Lactic acid, also known as 2-hydroxypropionic acid and α-hydroxypropionic acid, contains an asymmetric carbon atom in its structure, resulting in three optical isomers: d-isomer, l-isomer, and the racemic dl-isomer. First isolated by Scheele in yogurt in 1780, it is present in human and animal tissues as right-hand and racemic isomers, with the left-hand isomer being a normal metabolite in mammals. Lactic acid is also found naturally in fruits like poppy, apple, and tomato juice. Commercially, whether produced via fermentation or synthesis, it is typically available as racemic isomers.
Due to its hydroxyl and carboxyl groups, lactic acid forms esters with acid anhydrides and alcohols, salts with metals like sodium, calcium, and iron, and can self-esterify to produce linear polyesters and cyclic compounds like lactide. Under slow oxidation, it forms pyruvic acid, and when heated above 250°C, it decomposes into acetaldehyde, releasing carbon dioxide and water.
Parameters
Melting point | 18°C |
Boiling point | 122 °C/15 mmHg (lit.) |
alpha | -0.05 º (c= neat 25 ºC) |
density | 1.209 g/mL at 25 °C (lit.) |
vapor density | 0.62 (vs air) |
vapor pressure | 19 mm of Hg (@ 20°C) |
FEMA | 2611 | LACTIC ACID |
refractive index | n20/D 1.4262 |
Fp | >230 °F |
storage temp | 2-8°C |
solubility | Miscible with water and with ethanol (96 per cent). |
form | syrup |
pka | 3.08(at 100℃) |
color | Colorless to yellow |
Specific Gravity | 1.209 |
PH | 3.51(1 mM solution);2.96(10 mM solution);2.44(100 mM solution); |
Odor | at 100.00 %. odorless |
Odor Type | odorless |
Water Solubility | SOLUBLE |
Merck | 14,5336 |
JECFA Number | 930 |
BRN | 1209341 |
Dielectric constant | 22.0（16℃） |
Stability | Stable. Combustible. Incompatible with strong oxidizing agents. |
InChIKey | JVTAAEKCZFNVCJ-UHFFFAOYSA-N |
LogP | -0.72 |
CAS DataBase Reference | 50-21-5(CAS DataBase Reference) |
NIST Chemistry Reference | Propanoic acid, 2-hydroxy-(50-21-5) |
EPA Substance Registry System | Lactic acid (50-21-5) |
Safety Information
Hazard Codes | Xi,C |
Risk Statements | 38-41-34-37/38 |
Safety Statements | 26-39-45-36/37/39 |
RIDADR | 3265 |
WGK Germany | 2 |
RTECS | OD2800000 |
F | 3 |
TSCA | Yes |
HazardClass | 8 |
PackingGroup | III |
HS Code | 29181100 |
Hazardous Substances Data | 50-21-5(Hazardous Substances Data) |
