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Acetamide
View on Wikipediafrom Wikipedia
| |||
| Names | |||
|---|---|---|---|
| Preferred IUPAC name
Acetamide[1] | |||
| Systematic IUPAC name
Ethanamide | |||
| Other names
Acetic acid amide
Acetylamine | |||
| Identifiers | |||
3D model (JSmol)
|
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| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| DrugBank | |||
| ECHA InfoCard | 100.000.430 | ||
| EC Number |
| ||
| KEGG | |||
PubChem CID
|
|||
| RTECS number |
| ||
| UNII | |||
CompTox Dashboard (EPA)
|
|||
| |||
| |||
| Properties | |||
| C2H5NO | |||
| Molar mass | 59.068 g·mol−1 | ||
| Appearance | colorless, hygroscopic solid | ||
| Odor | odorless mouse-like with impurities | ||
| Density | 1.159 g cm−3 | ||
| Melting point | 79 to 81 °C (174 to 178 °F; 352 to 354 K) | ||
| Boiling point | 221.2 °C (430.2 °F; 494.3 K) (decomposes) | ||
| 2000 g L−1[2] | |||
| 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] | ||
| −0.577 × 10−6 cm3 g−1 | |||
Refractive index (nD)
|
1.4274 | ||
| Viscosity | 2.052 cP (91 °C) | ||
| Structure | |||
| trigonal | |||
| Thermochemistry[4] | |||
Heat capacity (C)
|
91.3 J·mol−1·K−1 | ||
Std molar
entropy (S⦵298) |
115.0 J·mol−1·K−1 | ||
Std enthalpy of
formation (ΔfH⦵298) |
−317.0 kJ·mol−1 | ||
| Hazards | |||
| GHS labelling: | |||
| |||
| Warning | |||
| H351 | |||
| P201, P202, P281, P308+P313, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 126 °C (259 °F; 399 K) | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
|
7000 mg kg−1 (rat, oral) | ||
| Safety data sheet (SDS) | External MSDS | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |||
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.[5] 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[6] with the IMA symbol: Ace.[7]
Production
[edit]
Laboratory scale
[edit]Acetamide can be produced in the laboratory from ammonium acetate by dehydration:[9]
- [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.[10]
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
[edit]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:[5]
- CH3CN + H2O → CH3C(O)NH2
Uses
[edit]Acetamide is used as a plasticizer and an industrial solvent.[5] 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.[11] Acetamide has uses in electrochemistry and the organic synthesis of pharmaceuticals, pesticides, and antioxidants for plastics.[12] It is a precursor to thioacetamide.[13]
Occurrence
[edit]Acetamide has been detected near the center of the Milky Way galaxy.[14] 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[15][16][17] – 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.[18][19]
References
[edit]- ^ "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 841. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
- ^ a b c d The Merck Index, 14th Edition, 36
- ^ Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. pp. 5–88. ISBN 9781498754293.
- ^ John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99th ed.). CRC Press. pp. 5–3. ISBN 978-1138561632.
- ^ a b c Cheung, H.; Tanke, R. S.; Torrence, G. P. "Acetic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_045.pub2. ISBN 978-3-527-30673-2.
- ^ Mindat: Naturally occurring acetamide
- ^ Warr, L.N. (2021). "IMA-CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Bats, Jan W.; Haberecht, Monika C.; Wagner, Matthias (2003). "A new refinement of the orthorhombic polymorph of acetamide". Acta Crystallographica Section E. 59 (10): o1483 – o1485. doi:10.1107/S1600536803019494.
- ^ Coleman, G. H.; Alvarado, A. M. (1923). "Acetamide". Organic Syntheses. 3: 3. doi:10.15227/orgsyn.003.0003; Collected Volumes, vol. 1, p. 3.
- ^ Schwoegler, Edward J.; Adkins, Homer (1939). "Preparation of Certain Amines". J. Am. Chem. Soc. 61 (12): 3499–3502. doi:10.1021/ja01267a081.
- ^ Stafford, O. F. (1933). "Acetamide as a Solvent". J. Am. Chem. Soc. 55 (10): 3987–3988. doi:10.1021/ja01337a011.
- ^ Wagner, Frank S. (2002). Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons. doi:10.1002/0471238961.0103052023010714.a02.pub2. ISBN 9780471238966.
