 | |
 Ball-and-stick model of meso-tartaric acid | |
| Names | |
|---|---|
| IUPAC name Tartaric acid[2] | |
| Preferred IUPAC name 2,3-Dihydroxybutanedioic acid | |
| Systematic IUPAC name | |
| Other names Tartaric acid 2,3-Dihydroxysuccinic acid Threaric acid Racemic acid Uvic acid Paratartaric acid Winestone | |
| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| DrugBank |
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| ECHA InfoCard | 100.121.903 |
| E number | E334(antioxidants, ...) |
| KEGG |
|
| MeSH | tartaric+acid |
| |
| UNII | |
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| |
| Properties | |
| C4H6O6 (basic formula) HO2CCH(OH)CH(OH)CO2H (structural formula) | |
| Molar mass | 150.087 g/mol |
| Appearance | White powder |
| Density | 1.737 g/cm3 (R,R- and S,S-) 1.79 g/cm3 (racemate) 1.886 g/cm3 (meso) |
| Melting point | 169, 172 °C (R,R- and S,S-) 206 °C (racemate) 165-6 °C (meso) |
| |
| Acidity (pKa) | L(+) 25 °C : pKa1= 2.89, pKa2= 4.40 meso 25 °C: pKa1= 3.22, pKa2= 4.85 |
| Conjugate base | Bitartrate |
| −67.5·10−6 cm3/mol | |
| Hazards | |
| GHS labelling:[6] | |
 | |
| Danger | |
| H318 | |
| P280,P305+P351+P338+P310 | |
| Related compounds | |
Othercations | Monosodium tartrate Disodium tartrate Monopotassium tartrate Dipotassium tartrate |
Relatedcarboxylic acids | Butyric acid Succinic acid Dimercaptosuccinic acid Malic acid Maleic acid Fumaric acid |
Related compounds | 2,3-Butanediol Cichoric acid |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Tartaric acid is a white, crystallineorganic acid that occurs naturally in many fruits, most notably ingrapes but also intamarinds,bananas,avocados, andcitrus.[1] Itssalt,potassium bitartrate, commonly known as cream of tartar, develops naturally in the process offermentation. Potassium bitartrate is commonly mixed withsodium bicarbonate and is sold asbaking powder used as aleavening agent in food preparation. The acid itself is added to foods as anantioxidantE334 and to impart its distinctive sour taste.Naturally occurring tartaric acid is a useful raw material inorganic synthesis. Tartaric acid, an alpha-hydroxy-carboxylic acid, isdiprotic andaldaric in acid characteristics and is a dihydroxyl derivative ofsuccinic acid.
Tartaric acid has been known towinemakers for centuries. However, the chemical process for extraction was developed in 1769 by theSwedish chemistCarl Wilhelm Scheele.[7]
Tartaric acid played an important role in the discovery ofchemical chirality. This property of tartaric acid was first observed in 1832 byJean Baptiste Biot, who observed its ability to rotatepolarized light.[8][9]Louis Pasteur continued this research in 1847 by investigating the shapes ofsodium ammonium tartrate crystals, which he found to be chiral. By manually sorting the differently shaped crystals, Pasteur was the first to produce a pure sample of levotartaric acid.[10][11][12][13][14]
Naturally occurring form of the acid isdextro tartaric acid orL-(+)-tartaric acid (obsolete named-tartaric acid). Because it is available naturally, it is cheaper than itsenantiomer and themeso isomer. Thedextro andlevo prefixes are archaic terms.[15] Modern textbooks refer to the natural form as (2R,3R)-tartaric acid(L-(+)-tartaric acid), and its enantiomer as (2S,3S)-tartaric acid(D-(−)-tartaric acid). Themeso diastereomer is referred to as (2R,3S)-tartaric acid or (2S,3R)-tartaric acid.
Tartaric acid inFehling's solution binds to copper(II) ions, preventing the formation of insoluble hydroxide salts.
