Galactaric acid, also known as saccharic acid, is a naturally occurring dicarboxylic acid derived from the oxidation of galactose, featuring a chemical formula of C6H8O8 and two carboxyl groups attached to a six-carbon backbone.

Galactaric acid acts as a chelating agent for heavy metals, making it valuable in environmental remediation to reduce toxicity in contaminated soils and waters, and it also has applications as a preservative and flavor enhancer in the food industry.

In pharmaceuticals, galactaric acid is used as a formulation stabilizer due to its chelating and antioxidant properties, helping to prevent the degradation of active ingredients and potentially offering health benefits through its protective effects against oxidative stress and infections.

CAS Number: 526-99-8

EC Number: 208-404-0

Molecular Formula: C6H10O8

Molecular Weight: 210.14 g/mol

Synonyms: mucic acid, galactaric acid, 526-99-8, Saccharolactic acid, (2R,3S,4R,5S)-2,3,4,5-tetrahydroxyhexanedioic acid, Galactosaccharic acid, D-Galactaric acid, galactarate, Schleimsaure, D-galactarate, Tetrahydroxyadipic acid, meso-galactaric acid, MFCD00004239, E149J5OTIF, (2S,3R,4S,5R)-2,3,4,5-tetrahydroxyhexanedioic acid, DTXSID7048740, CHEBI:30852, MUCICACID, 2R,3S,4R,5S-tetrahydroxy-hexanedioic acid, DTXCID0028666, 2,3,4,5-Tetrahydroxyhexanedioic acid, CAS-526-99-8, Schleimsaure [German], UNII-E149J5OTIF, Galactarsaeure, Galaktarsaeure, Mucinsaeure, Saccharolactate, Schleimsaeure, acido mucico, hexaric acid, d-Zuckersaure, NSC-8127, Galactosaccharate, acido galactarico, (2R,3S,4R,5S)-2,3,4,5-tetrahydroxyhexanedioate, HSDB 2116, D-Mucic acid, NCGC00096080-01, NSC 8127, EINECS 208-404-0, MUCILIANCE, Mucic acid, 97%, Mucic acid, 98%, ORISTAR MCA, BRN 1728117, AI3-06294, AI3-19582, Tetrahydroxyhexanedioic acid, SCHEMBL5901, GALACTARIC ACID [MI], mucic acid (galactaric acid), 4-03-00-01292 (Beilstein Handbook Reference), GALACTARIC ACID [HSDB], GALACTARIC ACID [INCI], CHEMBL1232958, DSLZVSRJTYRBFB-DUHBMQHGSA-N, 2,3,4,5-Tetrahydroxyadipic Acid, GALACTARIC ACID, (+/-)-, Tox21_113190, BDBM50346168, LMFA01170107, AKOS016009395, Tox21_113190_1, CS-W015126, HY-W014410, NCGC00344532-01, AS-35302, M0466, S3964, C00879, EN300-128455, A870928, Q424916, 5E407223-AAEF-4D79-BCED-63F0DECB8CE2, W-109551, (R)-3-(pyrrolidin-2-ylethynyl)pyridine hemigalactarate, GAE

Galactaric acid, also known as saccharic acid, is a naturally occurring dicarboxylic acid derived from the oxidation of galactose.

Galactaric acid's chemical formula is C6H8O8, and it features two carboxyl groups attached to a six-carbon backbone.

Galactaric acid is found in various fruits and vegetables, where it plays a role in the metabolic processes of plants.

In terms of properties, galactaric acid is known for its role in chelating metals, which can be beneficial in reducing the toxic effects of heavy metals in the environment.

Additionally, Galactaric acid exhibits antioxidant properties that may help mitigate oxidative stress.

Galactaric acid's applications extend to food and pharmaceutical industries, where it is utilized for its potential health benefits and its ability to stabilize formulations.

Galactaric acid's presence in natural sources and its functional benefits make it a valuable compound in both scientific research and practical applications.

Galactaric acid is a hexaric acid resulting from formal oxidative ring cleavage of galactose. 

Galactaric acid has a role as a human metabolite. 

Galactaric acid is a conjugate acid of a galactarate(1-) and a galactaric acid anion.

Galactaric acid is an aldaric acid obtained by nitric acid oxidation of galactose or galactose-containing compounds such as lactose, dulcite, quercite, and most varieties of gum.

Galactaric acid forms a crystalline powder, which melts at 210–230 °C.

Galactaric acid is insoluble in alcohol, and nearly insoluble in cold water.

Due to the symmetry in the molecule, Galactaric acid is optically inactive even though it has chiral carbon atoms (i.e., it is a meso compound).