- ^ Schwarz, G. (1945). "2,4-Dimethylthiazole". Organic Syntheses. 25: 35; Collected Volumes, vol. 3, p. 332.
- ^ Hollis, J. M.; Lovas, F. J.; Remijan, A. J.; Jewell, P. R.; Ilyushin, V. V.; Kleiner, I. (2006). "Detection of Acetamide (CH3CONH2): The Largest Interstellar Molecule with a Peptide Bond". Astrophys. J. 643 (1): L25 – L28. Bibcode:2006ApJ...643L..25H. doi:10.1086/505110.
- ^ Jordans, Frank (30 July 2015). "Philae probe finds evidence that comets can be cosmic labs". The Washington Post. Associated Press. Archived from the original on 23 December 2018. Retrieved 30 July 2015.
- ^ "Science on the Surface of a Comet". European Space Agency. 30 July 2015. Retrieved 30 July 2015.
- ^ Bibring, J.-P.; Taylor, M.G.G.T.; Alexander, C.; Auster, U.; Biele, J.; Finzi, A. Ercoli; Goesmann, F.; Klingehoefer, G.; Kofman, W.; Mottola, S.; Seidenstiker, K.J.; Spohn, T.; Wright, I. (31 July 2015). "Philae's First Days on the Comet - Introduction to Special Issue". Science. 349 (6247): 493. Bibcode:2015Sci...349..493B. doi:10.1126/science.aac5116. PMID 26228139.
- ^ "Acetamide". Mindat.org.
- ^ "Acetamide" (PDF). Handbook of Mineralogy. RRUFF Project.
External links
[edit]
Look up acetamide in Wiktionary, the free dictionary.
- International Chemical Safety Card 0233
- "Acetamide". Webmineral.org.
Acetamide
View on Grokipediafrom Grokipedia
Acetamide, systematically named ethanamide, is the simplest amide derived from acetic acid and ammonia, with the molecular formula CH₃CONH₂ and a molecular weight of 59.07 g/mol. It exists as a colorless, hygroscopic crystalline solid that is odorless when pure but may exhibit a mousy odor if impure, and it readily absorbs moisture from the air.[1]
Key physical properties include a melting point of 81 °C, a boiling point of 222 °C at standard pressure, and a density of 1.159 g/cm³ at 20 °C. Acetamide is highly soluble in water (approximately 2,250 g/L at 25 °C), as well as in ethanol, chloroform, and glycerol, making it versatile for various chemical applications. Chemically, it is a polar organic compound that acts as a weak base and can undergo hydrolysis to form acetic acid and ammonia under acidic or basic conditions.[1]
Acetamide is industrially produced through the dehydration of ammonium acetate or by the reaction of ethyl acetate with aqueous ammonia, processes that release it into the environment via industrial waste streams. Its primary uses include serving as a solvent and plasticizer in the manufacture of films and coatings, a stabilizer for hydrogen peroxide, and a solubilizer in organic synthesis for pharmaceuticals, pesticides, and polymers. Additionally, it finds application as a humectant in cosmetics, and a component in soldering fluxes and explosives.[1]
Due to its potential as a possible human carcinogen (classified as IARC Group 2B) and its irritant effects on skin and eyes, acetamide requires careful handling in occupational settings, with exposure primarily occurring through inhalation or dermal contact in chemical and plastics industries.[1]
This reaction is particularly valuable in research settings for preparing thioamides that facilitate sulfur introduction into complex molecules without harsh conditions.[19][20] In electrochemical research, acetamide functions as a component in deep eutectic solvents (DES) and additives for advanced battery electrolytes, offering high ionic conductivity, low volatility, and stability at extreme potentials. For instance, acetamide-caprolactam DES-based electrolytes enable dendrite-free zinc plating/stripping in zinc-metal batteries, achieving an average Coulombic efficiency of 98.37% in Zn||Ti cells and stable cycling for over 2000 hours at 1 mA cm⁻² in symmetric cells, due to the formation of robust solid-electrolyte interphases.[21] Similarly, acetamide as a co-solvent in aqueous potassium-ion batteries widens the electrochemical stability window beyond that of pure water (1.23 V), supporting high-rate performance in sustainable energy storage systems.