Tautomers are constitutional isomers of organic compounds that readily interconvert with each other. The chemical reaction interconverting the two is called tautomerization. This reaction commonly results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond. The concept of tautomerizations is called tautomerism. Because of the rapid interconversion, tautomers are generally considered to be the same chemical compound. Tautomerism is a special case of structural isomerism and can play an important role in non-canonical base pairing in DNA and especially RNA molecules.
In solutions in which tautomerization is possible, a chemical equilibrium of the tautomers will be reached. The exact ratio of the tautomers depends on several factors, including temperature, solvent, and pH.
Common tautomeric pairs include:
Into the fire I go, flames dancing before my eyes
Lust and desire, Satan's call, I can feel it burning, I can feel the fire
Inferno of glorious pain, the moon glows red as I cut open my veins
Eternity opens, I heed its call, take me beyond the underworld
My body is burning bright as the bells of doom chimes in the night
Lord of sin, guide me on my way as I face the gates of Hell
Kneeling before the endless flames, I'm one with the night, I broke my mortal chains
Blessed by Satan and ready for death, I enter the eternal fire...
Dwelling beyond the netherworlds
My life was just a dream
In death is where I find the truth of life
At one with the raging fires
I've reach my final end