LACTIC ACID

CAS No: 50-21-5

synonyms:
-2-Hydroxypropionic acid, Sarcolactic acid;201-196-2;2-Hydroxypropionic acid;DL-Lactic acid;Sarcolactic acid;;2 Hydroxypropanoic Acid;2 Hydroxypropionic Acid;2-Hydroxypropanoic Acid;2-Hydroxypropionic Acid;Ammonium Lactate;D Lactic Acid;D-Lactic Acid;L Lactic Acid;L-Lactic Acid;Lactate;Lactate, Ammonium;Lactic Acid;Propanoic Acid, 2-Hydroxy-, (2R)-;Propanoic Acid, 2-Hydroxy-, (2S)-;Sarcolactic Acid;lactic acid;2-hydroxypropanoic acid;DL-Lactic acid;50-21-5;2-hydroxypropionic acid;lactate;Milk acid;Polylactic acid;Ethylidenelactic acid;Lactovagan;Tonsillosan;Racemic lactic acid;Propanoic acid, 2-hydroxy-;Ordinary lactic acid;Milchsaeure;Acidum lacticum;Kyselina mlecna;DL-Milchsaeure;Lactic acid USP;1-Hydroxyethanecarboxylic acid;Aethylidenmilchsaeure;Milchsaure;L(+)-LACTIC ACID;Lactic acid (natural);(+/-)-Lactic acid,Poly(lactic acid);Lactic acid, dl-;alpha-Hydroxypropionic acid;Kyselina 2-hydroxypropanova;Milchsaure [German];Propionic acid, 2-hydroxy-;(RS)-2-Hydroxypropionsaeure;FEMA No. 2611;CCRIS 2951;HSDB 800;(+-)-2-Hydroxypropanoic acid;FEMA Number 2611;Kyselina mlecna [Czech];SY-83;598-82-3;Propel;NSC 367919,26100-51-6;AI3-03130;2-hydroxy-propionic acid;Kyselina 2-hydroxypropanova [Czech];EINECS 200-018-0;EINECS 209-954-4;EPA Pesticide Chemical Code 128929;BRN 5238667;CHEBI:78320;JVTAAEKCZFNVCJUHFFFAOYSAN;MFCD00004520;SBB065762;C3H6O3;NCGC0009097201;E270;DSSTox_CID_3192;C01432;DSSTox_RID_76915;DSSTox_GSID_23192;Polactide;CAS-50-21-5;Cheongin Haewoohwan;Cheongin Haejanghwan;Lactic acid [JAN];alpha-Hydroxypropanoic acid;lactasol;1-Hydroxyethane 1-carboxylic acid;Biolac;2-Hydroxy-2-methylacetic acid;Cheese whey;hydrogen lactate;Lactide Polymer;Penederm Lotion;Milk serum;DL-Lacticacid;MFCD00064266;Chem-Cast;Whey, cheese;Cheongin Samrakhwan;Lactate (TN);DL-EeEa;D(-)-lactic acid;2-Hydroxypropionicacid;Purac FCC 80;Purac FCC 88;Propanoic acid, 2-hydroxy-, homopolymer;4b5w;Lactimol - Crm 10%,AC1Q1LFG;Propanoic acid, (+-),Herbal Stemcell Aha Peel;2-oC>>u+/-uEa;(.+/-.)-Lactic acid;AC1L19MD,D-LACTIC ACID, ACS;Lactic acid (7CI,8CI),ACMC-1B0N9;Lactic acid (JP17/USP);Lactic acid, 85%, FCC;NCIOpen2_000884;UNII-33X04XA5AT;.alpha.-Hydroxypropanoic acid;.alpha.-Hydroxypropionic acid;Fresh Morning Bifidus Bifidus;KSC269O0T;L-LACTIC ACID, Ca SALT;Lactic Acid (Fragrance Grade);Jsp000339;L-(+)-Lactic acid, 98%;(2RS)-2-Hydroxypropanoic acid;CHEMBL1200559;DTXSID7023192;Lactic acid, natural, >=85%;BDBM23233;CTK1G9709;HSDB 8244;DL-Lactic acid, ~90% (T);DL-Lactic acid, AR, >=88%;DL-Lactic acid, LR, >=88%;MolPort-001-788-303;L-LACTIC ACID, CALCIUM SALT;Lacticacid,1.0NStandardizedSolution;EINECS 295-890-2;Keri Original - Aha - Lotion 5%;Propanoic acid, 2-hydroxy- (9CI);Tox21_111049;Tox21_202455;Tox21_303616;ANW-43668;BBL027466;NSC367919;STL282744;AKOS000118855;AKOS017278364;ETHYL, 1-CARBOXY-1-HYDROXY-;Tox21_111049_1;AM87208;DB04398;Keri Fast Absorbing - Aha - Lot 5%;LS-2145;MCULE-5387110670;NSC-367919;RP18533;RTR-036893;TRA0023918;VC30148;DL-Lactic acid, 85 % (w/w), syrup;Propanoic acid,2-hydroxy-,(.+/-.)