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Lactose

IUPAC: (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol

C12H22O11 Organic Compounds CAS 63-42-3
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Quick Reference
Formula / NotationC12H22O11
CAS Number63-42-3
Molecular Weight342.30
Melting Point433 °F (NTP, 1992)
Density1.525
Solubility50 to 100 mg/mL at 68 °F (NTP, 1992)
AppearanceLactose is a white hard crystalline powder. (NTP, 1992)
Also Known As(2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol; Milk sugar; CHEBI:17716; beta-D-Gal-(1->4)-D-Glc; beta-D-Galp-(1->4)-D-Glcp; (+)-Lactose; 1-beta-D-Galactopyranosyl-4-D-glucopyranose; beta-D-galactopyranosyl-(1->4)-D-glucopyranose; Lactin; Anhydrous lactose
CategoryOrganic Compounds

What is Lactose?

Lactose is a glycosylglucose disaccharide, found most notably in milk, that consists of D-galactose and D-glucose fragments bonded through a beta-14 glycosidic linkage. The glucose fragment can be in either the alpha- or beta-pyranose form, whereas the galactose fragment can only have the beta-pyranose form. It has a role as a human metabolite.

Formula & Notation

C12H22O11

IUPAC Name: (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol

Other Names / Synonyms: (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol; Milk sugar; CHEBI:17716; beta-D-Gal-(1->4)-D-Glc; beta-D-Galp-(1->4)-D-Glcp; (+)-Lactose; 1-beta-D-Galactopyranosyl-4-D-glucopyranose; beta-D-galactopyranosyl-(1->4)-D-glucopyranose; Lactin; Anhydrous lactose

Properties & Characteristics

Appearance: Lactose is a white hard crystalline powder. (NTP, 1992). Molecular formula: C12H22O11. Molecular weight: 342.30 g/mol. Melting point: 433 °F (NTP, 1992). Density: 1.525. Solubility: 50 to 100 mg/mL at 68 °F (NTP, 1992). LogP: -4.7.

Physical Data

PropertyValue
Melting Point433 °F (NTP, 1992)
Density1.525
Molecular Weight342.30
Solubility50 to 100 mg/mL at 68 °F (NTP, 1992)
AppearanceLactose is a white hard crystalline powder. (NTP, 1992)

Uses & Applications

Used as an industrial feedstock, solvent, pharmaceutical intermediate, flavoring agent, or chemical building block.

Safety Information

Flammable or irritant. Many organic compounds are flammable liquids or vapours. Keep away from ignition sources. Consult SDS for specific hazard data.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Lactose
Formula C12H22O11
CAS Number 63-42-3
Molecular Weight 342.30
Synonyms (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol; Milk sugar; CHEBI:17716; beta-D-Gal-(1->4)-D-Glc; beta-D-Galp-(1->4)-D-Glcp; (+)-Lactose; 1-beta-D-Galactopyranosyl-4-D-glucopyranose; beta-D-galactopyranosyl-(1->4)-D-glucopyranose; Lactin; Anhydrous lactose

Frequently Asked Questions

Lactose is a glycosylglucose disaccharide, found most notably in milk, that consists of D-galactose and D-glucose fragments bonded through a beta-14 glycosidic linkage. The glucose fragment can be in either the alpha- or beta-pyranose form, whereas the galactose fragment can only have the beta-pyranose form. It has a role as a human metabolite.

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Editorial standards: Chemical data is sourced from peer-reviewed literature, CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA, and IAEA. For educational purposes only — always consult official SDS documentation and qualified professionals before handling chemicals.