Toxic and hazardous effects
Acetonitrile class is produced by heating a mixture of glacial acetic acid and acetamide. It is an important industrial solvent primarily used for the medium of organic synthesis (e.g. acetophenone, 1-naphthyl acetic acid, thiamine, etc.), extracting agent of fatty acids, and alcohol denaturant. During the production process, exposure to liquid or vapor may cause poisoning.
[Clinical manifestations] Acute and occupational acetonitrile poisoning is not uncommon. There are many reports at both home and abroad. Vapor of acetonitrile has mild irritation so it can cause some degree of upper respiratory tract irritation in the case of high concentrations. Compared with hydrogen cyanide, acetonitrile although causes symptoms like nausea, vomiting, abdominal pain, diarrhea, chest pain, fatigue, and weakness, even respiratory depression in severe case, sometimes also causes hypotension, coma, and convulsions, but its onset process is relatively slow with the incubation period over 4H; nor does it cause illness as severe as hydrogen cyanide. It also rarely causes sudden death; For poisoned patients, their heart rates, pulse rates as well as the respiration rates decrease. They often got pale faces and also suffer kidney impairment like protein-urine. The toxicity of acetonitrile is not only related to the released CN-in vivo but also related to itself and its thiocyanate metabolites. There are currently no clinic products for treating chronic acetonitrile poisoning.
[Diagnosis and differential diagnosis] Diagnosis is mainly based on reliable history of exposure to large doses of acetonitrile and clinical characteristics, the appearance of similar poisoning effects for mutual contractees plays a obvious indication role; timely determination of plasma CN-, SCN-, and acetonitrile content is also indicative, and is the biomarker of contacting with acetonitrile. However, it cannot tell the existence and extent of poisoning. Acute acetonitrile poisoning should be paid attention to distinguish with toxic poisoning caused by other industrial toxic substance such as organic solvents, asphyxiating gas. It should also be distinguished from cerebrovascular accident, diabetic coma.
[Treatment] Refer to the content on treatment of hydrogen cyanide but cut the dose of methemoglobin forming agent by half. In the presence of sodium thiosulfate, we can apply in early phase of the slowly acted methemoglobin generation agents such as amino benzene acetone (PAPP). Taken one orally each time, and can repeat for every 4H. For the next day, maintaining with sodium thiosulfate is enough. The dosage of sodium thiosulfate can also be cut by half two days later and totally stopped after 3 to 5 days.
Because of the toxic effect of the acetonitrile, when apply it as the antidote of cyanide antidote, people should be particularly participate in actively supportive treatment according to the symptomatic and supportive treatment, pay attention to the function maintenance of the heart, lung, brain, and apply rehydration for diuresis to accelerate the toxic discharge and reduce kidney impairment.
Acetonitrile is the raw material for preparing orthoacetate. It is also used as the intermediate of producing DV-acid methyl ester and 2-chloro-3,3,3-trifluoro-1-propenyl-2,2-dimethyl cyclopropanecarboxylate. It can also be used as the raw materials of making pyrimidine derivatives which is the intermediate of sulfonylurea herbicides. Moreover, it can be used for making vitamin B1 in the field of pharmaceutical industry and as the extraction agent of C4 fraction in the synthetic rubber industry.
Used as nitrile rubber monomer; Used for pharmaceutical industry and extraction of carbon IV.
As standard reference in chromatographic analysis; also as solvent and stationary phase for gas chromatography.
The major application of acetonitrile is as a solvent such as solvents for butadiene extraction, solvent for synthetic fibers and solvents for some special paints. In the oil industry, acetonitrile is used as the solvent for removing tar, phenol and other substances from petroleum hydrocarbons. It is also used as the solvent for extracting fatty acids from vegetable and animal oil in the fatty acid industry, and used as the reaction medium of the recrystallization of steroidal drugs in medicine industry. The binary azeotropic mixtures of acetonitrile and water are often used when a polar solvent of high dielectric constant is demanded: containing 84% acetonitrile, boiling point: 76 °C. Acetonitrile is used as the intermediate of pharmaceutical (vitamin B1) and spices, as the raw materials for making the synergist of triazine nitrogenous fertilizer, and also as a denaturant for ethyl alcohol. Moreover, it can also be used for synthesizing ethylamine, acetic acid, etc., and have many applications in textile dyeing and light industry.
It is used as the solvent of most inorganic compounds. It is also used as the solvent for spectrophotometric measurement, as a non-aqueous solvent, and as the diluents for determination of the carboxyl group. Furthermore, it is also applied in recrystallization of steroids and extraction of fatty acid, and also used as the solvents of High pressure liquid chromatography (HPLC).
Can be explosive when mixed with air.