-;NCGC00090972-02;NCGC00090972-03,NCGC00257515-01;NCGC00260004-01;163894-00-6;AK307323;AK308539;AN-21582;AN-23990;AN-24369;I487;KB-53095;Lactic acid, 1.0N Standardized Solution;OR034131;OR225681;OR230597;OR249756;SC-18578;SC-86055,DL-Lactic acid, 80-85% aqueous solution;LS-180647;RT-001148;TR-036893;235-EP2269610A2;235-EP2269986A1;235-EP2269988A2;235-EP2270000A1;235-EP2270006A1;235-EP2270008A1;235-EP2270014A1;235-EP2272516A2;235-EP2272537A2;235-EP2272817A1;235-EP2272822A1;235-EP2272835A1;235-EP2272844A1;235-EP2275401A1;235-EP2275413A1;235-EP2275421A1;235-EP2277507A1;235-EP2277848A1;235-EP2277858A1;235-EP2281559A1;235-EP2281563A1;235-EP2281819A1;235;EP2284160A1;235-EP2284178A2;235-EP2284179A2;235-EP2286795A1;235-EP2287147A2;235-EP2287153A1;235-EP2287156A1;235-EP2287160A1;235-EP2289510A1;235-EP2289518A1;235-EP2289879A1;235-EP2289883A1;235-EP2289890A1;235-EP2292227A2;235-EP2292231A1;235-EP2292234A1;235-EP2292592A1;235-EP2292611A1;235-EP2292617A1;235-EP2292619A1;235-EP2295416A2;235-EP2295433A2;235-EP2295439A1;235-EP2298734A2;235;EP2298742A1;235-EP2298746A1;235-EP2298747A1;235-EP2298748A2;235-EP2298755A1;235-EP2298757A2;235;EP2298768A1;235-EP2301544A1;235-EP2301919A1;235-EP2301922A1;235-EP2301940A1;235-EP2305248A1;235-EP2305633A1;235-EP2305641A1;235-EP2305646A1;235-EP2305651A1;235-EP2305653A1;235-EP2305655A2;235-EP2305657A2;235-EP2305659A1;235-EP2305662A1;235-EP2305663A1;235-EP2305668A1;235-EP2305672A1;235-EP2308849A1;235-EP2308850A1;235-EP2308854A1;235-EP2308857A1;235-EP2308861A1;235-EP2308869A1;235-EP2308873A1;235-EP2308874A1;235-EP2308875A1;235-EP2308881A1;235-EP2308883A1;235-EP2311801A1;235-EP2311802A1;235-EP2311803A1;235-EP2311807A1;235-EP2311809A1;235-EP2311810A1;235-EP2311811A1;235-EP2311814A1;235-EP2311818A1;235-EP2311821A1;235-EP2311831A1;235-EP2311842A2;235-EP2314575A1;235-EP2314579A1;235-EP2314581A1;235-EP2314583A1;235-EP2314584A1;235-EP2314585A1;235-EP2314586A1;235-EP2314588A1;235-EP2316457A1;235-EP2316458A1;235-EP2316459A1;235-EP2316825A1;235-EP2316826A1;235-EP2316827A1;235-EP2316828A1;235-EP2316836A1;235-EP2371797A1;235-EP2371800A1;235-EP2371814A1;235-EP2372017A1;235-EP2374895A1;E 270;FT-0624390;FT-0625477;FT-0627927;L0226;Lactic acid solution, ACS reagent, >=85%;Lactic acid solution, USP, 88.0-92.0%;Lactic acid solution, p.a., 84.5-85.5%;Lactic acid, meets USP testing specifications;D00111;DL-Lactic acid, SAJ first grade, 85.0-92.0%;Propanoic acid, 2-hydroxy-, (+-)-, homopolymer;DL-Lactic acid, JIS special grade, 85.0-92.0%;I04-0181;I04-0197;Lactic acid solution, Vetec(TM) reagent grade, 85%;F2191-0200;BC10F553-5D5D-4388-BB74-378ED4E24908;Lactic acid, pharmaceutical secondary standard; traceable to USP;Lactic acid, United States Pharmacopeia (USP) R;ALPHA/BETA HYDROXY ACIDS (LACTIC ACID) (ALPHA/BETA HYDROXY ACIDS);1104201-86-6;1148011-07-7;1384255-85-9;152-36-3;31587-11-8;947236-64-8;DL-Lactic acid;Lactic acid;«alpha»-Hydroxypropanoic acid;«alpha»-Hydroxypropionic acid;Acetonic acid;Milk acid;2-Hydroxypropionic acid;Ethylidenelactic acid;1 Hydroxyethanecarboxylic acid;2-Hydroxypropanoic acid;Kyselina 2-hydroxypropanova;Kyselina mlecna;DL-Lactic acid;Milchsaure;Ordinary lactic acid;Propionic acid, 2-hydroxy-;Racemic lactic acid;1-Hydroxyethane 1-carboxylic acid;Patlac