# Alpha-Lactose monohydrate

**CAS:** 64044-51-5  
**PubChem CID:** [104938](https://pubchem.ncbi.nlm.nih.gov/compound/104938)  
**Molecular formula:** C₁₂H₂₄O₁₂  
**Molar mass:** 360.31 g/mol  
**IUPAC:** (2R,3R,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol;hydrate  
**SMILES:** `C([C@@H]1[C@@H]([C@@H]([C@H]([C@@H](O1)O[C@@H]2[C@H](O[C@@H]([C@@H]([C@H]2O)O)O)CO)O)O)O)O.O`  
**InChIKey:** `WSVLPVUVIUVCRA-KPKNDVKVSA-N`  
**InChI:** `InChI=1S/C12H22O11.H2O/c13-1-3-5(15)6(16)9(19)12(22-3)23-10-4(2-14)21-11(20)8(18)7(10)17;/h3-20H,1-2H2;1H2/t3-,4-,5+,6+,7-,8-,9-,10-,11+,12+;/m1./s1`  

## Physicochemical properties

| Parameter | Value |
|---|---|
| PSA | 191 Ų |
| Hydrogen bond donors | 9 |
| Hydrogen bond acceptors | 12 |
| Rotatable bonds | 4 |
| Heavy atoms | 24 |

## 3D structure

The molecule contains 48 atoms connected by 48 chemical bonds. Interactive 3D model available at: https://molgod.org/molecule/64044-51-5/

## Synonyms

- 5989-81-1
- alpha-Lactose monohydrate
- alpha-D-Glucopyranose, 4-O-beta-D-galactopyranosyl-, monohydrate
- RefChem:1076517
- DTXCID90820517
- 611-913-4
- Lactose monohydrate
- alpha-D-Lactose monohydrate
- D-Lactose monohydrate
- 64044-51-5

## Data sources

- [PubChem CID 104938](https://pubchem.ncbi.nlm.nih.gov/compound/104938)
- [Wikidata](https://www.wikidata.org/wiki/Q27277391)
- [NIST WebBook](https://webbook.nist.gov/cgi/cbook.cgi?ID=64044-51-5)
- [ChEMBL](https://www.ebi.ac.uk/chembl/g/#search_results/all/query=64044-51-5)

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*Last updated: 2026-10-17 · Generator: MOL-GOD v3.12.33*