When heated with pyridine to 140 °C, Galactaric acid is converted into allomucic acid.

When digested with fuming hydrochloric acid for some time Galactaric acid is converted into αα′ furfural dicarboxylic acid while on heating with barium sulfide it is transformed into α-thiophene carboxylic acid.

The ammonium salt yields on dry distillation carbon dioxide, ammonia, pyrrol and other substances.

The acid when fused with caustic alkalis yields oxalic acid.

With potassium bisulfate mucic acid forms 3-hydroxy-2-pyrone by dehydration and decarboxylation.

Galactaric acid can be used to replace tartaric acid in self-raising flour or fizzies.

Galactaric acid has been used as a precursor of adipic acid in the way to nylon by a rhenium-catalyzed deoxydehydration reaction.

Galactaric acid has been used as a precursor of Taxol in Nicolaou Taxol total synthesis (1994).

Galactaric acid is a metal chelate that stimulates the metabolism of carbohydrates, fats and proteins. 

Galactaric acid also plays a role in the production of energy in the body. 

Galactaric acid has been shown to have a protective effect against infectious diseases, as it activates toll-like receptor 2 (TLR2) and TLR4, which are molecules involved in innate immunity. 

Galactaric acid has been shown to protect against influenza virus infection by increasing the expression of interferon-gamma (IFN-γ) and IL-12, which are cytokines that inhibit viral replication. 

Galactaric acid can be used as a fluorescence probe for detection of polymorphonuclear leucocytes in blood samples.

Applications of Galactaric Acid:

Galactaric acid, also known as saccharic acid, has diverse applications across several industries due to its unique chemical properties.

In environmental science, Galactaric acid is used as a chelating agent to bind heavy metals, reducing their toxicity and aiding in the remediation of contaminated soils and waters.

In the food industry, galactaric acid serves as a preservative and flavor enhancer, extending shelf life and improving product stability.

Galactaric acid's utility extends to pharmaceuticals, where it stabilizes formulations and potentially offers antioxidant benefits.

In cosmetics, Galactaric acid's antioxidant properties help protect the skin from oxidative damage.

Additionally, galactaric acid finds applications in chemical synthesis and research, making it a valuable compound with significant practical and scientific relevance.

Environmental Applications:

Heavy Metal Chelation:

Galactaric acid acts as a chelating agent, binding to heavy metals and reducing their toxicity.

This property makes Galactaric acid useful in environmental remediation and pollution control, helping to clean up contaminated soils and water.

Food Industry:

Preservative:

Galactaric acid can be used as a food preservative due to its ability to inhibit the growth of microorganisms.

This helps in extending the shelf life of food products.

Flavor Enhancer:

Galactaric acid can be used to enhance flavors and stabilize certain food products.

Pharmaceuticals:

Formulation Stabilizer:

Galactaric acid's ability to chelate metals and its antioxidant properties make it useful in stabilizing pharmaceutical formulations, preventing degradation of active ingredients.

Potential Health Benefits:

actaric acid's health benefits is ongoing, with studies exploring its role in reducing oxidative stress and its potential therapeutic effects.

Cosmetics:

Antioxidant:

In cosmetic formulations, galactaric acid’s antioxidant properties help protect the skin from oxidative damage, which can contribute to aging and other skin issues.

Industrial Applications:

Chemical Synthesis:

Galactaric acid is used in various chemical processes and as a precursor in the synthesis of other chemical compounds.

Research:

Biochemical Studies:

Galactaric acid is studied for its role in metabolic pathways and its potential applications in biochemistry and molecular biology.

Features of Galactaric Acid:

Chemical Structure:

Dicarboxylic Acid:

Galactaric acid is characterized by its two carboxyl groups (-COOH) attached to a six-carbon backbone.

This structure is derived from the oxidation of galactose.

Solubility:

Water-Soluble:

Galactaric acid is highly soluble in water, which enhances its utility in various aqueous formulations and processes.

Chelating Properties:

Heavy Metal Chelation:

Galactaric acid's ability to bind metal ions makes it effective in reducing the toxicity of heavy metals in environmental and industrial applications.

Antioxidant Activity:

Oxidative Stress Mitigation:

Galactaric acid exhibits antioxidant properties, helping to neutralize free radicals and potentially reduce oxidative stress.

Natural Occurrence:

Plant-Based:

Galactaric acid is naturally found in various fruits and vegetables, integrating seamlessly into natural and organic formulations.

Stability:

Chemical Stability:

Galactaric acid is stable under standard conditions, which contributes to its effectiveness in various industrial and research applications.