LA;Purac;Lactic Acid; DL-2-Hydroxypropanoic Acid;LACTICACID;Acetonic Acid,Ethylidenelacticacid;milk acid;tisulac;espiritin;paralactic acid;sarcolactic acid;paraliytikacid;acidum;lacticum;acidum;sarcolacticum;aethylidenmilchsaeure;biolac;espiritin;ethylidene lactic acid;2-hydroxy-2-methylacetic acid;1-hydroxyethane carboxylic acid;(±)-2-hydroxypropanoic acid;a-hydroxypropionic acid;alpha-hydroxypropionic acid;(RS)-2-hydroxypropionsaeure;lactacyd;lactasol;(±)-lactic acid;DL-lactic acid;lactic acid 50% FCC;lactic acid 80%, (naturals);lactic acid 88% USP heat stable (fermented);DL-lactic acid FCC;lactic acid natural;lactic acid powder;lactic acid synthetic;lactic acid, 88% USP;lacticacid;lactovagan;dextro,laevo-milchsaeure;DL-milchsaeure;milk acid;paramilchsaeure;propanoic acid, 2-hydroxy-;propel;propionic acid, 2-hydroxy-;tisulac;tonsillosan;dextro,laevo-2-hydroxypropanoic acid;DL-Lactic Acid;(±)-lactic acid;(±)-lactic acid;(±)-Lactic acid;(RS)-2-Hydroxypropionsaeure [German];200-018-0 [EINECS];209-954-4 [EINECS];26100-51-6 [RN];2-Hydroxy-2-methylacetic acid;2-Hydroxypropanoic acid [ACD/IUPAC Name];2-Hydroxypropansäure [German] [ACD/IUPAC Name];2-Hydroxypropionic acid;50-21-5 [RN];598-82-3 [RN];Acide 2-hydroxypropanoïque [French] [ACD/IUPAC Name];d,l-lactic acid;Kyselina 2-hydroxypropanova [Czech];Lactic acid [JAN];Lactic acid (7CI,8CI);Propanoic acid, 2-hydroxy- [ACD/Index Name];Propanoic acid, 2-hydroxy-, (±);QY1&VQ [WLN];UNII:3B8D35Y7S4;α-Hydroxypropanoic acid;α-Hydroxypropionic acid;[50-21-5];1209341 [Beilstein];1704069-23-7 [RN];1-Hydroxyethane 1-carboxylic acid;1-Hydroxyethanecarboxylic acid;2-?hydroxy-Propanoic acid;26023-30-3 [RN];2-HYDROXYPROPIONICACID;3B8D35Y7S4;4-03-00-00633 [Beilstein];79-33-4;92129-90-3 [RN];Acidum lacticum;Acidum sarcolacticum;A-HYDROXYPROPIONIC ACID;Biolac;Calcium lactate [JP15] [Trade name] [USP];D(-)-Lactic Acid;DL-2-hydroxypropionic acid;DL-Milchsaeure;E270;Espiritin;ETHYLIDENELACTIC ACID;Fleischmilchsaeure [German];hydrogen lactate;hydroxypropanoic acid;Jsp000339;Kyselina 2-hydroxypropanova;Kyselina mlecna [Czech];Lac;Lacolin;Lactacyd;lactasol;LACTIC ACID, DL-;Lacticacid;Lactovagan;MFCD00004520 [MDL number];MFCD00064266 [MDL number];MFCD00081867;Milchsaeure;Milchsaure;MILK ACID;Paralactic acid;Paramilchsaeure;PROPANOIC ACID, HYDROXY-;Propel;Propionic acid, 2-hydroxy-;RACEMIC LACTIC ACID;Sarcolactic acid;Tisulac;Tonsillosan;UNII-XO254YE73I;WHEY;α-Hydroxypropanoic acid;α-Hydroxypropionic acid;FEMA;2611;DL-ALPHA-HYDROXYPROPIONIC ACID;(+/-)-LACTIC ACID;LACTIC ACID;LACTIC ACID, RACEMIC;2-HYDROXYPROPIONIC ACID, RACEMIC;(+/-)-2-HYDROXYPROPIONIC ACID;2-HYDROXYPROPIONIC ACID;1,3-dioxan-2-one; Lactic acid; Hydroxyapatite Calcium lactate; Malic acid; Clofibrate; 9-HYDROXYFLUORENE-9-CARBOXYLIC ACID; TRICHLORO PYRUVIC ACID; 2-ETHYL-2-HYDROXYBUTYRIC ACID; Chlorogenic acid; Quinic acid; SODIUM DIHYDROXYTARTRATE; Nisin; 3-HYDROXYPROPIONIC ACID; 2,3-Dibromopropionic acid; ACETIC ACID; Citric acid; Hydroxy silicone oil.; LACTİC ACİD; Lactic Acit; Laktic Acit; LACTIC ACİD; Laktic Acite; Laktic Acit; Laktik asit; laktik asit; LAKTİK ASİT; LAKTIK ASIT; LAKTİK ASİTE; LAKTİK ACİT

