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Acetone cyanohydrin

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Acetone cyanohydrin
Skeletal formula of acetone cyanohydrin
Ball and stick model of acetone cyanohydrin
Spacefill model of acetone cyanohydrin
Names
IUPAC name
2-Hydroxy-2-methylpropanenitrile[2]
Other names
Cyanohydrin-2-propanone[1]

α-Hydroxyisobutyronitrile[1]

2-Hydroxy-2-methyl-propionitrile[1]
Identifiers
3D model (JSmol)
3DMet
ChEBI
ChemSpider
DrugBank
EC Number
  • 200-909-4
KEGG
MeSH acetone+cyanohydrin
RTECS number
  • OD9275000
Properties
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)
1.399
Thermochemistry
−121.7 to −120.1 kJ mol−1
−2.4514 to −2.4498 MJ mol−1
Hazards
Safety data sheet fishersci.com
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no codeNFPA 704 four-colored diamond
1
4
2
Flash point 75 °C (167 °F; 348 K)
Explosive limits 2.25–11%
Lethal dose or concentration (LD, LC):
  • 15.8 mg kg−1 (dermal, rabbit)
  • 18.65 mg kg−1 (oral, rat)
NIOSH (US health exposure limits):
PEL (Permissible)
none[1]
REL (Recommended)
C 1 ppm (4 mg/m3) [15-minute][1]
IDLH (Immediate danger)
N.D.[1]
Related compounds
Related alkanenitriles
Related compounds
DBNPA
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☑Y verify (what is ☑Y☒N ?)
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[edit source | edit]

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

Synthesis of acetone cyanohydrin.png

Considering the high toxicity of acetone cyanohydrin, a lab scale production has been developed using microreactor technology.[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[edit source | edit]

It is used as a surrogate in place of HCN, as illustrated by this synthesis of lithium cyanide:[6]

(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.[7] In the hydrocyanation reaction of butadiene, the transfer is irreversible.[8]

Acetone cyanohydrin is an intermediate en route to methyl methacrylate. Treated with sulfuric acid give the sulfate ester of the methacrylamide, methanolysis of which gives ammonium bisulfate and methyl methacrylate.[9]

Natural occurrence[edit source | edit]

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

Safety[edit source | edit]

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

References[edit source | edit]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  2. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  3. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).; Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  4. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  5. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).; Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  6. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  7. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  8. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil).
  9. Lua error in ...ribunto/includes/engines/LuaCommon/lualib/mwInit.lua at line 23: bad argument #1 to 'old_ipairs' (table expected, got nil)..

External links[edit source | edit]