[22] These applications highlight acetamide's role in developing non-flammable, cost-effective alternatives to traditional carbonate solvents. Acetamide plays a crucial role in organic synthesis for research into pharmaceuticals, pesticides, and antioxidants, often through N-substitution reactions that introduce amide functionalities for enhanced bioactivity. In pharmaceutical development, N-substituted acetamide derivatives act as potent P2Y₁₄ receptor antagonists, inhibiting UDP-glucose-induced inflammatory responses with IC₅₀ values in the nanomolar range, as demonstrated in structure-activity relationship studies. For pesticides, novel thienylpyridyl-acetamide hybrids exhibit insecticidal activity against agricultural pests like aphids, with LC₅₀ values below 10 mg L⁻¹, attributed to disruption of insect nervous systems via nicotinic acetylcholine receptor modulation. In antioxidant research, acetamide derivatives, such as those bearing hydroxyimino or naphthyl groups, scavenge free radicals effectively in DPPH assays, showing IC₅₀ values comparable to ascorbic acid (around 20-50 μM), and protect cellular lipids from peroxidation in biomedical models. These N-substitution strategies, typically involving acylation of amines with acetamide precursors, enable modular synthesis of bioactive scaffolds.[23][24][25] In analytical chemistry, acetamide is employed as an internal standard in quantitative NMR (qNMR) spectroscopy for purity assessment in pharmaceuticals, providing a reliable proton signal at δ 2.00 ppm for calibration against analytes like antibiotics, with relative response factors determined via ¹H NMR integration. Its well-characterized IR spectrum, featuring distinct amide I (ν ≈ 1650 cm⁻¹) and amide II (ν ≈ 1550 cm⁻¹) bands, serves as a reference for calibrating Fourier-transform infrared (FTIR) instruments in studies of protein secondary structures and hydrogen bonding. These applications ensure accurate quantification and structural elucidation in low-volume laboratory analyses.[26] Recent post-2020 studies utilize acetamide as a model compound to investigate amide bond dynamics in peptide mimetics and catalytic hydrolysis, bridging computational and experimental biochemistry. Density functional theory (DFT) simulations of acetamide hydrolysis on ceria surfaces reveal low activation barriers (≈0.8 eV) for nucleophilic attack by water, informing catalyst design for peptide degradation in drug delivery systems and environmental remediation of amide pollutants. These models elucidate trans-cis isomerization and hydrogen bonding in peptide backbones, aiding the rational design of stable peptidomimetics for therapeutic applications.[27]
Properties
Physical Properties
Acetamide is a colorless, hygroscopic solid that typically appears as deliquescent crystals, often exhibiting a mousy odor.[1] Its molar mass is 59.068 g·mol⁻¹, reflecting the molecular formula C₂H₅NO.[1] The compound has a melting point ranging from 79 to 81 °C, allowing it to transition from solid to liquid at relatively low temperatures.[2] It boils at 221.2 °C but decomposes before fully vaporizing under standard conditions.[2] The density of acetamide is 1.159 g·cm⁻³ at 20 °C, indicating a moderately dense solid for an organic amide.[1] Acetamide demonstrates high solubility in water, with approximately 2000 g·L⁻¹ at 20 °C, and is also soluble in organic solvents such as ethanol, chloroform, glycerol, and benzene.[1] This solubility profile stems from its polar amide group, which facilitates interactions with both protic and aprotic solvents. Due to its hygroscopic nature, acetamide readily absorbs moisture from the air, leading to deliquescence and the formation of a hydrated state in humid environments.[1]Chemical Properties
Acetamide has the molecular formula CH₃CONH₂ and the IUPAC name ethanamide.[1] The molecule exhibits a planar structure in the amide group owing to resonance delocalization, wherein the nitrogen lone pair conjugates with the carbonyl π-system, lending partial double bond character to the C-N linkage. This resonance shortens the C-N bond length to approximately 1.334 Å, intermediate between typical single (1.47 Å) and double (1.27 Å) C-N bonds.[3] The amide functionality dictates acetamide's reactivity, particularly its susceptibility to hydrolysis. Under acidic or basic conditions, it undergoes nucleophilic attack at the carbonyl carbon, yielding acetic acid and ammonia according to the equation: [4][5] Acetamide also participates in dehydration reactions, converting to acetonitrile and water: [6] Acetamide demonstrates stability toward hydrolysis in neutral aqueous environments at ambient temperatures, requiring catalysis for appreciable reaction rates. However, it undergoes thermal decomposition at elevated temperatures exceeding 200°C, producing nitrogen oxides and other fumes.[7][8] Spectroscopic characterization highlights the amide group's features. Infrared spectroscopy reveals the carbonyl stretch at approximately 1650 cm⁻¹ and N-H stretches near 3300 cm⁻¹, reflecting the conjugated system's influence on vibrational modes.[9] In ¹H NMR spectroscopy, the methyl protons resonate at about 2.0 ppm, deshielded by the adjacent carbonyl.[10]Synthesis
