Acetamide

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Acetamide
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Template:Longitem Template:Chembox Elements/molecular formula
Molar mass Template:Chem molar mass
Appearance colorless, hygroscopic solid
Odor odorless
mouse-like with impurities
Density 1.159 g cm−3
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Solubility ethanol 500 g L−1[2]
pyridine 166.67 g L−1[2]
soluble in chloroform, glycerol, benzene[2]
log P −1.26
Vapor pressure 1.3 Pa
Acidity (pKa) 15.1 (25 °C, H2O)[3]
Template:Longitem −0.577 × 10−6 cm3 g−1
Template:Longitem 1.4274
Viscosity 2.052 cP (91 °C)
Template:Longitem trigonal
Template:Longitem 91.3 J·mol−1·K−1
Template:Longitem 115.0 J·mol−1·K−1
Template:Longitem −317.0 kJ·mol−1
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Acetamide (systematic name: ethanamide) is an organic compound with the formula CH3CONH2. It is an amide derived from ammonia and acetic acid. It finds some use as a plasticizer and as an industrial solvent.[4] The related compound N,N-dimethylacetamide (DMA) is more widely used, but it is not prepared from acetamide. Acetamide can be considered an intermediate between acetone, which has two methyl (CH3) groups either side of the carbonyl (CO), and urea which has two amide (NH2) groups in those locations. Acetamide is also a naturally occurring mineral[5] with the IMA symbol: Ace.[6]

Production

File:CSD CIF ACEMID06.jpg
Structure of acetamide hydrogen-bonded dimer from X-ray crystallography. Selected distances: C-O: 1.243, C-N, 1.325, N---O, 2.925 Å. Color code: red = O, blue = N, gray = C, white = H.[7]

Laboratory scale

Acetamide can be produced in the laboratory from ammonium acetate by dehydration:[8]

[NH4][CH3CO2] → CH3C(O)NH2 + H2O

Alternatively acetamide can be obtained in excellent yield via ammonolysis of acetylacetone under conditions commonly used in reductive amination.[9]

It can also be made from anhydrous acetic acid, acetonitrile and very well dried hydrogen chloride gas, using an ice bath, alongside more valuable reagent acetyl chloride. Yield is typically low (up to 35%), and the acetamide made this way is generated as a salt with HCl.

Industrial scale

In a similar fashion to some laboratory methods, acetamide is produced by dehydrating ammonium acetate or via the hydration of acetonitrile, a byproduct of the production of acrylonitrile:[4]

CH3CN + H2O → CH3C(O)NH2

Uses

Acetamide is used as a plasticizer and an industrial solvent.[4] Molten acetamide is good solvent with a broad range of applicability. Notably, its dielectric constant is higher than most organic solvents, allowing it to dissolve inorganic compounds with solubilities closely analogous to that of water.[10] Acetamide has uses in electrochemistry and the organic synthesis of pharmaceuticals, pesticides, and antioxidants for plastics.[11] It is a precursor to thioacetamide.[12]

Occurrence

Acetamide has been detected near the center of the Milky Way galaxy.[13] This finding is potentially significant because acetamide has an amide bond, similar to the essential bond between amino acids in proteins. This finding lends support to the theory that organic molecules that can lead to life (as we know it on Earth) can form in space.

On 30 July 2015, scientists reported that upon the first touchdown of the Philae lander on comet 67/P's surface, measurements by the COSAC and Ptolemy instruments revealed sixteen organic compounds, four of which – acetamide, acetone, methyl isocyanate, and propionaldehyde[14][15][16] – were seen for the first time on a comet.

In addition, acetamide is found infrequently on burning coal dumps, as a mineral of the same name.[17][18]

References

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  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ a b c d The Merck Index, 14th Edition, 36
  3. ↑ Script error: No such module "citation/CS1".
  4. ↑ a b c Template:Ullmann
  5. ↑ Mindat: Naturally occurring acetamide
  6. ↑ Script error: No such module "Citation/CS1".
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  13. ↑ Script error: No such module "Citation/CS1".
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External links

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