LACTİC ACİD
Lactic acid is an organic acid. It has a molecular formula CH3CH(OH)COOH. It is white in solid state and it is miscible with water.[2] While in liquid state (dissolved state) it is a colorless solution. Production includes both artificial synthesis as well as natural sources. Lactic acid is an alpha-hydroxy acid (AHA) due to the presence of carboxyl group adjacent to the hydroxyl group. It is used as a synthetic intermediate in many organic synthesis industries and in various biochemical industries. The conjugate base of lactic acid is called lactate.

In solution, it can ionize a proton from the carboxyl group, producing the lactate ion CH
3CH(OH)CO−
2. Compared to acetic acid, its pKa is 1 unit less, meaning lactic acid is ten times more acidic than acetic acid. This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group.

Lactic acid is chiral, consisting of two enantiomers. One is known as l-(+)-lactic acid or (S)-lactic acid and the other, its mirror image, is d-(−)-lactic acid or (R)-lactic acid. A mixture of the two in equal amounts is called dl-lactic acid, or racemic lactic acid. Lactic acid is hygroscopic. dl-Lactic acid is miscible with water and with ethanol above its melting point, which is around 16, 17 or 18 °C. d-Lactic acid and l-lactic acid have a higher melting point. Lactic acid produced by fermentation of milk is often racemic, although certain species of bacteria produce solely (R)-lactic acid. On the other hand, lactic acid produced by anaerobic respiration in animal muscles has the (S) configuration and is sometimes called "sarcolactic" acid, from the Greek "sarx" for flesh.

