Adiponitrile

Chemical properties

Adiponitrile is a combustible, colorless transparent to yellow, oily liquid with a slight bitter taste. Soluble in methanol, ethanol, chloroform. Insoluble in water, cyclohexane, ether, carbon disulfide and carbon tetrachloride. It decomposes on heating to react violently with strong oxidants. Upon burning, the highly toxic hydrogen cyanide is produced.

The Uses of Adiponitrile

Adiponitrile is mainly used in the production of hexamethylenediamine for manufacturing nylon 6,6. Lesser uses include that in organic synthesis and in the preparation of adipoguanamine, which is used as an extractant for aromatic hydrocarbons. This chemical is an important intermediate for the manufacture of synthetic fiber.

Production Methods

Adiponitrile may be prepared by reacting butadiene with hydrogen cyanide, by the electrodimerization of acrylonitrile, by heating adipamide with acetic anhydride in the presence of cobalt or by reacting 1,4-dichlorobutane with sodium cyanide (HSDB 1988). Impurities such as propionitrile, bis (cyanoethyl) ether or acrylonitrile may be present depending on the method of manufacture (Smiley 1981).

What are the applications of Application

Adiponitrile is used as a synthetic rubber accelerator, a rust inhibitor, an additive for detergents, a spinning solvent for acrylonitrile, methacrylonitrile and methyl methacrylate terpolymers, a solvent for wet spinning and dry spinning of polyvinyl chloride fibers , polyamide colorants, auxiliaries for fabric bleaches, acetate, propionate, butyrate and mixed ester plasticizers; and aromatic extracted extractants.

Preparation

The main method of industrial production of adiponitrile is the amination of adipic acid. Adipic acid and excess ammonia are reacted in the presence of catalyst phosphoric acid or its salts or esters at a temperature of 270-290°C to generate diammonium adipate, which is then heated and dehydrated to generate crude adiponitrile, The product is obtained by rectification.

Synthesis Reference(s)

Synthetic Communications, 10, p. 279, 1980 DOI: 10.1080/00397918008062751

General Description

Adiponitrile appears as a colorless to light yellow liquid which is fairly soluble and is less dense than water. Contact may irritate skin, eyes and mucous membranes. May be toxic by ingestion, inhalation and skin absorption.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

1,4-Dicyanobutane is incompatible with strong oxidizers. 1,4-Dicyanobutane is also incompatible with strong acids, strong bases and strong reducing agents. .

Health Hazard

The acute toxicity of adiponitrile is somewhat lower than that of malononitrile. It is toxic by inhalation and oral routes. Inhalation of its vapors can cause nausea, vomiting, respiratory tract irritation, and dizziness. The symptoms are similar to those of other aliphatic mono- and dinitriles. Similar poisoning effects may be manifested from ingestion of this compound. However, its toxicity is very low from skin absorption.
Short et al. (1990) reported mortality and reduced weight gain in rats within one week after exposed to adiponitrile at 493 mg/m³. However, at an exposure level of 99 mg/m³ for 13 weeks the animals showed the sign of slight anemia but no histopathological evidence of organ toxicity.
LC50 value, inhalation (rats): 1710 mg/m³/ 4 hr
LD50 value, oral (mice): 172 mg/kg
There is no report of its teratogenicity or cancer-causing effects in animals or humans.

Fire Hazard

Combustion products may contain hydrocyanic acid (HCN). Vapor may explode if ignited in an enclosed area. When heated to decomposition, 1,4-Dicyanobutane emits highly toxic fumes. Avoid oxidizing material. Hazardous polymerization may not occur.

Industrial uses

Adiponitrile is used in nylon manufacturing, synthetic fiber synthesis, and in the manufacture of rubber accelerators and corrosion inhibitors. It is also used as an extractant for aromatic hydrocarbons (Smiley 1981).

Safety Profile

Poison by inhalation, ingestion, subcutaneous, and intraperitoneal routes. The nitrile group wdl behave as a cyanide when ingested or absorbed in the body. It produces disturbances of the respiration and circulation, irritation of the stomach and intestines, and loss of weight. Its low vapor pressure at room temperature makes exposure to harmful concentrations of its vapors unlikely if handled with Flammable when exposed to heat or flame. When heated to decomposition it emits toxic fumes of CN-. Can react with oxidizing materials. To fight fire, use foam, CO2, dry chemical. See also HYDROCYANIC ACID and NITRILESreasonable care in well-venulated areas.

Potential Exposure

Is used to manufacture corrosion inhibitors, rubber accelerators, and Nylon 66; and in organic synthesis.

Environmental Fate

The mechanism of adiponitrile’s toxicity relates to its ability to release cyanide both in vitro and in vivo. Cyanide then forms a stable complex with ferric iron in the cytochrome oxidase enzyme. Since this enzyme occupies a central role in the utilization of oxygen in practically all cells, inhibition produces an inhibition of cellular respiration.

Metabolism

Animal studies indicated that the concentrations of thiocyanate in the blood and urine of guinea pigs injected with adiponitrile were proportional to the doses administered. Following administration of adiponitrile, 79% was eliminated as thiocyanate in the urine of guinea pigs (H?rtung 1982). Of the cyanide antidotes, thiosulfate was most effective in protecting against adiponitrile poisoning, and nitrite was less effective. However, on the basis of the ratio between administered adiponitrile dose and quantity of cyanide detected, Ghiringhelli, (1955) concluded that a greater part of the dose was metabolized to cyanide.

Shipping

UN2205 Adiponitrile, Hazard Class: 6.1; Labels: 6.1-Poisonous materials

Purification Methods

Reflux adiponitrile over P2O5 and POCl3, and fractionally distil it, then fractionate it through an efficient column. The liquid is TOXIC and is an IRRITANT. [Braun & Rudolph Chem Ber 67 1770 1934, Reppe et al. Justus Liebigs Ann Chem 596 127 1955, Gagnon et al. Can J Chem 34 1662 1956, Copley et al. J Am Chem Soc 62 228 1940, Beilstein 2 IV 1947.]

Toxicity evaluation

Adiponitrile will exist solely as a vapor in the ambient atmosphere. The chemical can be degraded in air by photochemically produced hydroxyl radicals with a half-life of 23 days. Adiponitrile is expected to have very high mobility in soil, with volatilization from soil or water surfaces not expected to be an important fate process. The chemical is expected to biodegrade in aquatic and soil systems. The potential for bioconcentration in aquatic organisms is low.

Incompatibilities

May form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause violent reactions: fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Also incompatible with strong reducing agents such as hydrideds and active metals. Permissible Exposure Limits in Air

Waste Disposal

Add excess alcoholic KOH. Than evaporate alcohol and add calcium hypochlorite. After 24 hours, flush to sewer with water. Can also be incinerated with afterburner and scrubber to remove nitrogen oxides.