Tartaric acid

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Tartaric acid[1]
Tartaric acid.svg
Tartaric-acid-3D-balls.png
Identifiers
CAS number526-83-0 YesY
PubChem875
ChemSpider852 YesY
DrugBankDB01694
KEGGC00898 YesY
MeSHtartaric+acid
ChEBICHEBI:15674 YesY
ChEMBLCHEMBL333714 YesY, CHEMBL1200861
Jmol-3D imagesImage 1
Properties
Molecular formulaC4H6O6 (Basic formula)
HO2CCH(OH)CH(OH)CO2H (Structural formula)
Molar mass150.087 g/mol
Appearancewhite powder
Density1.79 g/mL (H2O)
Melting point171–174 °C (L or D-tartaric; pure)
206 °C (DL, racemic)
165–166°C ("meso-anhydrous")
146–148 °C (meso-hydrous)[2]
Solubility in water133 g/100ml (20 °C)
Acidity (pKa)L(+) 25 °C :
pKa1= 2.89 pKa2= 4.40
meso 25 °C:
pKa1= 3.22 pKa2= 4.85

[3]

Hazards
EU classificationIrritant(Xi)
R-phrasesR36
Related compounds
Other cationsMonosodium tartrate
Disodium tartrate
Monopotassium tartrate
Dipotassium tartrate
Related carboxylic acidsButyric acid
Succinic acid
Dimercaptosuccinic acid
Malic acid
Maleic acid
Fumaric acid
Related compounds2,3-Butanediol
Cichoric acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references
 
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Tartaric acid[1]
Tartaric acid.svg
Tartaric-acid-3D-balls.png
Identifiers
CAS number526-83-0 YesY
PubChem875
ChemSpider852 YesY
DrugBankDB01694
KEGGC00898 YesY
MeSHtartaric+acid
ChEBICHEBI:15674 YesY
ChEMBLCHEMBL333714 YesY, CHEMBL1200861
Jmol-3D imagesImage 1
Properties
Molecular formulaC4H6O6 (Basic formula)
HO2CCH(OH)CH(OH)CO2H (Structural formula)
Molar mass150.087 g/mol
Appearancewhite powder
Density1.79 g/mL (H2O)
Melting point171–174 °C (L or D-tartaric; pure)
206 °C (DL, racemic)
165–166°C ("meso-anhydrous")
146–148 °C (meso-hydrous)[2]
Solubility in water133 g/100ml (20 °C)
Acidity (pKa)L(+) 25 °C :
pKa1= 2.89 pKa2= 4.40
meso 25 °C:
pKa1= 3.22 pKa2= 4.85

[3]

Hazards
EU classificationIrritant(Xi)
R-phrasesR36
Related compounds
Other cationsMonosodium tartrate
Disodium tartrate
Monopotassium tartrate
Dipotassium tartrate
Related carboxylic acidsButyric acid
Succinic acid
Dimercaptosuccinic acid
Malic acid
Maleic acid
Fumaric acid
Related compounds2,3-Butanediol
Cichoric acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Tartaric acid is a white crystalline diprotic acid. This aldaric acid occurs naturally in many plants, particularly grapes, bananas, and tamarinds, is commonly combined with baking soda to function as a leavening agent in recipes, and is one of the main acids found in wine. It is added to other foods to give a sour taste, and is used as an antioxidant. Salts of tartaric acid are known as tartrates. It is a dihydroxyl derivative of succinic acid.

Tartaric acid was first isolated from potassium tartrate, known to the ancients as tartar, circa 800 AD, by the alchemist Jabir ibn Hayyan.[4] The modern process was developed in 1769 by the Swedish chemist Carl Wilhelm Scheele.

Tartaric acid played an important role in the discovery of chemical chirality. This property of tartaric acid was first observed in 1832 by Jean Baptiste Biot, who observed its ability to rotate polarized light. Louis Pasteur continued this research in 1847 by investigating the shapes of ammonium sodium tartrate crystals, which he found to be chiral. By manually sorting the differently shaped crystals under magnification, Pasteur was the first to produce a pure sample of levotartaric acid.[5][6][7][8]

Stereochemistry[edit]

Tartaric acid crystals drawn as if seen through an optical microscope

Naturally occurring tartaric acid is chiral, meaning it has molecules that are not superimposable on their mirror images. It is a useful raw material in organic chemistry for the synthesis of other chiral molecules. The naturally occurring form of the acid is L-(+)-tartaric acid or dextrotartaric acid. The mirror-image (enantiomeric) form, levotartaric acid or D-(−)-tartaric acid, and the achiral form, mesotartaric acid, can be made artificially. The dextro and levo prefixes are not related to the D/L configuration (which is derived rather indirectly[9] from their structural relation to D- or L-glyceraldehyde), but to the orientation of the optical rotation, (+) = dextrorotatory, (−) = levorotatory. Sometimes, instead of capital letters, small italic d and l are used. They are abbreviations of dextro- and levo- and, nowadays, should not be used. Levotartaric and dextrotartaric acid are enantiomers, mesotartaric acid is a diastereomer of both of them.[10][11]

A rarely occurring, optically inactive form of tartaric acid, DL-tartaric acid is a 1:1 mixture of the levo and dextro forms. It is distinct from mesotartaric acid and was called racemic acid (from Latin racemus – "a bunch of grapes"). The word racemic later changed its meaning, becoming a general term for 1:1 enantiomeric mixtures – racemates.

