Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in

grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus '' Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years a ...

s, but also in bananas,

tamarind Tamarind (''Tamarindus indica'') is a leguminous tree bearing edible fruit that is probably indigenous to tropical Africa. The genus ''Tamarindus'' is monotypic, meaning that it contains only this species. It belongs to the family Fabaceae ...

s, and

citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...

. Its

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

potassium bitartrate Potassium bitartrate, also known as potassium hydrogen tartrate, with formula K C4 H5 O6, is a byproduct of winemaking. In cooking, it is known as cream of tartar. It is processed from the potassium acid salt of tartaric acid (a carboxylic ac ...

, commonly known as cream of tartar, develops naturally in the process of fermentation. It is commonly mixed with sodium bicarbonate and is sold as

baking powder Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch. Baking powder is used to increas ...

used as a

leavening agent In cooking, a leavening agent () or raising agent, also called a leaven () or leavener, is any one of a number of substances used in doughs and batters that cause a foaming action (gas bubbles) that lightens and softens the mixture. An altern ...

in food preparation. The acid itself is added to foods as an antioxidant E334 and to impart its distinctive sour taste.

Naturally occurring A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical sy ...

tartaric acid is a useful raw material in organic

chemical synthesis As a topic of chemistry, chemical synthesis (or combination) is the artificial execution of chemical reactions to obtain one or several products. This occurs by physical and chemical manipulations usually involving one or more reactions. In mod ...

. Tartaric acid is an alpha-hydroxy- carboxylic acid, is

diprotic In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

and aldaric in acid characteristics, and is a dihydroxyl derivative of

succinic acid Succinic acid () is a dicarboxylic acid with the chemical formula (CH2)2(CO2H)2. The name derives from Latin ''succinum'', meaning amber. In living organisms, succinic acid takes the form of an anion, succinate, which has multiple biological ro ...

History

Tartaric acid has been known to

winemakers A winemaker or vintner is a person engaged in winemaking. They are generally employed by wineries or wine companies, where their work includes: *Cooperating with viticulturists *Monitoring the maturity of grapes to ensure their quality and to dete ...

for centuries. However, the chemical process for extraction was developed in 1769 by the

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

chemist

Carl Wilhelm Scheele Carl Wilhelm Scheele (, ; 9 December 1742 – 21 May 1786) was a Swedish German pharmaceutical chemist. Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, hyd ...

. 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

sodium ammonium tartrate Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable is ...

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.

Stereochemistry

Naturally occurring form of the acid is dextro tartaric acid or L-(+)-tartaric acid (obsolete name ''d''-tartaric acid). Because it is available naturally, it is cheaper than its enantiomer and the

meso isomer A meso compound or meso isomer is a non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereocenters, the molecule is not chiral. A meso compound is "sup ...

. The ''dextro'' and ''levo'' prefixes are archaic terms. Modern textbooks refer to the natural form as (2''R'',3''R'')-tartaric acid (L-(+)-tartaric acid), and its enantiomer as (2''S'',3''S'')-tartaric acid (D-(-)-tartaric acid). The ''meso'' diastereomer is referred to as (2''R'',3''S'')-tartaric acid or (2''S'',3''R'')-tartaric acid. *Dextro and levo form monoclinic sphenoidal crystals and orthorhombic crystals. *Racemic tartaric acid forms

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

CRC Handbook of Chemistry and Physics, 49th edition. and

triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal i ...

crystals (

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

P). *Anhydrous meso tartaric acid form two anhydrous polymorphs: triclinic and orthorhombic. *Monohydrated meso tartaric acid crystallizes as monoclinic and triclinic polymorphys depending on the temperature at which crystallization from aqueous solution occurs. Tartaric acid in

Fehling's solution In organic chemistry, Fehling's solution is a chemical reagent used to differentiate between water-soluble carbohydrate and ketone () functional groups, and as a test for reducing sugars and non-reducing sugars, supplementary to the Tollens' reag ...

binds to copper(II) ions, preventing the formation of insoluble hydroxide salts.

Production

L-(+)-Tartaric acid

The L-(+)-tartaric acid isomer of tartaric acid is industrially produced in the largest amounts. It is obtained from lees, a solid byproduct of fermentations. The former byproducts mostly consist of potassium bitartrate (KHC₄H₄O₆). This potassium salt is converted to calcium tartrate (CaC₄H₄O₆) upon treatment with calcium hydroxide "milk of lime" (Ca(OH)₂):J.-M. Kassaian "Tartaric acid" in Ullmann's Encyclopedia of Industrial Chemistry; VCH: Weinheim, Germany, 2002, 35, 671-678. :KH(C4H4O6) + Ca(OH)2 -> Ca(C4H4O6) + KOH + H2O In practice, higher yields of calcium tartrate are obtained with the addition of

calcium chloride Calcium chloride is an inorganic compound, a salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide. Ca ...

. Calcium tartrate is then converted to tartaric acid by treating the salt with aqueous sulfuric acid: :Ca(C4H4O6) + H2SO4 -> H2(C4H4O6) + CaSO4

Racemic tartaric acid

Racemic tartaric acid can be prepared in a multistep reaction from

maleic acid Maleic acid or ''cis''-butenedioic acid is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Its chemical formula is HO2CCH=CHCO2H. Maleic acid is the ''cis''-isomer of butenedioic acid, whereas fumaric ac ...

