D-Galactose (59-23-4) Physical and Chemical Properties
D-Galactose
A naturally occurring aldohexose (monosaccharide) commonly supplied as a white crystalline powder for use as an analytical standard, reagent in carbohydrate chemistry and a raw material for formulation and R&D workflows.
| CAS Number | 59-23-4 |
| Family | Monosaccharide (aldohexose) |
| Typical Form | White crystalline powder |
| Common Grades | EP |
D-Galactose is a naturally occurring aldohexose monosaccharide belonging to the hexopyranose structural class; in its predominant cyclic form it exists as D-galactopyranose. Structurally it is a six‑carbon carbohydrate with four defined stereocenters in the ring and an exocyclic hydroxymethyl group at C‑6; the systematic name is (3R,4S,5R,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol. The molecule is polyhydroxylated (five hydroxyl groups) and is a reducing sugar: the anomeric center can interconvert (mutarotation) between alpha and beta anomers in aqueous solution. The ring‑closed pyranose form imparts a rigid chair‑like geometry for many of the conformers encountered in solution and solid state.
Electronically and physicochemically D‑galactose is highly polar and strongly hydrative: computed descriptors show a topological polar surface area of 110 \(\text{Å}^2\), five hydrogen‑bond donors and six hydrogen‑bond acceptors, and an XLogP3 value of -2.6, consistent with marked water solubility and low lipophilicity. As an aldohexose it is susceptible to standard carbohydrate reactions: reversible mutarotation, glycosylation at the anomeric position to form glycosides, oxidation of the aldehyde (or hemiacetal) to give aldonic acids, and participation in enzymatic pathways (notably the Leloir pathway) under biological conditions.
D‑Galactose is biologically and industrially significant: it is a component of lactose and of numerous oligo‑ and polysaccharides (e.g., cerebrosides, gangliosides, mucopolysaccharides) and is used diagnostically to assess hepatic functional capacity. It also serves as a biosynthetic building block (glycoconjugates) and appears as an excipient or ingredient in some vaccine and formulation contexts. Common commercial grades reported for this substance include: EP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting Point
No experimentally established value for this property is available in the current data context.
Boiling Point
No experimentally established value for this property is available in the current data context.
Vapor Pressure
Vapor pressure reported: 0.00000002 \(\mathrm{mmHg}\). This extremely low vapour pressure is consistent with a non‑volatile, high‑molecular‑polarity solid that will not appreciably evaporate under ambient conditions.
Flash Point
No experimentally established value for this property is available in the current data context.
Chemical Properties
Solubility and Phase Behavior
D‑Galactose is a highly hydrophilic, crystalline white powder with extensive hydrogen‑bonding capacity (HBond donor count = 5; HBond acceptor count = 6) and a low computed XLogP3 (−2.6). These descriptors are consistent with high solubility in water and limited solubility in nonpolar organic solvents; in aqueous media galactose exists primarily as a hydrated pyranose and shows mutarotation between anomeric forms. The solid phase is typically a crystalline monohydrate or anhydrous powder depending on processing; provided material descriptions include "White powder."
Reactivity and Stability
Chemically, galactose behaves as a typical reducing monosaccharide. It undergoes mutarotation (interconversion of alpha and beta anomers), can form glycosidic bonds at the anomeric center, and is susceptible to oxidation (to galactonic acids) and reduction under appropriate conditions. Enzymatically, it is metabolized via the Leloir pathway (conversion through galactokinase, galactose-1-phosphate uridyltransferase, and UDP‑galactose 4‑epimerase). Solid samples are generally stable if kept dry and protected from prolonged exposure to strong oxidants and high temperatures that can induce caramelization or decomposition; hydrolysis is not a concern for the monosaccharide itself but is relevant when it is part of glycosidic linkages in oligo‑ and polysaccharides.
Thermodynamic Data
Standard Enthalpies and Heat Capacity
No experimentally established value for this property is available in the current data context.
Molecular Parameters
Molecular Weight and Formula
Molecular formula: \(\mathrm{C_6H_{12}O_6}\).
Molecular weight (listed): 180.16 \(\mathrm{g}\,\mathrm{mol}^{-1}\).
LogP and Polarity
Computed XLogP3 (XLogP3‑AA): −2.6, indicating strong hydrophilicity and low membrane partitioning into nonpolar phases. Topological polar surface area (TPSA): 110 \(\text{Å}^2\). Rotatable bond count: 1. These molecular parameters reflect a small, highly polar polyol likely to remain in aqueous compartments rather than partition into lipid environments.