Tartaric acid is used to prevent copper(II) ions from reacting with the hydroxide ions present in the preparation of copper(I) oxide. Copper(I) oxide is a reddish-brown solid, and is produced by the reduction of a Cu(II) salt with an aldehyde, in an alkaline solution.

levotartaric acid
(D-(−)-tartaric acid)
dextrotartaric acid
(L-(+)-tartaric acid)
mesotartaric acid

D-tartaric acid.png

L-tartaric acid.pngMeso-Weinsäure Spiegel.svg

DL-tartaric acid (racemic acid)
(when in 1:1 ratio)

Forms of tartaric acid
Common nametartaric acidlevotartaric aciddextrotartaric acidmesotartaric acidracemic acid
SynonymsD-(S,S)-(−)-tartaric acid
unnatural isomer
L-(R,R)-(+)-tartaric acid
natural isomer
(2R,3S)-tartaric acidDL-(S,S/R,R)-(±)-tartaric acid
PubChemCID 875CID 439655CID 444305CID 78956CID 5851
EINECS number205-695-6201-766-0205-696-1205-105-7
CAS number526-83-0147-71-787-69-4147-73-9133-37-9

Production[edit]

L-(+)-tartaric acid[edit]

L-(+)-tartaric acid is the isomer of tartaric acid that is industrially produced in the largest amounts. It is obtained from naturally-occurring component of lees, a solid by-products of fermentations. The former by-products mostly consist of potassium bitartrate (KHC4H4O6). This potassium salt is converted to calcium tartrate (CaC4H4O6) upon treatment with milk of lime (Ca(OH)2):[12]

KO2CCH(OH)CH(OH)CO2H + Ca(OH)2 → Ca(O2CCH(OH)CH(OH)CO2) + KOH + H2O

In practice higher yields of calcium tartrate are obtained with the addition of calcium chloride. Calcium tartrate is then converted to tartaric acid by treating the salt with aqueous sulfuric acid. This process yields free L-(+)-tartaric acid:

Ca(O2CCH(OH)CH(OH)CO2) + H2SO4 → HO2CCH(OH)CH(OH)CO2H + CaSO4

Racemic tartaric acid[edit]

Racemic tartaric acid can be prepared in a multistep reaction from maleic acid. In the first step the maleic acid is epoxidized by hydrogen peroxide using potassium tungstate as a catalyst.[12]

HO2CC2H4CO2H + H2O2 → OC2H2(CO2H) 2

In the next step, the epoxide is hydrolyzed to form racemic tartaric acid.

OC2H2(CO2H)2 + H2O → (HOCH)2(CO2H)2

Meso-tartaric acid[edit]

Meso-tartaric acid is formed via thermal isomerzation. Dextro-tartaric acid is heated in water at 165 °C for about 2 days. Meso-tartaric acid can also be prepared from dibromosuccinic acid using silver hydroxide.[13]

HO2CCHBrCHBrCO2H + 2 AgOH → HO2CCH(OH)CH(OH)CO2H + 2 AgBr

Meso-tartaric acid can be separated from the racemic acid by crystallization, the racemate being less soluble.

Reactivity[edit]

L-(+)-tartaric acid, can participate in several reactions. As shown the reaction scheme below, dihydroxymaleic acid is produced upon treatment of L-(+)-tartaric acid with hydrogen peroxide in the presence of a ferrous salt.

HO2CCH(OH)CH(OH)CO2H + H2O2 → HO2CC(OH)C(OH)CO2H + 2 H2O

Dihydroxymaleic acid can then be oxidized to tartronic acid with nitric acid.[14]

Derivatives[edit]

Tartar emetic
Commercially produced tartaric acid.

Important derivatives of tartaric acid include its salts, cream of tartar (potassium bitartrate), Rochelle salt (potassium sodium tartrate, a mild laxative), and tartar emetic (antimony potassium tartrate).[15][16][17] Diisopropyl tartrate is used as a catalyst in asymmetric synthesis.

Tartaric acid is a muscle toxin, which works by inhibiting the production of malic acid, and in high doses causes paralysis and death.[18] The median lethal dose (LD50) is about 7.5 grams/kg for a human, ~5.3 grams/kg for rabbits and ~4.4 grams/kg for mice.[19] Given this figure, it would take over 500 g (18 oz) to kill a person weighing 70 kg (150 lb), and so it may be safely included in many foods, especially sour-tasting sweets. As a food additive, tartaric acid is used as an antioxidant with E number E334, tartrates are other additives serving as antioxidants or emulsifiers.