. In the first step, the maleic acid is epoxidized by

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

using

potassium tungstate Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

as a catalyst. :HO₂CC₂H₂CO₂H + H₂O₂ → OC₂H₂(CO₂H) ₂ In the next step, the epoxide is hydrolyzed. :OC₂H₂(CO₂H)₂ + H₂O → (HOCH)₂(CO₂H)₂

''meso''-Tartaric acid

A mixture of racemic acid and ''meso''-tartaric acid is formed when ''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:Augustus Price West. Experimental Organic Chemistry. World Book Company: New York, 1920, 232-237. :HO₂CCHBrCHBrCO₂H + 2 AgOH → HO₂CCH(OH)CH(OH)CO₂H + 2 AgBr ''meso''-Tartaric acid can be separated from residual racemic acid by crystallization, the racemate being less soluble.

Reactivity

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 Tartronic acid or 2-hydroxymalonic acid is an organic compound with the structural formula of HOHC(CO2H)2. This dicarboxylic acid is related to malonic acid. Its derivative, 2-methyltartronic acid, is isomalic acid. Uses Tartronic acid is best ...

with nitric acid.

Derivatives

Important derivatives of tartaric acid include its salts, cream of tartar (

Rochelle salt Potassium sodium tartrate tetrahydrate, also known as Rochelle salt, is a double salt of tartaric acid first prepared (in about 1675) by an apothecary, Pierre Seignette, of La Rochelle, France. Potassium sodium tartrate and monopotassium phospha ...

(potassium sodium tartrate, a mild

laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...

), and tartar emetic (antimony potassium tartrate).

Diisopropyl tartrate Diisopropyl tartrate (DIPT) is a diester of tartaric acid. It has a two chiral carbon atoms giving rise to three stereoisomeric variants. It is commonly used in asymmetric synthesis as a catalyst and as chiral building block for pharmaceuticals ...

is used as a

co-catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

in asymmetric synthesis. Tartaric acid is a muscle

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849 ...

, which works by inhibiting the production of

malic acid Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...

, and in high doses causes paralysis and death. 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. Given this figure, it would take over to kill a person weighing , so it may be safely included in many foods, especially sour-tasting

sweets Candy, also called sweets (British English) or lollies (Australian English, New Zealand English), is a confection that features sugar as a principal ingredient. The category, called ''sugar confectionery'', encompasses any sweet confection, i ...

. As a food additive, tartaric acid is used as an antioxidant with E number E334;

tartrate A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. The formula of the tartrate dianion is O−OC-CH(OH)-CH(OH)-COO− or C4H4O62−. The main forms of tartrates used commercially are pure crystalline ta ...

s are other additives serving as antioxidants or

emulsifiers An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although ...

. When cream of tartar is added to water, a suspension results which serves to clean copper

coin A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order t ...

s 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

Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds", the small

crystals that sometimes form spontaneously on the

cork Cork or CORK may refer to: Materials * Cork (material), an impermeable buoyant plant product ** Cork (plug), a cylindrical or conical object used to seal a container ***Wine cork Places Ireland * Cork (city) ** Metropolitan Cork, also known as G ...

or bottom of the bottle. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines through cold stabilization (which is not always preferred since it can change the wine's profile). The tartrates remaining on the inside of

aging barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...

s 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

s also play a role.

Tartaric acid in citrus

Results from a study showed that in citrus, fruits produced in organic farming contain higher levels of tartaric acid than fruits produced in conventional agriculture.

Applications

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. The potassium antimonyl derivative of the acid known as tartar emetic is included, in small doses, in

cough syrup Cold medicines are a group of medications taken individually or in combination as a treatment for the symptoms of the common cold and similar conditions of the upper respiratory tract. The term encompasses a broad array of drugs, including ...

as an

expectorant Mucoactive agents are a class of chemical agents that aid in the clearance of mucus or sputum from the upper and lower airways, including the lungs, bronchi, and trachea. Mucoactive drugs include expectorants, mucolytics, mucoregulators, and muco ...

. Tartaric acid also has several applications for industrial use. The acid has been observed to

chelate Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...

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 A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

and for cleaning metal surfaces consisting of aluminium, copper, iron, and alloys of these metals, respectively.

Toxicity in canines

While tartaric acid is well tolerated by humans and lab animals, an April 2021 letter to the editor of ''

JAVMA The American Veterinary Medical Association (AVMA), founded in 1863, is a not-for-profit association representing more than 99,500 veterinarians in the US. The AVMA provides information resources, continuing education opportunities, publicatio ...

'' hypothesized that the tartaric acid in grapes could be the cause of grape and raisin toxicity in dogs.

References

External links

PDB file for MSE
{{DEFAULTSORT:Tartaric Acid Crystals in space group 14 Chirality Racemic mixtures Food antioxidants Food acidity regulators Acids in wine Alpha hydroxy acids Dicarboxylic acids Vicinal diols E-number additives