Betulin is an abundant, naturally occurring triterpene. It is commonly isolated from the bark of birch trees. It forms up to 30% of the dry weight of silver birch bark.^[2] It is also found in birch sap.^{[citation needed]} Inonotus obliquus contains betulin.^[3]

Quick Facts Names, Identifiers ...

Betulin

Names
IUPAC name Lup-20(29)-ene-3β,28-diol
Systematic IUPAC name (1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-3a-(Hydroxymethyl)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysen-9-ol
Other names Betulinol, betuline, betulol, betulinic alcohol, trochol
Identifiers
CAS Number	473-98-3 Y
3D model (JSmol)	Interactive image Interactive image
ChEMBL	ChEMBL23236 Y
ChemSpider	65272 Y
ECHA InfoCard	100.006.797
EC Number	207-475-5
KEGG	C08618 Y
PubChem CID	72326
UNII	6W70HN7X7O Y
InChI InChI=1S/C30H50O2/c1-19(2)20-10-15-30(18-31)17-16-28(6)21(25(20)30)8-9-23-27(5)13-12-24(32)26(3,4)22(27)11-14-29(23,28)7/h20-25,31-32H,1,8-18H2,2-7H3/t20-,21+,22-,23+,24-,25+,27-,28+,29+,30+/m0/s1 Y Key: FVWJYYTZTCVBKE-ROUWMTJPSA-N Y InChI=1/C30H50O2/c1-19(2)20-10-15-30(18-31)17-16-28(6)21(25(20)30)8-9-23-27(5)13-12-24(32)26(3,4)22(27)11-14-29(23,28)7/h20-25,31-32H,1,8-18H2,2-7H3/t20-,21+,22-,23+,24-,25+,27-,28+,29+,30+/m0/s1 Key: FVWJYYTZTCVBKE-ROUWMTJPBQ
SMILES O[C@H]5CC[C@@]4([C@@H]3[C@@]([C@]2([C@@H]([C@@H]1[C@](CO)(CC[C@H]1C(=C)C)CC2)CC3)C)(C)CC[C@H]4C5(C)C)C CC(=C)[C@@H]1CC[C@]2([C@H]1[C@H]3CC[C@@H]4[C@]5(CC[C@@H](C([C@@H]5CC[C@]4([C@@]3(CC2)C)C)(C)C)O)C)CO
Properties
Chemical formula	C30H50O2
Molar mass	442.728 g·mol−1
Appearance	solid with needle-like crystals[1]
Melting point	256 to 257 °C (493 to 495 °F; 529 to 530 K)
Solubility in water	insoluble[1]
Solubility	slightly soluble in ethanol and benzene; soluble in diethyl ether, ethyl acetate and ligroin[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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The compound in the bark gives the tree its white color which appears to protect the tree from mid-winter overheating by the sun. As a result, birches are some of the northernmost occurring deciduous trees.

Betulin was discovered in 1788 by German-Russian chemist Johann Tobias Lowitz.^[4][5]

Chemically, betulin is a triterpenoid of lupane structure. It has a pentacyclic ring structure, and hydroxyl groups in positions C3 and C28.

• Abietic acid
• Stanol ester
• Phytosterols