por What is acetonitrile?
He acetonitrile It is a substance of organic origin composed only of carbon, hydrogen and nitrogen. This chemical species belongs to the group of nitriles, with acetonitrile being the one with the simplest structure among the organic ones.
Nitriles are a class of chemical compounds whose structure is constituted by a cyanide group (CN–) and a radical chain (-R). These elements are represented by the following general formula: RC≡N.
It is known that this substance originates primarily during the production of another species called acrylonitrile (another simple nitrile, with the molecular formula C3H3N, which is used in the manufacture of products in the textile industry) as a by-product of it.
In addition, acetonitrile is considered a solvent with medium polarity properties, which is why it is used quite regularly in RP-HPLC (reverse phase high performance liquid chromatography) analyses.
Structure
As previously mentioned, acetonitrile belongs to the functional group of nitriles, having a molecular formula commonly represented as C2H3N, which can be seen in the structural formula exemplified in the upper figure.
This image shows a kind of lobe attached to the nitrogen atom, which represents the unpaired pair of electrons that this atom possesses, and which give it a large part of its characteristic reactivity and stability properties.
In this way, this species shows a very particular behavior due to its structural arrangement, which translates into a weakness to receive hydrogen bonds and little ability to donate electrons.
Also, this substance originated for the first time in the second half of the 1840s, being manufactured by the scientist named Jean-Baptiste Dumas, whose nationality was French.
The structural conformation of this substance allows it to have the characteristics of an organic solvent of its own.
In turn, this property allows acetonitrile to be mixed with water, as well as a series of other solvents of organic origin, with the exception of hydrocarbons or saturated hydrocarbon species.
properties of acetonitrile
This compound has a series of properties that distinguish it from others of the same class, which are listed below:
It is in a state of liquid aggregation under standard conditions of pressure and temperature (1 atm and 25 °C).
Its molecular configuration gives it a molar mass or molecular weight of approximately 41 g/mol.
It is considered as the nitrile that has the simplest structure, among the organic type.
Its optical properties allow it to be colorless in this liquid phase and with limpid characteristics, in addition to having an aromatic odor.
It has a flash point around 2 °C, which is equivalent to 35.6 °F or 275.1 K.
It has a boiling point in the range of 81.3 to 82.1 °C, a density of approximately 0.786 g/cm3 and a melting point that is between -46 to -44 °C.
It is less dense than water but miscible with it and with a variety of organic type solvents.
It manifests a dielectric constant of 38.8 in addition to a dipole moment of approximately 3.92 D.
It is capable of dissolving a wide variety of substances of ionic origin and nonpolar nature.
It is widely used as a mobile phase in HPLC analysis, which has high flammability properties.
Uses/applications
Among the large number of applications that acetonitrile has, the following can be counted:
Similarly to other species of nitriles, this can go through a metabolization process in microsomes (vesicular elements that are part of the liver), especially in this organ, to originate hydrocyanic acid.
It is widely used as a mobile phase in the type of analysis called reverse phase high performance liquid chromatography (RP-HPLC); that is, as an eluting substance that has high stability, great eluting power, and low viscosity.
In the case of applications of industrial magnitude, this chemical compound is used in crude oil refineries as a solvent in certain processes, such as the purification of the alkene called butadiene.
It is also used as a ligand (a chemical species that combines with an atom of a metallic element, considered central in the given molecule, to form a coordination compound or complex) in a large number of nitrile compounds with transition group metals. .
Similarly, it is used in organic synthesis for a large number of chemical substances as advantageous as α-naphthaleneacetic acid, thiamine or acetamidine hydrochloride.
risks
The risks associated with exposure to acetonitrile are diverse. Among these is a decreased toxicity when exposure is for a short period of time and in low amounts, being metabolized for the production of hydrocyanic acid.
Likewise, there have rarely been cases of people who have been intoxicated with this chemical species, being poisoned by the cyanide present in the molecule after having been in contact with acetonitrile in different degrees (by inhaling it, ingesting it or absorbing it through the skin ).
For this reason, the consequences of its toxicity are delayed because the body does not easily metabolize this substance into cyanide, since it takes two to twelve hours for this to occur.
However, acetonitrile is easily absorbed in the lung area and gastrointestinal tract. Subsequently, its distribution occurs throughout the body, happening in people and even in animals and reaching the kidneys and spleen.
On the other hand, in addition to the flammability risks it presents, acetonitrile is a precursor of substances as toxic as hydrocyanic acid or formaldehyde. Its use was even prohibited in products belonging to the cosmetic area in the so-called European Economic Area in the year 2000.