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Lactic acid(CAS No. 50-21-5)

Lactic acid C3H6O3 (cas 50-21-5) Molecular Structure

50-21-5 Structure

Identification and Related Records

Lactic acid
【CAS Registry number】
Propanoic acid, 2-hydroxy-
2-Hydroxy-2-methylacetic acid
Purac FCC 88
2-Hydroxypropionic acid
Racemic lactic acid
Milk acid
alpha-Hydroxypropanoic acid
FEMA No. 2611
Lactate (TN)
2-hydroxypropanoic acid
Propanoic acid, 2-hydroxy- (9CI)
(+-)-2-Hydroxypropanoic acid
Fermentationlactic acid Propanoic acid,2-hydroxy-
Ordinary lactic acid
Acidum lacticum
Lactic acid (7CI,8CI)
alpha-hydroxypropionic acid
1-Hydroxyethanecarboxylic acid
【Molecular Formula】
C3H6O3 (Products with the same molecular formula)
【Molecular Weight】
【Canonical SMILES】
【MOL File】

Chemical and Physical Properties

colourless to yellow liquid
1.276 g/cm3
【Melting Point】
18 oC
【Boiling Point】
227.6 °C at 760 mmHg
【Refractive Index】
【Flash Point】
109.9 °C
-0.05 o (C= NEAT 25 oC)
Yellow to colorless crystals or syrupy 50% liquid
Stable. Combustible. Incompatible with strong oxidizing agents.
【Storage temp】
【Spectral properties】
Index of refraction = 1.4392 at 20 deg C
IR: 467 (Sadtler Research Laboratories IR Grating Collection)
1H NMR: 9265 (Sadtler Research Laboratories Spectral Collection)
MASS: 176 (Atlas of Mass Spectral Data, John Wiley & Sons, New York)
【Computed Properties】
Molecular Weight:90.07794 [g/mol]
Molecular Formula:C3H6O3
H-Bond Donor:2
H-Bond Acceptor:3
Rotatable Bond Count:1
Exact Mass:90.031694
MonoIsotopic Mass:90.031694
Topological Polar Surface Area:57.5
Heavy Atom Count:6
Formal Charge:0
Isotope Atom Count:0
Defined Atom Stereocenter Count:0
Undefined Atom Stereocenter Count:1
Defined Bond Stereocenter Count:0
Undefined Bond Stereocenter Count:0
Covalently-Bonded Unit Count:1
Feature 3D Acceptor Count:3
Feature 3D Donor Count:1
Feature 3D Anion Count:1
Effective Rotor Count:1
Conformer Sampling RMSD:0.4
CID Conformer Count:4

Safety and Handling

【Hazard Codes】
Xi: Irritant;C: Corrosive;
【Risk Statements】
【Safety Statements 】

Hazard Codes:?IrritantXi,CorrosiveC
Risk Statements: 38-41-34?
R38: Irritating to skin.?
R41: Risk of serious damage to the eyes.?
R34: Causes burns.
Safety Statements: 26-39-45-36/37/39
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.?
S39: Wear eye / face protection.?
S45: In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)?
S36/37/39: Wear suitable protective clothing, gloves and eye/face protection.
RIDADR: 3265
WGK Germany: 2
RTECS: OD2800000
F: 3
HazardClass: 8
PackingGroup: III
Moderately toxic by ingestion and rectal routes. Mutation data reported. A severe skin and eye irritant. Mixtures with nitric acid + hydrofluoric acid may react vigorously and are storage hazards. When heated to decomposition it emits acrid smoke and irritating fumes.

【PackingGroup 】
【Skin, Eye, and Respiratory Irritations】
In general, on the basis of animal studies and human use, the most significant effects caused by exposure to lactate esters are respiratory, dermal, and ocular irritation. Irritation may be associated with the formation of lactic acid, a product of hydrolysis of lactate esters. /Hydroxyal esters: lactates/
【Cleanup Methods】
Collect leaking liquid in sealable containers. Cautiously neutralize spilled liquid with weak alkaline solution, e.g. disodium carbonate. Then wash away with plenty of water.
UN 1760
Lactic acid is available in edible grades (22-44% concn) and in 50-80% concn for plastic and usp grades.
Grade: Technical, 22% and 44%; food 50 to 80%; plastic 50 to 80%; USP (85-90%); CP; FCC
Has one asymmetric carbon and two enantiomorphic isomers. The commercial form is a racemic mixture.
【Exposure Standards and Regulations】
Substance added directly to human food affirmed as generally recognized as safe (GRAS).
Drug products containing certain active ingredients offered over-the-counter (OTC) for certain uses. A number of active ingredients have been present in OTC drug products for various uses, as described below. However, based on evidence currently available, there are inadequate data to establish general recognition of the safety and effectiveness of these ingredients for the specified uses: lactic acid is included in digestive drug products.
Lactic acid used as a general purpose food additive inanimal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.
【Reactivities and Incompatibilities】
A mixture of 5 parts lactic acid, 5 parts nitric acid, 2 parts water, and 1 part hydrofluoric acid being stored in a plastic bottle ruptured with explosive force. /Nitric acid/
Mixtures of /lactic acid, hydrofluoric acid and nitric acid/, used as metal polishing solutions, are unstable and should not be stored. Lactic acid and nitric acid react autocatalytically after a quiescent period, attaining a temperature of about 90 deg C with vigorous gas evolution after about 12 hr. Prepare freshly, discard after use and handle carefully. /Nitric acid/
【Protective Equipment and Clothing】
In general, on the basis of animal studies and human use, the most significant effects caused by exposure to lactate esters are respiratory, dermal, and ocular irritation. Irritation may be associated with the formation of lactic acid, a product of hydrolysis of lactate esters. /Hydroxyal esters: lactates/

