Academic journal article International Journal of Child Health and Human Development

The Impact of Acetonitrile on Human Health: Clinical and Toxicological Overview

Academic journal article International Journal of Child Health and Human Development

The Impact of Acetonitrile on Human Health: Clinical and Toxicological Overview

Article excerpt

Introduction

Acetonitrile, also known as cyanomethane, methylcyanide, ethanenitrile, methanecarbonitrile, ethylnitrile and methylcyanure, is a volatile colorless liquid with an odor similar to ether (1). It occurs naturally or is obtained as a by-product of acrylonitrile, an important starting material in the manufacture of plastics and synthetic rubber (1-3).

In manufacturing operations, acetonitrile has been utilized as an intermediate substance to produce other organic chemicals. Due to its unique chemical properties such as its polarity, miscibility with water, low boiling point and low UV cut-off, acetonitrile is considered a versatile solvent with ample uses in analytical applications. It is also used in extractive processes, distillation in the petrochemical industry and the development and manufacturing of cosmetics, pharmaceutical and agricultural products, among other uses (1,4-8).

In recent years, the utilization of acetonitrile has increased substantially, with the pharmaceutical industry being responsible for more than 70% of its consumption (9). The global economic crisis in 2008 caused a drastic decline in acrylonitrile production, and because acetonitrile is a by-product of acrylonitrile, the production of acetonitrile also decreased. In the same year, an environmental disaster in the United States (hurricane Ike) also contributed to a reduction in acetonitrile production (10), increasing its price by approximately 800% and making the replacement of acetonitrile by other solvents necessary. Acetonitrile production has currently gone back to normal levels, and it is expected that the global consumption of acetonitrile will continue to grow at a rate of approximately 5% per year (9).

Physical and chemical properties

Acetonitrile (CAS Registry number: 75-05-8) is a chemical compound with the molecular formula C2H3N and a molar mass of 41.05 g/mol. It has a pKa of 25.0, a melting point of -45°C and a boiling point of 81.6 °C (760 mmHg). At 20 °C, this substance has a vapor pressure of 73 mmHg and a specific gravity of 0.77 g/mL. Its flash point is 5.6 °C, and its ignition temperature is 524 °C. Its vapor density is 1.42, and its refractive index is 1.34604 at 15°C. The chemical structure of acetonitrile is shown in figure 1.

The high dielectric constant and dipole moment of acetonitrile make it an excellent solvent for both inorganic and organic compounds, including polymers (11).

It is readily miscible with solvents of different polarities, including water, alcohols, ethers, methyl acetate, ethyl acetate, acetone, acetamide solutions, carbon tetrachloride, chloroform, ethylene chloride and unsaturated hydrocarbons (alkenes); however, it is immiscible with many saturated hydrocarbons (1,7).

Although acetonitrile has been described as one of the more stable and inert nitriles, it forms a lowboiling azeotrope with other organic solvents. When heated to decomposition or reacted with acids or oxidizing agents, hydrogen cyanide is produced (11).

Applications

Acetonitrile is primary used as an organic solvent in extractive process, especially for fatty acids (e.g., from fish liver oils and other animal and vegetable oils) and unsaturated hydrocarbons (4,5,11).

Numerous advantages have been reported for using acetonitrile in industrial processes, especially because this substance can be used as a catalyst in chemical reactions; consequently, acetonitrile has been considered a key reagent to synthesize amines, amides, ketones, aldehydes, and other compounds (2,6).

In manufacturing processes, acetonitrile commonly replaces acrylonitrile, a starting material in the production of fibers and resins (2). It has also been applied in extractive distillation in the petrochemical industry, especially as an extraction solvent for butadiene and for separating olefin-diolefin mixtures. This chemical may be applied as a solvent for polymer spinning and casting because it presents high solubility and desirable intermediate volatility (1,7,8). …

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