Thymine

Thymine
Names
	Preferred IUPAC name 5-Methylpyrimidine-2,4(1H,3H)-dione
	Other names 5-Methyluracil
Identifiers
CAS Number	65-71-4 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:17821 ;
ChEMBL	ChEMBL993 ;
ChemSpider	1103 ;
ECHA InfoCard	100.000.560
IUPHAR/BPS	4581;
MeSH	Thymine
PubChem CID	1135;
UNII	QR26YLT7LT ;
CompTox Dashboard (EPA)	DTXSID4052342 ;
	InChI InChI=1S/C5H6N2O2/c1-3-2-6-5(9)7-4(3)8/h2H,1H3,(H2,6,7,8,9) Key: RWQNBRDOKXIBIV-UHFFFAOYSA-N ;
	SMILES O=C1NC(=O)NC=C1C;
Properties
Chemical formula	C5H6N2O2
Molar mass	126.115 g·mol−1
Density	1.223 g cm−3 (calculated)
Melting point	316 to 317 °C (601 to 603 °F; 589 to 590 K)
Boiling point	335 °C (635 °F; 608 K) (decomposes)
Solubility in water	3.82 g/L
Acidity (pKa)	9.7
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Thymine (/ˈθaɪmɪn/) (symbol T or Thy) is one of the four nucleotide bases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. In RNA, thymine is replaced by the nucleobase uracil. Thymine was first isolated in 1893 by Albrecht Kossel and Albert Neumann from calf thymus glands, hence its name.^[2]

^ Dannenfelser, R.-M.; Yalkowsky, S.H. (December 1991). "Data base of aqueous solubility for organic non-electrolytes". Science of the Total Environment. 109 (C): 625–628. Bibcode:1991ScTEn.109..625D. doi:10.1016/0048-9697(91)90214-Y. Retrieved 2021-11-14.
^ Albrecht, Kossel; Neumann, Albert (Oct–Dec 1893). "Ueber das Thymin, ein Spaltungsproduct der Nucleïnsäure" [On thymine, a cleavage product of nucleic acid]. Berichte der Deutschen Chemischen Gesellschaft. 26 (3): 2753–2756. doi:10.1002/cber.18930260379. Retrieved 2021-11-14. p. 2754: Wir bezeichnen diese Substanz als Thymin. [We designate this substance as thymine.]