Periodate (IPA: /pəˈraɪ.ədeɪt/) is an anion composed of iodine and oxygen. Periodates include two forms. The metaperiodate ion is IO4; the orthoperiodate ion is IO65−. Usually both forms are called periodates. Periodate is the conjugate base of periodic acid.

In neutral or weak acid conditions, IO4 is most common, in equilibrium with a smaller amount of H4IO6. In basic conditions, H3IO62− is formed, plus some other ions.

Like its neighbor, tellurium, and unlike lighter halogens, iodine tends to be hexacoordinate, and the units HnIO6(5−n)- are quite common; but tetracoordinate units, such as IO4, are also quite common with iodine, tetracoordinate being the only form possible with lighter perhalogenates, such as perchlorate.

Sodium metaperiodate can be isolated from the oxidation of sodium iodide with sodium hypochlorite and is best recrystallized from nitric acid. However, electrochemistry offers an easier alternative.


Periodates can cleave carbon-carbon bonds when both carbon atoms bear an oxygen atom, either in the form of a hydroxyl or a carbonyl group. This property is often utilized in molecular biochemistry for the purposes of modifying saccharide rings, as many five- and six-membered sugars often have vicinal diols.



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  • Periodate — Per*i o*date, n. (Chem.) A salt of periodic acid. [1913 Webster] …   The Collaborative International Dictionary of English

  • periodate — [pə rī′ə dāt΄] n. a salt of periodic acid containing the monovalent, negative radical IO4 …   English World dictionary

  • periodate — /peuh ruy euh dayt /, n. Chem. a salt of a periodic acid, as sodium periodate, Na2H3IO6. [1830 40; PERIOD(IC ACID) + ATE2] * * * …   Universalium

  • periodate — noun Either of two oxyanions of iodine; any salt containing these anions See Also: periodic acid …   Wiktionary

  • periodate — A salt of periodic acid. * * * per·io·date ( )pər ī ə .dāt, ī əd ət n a salt of a periodic acid * * * per·io·date (per iґo dāt) a salt of periodic acid …   Medical dictionary

  • periodate — [pə: rʌɪədeɪt] noun Chemistry a salt or ester of periodic acid …   English new terms dictionary

  • periodate — per·iodate …   English syllables

  • periodate — /pɜˈraɪədeɪt/ (say per ruyuhdayt) noun a salt of periodic acid. {per + iod(ic) + ate2} …   Australian English dictionary

  • periodate — n. Chem. a salt or ester of periodic acid …   Useful english dictionary

  • Periodate de sodium — Général Nom IUPAC periodate de sodium Synonymes …   Wikipédia en Français