? ?Lactic acid ,?its cas register number is 50-21-5. It also can be called?(RS)-2-Hydroxypropionsaeure ; 1-Hydroxyethanecarboxylic acid ; 2-Hydroxypropanoic acid ; Acidum lacticum ; Aethylidenmilchsaeure ; DL-Lactic acid ; DL-Milchsaeure ; Ethylidenelactic acid ; Kyselina 2-hydroxypropanova ; Kyselina mlecna ; Lactate?; Lactovagan ; Milchsaeure ;
?Milchsaure ; Milk acid ; Ordinary lactic acid ; Propionic acid, 2-hydroxy- ; Racemic lactic acid ; Tonsillosan ; alpha-Hydroxypropionic acid .?Lactic acid (CAS NO.50-21-5) is a?colourless to yellow liquid.

【Octanol/Water Partition Coefficient】
log Kow = -0.72

Reported in EPA TSCA Inventory.

【Disposal Methods】
SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.
The following wastewater treatment technology has been investigated for lactic acid: Concentration process: Biological treatment.

Use and Manufacturing

【Use and Manufacturing】
Methods of Manufacturing

Hydrolysis of lactonitrile (synthetic); fermentation of carbohydrates (natural)
Chemically prepared from acetaldehyde and carbon monoxide in dilute sulfuric acid at 130-200 deg C and 900 atm: Loder, US patent 2,265,945 (1938 to du Pont); by hydrolysis of hexoses with sodium hydroxide: Lock, US patent 2,382,889 (1943).
Chemical Synthesis: The commercial process is based on lactonitrile, which used to be a by-product of acrylonitrile synthesis. It involves base-catalyzed addition of hydrogen cyanide to acetaldehyde to produce lactonitrile. This is a liquid-phase reaction and occurs at atmospheric pressures. The crude lactonitrile is then recovered and purified by distillation and is hydrolyzed to lactic acid using either concentrated hydrochloric or sulfuric acid, producing the corresponding ammonium salt as a by-product. This crude lactic acid is esterified with methanol, producing methyl lactate. The latter is recovered and purified by distillation and hydrolyzed by water under acid catalysts to produce lactic acid, which is further concentrated, purified, and shipped under different product classifications, and methanol, which is recycled
Carbohydrate Fermentation: The existing commercial production processes use homolactic organisms such as Lactobacillus delbrueckii, L. bulgaricus, and L. leichmanii. A wide variety of carbohydrate sources, eg, molasses, corn syrup, whey, dextrose, and cane or beet sugar, can be used. ... Proteinaceous and other complex nutrients required by the organisms are provided by corn steep liquor, yeast extract, soy hydrolysate, etc. Excess calcium carbonate is added to the fermenters to neutralize the acid and produce a calcium salt of the acid in the broth. The fermentation is conducted batchwise, taking 4-6 days to complete, and lactate yields of approximately 90 wt% from a dextrose equivalent of carbohydrate are obtained. It is usually desired to keep the calcium lactate in solution so that it can be easily separated from the cell biomass and other insolubles, and this limits the concentration of carbohydrates that can be fed in the fermentation and the concentration lactate in the fermentation broth, which is usually around 10 wt%. The calcium lactate-containing broth is filtered to remove cells, carbon-treated, evaporated, and acidified with sulfuric acid to convert the salt into lactic acid and insoluble calcium sulfate, which is removed by filtration. The filtrate is further purified by carbon columns and ion exchange and evaporated to produce technical- and food-grade lactic acid, but not a heat-stable product, which is required for the stearoyl lactylates, polymers, solvents and other value-added applications. The technical-grade lactic acid can be esterified with methanol or ethanol and the ester is recovered by distillation, hydrolyzed by water, evaporated, and the alcohol recycled. This separation process produces a highly pure product which, like the synthetic product, is water-white and heat stable.
U.S. Exports