In animals, l-lactate is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH) in a process of fermentation during normal metabolism and exercise. It does not increase in concentration until the rate of lactate production exceeds the rate of lactate removal, which is governed by a number of factors, including monocarboxylate transporters, concentration and isoform of LDH, and oxidative capacity of tissues. The concentration of blood lactate is usually 1–2 mM at rest, but can rise to over 20 mM during intense exertion and as high as 25 mM afterward.[6][7] In addition to other biological roles, l-lactic acid is the primary endogenous agonist of hydroxycarboxylic acid receptor 1 (HCA1), which is a Gi/o-coupled G protein-coupled receptor (GPCR).[8][9]

In industry, lactic acid fermentation is performed by lactic acid bacteria, which convert simple carbohydrates such as glucose, sucrose, or galactose to lactic acid. These bacteria can also grow in the mouth; the acid they produce is responsible for the tooth decay known as caries.[10][11][12][13] In medicine, lactate is one of the main components of lactated Ringer's solution and Hartmann's solution. These intravenous fluids consist of sodium and potassium cations along with lactate and chloride anions in solution with distilled water, generally in concentrations isotonic with human blood. It is most commonly used for fluid resuscitation after blood loss due to trauma, surgery, or burns.

History
Swedish chemist Carl Wilhelm Scheele was the first person to isolate lactic acid in 1780 from sour milk. The name reflects the lact- combining form derived from the Latin word lac, which means milk. In 1808, Jöns Jacob Berzelius discovered that lactic acid (actually l-lactate) also is produced in muscles during exertion.[14] Its structure was established by Johannes Wislicenus in 1873.

In 1856, the role of Lactobacillus in the synthesis of lactic acid was discovered by Louis Pasteur. This pathway was used commercially by the German pharmacy Boehringer Ingelheim in 1895.

In 2006, global production of lactic acid reached 275,000 tonnes with an average annual growth of 10%.[15]

Production
Lactic acid is produced industrially by bacterial fermentation of carbohydrates, or by chemical synthesis from acetaldehyde that comes from coal or crude oil.[16] In 2009, lactic acid was produced predominantly (70–90%)[17] by fermentation. Production of racemic lactic acid consisting of a 1:1 mixture of d and l stereoisomers, or of mixtures with up to 99.9% l-lactic acid, is possible by microbial fermentation. Industrial scale production of d-lactic acid by fermentation is possible, but much more challenging.

Fermentative production
Fermented milk products are obtained industrially by fermentation of milk or whey by Lactobacillius species bacteria: Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus delbrueckii subsp. bulgaricus (Lactobacillus bulgaricus), Lactobacillus helveticus, Lactococcus lactis, and Streptococcus salivarius subsp. thermophilus (Streptococcus thermophilus).

As a starting material for industrial production of lactic acid, almost any carbohydrate source containing C5 and C6 sugars can be used. Pure sucrose, glucose from starch, raw sugar, and beet juice are frequently used.[18] Lactic acid producing bacteria can be divided in two classes: homofermentative bacteria like Lactobacillus casei and Lactococcus lactis, producing two moles of lactate from one mole of glucose, and heterofermentative species producing one mole of lactate from one mole of glucose as well as carbon dioxide and acetic acid/ethanol.[19]

Chemical production
Racemic lactic acid is produced by the addition of hydrogen cyanide to acetaldehyde and subsequent hydrolysis, forming lactonitrile. When hydrolysis performed by hydrochloric acid, ammonium chloride forms as a by-product; the Japanese company Musashino is one of the last big manufactures of lactic acid by this route.[20] Synthesis of both racemic and enantiopure lactic acids is also possible from other starting materials (vinyl acetate, glycerol, etc.) by application of catalytic procedures.[21]

