Lactic Acid

Identification

Molecular formula

C₃H₆O₃

CAS number

50-21-5

IUPAC name

2-hydroxypropanoic acid

State

At room temperature, lactic acid is typically in a liquid state, although it can also form a solid crystalline structure if it is isolated as a pure compound without any water.

Melting point (Celsius)

16.80

Melting point (Kelvin)

289.95

Boiling point (Celsius)

122.00

Boiling point (Kelvin)

395.15

General information

Molecular weight

90.08g/mol

Molar mass

90.0800g/mol

Density

1.2090g/cm³

Appearence

Lactic acid is a colorless to yellowish liquid that can also appear as a white crystalline solid when pure. It has a distinct sour taste and is hygroscopic, meaning it readily absorbs moisture from the environment.

Comment on solubility

Solubility of 2-hydroxypropanoic acid (C₃H₆O₃)

2-hydroxypropanoic acid, commonly known as lactic acid, exhibits a remarkable solubility profile that makes it notable among organic acids. Below are some key features of its solubility:

High Solubility in Water: Lactic acid is highly soluble in water, with solubility often reported to be around 85 g in 100 mL at room temperature. This high solubility is largely due to:

The presence of hydroxyl (-OH) groups which can form hydrogen bonds with water molecules, enhancing solvation.
The relatively small size of the lactic acid molecule, which facilitates its interaction with water.

Solubility in Organic Solvents: In addition to water, lactic acid is also soluble in organic solvents such as:

Ethanol
Acetone
Glycerol

This characteristic allows it to be utilized in various biochemical applications as a solvent or reagent.

Effect of pH: The solubility of 2-hydroxypropanoic acid can be influenced by the pH of the solution. As a weak acid:

It tends to be more soluble in basic conditions where it exists in its deprotonated form (lactate).
At lower pH, lactic acid exists predominantly in its protonated form, which may affect interactions with water.

Overall, lactic acid's solubility makes it an essential compound in various fields, ranging from the food industry to biochemistry. Its ability to dissolve in different mediums is a testament to its versatility and importance.

Interesting facts

Interesting Facts about 2-Hydroxypropanoic Acid

2-Hydroxypropanoic acid, commonly known as lactic acid, is a fascinating compound with significant roles in both biochemistry and various industrial applications. Here are some intriguing facts about this remarkable acid:

Biological Significance: Lactic acid is produced naturally in the body, primarily during anaerobic respiration. It is a crucial component of the Krebs cycle, which plays a key role in energy production.
Fermentation Process: This compound is widely recognized for its role in fermentation. It's produced by certain bacteria during the fermentation of carbohydrates, leading to the delicious tang found in foods like yogurt and pickles.
Dual Isomer Forms: Lactic acid exists in two enantiomeric forms: R-(+)-lactic acid and S-(-)-lactic acid. The former is often used in food and cosmetic applications, while the latter is found in sports drinks and minimally processed foods.
Used in Skincare: Due to its exfoliating properties and ability to retain moisture, lactic acid is a popular ingredient in many skincare products. It's known for giving skin a fresh, revitalized appearance.
Biodegradable Plastics: Lactic acid serves as a starting material for producing polylactic acid (PLA), a biodegradable plastic often used as an eco-friendly alternative in packaging and various disposable products.
pH Regulation: In food processing, lactic acid acts as a preservative and pH regulator, helping to maintain product stability and safety.

In summary, 2-hydroxypropanoic acid is not only prevalent in nature but also versatile in its applications across various fields, from food science to environmental sustainability. As the saying goes, “Science is not only a disciple of reason but, also, one of romance and passion," making compounds like lactic acid endlessly fascinating for study and application.

Synonyms

lactic acid

2-hydroxypropanoic acid

DL-Lactic acid

50-21-5

2-hydroxypropionic acid

lactate

Milk acid

Tonsillosan

Racemic lactic acid

Ordinary lactic acid

Ethylidenelactic acid

Lactovagan

Acidum lacticum

Milchsaeure

Lactic acid, dl-

Kyselina mlecna

Lacticum acidum

Propanoic acid, 2-hydroxy-

DL-Milchsaeure

598-82-3

Lactic acid USP

(+/-)-Lactic acid

Aethylidenmilchsaeure

1-Hydroxyethanecarboxylic acid

alpha-Hydroxypropionic acid

Lactic acid (natural)