Versatility:

Multiple Uses:

Galactaric acid's applications span from environmental remediation and food preservation to pharmaceutical stabilization and cosmetic formulations.

Experimental Properties of Galactaric Acid:

Galactaric acid is a monosaccharide that has been found in grape musts and wine and an oxidized form of galacturonic acid.

Galactaric acid (5-10 µM) increases mRNA expression of Runx2 in C3H/10T1/2 mouse mesenchymal stem cells.

Galactaric acid increases alkaline phosphatase (ALP) levels in, and mineralization of, C3H/10T1/2 cells when used in combination with gelatin as a coating on a 3D-poly (lactic acid) (PLA) scaffold at concentrations ranging from 10 to 20 µM.

Galactaric acid is a symmetrical six carbon diacid which can be produced by oxidation of galactose with nitric acid, electrolytic oxidation of D-galacturonate or microbial conversion of D-galacturonate. 

Both salts and the free acid of galactarate have relatively low solubility, which may create challenges for a microbial host. 

Galactaric acid was most soluble at pH values around 4.7 in the presence of ammonium or sodium ions and less soluble in the presence of potassium ions. 

Solubility increased with increasing temperature. 

Production of galactaric acid by Trichoderma reesei D-161646 was dependent on temperature, pH and medium composition, being best at pH 4 and 35 °C. 

Up to 20 g L-1 galactaric acid were produced from D-galacturonate using a fed-batch strategy with lactose as co-substrate and both ammonium and yeast extract as nitrogen sources. 

Crystals of galactaric acid were observed to form in the broth of some fermentations.

Reactions of Galactaric Acid:

Galactaric acid, also known as saccharic acid, participates in various chemical reactions due to its structure and functional groups.

Here are some notable reactions involving galactaric acid:

Oxidation:

Further Oxidation:

Galactaric acid itself is a product of the oxidation of galactose.

Under strong oxidative conditions, Galactaric acid may further oxidize, though it is relatively stable compared to its precursor.

Chelation:

Metal Ion Binding:

Galactaric acid can chelate metal ions due to its two carboxyl groups.

This reaction involves the formation of complexes with metal ions, which helps reduce the toxicity of heavy metals in environmental and industrial applications.

Establishment of Salts and Esters:

Salt Formation:

Reacts with bases to form salts, such as sodium saccharate.

These salts are used in various applications, including as food additives and in pharmaceuticals.

Esterification: Reacts with alcohols to form esters.

The esterification reaction involves the reaction of galactaric acid with alcohols in the presence of a catalyst, producing galactaric acid esters that can be used in different industrial processes.

Reduction Reactions:

Reduction to Galactose:

Under certain conditions, galactaric acid can be reduced back to galactose or its derivatives, although this is not a common reaction in practical applications.

Formation of Complexes:

Coordination Compounds:

Galactaric acid can form coordination compounds with transition metals, which can be used in various chemical and industrial processes.

Production of Galactaric Acid:

Oxidation of Galactose:

The primary method of producing galactaric acid involves the oxidation of galactose, a sugar found in various fruits and dairy products.

This can be achieved using strong oxidizing agents, such as nitric acid or potassium permanganate.

Conditions: 

This reaction typically requires controlled conditions to prevent over-oxidation and to ensure the formation of galactaric acid.

Oxidation of Lactose:

Galactaric acid can also be produced by the oxidation of lactose, a disaccharide composed of glucose and galactose.

The oxidation process involves similar reagents and conditions as those used for galactose.

Biotechnological Production:

Advances in biotechnology may enable the microbial fermentation of substrates to produce galactaric acid.

Specific strains of bacteria or yeast can be engineered to convert sugars or other precursors into galactaric acid through fermentation processes.

This method can offer a more sustainable and eco-friendly production route compared to chemical oxidation.

Extraction from Natural Sources:

Although less common, galactaric acid can be extracted from plant sources where it occurs naturally.

This involves the extraction and purification of galactaric acid from fruits, vegetables, or other plant materials.

The yield and purity of galactaric acid from natural sources may be lower compared to chemical or biotechnological methods.

Handling and Storage of Galactaric Acid:

Handling:

Handle galactaric acid with care, avoiding direct contact with skin and eyes. Use appropriate personal protective equipment (PPE) such as gloves, safety goggles, and lab coats.

Work in a well-ventilated area to avoid inhaling dust or vapors.

Avoid inhaling or ingesting the substance.

Storage:

Store in a cool, dry place away from moisture, direct sunlight, and sources of heat.

Keep the container tightly closed when not in use.

Store in a labeled, secure container to prevent accidental exposure or spillage.

Stability and Reactivity of Galactaric Acid:

Stability:

Galactaric acid is generally stable under recommended storage conditions.

