What Is Ethyl Lactate?
Ethyl lactate is the ester of lactic acid and ethanol, and is a clear, colorless liquid with a characteristic odor.
Also known as ethyl 2-hydroxypropanoate, it occurs in trace amounts in poultry, fruits, miso, and other foods. Ethyl lactate contains a chiral carbon atom in its lactic acid component, resulting in two optical isomers: the L- and D-forms. It features hydroxyl and ester functional groups, making it freely miscible with water and most organic solvents. It is also highly soluble in natural and synthetic resins, synthetic fibers, and various other materials.
It is classified as a Hazardous Substance, Class 4 under the Fire Service Law and as a Hazardous and Flammable Substance under the Industrial Safety and Health Law, requiring careful handling.
Uses of Ethyl Lactate
Ethyl lactate is widely used as an organic solvent because it is biodegradable, with a very low environmental impact in work environments and in the event of leaks. It serves as an ink and polymer solvent, benefiting from its high boiling point and low volatility.
Ethyl D-lactate is employed across a broad spectrum of fields, including as a resist solvent in semiconductor manufacturing, a cleaning agent in LCD panel production, a fragrance additive, a component in perfumes, pesticides, agricultural chemicals, and as a soil conditioner. It is also used as a starting material for compounds requiring an optically active D-lactic acid backbone.
Properties of Ethyl Lactate
1. Solubility
Ethyl lactate is soluble in water and organic solvents. Its ester bond provides polarity, acting as a hydrophilic group, while its hydroxyl group enhances water compatibility. The ethyl groups afford oil compatibility, making it dissolve well in organic solvents.
2. High Boiling Point
The boiling point of a substance generally increases with molecular weight due to greater intermolecular forces. Ethyl lactate has a higher boiling point than lactic acid due to its larger molecular weight and the strong hydrogen bonds it forms, unlike other esters.
| Name | Chemical Formula | Molecular Weight | Boiling Point |
| Lactic Acid | CH3CH(OH)COOH | 90 | 122℃ |
| Methyl Lactate | CH3CH(OH)COOCH3 | 104 | 144℃ |
| Ethyl Lactate | CH3CH(OH)COOC2H5 | 118 | 154℃ |
| Acetic Acid | CH3COOH | 60 | 118℃ |
| Methyl Acetate | CH3COOCH3 | 74 | 56℃ |
| Ethyl Acetate | CH3COOC2H5 | 88 | 77℃ |
3. Peculiar Aroma
Ethyl lactate has a distinctive aroma reminiscent of fruits, dairy, or nuts. Its molecules diffuse through the air upon vaporization, reaching the olfactory cells and interacting with olfactory receptors, thus producing specific aromas.
Found in sake, shochu, and other alcoholic beverages, ethyl lactate is an indicator of aroma, produced during alcoholic fermentation by the reaction of lactic acid with ethanol.
4. High Safety as an Organic Solvent
Compared to petroleum-based solvents, ethyl lactate is less toxic and biodegrades into harmless substances, positioning it as a “green solvent” with minimal environmental impact.
Other Information on Ethyl Lactate
1. Production Method of Ethyl Lactate
Produced through esterification of lactic acid and ethanol in the presence of a strong acid catalyst such as sulfuric acid, ethyl lactate formation is favored by the removal of water, shifting the reaction equilibrium to the right.
2. Safety Information on Ethyl Lactate
While ethyl lactate is among the less toxic organic solvents, its liquid and vapor forms are flammable, and it may irritate the eyes and respiratory tract. It is designated as a Hazardous Substance, Class 4 under the Fire Service Law and as a Hazardous and Flammable Substance under the Industrial Safety and Health Law, necessitating careful handling.