Laboratory Synthesis
Acetamide is commonly synthesized in the laboratory through the dehydration of ammonium acetate, a straightforward method utilizing a simple precursor derived from acetic acid and ammonia. The reaction proceeds by heating ammonium acetate, which eliminates water to form acetamide, as shown in the equation: This process is typically conducted via fractional distillation or in a sealed vessel to facilitate water removal and product isolation, with temperatures ranging from 165–200 °C to ensure efficient dehydration while minimizing further decomposition to byproducts like acetonitrile. Yields for this method generally range from 70–90%, depending on the scale and conditions, such as using anhydrous conditions to prevent hydrolysis.[11][1][12] An alternative laboratory approach involves the partial ammonolysis of acetyl chloride or acetic anhydride with ammonia gas or ammonium hydroxide. For acetyl chloride, the reaction is: With acetic anhydride, it yields acetamide and acetic acid: These nucleophilic acyl substitution reactions are rapid and exothermic, often performed in a cooled vessel with excess ammonia to neutralize the byproduct acid or salt, achieving high conversion rates suitable for small-scale preparations.[1] Following synthesis, acetamide's hygroscopic nature necessitates prompt purification to obtain a dry, crystalline product. Recrystallization from hot water or ethanol is effective, dissolving the compound at elevated temperatures and cooling to precipitate pure white needles with melting point around 81 °C.[11]Industrial Production
The primary industrial production of acetamide utilizes the acid-catalyzed hydration of acetonitrile, a common byproduct from acrylonitrile manufacturing. In this process, acetonitrile (CH₃CN) reacts with water to form acetamide (CH₃CONH₂) under acidic conditions, typically employing sulfuric acid or metal-based catalysts at temperatures ranging from 80–100 °C.[13][14] This method offers high efficiency and scalability, leveraging the availability of acetonitrile derived from the petroleum-based ammoxidation of propylene.[15] Process control is essential to minimize byproducts, as over-hydration can lead to the formation of acetic acid through further hydrolysis of the amide. Unreacted acetonitrile is typically recycled to optimize yield and reduce waste, enhancing the overall economic viability of the operation.[16] Much of acetamide production is tied to acrylonitrile output, which influences costs due to fluctuations in acetonitrile feedstock pricing and availability. The economics are further shaped by energy inputs for the hydration reaction and downstream purification steps.[14] As of 2024, recent expansions include BASF SE increasing capacity by 15,000 metric tons annually at its Ludwigshafen site in September and Merck KGaA adding 8,000 metric tons through an acquisition in March; the global market was valued at USD 1.08 billion in 2024, projected to reach USD 2.22 billion by 2034 at a CAGR of 7.58%.[17] Historically, acetamide production shifted in the mid-20th century from the dehydration of ammonium acetate—formed by reacting acetic acid with ammonia—to the acetonitrile hydration route, driven by the commercialization of the Sohio acrylonitrile process in the 1950s, which provided a reliable, low-cost nitrile source for large-scale synthesis.[13][15] This transition improved scalability and integrated acetamide output with petrochemical streams.[16]Applications
Industrial Applications
Acetamide serves as a plasticizer in various industrial formulations, enhancing flexibility in materials such as lacquers, explosives, leather, textiles, paper, and plastics.[1] Its ability to improve pliability stems from its compatibility with polar substances, making it suitable for applications requiring durable yet flexible coatings and films.[1] Acetamide is also used as a stabilizer for hydrogen peroxide, as a humectant and antacid in cosmetics production, and as a wetting and penetrating agent in the textile industry.[1] In the chemical manufacturing sector, acetamide functions as a solvent in inks, dyes, and adhesives, leveraging its high solubility for organic and inorganic compounds. It acts as a stabilizer to suppress acid buildup in printing inks and lacquers, ensuring consistent performance during production.[1] Additionally, its polarity enables effective dissolution in these media, facilitating processing and application.[1] Acetamide is employed in soldering fluxes to remove oxide layers from metal surfaces, promoting clean and efficient joints in electronics and metalworking industries.[1] This role exploits its reducing properties when molten, allowing it to dissolve surface oxides on metals like aluminum and magnesium.[18]Research and Laboratory Uses