(RS)-2-Hydroxypropionsaeure

FEMA No. 2611

Milchsaure

Kyselina 2-hydroxypropanova

Lurex

Propionic acid, 2-hydroxy-

Purac FCC 80

Purac FCC 88

Cheongin samrakhan

DL- lactic acid

FEMA Number 2611

CCRIS 2951

HSDB 800

Cheongin Haewoohwan

Cheongin Haejanghwan

SY-83

2-Hydroxypropionicacid

(+-)-2-Hydroxypropanoic acid

Biolac

NSC 367919

Lactic acid, tech grade

Chem-Cast

alpha-Hydroxypropanoic acid

AI3-03130

HIPURE 88

EINECS 200-018-0

EINECS 209-954-4

MFCD00004520

EPA Pesticide Chemical Code 128929

Lactic acid,buffered

NSC-367919

UNII-3B8D35Y7S4

2-Hydroxy-2-methylacetic acid

BRN 5238667

INS NO.270

DTXSID7023192

(+/-)-2-hydroxypropanoic acid

CHEBI:78320

INS-270

2 Hydroxypropanoic Acid

3B8D35Y7S4

E 270

LACTIC ACID (+-)

.alpha.-Hydroxypropanoic acid

.alpha.-Hydroxypropionic acid

DTXCID003192

E-270

EC 200-018-0

NCGC00090972-01

2-hydroxy-propionic acid

C01432

DL-Lactic Acid (90%)

Milchsaure [German]

Lactic acid [JAN]

Kyselina mlecna [Czech]

Propanoic acid, hydroxy-

CAS-50-21-5

(R)-2-Hydroxy-propionic acid;H-D-Lac-OH

2 Hydroxypropionic Acid

26811-96-1

Kyselina 2-hydroxypropanova [Czech]

Lactic acid [USP:JAN]

lactasol

1-Hydroxyethane 1-carboxylic acid

acido lactico

DL-Milchsaure

MFCD00064266

(2RS)-2-Hydroxypropanoic acid

Lactate (Standard)

Lactate (TN)

4b5w

Propanoic acid, (+-)

DL-Lactic Acid, Racemic

LACTIC ACID (II)

(.+/-.)-Lactic acid

Lactic acid (7CI,8CI)

Lactic acid (JP17/USP)

Lactic acid, 85%, FCC

Lactic Acid, Racemic, USP

NCIOpen2_000884

(+-)-LACTIC ACID

DL-LACTIC ACID [MI]

LACTIC ACID [WHO-IP]

(RS)-2-hydroxypropanoic acid

LACTIC ACID, DL-(II)

LACTICUM ACIDUM [HPUS]

1-hydroxyethane carboxylic acid

33X04XA5AT

DL-Lactic Acid (90per cent)

L-(+)-Lactic acid, 98%

CHEMBL1200559

Lactic acid, natural, >=85%

PROPANOIC ACID, 2-HYDROXY-, (2S)-, HOMOPOLYMER

BDBM23233

HY-B2227R

L-lactic acid or dl-lactic acid

Lactic Acid, 85 Percent, FCC

LACTIC ACID, DL- [II]

DL-Lactic acid, ~90% (T)

DL-Lactic acid, AR, >=88%

DL-Lactic acid, LR, >=88%

DL- LACTIC ACID [WHO-DD]

LACTIC ACID (EP MONOGRAPH)

Lactic Acid, 10 Percent Solution

HY-B2227

LACTIC ACID (USP MONOGRAPH)

Propanoic acid, 2-hydroxy- (9CI)

Tox21_111049

Tox21_202455

Tox21_303616

BBL027466

NSC367919

STL282744

AKOS000118855

AKOS017278364

Tox21_111049_1

ACIDUM LACTICUM [WHO-IP LATIN]

DB04398

FL14256

SB44647

SB44652

Propanoic acid,2-hydroxy-,(.+/-.)-

2-Hydroxypropionic acid, DL-Lactic acid

NCGC00090972-02

NCGC00090972-03

NCGC00257515-01

NCGC00260004-01

849585-22-4

FP158009

Lactic Acid, 85 Percent, Reagent, ACS

(R)-Lactate;(R)-2-Hydroxypropionic acid;

DB-071134

DB-347146

CS-0021601

L0226

Polylactic acid - MW 40,000~80,000

EN300-19542

Lactic acid, meets USP testing specifications

D00111

F71201

A877374

DL-Lactic acid, SAJ first grade, 85.0-92.0%

Q161249

2-Hydroxypropionic acid, Natural, Kosher Certified

DL-Lactic acid, JIS special grade, 85.0-92.0%

Dl-alpha-hydroxypropionic acid;2-hydroxypropionic acid

F2191-0200

Z104474158

BC10F553-5D5D-4388-BB74-378ED4E24908

Lactic acid, United States Pharmacopeia (USP) Reference Standard

Lactic acid, Pharmaceutical Secondary Standard; Certified Reference Material

DL-Lactic acid 90%, synthetic, meets the analytical specifications of Ph. Eur.

152-36-3

200-018-0

209-954-4

Solubility of 2-hydroxypropanoic acid (C3H6O3)

Interesting Facts about 2-Hydroxypropanoic Acid

Solubility of 2-hydroxypropanoic acid (C₃H₆O₃)