| DL-tartaric acid (racemic acid)(when in 1:1 ratio) | mesotartaric acid | |
|---|---|---|
| dextrotartaric acid (L-(+)-tartaric acid) | levotartaric acid (D-(−)-tartaric acid) | |
 |  |  |
| Common name | Tartaric acid | Levotartaric acid | Dextrotartaric acid | Mesotartaric acid | Racemic acid |
|---|---|---|---|---|---|
| Synonyms | (2S,3S)-tartaric acid (S,S)-tartaric acid (−)-tartaric acid l-tartaric acid(obsolete) levotartaric acid D-tartaric acid D-threaric acid ("unnatural isomer")[21] | (2R,3R)-tartaric acid (R,R)-tartaric acid (+)-tartaric acid d-tartaric acid(obsolete) L-tartaric acid L-threaric acid ("natural isomer")[22] | (2R,3S)-tartaric acid meso-tartaric acid erythraric acid | rac-(2R,3S)-tartaric acid (2RS,3SR)-tartaric acid (±)-tartaric acid DL-tartaric acid dl-tartaric acid(obsolete) paratartaric acid uvic acid | |
| PubChem | CID 875 fromPubChem | CID 439655 fromPubChem | CID 444305 fromPubChem | CID 78956 fromPubChem | CID 5851 fromPubChem |
| EINECS number | 205-695-6 | 201-766-0 | 205-696-1 | 205-105-7 | |
| CAS number | 526-83-0 | 147-71-7 | 87-69-4 | 147-73-9 | 133-37-9 |
TheL-(+)-tartaric acid isomer of tartaric acid is industrially produced in the largest amounts. It is obtained fromlees, a solid byproduct of fermentations. The former byproducts mostly consist of potassium bitartrate (KHC4H4O6). This potassium salt is converted tocalcium tartrate (CaC4H4O6) upon treatment withcalcium hydroxide (Ca(OH)2):[23]
In practice, higher yields of calcium tartrate are obtained with the addition ofcalcium sulfate. Calcium tartrate is then converted to tartaric acid by treating the salt with aqueous sulfuric acid:
Racemic tartaric acid can be prepared in a multistep reaction frommaleic acid. In the first step, the maleic acid isepoxidized byhydrogen peroxide usingpotassium tungstate [de] as a catalyst.[23]
In the next step, the epoxide is hydrolyzed.
A mixture of racemic acid andmeso-tartaric acid is formed whendextro-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:[24]
meso-Tartaric acid can be separated from residual racemic acid by crystallization, the racemate being less soluble.
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 aferrous salt.
Dihydroxymaleic acid can then be oxidized totartronic acid with nitric acid.[25]
Important derivatives of tartaric acid include:
Tartaric acid is amuscletoxin, which works by inhibiting the production ofmalic acid, and in high doses causes paralysis and death.[29] Themedian 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.[30] Given this figure, it would take over 500 g (18 oz) to kill a person weighing 70 kg (150 lb) with 50% probability, so it may be safely included in many foods, especially sour-tastingsweets. As afood additive, tartaric acid is used as anantioxidant withE numberE334;tartrates are other additives serving as antioxidants oremulsifiers.
When cream of tartar is added to water, a suspension results which serves to clean coppercoins 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.
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Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds", the smallpotassium bitartrate crystals that sometimes form spontaneously on thecork or bottom of the bottle. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines throughcold stabilization (which is not always preferred since it can change the wine's profile). The tartrates remaining on the inside ofaging 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 afterfermentation. In the mouth, tartaric acid provides some of the tartness in the wine, althoughcitric andmalic acids also play a role.
Grapes and tamarinds have the highest levels of tartaric acid concentration. Other fruits with tartaric acid arebananas,avocados,prickly pear fruit,apples,cherries,papayas,peaches,pears,pineapples,strawberries,mangoes andcitrus fruits.[1][31]
Trace amounts of tartaric acid have been found incranberries and otherberries.[32]
Tartaric acid is also present in the leaves and pods ofPelargonium plants andbeans.
Tartaric acid and its derivatives have a plethora of uses in the field of pharmaceuticals. For example, it has been used in the production of effervescent salts, in combination with citric acid, to improve the taste of oral medications.[25] The potassium antimonyl derivative of the acid known as tartar emetic is included, in small doses, incough syrup as anexpectorant.
Tartaric acid also has several applications for industrial use. The acid has been observed tochelate 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 soilfertilizer and for cleaning metal surfaces consisting of aluminium, copper, iron, and alloys of these metals, respectively.[23]
While tartaric acid is well-tolerated by humans and lab animals, an April 2021 letter to the editor ofJAVMA hypothesized that the tartaric acid in grapes could be the cause ofgrape and raisin toxicity in dogs.[33][34] Other studies have observed tartaric acid toxicity in kidney cells of dogs, but not in human kidney cells.[35]
In dogs, the tartaric acid oftamarind causesacute kidney injury, which can often be fatal.[36]
A review identified a relationship between grape ingestion and illness, though the specific type or quantity of grapes that cause toxicity remains unclear. Grape ingestion commonly leads to gastrointestinal and/or renal issues, with treatment depending on the symptoms; outcomes can vary.[37]
{{cite journal}}: CS1 maint: multiple names: authors list (link), based on P. Groth’s “Chemische Krystallographie".