Avoid exposure to excessive heat and moisture to prevent degradation.

Reactivity:

Incompatibilities:

Avoid contact with strong oxidizing agents, strong acids, and strong bases.

Reactions:

Galactaric acid can chelate metal ions and may participate in oxidation-reduction reactions under certain conditions.

First Aid Measures of Galactaric Acid:

Inhalation:

Move the person to fresh air immediately.

If symptoms such as coughing or difficulty breathing persist, seek medical attention.

Skin Contact:

Wash the affected area with plenty of soap and water.

Remove contaminated clothing and seek medical advice if irritation or an allergic reaction occurs.

Eye Contact:

Rinse eyes with plenty of water for at least 15 minutes, holding the eyelids open.

Seek medical attention immediately.

Ingestion:

Rinse the mouth with water and drink plenty of water.

Do not induce vomiting unless instructed by a medical professional. Seek medical attention promptly.

Firefighting Measures of Galactaric Acid:

Extinguishing Media:

Use water spray, foam, dry chemical, or carbon dioxide (CO2) to extinguish fires involving galactaric acid.

Special Hazards:

During a fire, toxic fumes or gases may be released.

Wear self-contained breathing apparatus (SCBA) and protective clothing.

Firefighting Procedures:

Evacuate the area and approach the fire from upwind. 

Use appropriate firefighting techniques and ensure proper ventilation.

Accidental Release Measures of Galactaric Acid:

Personal Precautions:

Wear appropriate PPE, including gloves, goggles, and protective clothing.

Avoid inhalation and direct contact with the substance.

Environmental Precautions:

Prevent the substance from entering drains, waterways, or the environment.

Contain the spill to prevent contamination.

Cleanup Methods:

Collect the spilled material using appropriate tools and place Galactaric acid in a suitable container for disposal.

Clean the affected area with water and detergent to remove residual material.

Exposure Controls/Personal Protective Equipment of Galactaric Acid:

Engineering Controls:

Use local exhaust ventilation or fume hoods to minimize inhalation exposure.

Personal Protective Equipment (PPE):

Respiratory Protection:

Use a respirator if ventilation is inadequate or if there is a risk of inhaling dust or vapors.

Hand Protection:

Wear chemical-resistant gloves to prevent skin contact.

Eye Protection:

Use safety goggles or face shields to protect eyes from splashes.

Skin Protection:

Wear protective clothing, such as lab coats or aprons, to avoid skin contact.

Identifiers of Galactaric Acid:

CAS: 526-99-8

European Community (EC) Number: 208-404-0

IUPAC Name: (2S,3R,4S,5R)-2,3,4,5-tetrahydroxyhexanedioic acid

Molecular Formula: C6H10O8

Molecular Weight: 210.14 g/mol

IUPAC Name: 2,3,4,5-tetrahydroxyhexanedioic acid

Common Name: Saccharic acid

Molecular Formula: C6H8O8

CAS Number: 97-77-8

PubChem CID: 444964

ChemSpider ID: 393398

UNII: 47E4ZV66Z2

SMILES Notation:

SMILES: O(C(=O)O)C(C(C(=O)O)O)O

InChI: InChI=1S/C6H8O8/c7-1(8)4(10)2(9)5(11)3(6(12)13)14/h2-5,9-11H,7H2,(H,12,13)

InChIKey: CDOAHYPFDIVSNW-UHFFFAOYSA-N

Beilstein Reference: 1214949

EC Number: 202-583-8

Molecular Weight: 176.13 g/mol

Melting Point: Approximately 164-166°C (327-331°F)

Density: Approximately 1.87 g/cm³ (for solid form)

Structural Formula:

ChEBI ID: CHEBI:28931

RSC Database: 3093

Speifications of Galactaric Acid:

Appearance: White or off-white crystalline solid

Purity: Generally > 98% (as determined by HPLC, titration, or other analytical methods)

Melting Point: 164-166°C (327-331°F)

Solubility: Soluble in water

pH (1% Solution): Typically around 2.5 to 3.5

Density: Approximately 1.87 g/cm³ (solid form)

Chemical Tests:

Identification: Confirmed by methods such as IR spectroscopy, NMR spectroscopy, or HPLC

Assay: Typically performed using high-performance liquid chromatography (HPLC) or titration to ensure proper concentration

Heavy Metals:

Limit: Typically < 10 ppm (parts per million)

Loss on Drying:

Limit: Generally < 0.5% (measured by drying the sample at a specified temperature)

Residue on Ignition:

Limit: Generally < 0.1% (determined by heating the sample to high temperatures and measuring the remaining residue)