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Acetone cyanohydrin (ACH) is an
Considering the high toxicity of acetone cyanohydrin, a lab scale production has been developed using a microreactor-scale flow chemistry 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.
CDC - NIOSH Pocket Guide to Chemical Hazards - Acetone Cyanohydrin
Cyanohydrins
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
used in the production of methyl methacrylate, the monomer
A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization.
Classification
Chemis ...
of the transparent plastic polymethyl methacrylate (PMMA), also known as acrylic. It liberates hydrogen cyanide
Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the chemical formula, formula HCN and structural formula . It is a highly toxic and flammable liquid that boiling, boils slightly above room temperature, at . HCN is ...
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 withacetone
Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...
, followed by acidification:
:
Considering the high toxicity of acetone cyanohydrin, a lab scale production has been developed using a microreactor-scale flow chemistry 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.
Reactions
Acetone cyanohydrin is an intermediate en route to methyl methacrylate. Treatment withsulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
gives the sulfate ester of the methacrylamide, methanolysis of which gives ammonium bisulfate and methyl methacrylate.
It is used as a surrogate in place of HCN, as illustrated by its use as a precursor to lithium cyanide:
:(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. In the hydrocyanation reaction of butadiene, the transfer is irreversible.
Natural occurrence
Cassava
''Manihot esculenta'', common name, commonly called cassava, manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America, from Brazil, Paraguay and parts of the Andes. Although ...
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 USEmergency Planning and Community Right-to-Know Act
The Emergency Planning and Community Right-to-Know Act of 1986 is a United States federal law passed by the 99th United States Congress located at Title 42, Chapter 116 of the U.S. Code, concerned with emergency response preparedness.
On Octobe ...
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
Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the chemical formula, formula HCN and structural formula . It is a highly toxic and flammable liquid that boiling, boils slightly above room temperature, at . HCN is ...
.
References
External links
*{{SIDS, name=Acetone cyanohydrin, id=75865CDC - NIOSH Pocket Guide to Chemical Hazards - Acetone Cyanohydrin
Cyanohydrins