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What is the number of analytical methods available for studying the periodate oxidation of polyhydroxy compounds?
What is the number of analytical methods available for studying the periodate oxidation of polyhydroxy compounds?
What is the condition required for periodate to react with iodide?
What is the condition required for periodate to react with iodide?
What is the result of the cleavage reaction in periodate oxidation?
What is the result of the cleavage reaction in periodate oxidation?
What is the purpose of adding NaHCO3 in the reaction?
What is the purpose of adding NaHCO3 in the reaction?
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What is the effect on the sites of possible cleavage when a hemiacetal carbon is involved in a glycosidic linkage or is methylated?
What is the effect on the sites of possible cleavage when a hemiacetal carbon is involved in a glycosidic linkage or is methylated?
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What is the product of the reaction between periodate and iodide in a neutral solution?
What is the product of the reaction between periodate and iodide in a neutral solution?
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Study Notes
Periodate Oxidation of Carbohydrates
- There are three analytical methods for studying periodate oxidation of polyhydroxy compounds: iodometric, acidimetric, and spectrophotometric.
- Compounds containing hydroxyl groups on adjacent carbon atoms undergo qualitative oxidation at room temperature with an excess of periodic acid or its salts.
- Periodic acid (HIO4) is a useful reagent in carbohydrate analysis, cleaving C—C bonds if:
- Both carbons have hydroxyl groups
- One carbon has a hydroxyl group and is adjacent to another carbon with an amino group, keto, or aldo oxygen
- Every cleavage results in an oxidation, with the carbon participating in the cleavage reaction being oxidized to the next level (e.g., alcohol to aldehyde, aldehyde to carboxylic)
- The hemiacetal C in a glycosidic linkage or methylated reduces the sites of possible cleavage due to the inability to open-out the ring structure into a straight chain
- Periodate oxidation consumes one mole of periodate and produces one mole each of iodate and water for every pair of vicinal hydroxyl groups
- Periodate reacts with iodide in neutral solution to give iodine and iodate, requiring alkaline conditions to prevent iodate from oxidizing iodide to iodine
- NaHCO3 is added to maintain alkaline conditions
- Iodine formed is immediately reacted with arsenite, which is added at the end of the periodate oxidation
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Description
This quiz covers the periodate oxidation of polyhydroxy compounds, specifically the iodometric technique, and its application in carbohydrate analysis.