The simplest organic nitrile
Acetonitrile is the simplest organic nitrile, usually also called as nitrile methyl cyanide and methane. It is a colorless transparent liquid at room temperature. It is highly volatile, with special smell like ether, and flammable with flame burning brightly. It is mutually soluble in water, methanol, carbon tetrachloride, methyl acetate, ethyl acetate, ethylene dichloride, and many other non-saturated hydrocarbon solvents. It is toxic and can be metabolized into hydrogen cyanide and thiocyanate. Acetonitrile is a good solvent with excellent performance and is an important organic intermediate. It is also widely used as a polar aprotic solvent. The biggest application of acetonitrile is as a solvent which can be used as the solvents for the synthesis of vitamin A, cortisone, carbon amine drugs and their intermediates solvent. It also used as an active medium solvent in the manufacture of vitamin B1 and amino acids. It can substitute chlorinated solvents as a vinyl coating, an extracting agent of fatty acid, a alcohol denaturant, the extracting agent of butadiene, and the solvent of acrylonitrile synthetic fibers. It also has a lot of applications in fabric dyeing, light industry, spice manufacturing, and photographic materials manufacturing.
TWA 70 mg/m3; STEL 105 mg/m3.
Commercial acetonitrile is a by-product of the reaction of propylene and ammonia to acrylonitrile. The following procedure that significantly reduces the levels of acrylonitrile, allyl alcohol, acetone and *benzene was used by Kiesel [Anal Chem 52 2230 1988]. Methanol (300mL) is added to 3L of acetonitrile fractionated at high reflux ratio until the boiling temperature rises from 64o to 80o, and the distillate becomes optically clear down to = 240nm. Add sodium hydride (1g) free from paraffin, to the liquid, reflux for 10minutes, and then distil rapidly until about 100mL of residue remains. Immediately pass the distillate through a column of acidic alumina, discarding the first 150mL of percolate. Add 5g of CaH2 and distil the first 50mL at a high reflux ratio. Discard this fraction, and collect the following main fraction. The best way of detecting impurities is by gas chromatography. Usual contaminants in commercial acetonitrile include H2O, acetamide, NH4OAc and NH3. Anhydrous CaSO4 and CaCl2 are inefficient drying agents. Preliminary treatment of acetonitrile with cold, saturated aqueous KOH is undesirable because of base-catalysed hydrolysis and the introduction of water. Drying by shaking with silica gel or Linde 4A molecular sieves removes most of the water in acetonitrile. Subsequent stirring with CaH2 until no further hydrogen is evolved leaves only traces of water and removes acetic acid. The acetonitrile is then fractionally distilled at high reflux, taking precaution to exclude moisture by refluxing over CaH2 [Coetzee Pure Appl Chem 13 429 1966]. Alternatively, 0.5-1% (w/v) P2O5 is often added to the distilling flask to remove most of the remaining water. Excess P2O5 should be avoided because it leads to the formation of an orange polymer. Traces of P2O5 can be removed by distilling from anhydrous K2CO3. Kolthoff, Bruckenstein and Chantooni [J Am Chem Soc 83 3297 1961] removed acetic acid from 3L of acetonitrile by shaking for 24hours with 200g of freshly activated alumina (which had been reactivated by heating at 250o for 4hours). The decanted solvent was again shaken with activated alumina, followed by five batches of 100-150g of anhydrous CaCl2. (Water content of the solvent was then less than 0.2%.) It was shaken for 1hour with 10g of P2O5, twice, and distilled in a 1m x 2cm column, packed with stainless steel wool and protected from atmospheric moisture by CaCl2 tubes. The middle fraction had a water content of 0.7 to 2mM. Traces of unsaturated nitriles can be removed by initially refluxing with a small amount of aqueous KOH (1mL of 1% solution per L). Acetonitrile can be dried by azeotropic distillation with dichloromethane, *benzene or trichloroethylene. Isonitrile impurities can be removed by treatment with conc HCl until the odour of isonitrile has gone, followed by drying with K2CO3 and distilling. Acetonitrile is refluxed with, and distilled from alkaline KMnO4 and KHSO4, followed by fractional distillation from CaH2. (This is better than fractionation from molecular sieves or passage through a type H activated alumina column, or refluxing with KBH4 for 24hours and fractional distillation)[Bell et al. J Chem Soc, Faraday Trans 1 73 315 1977, Moore et al. J Am Chem Soc 108 2257 1986]. Material suitable for polarography is obtained by refluxing over anhydrous AlCl3 (15g/L) for 1hour, distilling, refluxing over Li2CO3 (10g/L) for 1hour and redistilling. It is then refluxed over CaH2 (2g/L) for 1hour and fractionally