Carbonic acid is a carboxylic acid with a hydroxyl group as the substituent. Together, the hydroxyl and carbonyl group form the functional group carboxyl. Its functional groups include aldehyde, hydroxyl, and ether. Acetic anhydride is commonly used as an acetylating agent reacting with free hydroxyl groups. Plants produce flavonoids and isoflavones with methylations on hydroxyl groups, i.e. methoxy bonds. New substrates based on dendrons with hydroxyl or amine peripheries show low toxicity. Oxidizing species include singlet oxygen, hydroxyl, monatomic oxygen, and hydroperoxyl. If reaction is between the C-4 hydroxyl and the aldehyde, a furanose is formed instead. Methanol is the simplest alcohol, consisting of a methyl group linked to a hydroxyl group. This proceeds via single electron oxidation and hydroxyl radicals. They are aldehydes or ketones with two or more hydroxyl groups. The solution detects both Fe ions and hydroxyl ions. Isophorone is degraded by attack of hydroxyl radicals. Typical equations showing persulfate generation of hydroxyl radicals follows. IP has three hydrogen bond donors in the form of its three hydroxyl groups.