Acetamide serves as a key precursor in the laboratory synthesis of thioacetamide, a widely used reagent in qualitative analysis for metal sulfides and in organic synthesis. The conversion involves thionation of acetamide with phosphorus pentasulfide, typically under microwave-assisted or mechanochemical conditions to enhance efficiency and reduce environmental impact, yielding thioacetamide alongside phosphorus oxides and sulfides as byproducts:This reaction is particularly valuable in research settings for preparing thioamides that facilitate sulfur introduction into complex molecules without harsh conditions.[19][20] In electrochemical research, acetamide functions as a component in deep eutectic solvents (DES) and additives for advanced battery electrolytes, offering high ionic conductivity, low volatility, and stability at extreme potentials. For instance, acetamide-caprolactam DES-based electrolytes enable dendrite-free zinc plating/stripping in zinc-metal batteries, achieving an average Coulombic efficiency of 98.37% in Zn||Ti cells and stable cycling for over 2000 hours at 1 mA cm⁻² in symmetric cells, due to the formation of robust solid-electrolyte interphases.[21] Similarly, acetamide as a co-solvent in aqueous potassium-ion batteries widens the electrochemical stability window beyond that of pure water (1.23 V), supporting high-rate performance in sustainable energy storage systems.[22] These applications highlight acetamide's role in developing non-flammable, cost-effective alternatives to traditional carbonate solvents. Acetamide plays a crucial role in organic synthesis for research into pharmaceuticals, pesticides, and antioxidants, often through N-substitution reactions that introduce amide functionalities for enhanced bioactivity. In pharmaceutical development, N-substituted acetamide derivatives act as potent P2Y₁₄ receptor antagonists, inhibiting UDP-glucose-induced inflammatory responses with IC₅₀ values in the nanomolar range, as demonstrated in structure-activity relationship studies. For pesticides, novel thienylpyridyl-acetamide hybrids exhibit insecticidal activity against agricultural pests like aphids, with LC₅₀ values below 10 mg L⁻¹, attributed to disruption of insect nervous systems via nicotinic acetylcholine receptor modulation. In antioxidant research, acetamide derivatives, such as those bearing hydroxyimino or naphthyl groups, scavenge free radicals effectively in DPPH assays, showing IC₅₀ values comparable to ascorbic acid (around 20-50 μM), and protect cellular lipids from peroxidation in biomedical models. These N-substitution strategies, typically involving acylation of amines with acetamide precursors, enable modular synthesis of bioactive scaffolds.[23][24][25] In analytical chemistry, acetamide is employed as an internal standard in quantitative NMR (qNMR) spectroscopy for purity assessment in pharmaceuticals, providing a reliable proton signal at δ 2.00 ppm for calibration against analytes like antibiotics, with relative response factors determined via ¹H NMR integration. Its well-characterized IR spectrum, featuring distinct amide I (ν ≈ 1650 cm⁻¹) and amide II (ν ≈ 1550 cm⁻¹) bands, serves as a reference for calibrating Fourier-transform infrared (FTIR) instruments in studies of protein secondary structures and hydrogen bonding. These applications ensure accurate quantification and structural elucidation in low-volume laboratory analyses.[26] Recent post-2020 studies utilize acetamide as a model compound to investigate amide bond dynamics in peptide mimetics and catalytic hydrolysis, bridging computational and experimental biochemistry. Density functional theory (DFT) simulations of acetamide hydrolysis on ceria surfaces reveal low activation barriers (≈0.8 eV) for nucleophilic attack by water, informing catalyst design for peptide degradation in drug delivery systems and environmental remediation of amide pollutants. These models elucidate trans-cis isomerization and hydrogen bonding in peptide backbones, aiding the rational design of stable peptidomimetics for therapeutic applications.[27]