1.6.3 Sodium Periodate
1.6.3.1 Introduction
Sodium periodate (NaIO4) is a sodium salt of periodic acid (HIO4). It is soluble in water and converts to sodium iodate (NaIO3) on heating. NaIO4 acts as oxidizing agent and mostly is used as a co-oxidant in oxidation reactions.
1.6.3.2 Oxidation of Sulfide to Sulfoxde
Sodium periodate can oxidize sulfide to sulfoxide by treating sulfide with aqueous solution of NaIO4 at 0°C.
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1.6.3.3 Cleavage of Glycol
The NaIO4 can cleave 1,2-diol to give carbonyl compounds (Scheme 17). The LTA can also cleave 1,2-diol but LTA is soluble in organic solvents and sparingly soluble in water, in contrast, NaIO4 is soluble in water therefore the NaIO4 is used for those compounds, which are soluble in water i.e. most of the sugar molecules (Scheme 18).
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Scheme 17 |
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Scheme 18 |
NaIO4 forms a cyclic intermediate with 1,2-diol that undergoes cleavage to give the carbonyl compounds.
1.6.3.4 Sodium Periodate as a Co-oxidant
The NaIO4 is mostly used as a co-oxidant for a variety of metal catalyzed oxidation processes. It oxidizes the reduced metal to its active oxidation state therefore it reduces the use of stoichiometric amount of metal salt or complex (Scheme 19)
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Scheme 19 |