(1972) ND
(1975) ND
(1986) ND
U.S. Imports

(1972) 3.43X10+8 GRAMS
(1973) 6.24X10+8 GRAMS
(1984) 4.96X10+9 g
U.S. Production

This chemical is listed as a High Production Volume (HPV) (65FR81686). Chemicals listed as HPV were produced in or imported into the U.S. in >1 million pounds in 1990 and/or 1994. The HPV list is based on the 1990 Inventory Update Rule. (IUR) (40 CFR part 710 subpart B; 51FR21438).
(1973) 4.99X10+9 GRAMS (EST)
(1975) GREATER THAN 9.1X10+5 GRAMS
(1983) 5.90X10+9 g
(1986) >1 million-10 million pounds
(1990) >1 million-10 million pounds
(1994) >1 million-10 million pounds
(1998) >1 million-10 million pounds
(2002) 10 thousand-500 thousand pounds
Consumption Patterns


Biomedical Effects and Toxicity

【Pharmacological Action】
Inhalation of mist causes coughing and irritation of mucous membranes. Ingestion, even of diluted preparations, has a corrosive effect on the esophagus and stomach. Contact with more concentrated solutions can cause severe burns of skin or eye.
【Therapeutic Uses】
MEDICATION (VET): Has been used as a caustic, and in dilute solutions to irrigate tissues; as an intestinal antiseptic and antiferment.
MEDICATION (VET):Used as a ruminal acidifying agent to treat ruminal stasis and acute urea poisoning.
Has limited usefulness as spermatocide /USP/
【Biomedical Effects and Toxicity】
L-Lactic Acid occurs in small quantities in the blood and muscle fluid of humans and animals; the concentration of Lactic Acid in these fluids increases after vigorous activity. L-Lactic Acid is also present in the liver, kidneys, thymus gland, human amniotic fluid, and other organs and body fluids.
A primed infusion study was performed /in humans/ using radioactive L-Lactic Acid. The virtual volume of distribution of lactate was 49.4% of body weight. The lactate pool size and turnover time were estimated as 0.029 g/kg and 18.4 min, respectively.
In the body, lactate is distributed equivalently to, or slightly less than, total body water. It diffuses readily across cell membranes, primarily by passive transport; under certain conditions, the distribution could be uneven or the lactate pool could consist of several smaller pools with differing rate constants.
The percutaneous absorption of topically applied 5% [14C]-Lactic Acid in an oil-in-water cream was measured using rats. After 3 days, 50% of the applied Lactic Acid had penetrated the skin.
The in vitro percutaneous absorption of Lactic Acid was determined using human abdominal skin. The skin was mounted in flow-through diffusion cells. Skin viability was maintained and barrier integrity was confirmed prior to formulations that were prepared to give an average dose of 0.55 uCi of 14C radioactivity per cell. The emulsions were applied to the skin at 3 mg/sq cm of exposed skin in the diffusion cells (exposed skin = 0.64 sq cm). At the end of each experiment, the skin was washed and rinsed three times, and it was tape stripped 10 times to remove the stratum corneum. The remaining epidermis was separated from the dermis using heat . The absorbed radioactivity in the 6-hr receptor fluid fractions and the skin layers was measured by liquid scintillation counting. The percutaneous absorption of 5% Lactic Acid in 2% PEG-100 stearate and 1% laureth-4 was determined at pH 3 and 7 using skin samples from three subjects for each pH. Total absorption was 30.4 and 9.73% at pH 3 and 7, respectively. With the pH 3 formulation, the amount of radioactivity found in the receptor fluid, stratum corneum, viable epidermis, and dermis was 3.6, 6.3, 6.6, and 13.9%, respectively.
Mongrel dogs were used to examine the tubular reabsorption of Lactic Acid. Following rapid iv Sodium Lactate loading, tubular reabsorption of Lactic Acid was limited. Lactic Acid excretion was urine flow-dependent at low filtered loads. The /investigators/ concluded that Lactic Acid was actively reabsorbed in the proximal tubule, that its transport rate was limited, and that it was either incompletely reabsorbed at low filtered loads or partially secreted at a distal site of the nephron.

Environmental Fate and Exposure Potential

【Environmental Fate/Exposure Summary】
TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 9.7(SRC), determined from a log Kow of -0.72(2) and a regression-derived equation(3), and experimental values of 5.7 and
AQUATIC FATE: Based on a classification scheme(1), experimental Koc values of 5.7 and
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), lactic acid, which has a vapor pressure of 0.0813 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase lactic acid is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 65 hours(SRC), calculated from its rate constant of 5.9X10-12 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). Lactic acid does not contain chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight(4).

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