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Lactose

Athanor · official

C12H22O11 · 342.3 g/mol

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

Also called milk sugar, lactobiose, lactose, 4-O-galactosylglucose

Carbohydrates
Open in Athanor
The structure of Lactose
Drawn from its SMILES with RDKit

Names and identifiers

IUPAC name
(3R,4S,5S,6R)-6-(hydroxymethyl)-3-[(2S,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxane-2,4,5-triol
Synonyms
milk sugar, lactobiose, lactose
+ 13 more

4-O-galactosylglucose, beta-D-Galp-(1->2)-D-Glcp, CHEBI:154519, RefChem:619153, GlyTouCan:G86236QS, G86236QS, Gal(b1-2)Glc, 2-O-beta-D-Galactopyranosyl-D-glucopyranose, 2-O-?-D-Galactopyranosyl-D-glucopyranose, DB-251621, beta-D-galacto-hexopyranosyl-(1->2)-D-gluco-hexopyranose, WURCS=2.0/2,2,1/[a2122h-1x_1-5][a2112h-1b_1-5]/1-2/a2-b1, (3R,4S,5S,6R)-6-(Hydroxymethyl)-3-[(2S,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxane-2,4,5-triol

Molecular formula
C12H22O11
Empirical formula
C12H22O11
Molecular weight
342.3 g/mol
Exact mass
342.11621
CAS number
63-42-3
PubChem CID
91858379
Canonical SMILES
C(C1C(C(C(C(O1)O)OC2C(C(C(C(O2)CO)O)O)O)O)O)O
Isomeric SMILES
C([C@@H]1[C@@H]([C@@H]([C@H]([C@@H](O1)O[C@@H]2[C@H]([C@@H]([C@H](OC2O)CO)O)O)O)O)O)O
InChI
InChI=1S/C12H22O11/c13-1-3-6(16)8(18)10(11(20)21-3)23-12-9(19)7(17)5(15)4(2-14)22-12/h3-20H,1-2H2/t3-,4-,5+,6-,7+,8+,9-,10-,11?,12+/m1/s1
InChIKey
HIWPGCMGAMJNRG-ABXHMFFYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Calculated

Heavy atoms
23
Rings
2
Aromatic rings
0
Fraction sp³ carbons (Fsp3)
1
H-bond donors
8
H-bond acceptors
11
Rotatable bonds
4
TPSA (Ų)
189.5 computed here · PubChem 190
Formal charge
0
XLogP3
-4.2 PubChem
Complexity
382 PubChem
Stereocenters
9 defined, 1 undefinedCIP: C3: R · C5: undefined · C7: R · C9: S · C11: R · C14: R · C16: S · C18: R · C20: S · C22: S
Double-bond geometry
None specified
Point group
C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C42.11%
  • H6.48%
  • O51.41%

Isotope pattern

100%342.11614%343.1203.1%344.121345.124

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
-5.4 Crippen (Wildman and Crippen 1999)
log S (water solubility)
1.7 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
4.29 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 342.3
  • log P ≤ 5 (Crippen): -5.4
  • H-bond donors ≤ 5: 8
  • H-bond acceptors ≤ 10: 11

Breaks 2 of the four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

No GHS hazard classification was found in the sources.

Safety data sheets on the supplier’s page: MuseChem, A2B Chem, Debye Scientific Co., Ltd.

Always read the supplier’s safety data sheet before working with it.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  2. ·Literature on PubChem

Data last updated 2026-10-14.