Biology
Molecular biology
l-Lactic acid is the primary endogenous agonist of hydroxycarboxylic acid receptor 1 (HCA1), a Gi/o-coupled G protein-coupled receptor (GPCR).[8][9]

Exercise and lactate
During power exercises such as sprinting, when the rate of demand for energy is high, glucose is broken down and oxidized to pyruvate, and lactate is then produced from the pyruvate faster than the body can process it, causing lactate concentrations to rise. The production of lactate is beneficial for NAD+ regeneration (pyruvate is reduced to lactate while NADH is oxidized to NAD+), which is used up in oxidation of glyceraldehyde 3-phosphate during production of pyruvate from glucose, and this ensures that energy production is maintained and exercise can continue. During intense exercise, the respiratory chain cannot keep up with the amount of hydrogen ions that join to form NADH, and cannot regenerate NAD+ quickly enough.

The resulting lactate can be used in two ways:

Oxidation back to pyruvate by well-oxygenated muscle cells, heart cells, and brain cells
Pyruvate is then directly used to fuel the Krebs cycle
Conversion to glucose via gluconeogenesis in the liver and release back into circulation; see Cori cycle[22]
If blood glucose concentrations are high, the glucose can be used to build up the liver's glycogen stores.
However, lactate is continually formed even at rest and during moderate exercise. Some causes of this are metabolism in red blood cells that lack mitochondria, and limitations resulting from the enzyme activity that occurs in muscle fibers having high glycolytic capacity.[22]

In 2004, Robergs et al. maintained that lactic acidosis during exercise is a "construct" or myth, pointing out that part of the H+ comes from ATP hydrolysis (ATP4− + H2O → ADP3− + HPO2−
4 + H+), and that reducing pyruvate to lactate (pyruvate− + NADH + H+ → lactate− + NAD+) actually consumes H+.[23] Lindinger et al.[24] countered that they had ignored the causative factors of the increase in [H+]. After all, the production of lactate− from a neutral molecule must increase [H+] to maintain electroneutrality. The point of Robergs's paper, however, was that lactate− is produced from pyruvate−, which has the same charge. It is pyruvate− production from neutral glucose that generates H+:

       C6H12O6 + 2 NAD+ + 2 ADP3− + 2 HPO2−
4    →    2 CH
3COCO−
2 + 2 H+ + 2 NADH + 2 ATP4− + 2 H2O
Subsequent lactate− production absorbs these protons:
2 CH
3COCO−
2 + 2 H+ + 2 NADH    →    2 CH
3CH(OH)CO−
2 + 2 NAD+
Overall:
C6H12O6 + 2 NAD+ + 2 ADP3− + 2 HPO2−
4    →    2 CH
3COCO−
2 + 2 H+ + 2 NADH + 2 ATP4− + 2 H2O
→    2 CH
3CH(OH)CO−
2 + 2 NAD+ + 2 ATP4− + 2 H2O
Although the reaction glucose → 2 lactate− + 2 H+ releases two H+ when viewed on its own, the H+ are absorbed in the production of ATP. On the other hand, the absorbed acidity is released during subsequent hydrolysis of ATP: ATP4− + H2O → ADP3− + HPO2−
4 + H+. So once the use of ATP is included, the overall reaction is

C6H12O6 → 2 CH
3COCO−
2 + 2 H+
The generation of CO2 during respiration also causes an increase in [H+].

Brain metabolism
Although glucose is usually assumed to be the main energy source for living tissues, there are some indications that it is lactate, and not glucose, that is preferentially metabolized by neurons in the brain of several mammalian species (the notable ones being mice, rats, and humans).[25][26] According to the lactate-shuttle hypothesis, glial cells are responsible for transforming glucose into lactate, and for providing lactate to the neurons.[27][28] Because of this local metabolic activity of glial cells, the extracellular fluid immediately surrounding neurons strongly differs in composition from the blood or cerebrospinal fluid, being much richer with lactate, as was found in microdialysis studies.[25]
LACTIC ACID

LACTIC ACID is a colorless to yellow odorless syrupy liquid. Corrosive to metals and tissue. Used to make cultured dairy products, as a food preservative, and to make chemicals.Lactic acid is a chemical compound that plays a role in various biochemical processes. Lactic acid is a carboxylic acid with the chemical formula C3H6O3. It has a hydroxyl group adjacent to the carboxyl group, making it an alpha hydroxy acid (AHA). Lactic acid is miscible with water or ethanol, and is hygroscopic. Lactic acid is chiral and has two optical isomers. One is known as L-(+)-lactic acid or (S)-lactic acid and the other, its mirror image, is D-(-)-lactic acid or (R)-lactic acid.

