What Is Ethyl Formate?
Ethyl Formate is an organic compound classified as a carbonate ester.
As a natural product, it is found in fruits such as pineapple and raspberries, cabbage, vinegar, butter, and brandy, and has a sweet fruity odor.
Its chemical formula is C3H6O2 and it is a colorless liquid with a molecular weight of 74.08. Its boiling point is 54.3℃ and its flash point is -20℃. When mixed with air, ethyl formate produces explosive gases. It is synthesized by reacting ethanol and carbon monoxide in the presence of a strong base.
Uses of Ethyl Formate
Ethyl Formate is used in a variety of applications, including as a flavoring agent in fruit flavors such as pineapple and in Western liquors such as whiskey, rum, and brandy. When sniffed in high concentrations, pure ethyl formate alone smells like a glue or nail polish remover.
At lower concentrations, however, the smell changes to the sweet smell characteristic of fresh fruit when first cut. It is common for the same ingredient to give a different aroma impression at higher and lower concentrations.
As a special example, it is said that ethyl formate adheres to spacesuits during spacecraft extra-vehicular activities. This is in trace amounts that has little to do with its use or manufacture on Earth, and may come from the formation of organic matter in space or from the combustion of spacecraft fuel. This rare phenomenon has led to the development of perfumes that reproduce the scent of space containing ethyl formate, as well as products themed around space activities.
There are also examples of its use as a non-electrolyte solvent in rechargeable batteries. When ethyl formate is used as a non-electrolyte solvent mixed with a compound that simultaneously has acrylic groups, the increase in battery thickness can be greatly reduced when stored at high temperatures. Even when mixed with other electrolyte additives, it has been confirmed that no offsetting or reduction in its effect occurs.
Ethyl formate, along with methyl formate, has been attracting attention as an electrolyte solvent for new high-performance rechargeable batteries.
Properties of Ethyl Formate
1. Solubility
Ethyl Formate is slightly soluble in water. The ester bond is polarized and has a carboxyl group like water molecules. Therefore, it is slightly soluble in water due to the formation of hydrogen bonds with water molecules. Containing ethyl groups that are compatible with oil, it is extremely soluble in ethanol and acetone.
2. Low Boiling Point
In general, the boiling point of a substance increases with its molecular weight. This is because the larger the molecular weight, the greater the intermolecular forces acting between molecules. In order to shake off the large intermolecular forces and vaporize the substance, it is necessary to give it a large amount of energy.
However, when formic acid forms an ester with methanol or ethanol, the boiling point of the ester is higher than that of formic acid, even though the molecular weight has increased. This is because formic acid and ethyl formate do not form hydrogen bonds with each other, whereas formic acid and ethyl formate form hydrogen bonds with each other.
3. Characteristic Aroma
Ethyl Formate has a distinctive aroma, with a sweet smell characteristic of fresh fruit. This is because ethyl formate is naturally occurring in fruits, such as raspberries and pineapples.
Other Information about Ethyl Formate
1. How Ethyl Formate Is Produced
Formic acid and ethanol are mixed, and when a catalyst is added, ethyl formate is formed by esterification. A strong acid such as concentrated sulfuric acid is used as a catalyst. In this reaction, H+ from sulfuric acid acts as a catalyst, and at the same time, the water produced is hydrated with concentrated sulfuric acid and eliminated from the reaction system, so the equilibrium in the figure below shifts to the right.
2. Safety Information on Ethyl Formate
Ethyl formate liquid and vapor are flammable. It may also be irritating to the eyes and respiratory tract. It must be handled with care.