distilled, retaining the middle portion. The product is not suitable for UV spectroscopy use. A better purification procedure uses refluxing over anhydrous AlCl3 (15g/L) for 1hour, distilling, refluxing over alkaline KMnO4 (10g KMnO4, 10g Li2CO3/L) for 15minutes, and distilling. A further reflux for 1hour over KHSO4 (15g/L), then distillation, is followed by refluxing over CaH2 (2g/L) for 1hour, and fractional distillation. The product is protected from atmospheric moisture and stored under nitrogen [Walter & Ramalay Anal Chem 45 165 1973]. Purificaton of "General Purity Reagent" for this purpose is not usually satisfactory because very large losses occur at the KMnO4/LiCO3 step. For electrochemical work involving high oxidation fluorides, further reflux over P2O5 (1g/mL for 0.5hours) and distilling (discarding 3% of first and last fractions) and repeating this step is necessary. The distillate is kept over molecular sieves in vacuo after degassing, for 24hours and distilling in a vacuum onto freshly activated 3A molecular sieves. The MeCN should have absorption at 200nm of <0.05 (H2O reference) and UV cutoff at ca 175nm. Also the working potential range of purified Et4N+ BF4 (0.1mol.dcm-3 in the MeCN) should be +3.0 to -2.7V vs Ag+/Ago. If these criteria are not realised then further impurities can be removed by treatment with activated neutral alumina (60 mesh) in vacuo before final molecular sieves treatment [Winfield J Fluorine Chem 25 91 1984]. Acetonitrile has been distilled from AgNO3, collecting the middle fraction over freshly activated Al2O3. After standing for two days, the liquid is distilled from the activated Al2O3. The specific conductivity should be 0.8-1.0 x 10-8 mhos [Harkness & Daggett Can J Chem 43 1215 1965]. Acetonitrile 14C is best purified by gas chromatography and is water free and distils at 81o. [Beilstein 2 H 183, 2 IV 419.]
There are many ways of making acetonitrile. Those major ways for industrial production include acetate amination method, acetylene amination method and propylene ammoxidation byproduct method. 1. Acetate amination method use acetate and ammonia as raw materials with reaction being performed at a temperature of 360-420 °C in the presence of aluminum oxide as the catalyst. This is a one-step synthesis method. The reaction mixture is further gone through water absorption and fine distillation to get the final product. Material consumption quantity: acetate (98%) 1763kg /t, ammonia (99.5%) 691kg/t. 2. Acetylene amination method uses ammonia and acetylene as the raw materials and the reaction is carried out at a temperature of 500-600 °C with aluminum oxide being the catalyst. It is again a one-step synthesis approach. Material consumption quantity: acetylene 10231 m3, ammonia (99.4%) 1007 kg/t. 3. Propylene amination and oxidation byproduct method use propylene, ammonia, and air as the raw materials. It produces acrylonitrile with the catalyst while producing acetonitrile as byproducts. Per ton of acrylonitrile can make 25-100kg byproduct of acetonitrile. 4. Made from the dehydration reaction between acetamide and phosphorus pentoxide. 5. Obtained from reaction between dimethyl sulfate and sodium cyanide.
Acetonitrile is usually the byproduct of ammoxidation reaction used for producing acrylonitrile. We can also apply acetate amination method with aluminum oxide as the catalyst. Acetonitrile is obtained by one-step reaction at 360 °C. Reaction equation:
CH3COOH + NH3 [Al2O3] → CH3CN + 2H2O.
Data of irritation
skin: rabbit 500 mg, Mild; Eyes-rabbit 79 mg/24 hours, moderate.
Air & Water Reactions
Highly flammable. Water soluble.
Acetonitrile decomposes when heated to produce deadly toxic hydrogen cyanide gas and oxides of nitrogen. Strongly reactive [Hawley]. May react vigorously with strong oxidizing reagents, sulfuric acid, chlorosulfonic acid, sulfur trioxide, perchlorates, nitrating reagents, and nitric acid. [Sax, 9th ed., 1996, p. 20]. Potentially explosive in contact with nitrogen-fluorine compounds (e.g., tetrafluorourea) [Fraser, G. W. et al., Chem. Comm., 1966, p. 532].
Acetonitrile is also used as a polar aprotic solvent.
In inorganic chemistry, acetonitrile is widely used as a ligand which is abbreviated MeCN. For example, acetonitrile complex PdCl2 (MeCN)2 can be produced by thermal polymerization of palladium chloride in the suspension of acetonitrile.
The high dielectric constant of acetonitrile makes it a popular cyclic voltammetry of solvents. Acetonitrile can also be used as a two-carbon raw material in organic synthesis. It can produce malononitrile via reaction with cyanogen chloride.
Acetonitrile can also be used as the mobile phase molecules which are commonly used in the column chromatography, more modernized high performance liquid chromatography (HPLC).