When cream of tartar is added to water, a suspension results which serves to clean copper coins very well, as the tartrate solution can dissolve the layer of copper(II) oxide present on the surface of the coin. The resulting copper(II)-tartrate complex is easily soluble in water.

Tartaric acid in wine[edit]

See also: Acids in wine and Tartrate
Unpurified potassium bitartrate can take on the color of the grape juice it was separated from.

Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds", the small potassium bitartrate crystals that sometimes form spontaneously on the cork. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines through cold stabilization. The tartrates remaining on the inside of aging barrels were at one time a major industrial source of potassium bitartrate.

Tartaric acid plays an important role chemically, lowering the pH of fermenting "must" to a level where many undesirable spoilage bacteria cannot live, and acting as a preservative after fermentation. In the mouth, tartaric acid provides some of the tartness in the wine, although citric and malic acids also play a role.

Applications[edit]

Tartaric acid and its derivatives have a plethora of uses in the field of pharmaceuticals. For example, tartaric acid has been used in the production of effervescent salts, in combination with citric acid, in order to improve the taste of oral medications.[14] The potassium antimonyl derivative of the acid known as tartar emetic is included, in small doses, in cough syrup as an expectorant.

Tartaric acid also has several applications for industrial use. The acid has been observed to chelate metal ions such as calcium and magnesium. Therefore, the acid has served in the farming and metal industries as a chelating agent for complexing micronutrients in soil fertilizer and for cleaning metal surfaces consisting of aluminum, copper, iron, and alloys of these metals, respectively.[12]

References[edit]

  1. ^ Tartaric Acid – Compound Summary, PubChem.
  2. ^ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5. 
  3. ^ Dawson, R.M.C. et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.
  4. ^ Lisa Solieri, Paolo Giudici (2009). Vinegars of the World. Springer. p. 29. ISBN 88-470-0865-4. 
  5. ^ L. Pasteur (1848) "Mémoire sur la relation qui peut exister entre la forme cristalline et la composition chimique, et sur la cause de la polarisation rotatoire" (Memoir on the relationship which can exist between crystalline form and chemical composition, and on the cause of rotary polarization)," Comptes rendus de l'Académie des sciences (Paris), vol. 26, pp. 535–538.
  6. ^ L. Pasteur (1848) "Sur les relations qui peuvent exister entre la forme cristalline, la composition chimique et le sens de la polarisation rotatoire" (On the relations that can exist between crystalline form, and chemical composition, and the sense of rotary polarization), Annales de Chimie et de Physique, 3rd series, vol. 24, no. 6, pages 442–459.
  7. ^ George B. Kauffman and Robin D. Myers (1998). "Pasteur's resolution of racemic acid: A sesquicentennial retrospect and a new translation". The Chemical Educator 3 (6): 1–4. doi:10.1007/s00897980257a. 
  8. ^ H. D. Flack (2009). "Louis Pasteur's discovery of molecular chirality and spontaneous resolution in 1848, together with a complete review of his crystallographic and chemical work". Acta Crystallographica A 65 (5): 371–389. doi:10.1107/S0108767309024088. PMID 19687573. 
  9. ^ J. M. McBride's Yale lecture on history of stereochemistry of tartaric acid, the D/L and R/S systems
  10. ^ various (2007-07-23). Organic Chemistry. Global Media. p. 65. ISBN 978-81-89940-76-8. Retrieved 2010-06-05. 
  11. ^ "(WO/2008/022994) Use of azabicyclo hexane derivatives". 
  12. ^ a b c J.-M. Kassaian "Tartaric acid" in Ullmann's Encyclopedia of Industrial Chemistry; VCH: Weinheim, Germany, 2002, 35, 671-678. doi:10.1002/14356007.a26_163
  13. ^ Augustus Price West. Experimental Organic Chemistry. World Book Company: New York, 1920, 232-237.
  14. ^ a b Blair G. T., DeFraties J. J. Hydroxy Dicarboxylic Acids, Kirk Othmer Encyclopedia of Chemical Technology. 2000, 1-19. doi:10.1002/0471238961.0825041802120109.a01.
  15. ^ Zalkin, Allan; Templeton, David H.; Ueki, Tatzuo (1973). "Crystal structure of l-tris(1,10-phenathroline)iron(II) bis(antimony(III) d-tartrate) octahydrate". Inorganic Chemistry 12 (7): 1641. doi:10.1021/ic50125a033. 
  16. ^ Haq, I; Khan, C (1982). "Hazards of a traditional eye-cosmetic--SURMA". JPMA. the Journal of the Pakistan Medical Association 32 (1): 7–8. PMID 6804665. 
  17. ^ McCallum, RI (1977). "President's address. Observations upon antimony". Proceedings of the Royal Society of Medicine 70 (11): 756–63. PMC 1543508. PMID 341167. 
  18. ^ Alfred Swaine Taylor, Edward Hartshorne (1861). Medical jurisprudence. Blanchard and Lea. p. 61. 
  19. ^ Joseph A. Maga, Anthony T. Tu (1995). Food additive toxicology. CRC Press. pp. 137–138. ISBN 0-8247-9245-9. 

External links[edit]