PHYSICAL and CHEMICAL PROPERTIES of LACTIC ACID

Lactic acid is a clear to slightly yellow liquid with a melting point of 16.8°C, a boiling point of 258°C at 1,000
hPa, a vapour pressure of 0.004 hPa at 20 ºC, the octanol-water partition coefficient (log Kow) of -0.62 and
water solubility of 876 g/L. As the dissociation constant (pKa) is 3.68, lactic acid is anticipated to exist
primarily in its dissociated form at environmentally relevant pH.Emprical Formula: C3H6O3
Linear Formula: CH3CH(OH)COOH
Molecular Weight: 90.08 
Appearance: colourless to yellow liquid
Density    1.21 g/cm3 (20 °C)
Melting Point: 18 C
Boiling Point: 122 C
Flashpoint    113 °C
pH value    2.8 (10 g/l, H₂O, 20 °C)
Vapor pressure    0.1 hPa (25 °C)
Stability: Stable. Combustible. Incompatible with strong oxidizing agents.
Storage Temperature    room temp
Department: Organics

LACTIC ACID REACTIVITY

Lactic acid is a carboxylic acid. Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water. Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in Lactic acid to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions. Slowly corrodes most metals [USCG, 1999].

MANUFACTURING PROCESS of LACTIC ACID

Lactic acid can be produced naturally or synthetically. Commercial lactic acid is produced naturally by fermentation of carbohydrates such as glucose, sucrose, or lactose.In the natural production process, lime or chalk is added and the raw materials are fermented in a fermenter and crude calcium lactate is formed. The gypsum is separated from the crude calcium lactate, which results in crude lactic acid. The crude lactic acid is purified and concentrated and L(+) lactic acid is the result.

=> Food Industry
Lactic acid is found primarily in sour milk products, such as koumiss, laban, yogurt, etc. The casein in fermented milk is coagulated by lactic acid. Lactic acid is also responsible for the sour flavor of sourdough breads. This acid is used in beer brewing to lower the wort pH in order to reduce some undesirable substances such as tannins without giving off-flavors such as citric acid and increase the body of the beer. Some brewers and breweries will use food grade lactic acid to lower the pH in finished beers. In winemaking, a bacterial process, natural or controlled, is often used to convert the naturally present malic acid to lactic acid, to reduce the sharpness and for other flavor-related reasons. This malolactic fermentation is undertaken by the family of lactic acid bacteria. As a food additive, lactic acid is used as a food preservative, curing agent, and flavoring agent. It is an ingredient in processed foods and is used as a decontaminant during meat processing.

=> Pharmaceutical Industry
Lactic acid is also employed to produce water-soluble lactates from otherwise-insoluble active ingredients. It finds further use in topical preparations and cosmetics to adjust acidity and for its disinfectant and keratolytic properties.

=> Other Applications
Lactic acid has gained importance in the detergent industry the last decade. It is a good descaler, soap-scum remover, and a registered anti-bacterial agent. It is also economically beneficial as well as part of a trend toward environmentally safer and natural ingredients.

STORAGE and TRANSPORTATION

Sealed and stored in ventilated, dry and shady warehouse, can't be mixed with other dangerous goods.