In the field of nuclear medicine, acetonitrile is used for the synthesis of radiopharmaceutical like fluoro-deoxy-glucose positron (FDG). During the synthesis of FDG, the evaporation of acetonitrile can take away the water in the reaction system. The exact content of acetonitrile in the reaction system plays a significant role in ensuring the synthesis efficiency and quality of medicines; at the same time, acetonitrile is also sued as the solvent and the matrix for the reaction system. In addition, in the routine quality inspection of FDG, acetonitrile: water mixture (for example, 85% v/v) is also applied as the mobile phase of TLC.
In organic synthesis as starting material for acetophenone, a-naphthaleneacetic acid, thiamine, acetamidine. To remove tars, phenols, and coloring matter from petroleum hydrocarbons which are not soluble in acetonitrile. To extract fatty acids from fish liver oils and other animal and vegetable oils. Can be used to recrystallize steroids. As an indifferent medium in physicochemical investigations. Wherever a polar solvent having a rather high dielectric constant is required. As medium for promoting reactions involving ionization. As a solvent in non-aqueous titrations. As a non-aqueous solvent for inorganic salts.
Industrially, acetonitrile is a byproduct of the reaction between propylene and ammonia which produces acrylonitrile, so often acetonitrile often contains water, acrylonitrile, ether, ammonia and some other impurities, even hydrolyzed acetic acid and ammonia. The purification method is as below:
1. Add phosphorus pentoxide (10-20g/L) into acetonitrile; heat and reflux until reaching colorless which can remove most water; avoid adding an excess of phosphorus pentoxide which will generate an orange polymer. Add a small amount of potassium carbonate into the distilled acetonitrile and continue distillation which can further remove excess phosphorus pentoxide; finally fractionate by fractional distillation column.
2. Use 36 g of mashed potassium permanganate and 28 g of mashed potassium carbonate to reflux 1L common anhydrous acetonitrile for 5 hours before evaporate it. Then add 10g of phosphorus pentoxide to the evaporated solvent; reflux for another 5 hours, fine slip, keeping the temperature constant, take the fraction of 81 °C.
3. Adding 4A molecular sieves or silica gel and shaking can also remove most of the water in acetonitrile. Next, stir it together with the calcium hydroxide until no hydrogen being further released; fractionate to get acetonitrile which also contain only a small amount of water without the existence of any acetate.
4. Acetonitrile can also be mixed together with methylene chloride, benzene and trichlorethylene for azeotropic distillation and drying.
The above information is edited by the Chemicalbook of Dai Xiongfeng.
Colorless; transparent liquid; has a unique fragrance similar to ether; miscible with water, methanol, methyl acetate, acetone, ether, chloroform, carbon tetrachloride and vinyl chloride miscible.
Treasury: ventilation, low-temperature, dry; store it separately from oxidants and acids.
Exposure to 160 ppm for 4 hours causes flushing of the face and a feeling of constriction in the chest; 500 ppm for brief periods is irritating to the nose and throat. Severe exposures cause irritability, skin eruptions, confusion, delirium, convulsions, paralysis, and death due to central nervous system depression.
A colorless limpid liquid with an aromatic odor. Flash point 42°F. Density 0.783 c / cm3. Toxic by skin absorption. Less dense than water. Vapors are denser than air.
Flammable in case of fire, high temperature and oxidant; thermally decomposed to release highly toxic fumes of cyanide and nitrogen oxides.
oral: rat LD50: 2730 mg/kg; Oral-Mouse LD50: 269 mg/kg.
Acetonitrile is a colourless liquid, with an ether-like odour, and a polar solvent.
Acetonitrile is predominantly used as a solvent in the manufacture of pharmaceuticals,
for spinning fibers and for casting and molding of plastic materials, in lithium batteries,
for the extraction of fatty acids from animal and vegetable oils, and in chemical laboratories
for the detection of materials such as pesticide residues. Acetonitrile is also used in
dyeing textiles and in coating compositions as a stabilizer for chlorinated solvents and in
perfume production as a chemical intermediate. It is a by-product from the manufacture
of acrylonitrile, and acetonitrile has, in fact, replaced the acrylonitrile. It is used as a starting
material for the production of acetophenone, alpha-naphthaleneacetic acid, thiamine,
and acetamidine. It has been used as a solvent in making pesticides, pharmaceuticals,
batteries, rubber products, and formulations for nail polish remover despite its low but
significant toxicity. Acetonitrile has been banned in cosmetic products in the European
Economic Area (EEA) since early 2000, and acetone and ethyl are often preferred as safer
for domestic use. Acetonitrile has a number of uses: primarily as an extraction solvent for
butadiene; as a chemical intermediate in pesticide manufacturing; as a solvent for both
inorganic and organic compounds to remove tars, phenols, and colouring matter from
petroleum hydrocarbons not soluble in acetonitrile; in the production of acrylic fibres; and
in pharmaceuticals, perfumes, nitrile rubber, and acrylonitrile butadiene styrene (ABS)
resins; in high-performance liquid and gas chromatographic analysis; and in extraction
and refining of copper.