Testing Information

Testing Status of Agents at NTP

CAS Registry Number: 50-21-5

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http://ntp.niehs.nih.gov/go/27723

Selected information from two of the National Library of Medicine's databases: ChemIDPlus1 and HSDB2.

Names (NTP)

  • 2-HYDROXYPROPANOIC ACID (9CI)
  • LACTIC ACID (ALPHA/BETA HYDROXY ACIDS)
  • alpha/beta Hydroxy acids (Lactic acid)
  • 2-HYDROXYPROPANOIC ACID (9CI)
  • Lactic acid
  • Lactic acid

Structure

Chemical Structure for CAS Registry Number 50-21-5 from NLM

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Chemical Properties2

Property Description
Color/Form
  • Crystals
  • Yellow to colorless crystals or syrupy 50% liquid
Odor
  • Odorless
  • AVAILABLE FORMS HAVE VERY SLIGHTLY ACRID ODOR
Taste
  • TASTE IS ACRID
Boiling Point
  • 122 deg C at 15 mm Hg
Melting Point
  • 16.8 deg C
Molecular Weight
  • 90.09
Corrosivity
  • Caustic in concentrated solutions
Critical Temperature & Pressure
  • None found
Density/Specific Gravity
  • 1.2
Disassociation Constants
  • pKa = 3.86 at 20 deg C
Heat of Combustion
  • 3615 cal/kg
Heat of Vaporization
  • None found
log P (octanol-water)
  • log Kow = -0.72
pH
  • None found
Solubilities
  • Miscible with alcohol, glycerol, and furfural
  • Soluble in alcohol and furfurol; slightly soluble in ether; insoluble in chloroform, petroleum ether, carbon disulfide. Miscible in alcohol-ether solution.
  • In water, miscible
Spectral Properties
  • Index of refraction = 1.4392 at 20 deg C
  • SADTLER REF NUMBER: 5338 (IR, PRISM)
  • 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)
Surface Tension
  • None found
Vapor Density
  • None found
Vapor Pressure
  • 0.0813 mm Hg at 25 deg C (est)
Relative Evaporation Rate
  • None found
Viscosity
  • VISCOSITIES OF AQ LACTIC ACID @ 25 DEG C: 64.89%, 6.69 CENTIPOISES; 75.33%, 13.03 CENTIPOISES; 85.32%, 28.50 CENTIPOISES
Other Properties
  • UNDERGOES SELF-ESTERIFICATION EVEN IN AQ SOLN
  • HYDROLYSIS TO MONOMERIC LACTIC ACID OCCURS UPON DILN WITH WATER
  • WHEN HEATED, DEHYDRATES FORMING SERIES OF POLYLACTIC ACIDS SUCH AS LACTYLLACTIC ACID, LINER TRIMER, & HIGHER POLYMERS
  • Hygroscopic ... Has one asymmetric carbon and two enantiomorphic isomers. The commercial form is a racemic mixture. ... Cannot be distilled at atmospheric pressure without decomposition; when concentrated above 50% it is partially converted to lactic anhydride.
  • SPECIFIC HEAT @ 20 DEG C: 0.505 CAL/G DEG C
  • WHEN SOLN IS HEATED, DEHYDRATION TAKES PLACE BETWEEN ALPHA-HYDROXYL GROUP OF 1 MOLECULE & CARBOXYL OF ANOTHER
  • MASS: 176 (Atlas of Mass Spectral Data, John Wiley & Sons, New York) /Lactic acid (D)/
  • MASS: 176 (Atlas of Mass Spectral Data, John Wiley & Sons, New York) /Lactic acid (L)/
  • Volatile with superheated steam.
  • Crystals from ether and isopropyl ether; melting point = 52.8 deg C; pK = 3.83; soluble in water, alcohol, acetone, ether, glycerol; practically insoluble in chloroform. /D-lactic acid/
  • Crystals from acetic acid or chloroform; melting point = 53 deg C; pK = 3.79 at 25 deg C. /L-lactic acid/
  • Henry's Law constant = 8.1X10-8 atm-cu m/mol at 25 deg C (est)
  • Hydroxyl radical reaction rate constant = 5.9X10-12 cu cm/molec-sec at 25 deg C (est)

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Uses2

  • In dyeing baths, as mordant in printing woolen goods, solvent for water-insoluble dyes (alcohol-soluble induline, nigrosine, spirit-blue); reducing chromates in mordanting wool; manuf cheese, confectionery; acidulant in beverages; for acidulating worts in brewing, for removing Clostridium butyricum in manuf of yeast; dehairing, plumping, and decalcifying hides; solvent for cellulose formate; flux for soft solder; manuf lactates which are used in food products, in medicine, and as solvents; plasticizer, catalyst in the casting of phenolaldehyde resins.
  • Plant grower regulator
  • Food acidulant, used in leather tanning, in textile finishing, in oil well acidizing, int for sodium lactate, int for calcium lactate, pharmaceutical, int for emulsifiers **PEER REVIEWED**
  • MEDICATION **PEER REVIEWED**
  • Lactic acid, when applied to pan-dried egg whites to adjust pH range from 4.8 to 5.1, permits rapid settling of any shell fragments, improves protein dispersion, and aids in producing more stable dried-egg powder ...
  • Lactic acid is used in packing Spanish-type olives, where it insures clarity of brine. ...
  • ... Used to adjust acidity and as flavoring agent in mfr of cheese and dried food case in ... in small amt, for acidifying fruit juice in prodn of wine ... to give improved flavor to carbonated fruit juices ... in certain frozen desserts to provide mild, tart flavor ... employed in some jams and jellies, in mfr of beer ...
  • It is employed ... in mincemeat, mayonnaise, and for solubilizing pepper oleoresin. Together with sorbic acid, it is employed in stabilizing sangria.
  • Used in ... adhesives ...
  • MEDICATION (VET) **PEER REVIEWED**

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Superlist Classes1

  • None found

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Notes (Sources: NTP,HSDB,RTECS,MESH)1

  • None found

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Other Registry Numbers1

  • 152-36-3
  • 598-82-3

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Synonyms (Sources: NTP, HSDB,RTECS,MESH)1

  • BRN 5238667
  • Ethylidenelactic acid
  • FEMA Number 2611
  • HSDB 800
  • 1-Hydroxyethanecarboxylic acid
  • 2-Hydroxypropanoic acid
  • alpha-Hydroxypropionic acid
  • 2-Hydroxypropionic acid
  • Lactate
  • DL-Lactic acid
  • Lactovagan
  • Milk acid
  • Ordinary lactic acid
  • Propanoic acid, 2-hydroxy-
  • Propel
  • Propionic acid, 2-hydroxy-
  • Racemic lactic acid
  • SY-83
  • Tonsillosan

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Links to Additional Information1

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Footnotes

1 Source: the National Library of Medicine's ChemIDPlus, 10/28/2007.

2 Source: the National Library of Medicine's Hazardous Substance Database, 10/28/2007.

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Web page last updated on May 14, 2008