Some evidence suggests that lactate is important at early stages of development for brain metabolism in prenatal and early postnatal subjects, with lactate at these stages having higher concentrations in body liquids, and being utilized by the brain preferentially over glucose.[25] It was also hypothesized that lactate may exert a strong action over GABAergic networks in the developing brain, making them more inhibitory than it was previously assumed,[29] acting either through better support of metabolites,[25] or alterations in base intracellular pH levels,[30][31] or both.[32]

Studies of brain slices of mice show that β-hydroxybutyrate, lactate, and pyruvate act as oxidative energy substrates, causing an increase in the NAD(P)H oxidation phase, that glucose was insufficient as an energy carrier during intense synaptic activity and, finally, that lactate can be an efficient energy substrate capable of sustaining and enhancing brain aerobic energy metabolism in vitro.[33] The study, "provides novel data on biphasic NAD(P)H fluorescence transients, an important physiological response to neural activation that has been reproduced in many studies and that is believed to originate predominately from activity-induced concentration changes to the cellular NADH pools."[34]

Blood testing

Reference ranges for blood tests, comparing lactate content (shown in violet at center-right) to other constituents in human blood
Blood tests for lactate are performed to determine the status of the acid base homeostasis in the body. Blood sampling for this purpose is often by arterial blood sampling (even if it is more difficult than venipuncture), because lactate differs substantially between arterial and venous levels, and the arterial level is more representative for this purpose.

Reference ranges
Lower limit    Upper limit    Unit
Venous    4.5[35]    19.8[35]    mg/dL
0.5[36]    2.2[36]    mmol/L
Arterial    4.5[35]    14.4[35]    mg/dL
0.5[36]    1.6[36]    mmol/L
During childbirth, lactate levels in the fetus can be quantified by fetal scalp blood testing.

Polymer precursor
Main article: polylactic acid
Two molecules of lactic acid can be dehydrated to the lactone lactide. In the presence of catalysts lactide polymerize to either atactic or syndiotactic polylactide (PLA), which are biodegradable polyesters. PLA is an example of a plastic that is not derived from petrochemicals.

Pharmaceutical and cosmetic applications
Lactic acid is also employed in pharmaceutical technology to produce water-soluble lactates from otherwise-insoluble active ingredients. It finds further use in topical preparations and cosmetics to adjust acidity and for its disinfectant and keratolytic properties.

Foods
Lactic acid is found primarily in sour milk products, such as koumiss, laban, yogurt, kefir, and some cottage cheeses. The casein in fermented milk is coagulated (curdled) by lactic acid. Lactic acid is also responsible for the sour flavor of sourdough bread.

In lists of nutritional information lactic acid might be included under the term "carbohydrate" (or "carbohydrate by difference") because this often includes everything other than water, protein, fat, ash, and ethanol.[37] If this is the case then the calculated food energy may use the standard 4 kilocalories (17 kJ) per gram that is often used for all carbohydrates. But in some cases lactic acid is ignored in the calculation.[38] The energy density of lactic acid is 362 kilocalories (1,510 kJ) per 100 g.[39]

Some beers (sour beer) purposely contain lactic acid, one such type being Belgian lambics. Most commonly, this is produced naturally by various strains of bacteria. These bacteria ferment sugars into acids, unlike the yeast that ferment sugar into ethanol. After cooling the wort, yeast and bacteria are allowed to “fall” into the open fermenters. Brewers of more common beer styles would ensure that no such bacteria are allowed to enter the fermenter. Other sour styles of beer include Berliner weisse, Flanders red and American wild ale.[40][41]

In winemaking, a bacterial process, natural or controlled, is often used to convert the naturally present malic acid to lactic acid, to reduce the sharpness and for other flavor-related reasons. This malolactic fermentation is undertaken by lactic acid bacteria.

While not normally found in significant quantities in fruit, lactic acid is the primary organic acid in akebia fruit, making up 2.12% of the juice.[42]

As a food additive it is approved for use in the EU,[43] USA[44] and Australia and New Zealand;[45] it is listed by its INS number 270 or as E number E270. Lactic acid is used as a food preservative, curing agent, and flavoring agent.[46] It is an ingredient in processed foods and is used as a decontaminant during meat processing.[47] Lactic acid is produced commercially by fermentation of carbohydrates such as glucose, sucrose, or lactose, or by chemical synthesis.[46] Carbohydrate sources include corn, beets, and cane sugar.