitrile
	Other names Cyanohydrin-2-propanone; α-Hydroxyisobutyronitrile; 2-Hydroxy-2-methyl-propionitrile;
Identifiers
CAS Number	75-86-5 ;
3D model (JSmol)	Interactive image;
3DMet	B00479;
Beilstein Reference	605391
ChEBI	CHEBI:15348 ;
ChemSpider	6166 ;
DrugBank	DB02203 ;
ECHA InfoCard	100.000.828
EC Number	200-909-4;
KEGG	C02659 ;
MeSH	acetone+cyanohydrin
PubChem CID	6406;
RTECS number	OD9275000;
UNII	CO1YOV1KFI ;
UN number	1541
CompTox Dashboard (EPA)	DTXSID7025427 ;
	InChI InChI=1S/C4H7NO/c1-4(2,6)3-5/h6H,1-2H3 Key: MWFMGBPGAXYFAR-UHFFFAOYSA-N ;
	SMILES CC(C)(O)C#N;
Properties
Chemical formula	C4H7NO
Molar mass	85.106 g·mol−1
Appearance	Colourless liquid
Density	932 mg·mL−1
Melting point	−21.2 °C; −6.3 °F; 251.9 K
Boiling point	95 °C; 203 °F; 368 K
Vapor pressure	2 kPa (at 20 °C)
Refractive index (nD)	1.399
Thermochemistry
Std enthalpy of; formation (ΔfH⦵298)	−121.7 to −120.1 kJ·mol−1
Std enthalpy of; combustion (ΔcH⦵298)	−2.4514 to −2.4498 MJ·mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H300, H310, H330, H410
Precautionary statements	P260, P273, P280, P284, P301+P310
NFPA 704 (fire diamond)	4 1 2
Flash point	75 °C (167 °F; 348 K)
Explosive limits	2.25–11%
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	15.8 mg·kg−1 (dermal, rabbit); 18.65 mg·kg−1 (oral, rat);
	NIOSH (US health exposure limits):
PEL (Permissible)	None
REL (Recommended)	C 1 ppm (4 mg·m−3) [15-minute]
IDLH (Immediate danger)	N.D.
Safety data sheet (SDS)	fishersci.com
Related compounds
Related alkanenitriles	Acetonitrile; Aminoacetonitrile; Glycolonitrile; Cyanogen; Propanenitrile; Aminopropionitrile; Malononitrile; Pivalonitrile; Butyronitrile; Succinonitrile; Tetramethylsuccinonitrile;
Related compounds	DBNPA
	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

Acetone cyanohydrin (ACH) is an organic compound used in the production of methyl methacrylate, the monomer of the transparent plastic polymethyl methacrylate (PMMA), also known as acrylic. It liberates hydrogen cyanide easily, so it is used as a source of such. For this reason, this cyanohydrin is also highly toxic.

Preparation

In the laboratory, this compound may be prepared by treating sodium cyanide with acetone, followed by acidification:^[3]

Considering the high toxicity of acetone cyanohydrin, a lab scale production has been developed using a microreactor-scale flow chemistry^[4] to avoid needing to manufacture and store large quantities of the reagent. Alternatively, a simplified procedure involves the action of sodium or potassium cyanide on the sodium bisulfite adduct of acetone prepared in situ. This gives a less pure product, one that is nonetheless suitable for most syntheses.^[5]

Reactions

Acetone cyanohydrin is an intermediate en route to methyl methacrylate.^[6] Treatment with sulfuric acid gives the sulfate ester of the methacrylamide,^{[clarification needed]} methanolysis of which gives ammonium bisulfate and methyl methacrylate.^[7]

It is used as a surrogate in place of HCN, as illustrated by its use as a precursor to lithium cyanide:^[8]

(CH₃)₂C(OH)CN + LiH → (CH₃)₂CO + LiCN + H₂

In transhydrocyanation, an equivalent of HCN is transferred from acetone cyanohydrin to another acceptor, with acetone as byproduct. The transfer is an equilibrium process, initiated by base. The reaction can be driven by trapping reactions or by the use of a superior HCN acceptor, such as an aldehyde.^[9] In the hydrocyanation reaction of butadiene, the transfer is irreversible.^[10]

Natural occurrence

Cassava tubers contain linamarin, a glucoside of acetohydrin, and the enzyme linamarase for hydrolysing the glucoside. Crushing the tubers releases these compounds and produces acetone cyanohydrin.

Safety

Acetone cyanohydrin is classified as an extremely hazardous substance in the US Emergency Planning and Community Right-to-Know Act and carries an RCRA P069 waste code. The principal hazards of acetone cyanohydrin arise from its ready decomposition on contact with water, which releases highly toxic hydrogen cyanide.

References

^ ^a ^b ^c ^d ^e ^f NIOSH Pocket Guide to Chemical Hazards. "#0005". National Institute for Occupational Safety and Health (NIOSH).
^ "acetone cyanohydrin - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification. Retrieved 8 June 2012.
^ Cox, R. F. B.; Stormont, R. T. "Acetone Cyanohydrin". Organic Syntheses; Collected Volumes, vol. 2, p. 7.
^ Heugebaert, Thomas S. A.; Roman, Bart I.; De Blieck, Ann; Stevens, Christian V. (2010-08-11). "A safe production method for acetone cyanohydrin". Tetrahedron Letters. 51 (32): 4189–4191. doi:10.1016/j.tetlet.2010.06.004.
^ Wagner, E. C.; Baizer, Manuel. "5,5-Dimethylhydantoin". Organic Syntheses; Collected Volumes, vol. 3, p. 323.
^ Wiley, Richard H.; Waddey, Walter E. (1949). "Methacrylamide". Organic Syntheses. 29: 61. doi:10.15227/orgsyn.029.0061.
^ Bauer, William Jr. "Methacrylic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a16_441. ISBN 978-3527306732..
^ Tom Livinghouse (1981). "Trimethylsilyl Cyanide: Cyanosilylation of p-Benzoquinone". Org. Synth. 60: 126. doi:10.15227/orgsyn.060.0126.
^ Haroutounian, Serkos A. (2001). "Acetone Cyanohydrin". Encyclopedia of Reagents for Organic Synthesis. eEROS. doi:10.1002/047084289X.ra014. ISBN 0471936235.
^ Bini, L.; Müller, C.; Wilting, J.; von Chrzanowski, L.; Spek, A. L.; Vogt, D. (October 2007). "Highly selective hydrocyanation of butadiene toward 3-pentenenitrile". J. Am. Chem. Soc. 129 (42): 12622–12623. doi:10.1021/ja074922e. hdl:1874/26892. PMID 17902667.