Ethylammonium nitrate or ethylamine nitrate (EAN) is a

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

with formula . It is an odorless and colorless to slightly yellowish liquid with a melting point of 12 °C. This compound was described by Paul Walden in 1914, and is believed to be the earliest reported example of a room-temperature

ionic liquid An ionic liquid (IL) is a salt (chemistry), salt in the liquid state at ambient conditions. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as wate ...

Synthesis and properties

Ethylammonium nitrate can be produced by heating ethyl nitrate with an alcoholic solution of ammonia or by reacting

ethylamine Ethylamine, also known as ethanamine, is an organic compound with the chemical formula, formula CH3CH2NH2. This colourless gas has a strong ammonia-like odor. It condenses just below room temperature to a liquid miscibility, miscible with virtual ...

with concentrated

nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

. It has a relatively low

viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...

of 0.28 poise or 0.028 Pa·s at 25 °C and therefore a high electrical conductivity of about 20 mS·cm⁻¹ at 25 °C. It boils at 240 °C and decomposes at about 250 °C. Its density at 20 °C is 1.261 g/cm³. The ethylammonium ion () has three easily detachable protons which are

tetrahedrally In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are arccos(−) = 109.4712206...° ≈ 109.5° when all four substituents are t ...

arranged around the central nitrogen atom, whereas the configuration of the anion is planar. Despite the structural differences, EAN shares many properties with water, such as

micelle A micelle () or micella () ( or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension (also known as associated colloidal system). ...

formation, aggregation of

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

s, negative

enthalpy Enthalpy () is the sum of a thermodynamic system's internal energy and the product of its pressure and volume. It is a state function in thermodynamics used in many measurements in chemical, biological, and physical systems at a constant extern ...

and

entropy Entropy is a scientific concept, most commonly associated with states of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynamics, where it was first recognized, to the micros ...

of dissolution of gases, etc. Similar to water, EAN can form three-dimensional

hydrogen bond In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ...

ing networks.

Applications

Ethylammonium nitrate is used as an electrically conductive

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

electrochemistry Electrochemistry is the branch of physical chemistry concerned with the relationship between Electric potential, electrical potential difference and identifiable chemical change. These reactions involve Electron, electrons moving via an electronic ...

and as a protein crystallization agent. It has a positive effect on the refolding of denaturated

lysozyme Lysozyme (, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside hydrolase ...

, with the refolding yield of about 90%. The refolding action was explained as follows: The ethyl group of ethylammonium nitrate interacts with the hydrophobic part of the protein and thereby protects it from intermolecular association, whereas the charged part of EAN stabilizes the electrostatic interactions.

References

{{reflist Ammonium compounds Nitrates Ionic liquids Substances discovered in the 1910s