Structural Features
IUPAC name (computed): (3R,4S,5R,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol. SMILES: C([C@@H]1C@@HO)O. InChI: InChI=1S/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2-,3+,4+,5-,6?/m1/s1. InChIKey: WQZGKKKJIJFFOK-SVZMEOIVSA-N.
The molecule is a pyranose (six‑membered ring) in its dominant cyclic form; computed descriptors indicate four defined atom stereocenters and one undefined stereocenter in some representations. The heavy atom count is 12 and the exact (monoisotopic) mass is 180.06338810.
Collision cross section (experimental, sodium adduct \([M+Na]^+\)): 142.39 \(\text{Å}^2\) (DT, stepped‑field); additional reported CCS values include 142.1 \(\text{Å}^2\), 141.9 \(\text{Å}^2\) (DT single field) and 136 \(\text{Å}^2\) (TW calibrated with polyalanine), reflecting typical conformer/ion mobility behavior of this small carbohydrate.
Identifiers and Synonyms
Registry Numbers and Codes
CAS number: 59-23-4.
Additional registry and database identifiers present in source data include: InChIKey WQZGKKKJIJFFOK-SVZMEOIVSA-N, SMILES C([C@@H]1C@@HO)O, and computed molecular formula \(\mathrm{C_6H_{12}O_6}\).
Other accession codes and registry-style identifiers appear in supplier and curation lists (e.g., EC/EINECS numbers and several database cross‑references); the primary CAS shown above is the conventional chemical registry identifier for D‑galactose.
Synonyms and Structural Names
Reported synonyms and common names include: Galactose; D‑Galactose; D‑galactopyranose; D(+)-Galactose; Gal; D‑Gal. IUPAC condensed or alternative names include D‑galacto‑hexopyranose and D‑galactopyranose. Other depositor and MeSH synonyms are listed in source material.
Industrial and Commercial Applications
Representative Uses and Industry Sectors
D‑Galactose is used as: (a) a diagnostic agent for assessing hepatic functional capacity; (b) a component or building block of oligo‑ and polysaccharides found in food ingredients (pectins, gums) and biological materials (cerebrosides, gangliosides, mucoproteins); and (c) an ingredient in certain formulations where a monosaccharide excipient or glycosyl component is required. It is also cited in vaccine development contexts where galactose residues or exogenous galactose influence glycosylation or bacterial LPS biosynthesis in attenuated strains. The compound is active in multiple sectors including pharmaceuticals (diagnostics, formulation), food ingredients, and biochemical research.
Role in Synthesis or Formulations
In synthetic and formulation chemistry, galactose functions as a monosaccharide reagent for glycosylation and as a substrate or epitope in glycoconjugate synthesis. It is a precursor unit in the manufacture or modification of disaccharides such as lactulose (a therapeutic laxative) and participates in enzymatic transformations (Leloir pathway enzymes) relevant to metabolic studies and biocatalysis. In vaccine manufacture, exogenous galactose can modulate the biosynthesis of surface glycans in certain bacterial strains used for live attenuated vaccines.
Safety and Handling Overview
Acute and Occupational Toxicity
Aggregated hazard listings indicate that D‑galactose is generally not classified as a hazardous substance by many suppliers; however, isolated notifications report eye irritation hazard H319 (Causes serious eye irritation) with associated precautionary statements (e.g., P264+P265, P280, P305+P351+P338, P337+P317). Toxicological summaries include historical animal findings: teratogenicity observed in rats at very high dietary loadings (reported at 55% of the diet in older studies) and various effects in acute subcutaneous studies in rodents (liver changes, neurological effects, renal alterations) reported in legacy toxicology compilations. Cosmetic safety assessments note that galactose is considered safe in the current practices of use and concentration for formulation purposes.
Occupational exposure concerns are primarily those characteristic of fine sugar powders: inhalation of dust may irritate mucous membranes; accidental eye contact may cause irritation. No routine dermal sensitizer classification is indicated in the aggregated information.
Storage and Handling Considerations
Store D‑galactose as a dry, well‑sealed powder in a cool, dry place to minimize hygroscopic uptake and caking. Avoid generation of dust and use appropriate local exhaust or dust control in processes that produce airborne particulate. Use standard laboratory/industrial personal protective equipment (gloves, eye protection); in situations with dust/aerosol generation, respiratory protection is advised. For spills and waste handling, avoid aqueous discharges with high organic load without appropriate treatment. For detailed hazard, transport and regulatory information, users should refer to the product‑specific Safety Data Sheet (SDS) and local legislation.
