Why is sugar not considered a weak organic acid ?

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ncchemist | eNotes Employee

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You did not specifiy what kind of sugar but I will use table sugar, or sucrose, as an example.  You can see the chemical structure of sucrose via the first reference link below but suffice it to say that the hydroxyl groups (OH) are what you are talking about in terms of acidity.  In general, hydrogens contained in hydroxyl groups are hardly acidic meaning they do not disassociate to lose their protons easily.  This is true even for small alcohols like methanol and ethanol and is also true for larger alcohols like sucrose.  In a certain sense they can be considered acids (called Lewis acids, to be precise) since if you reacted them with a very strong base they would lose OH protons in the process.  But when considering them on their own, sugars dissolved in pure water would show a neutral pH of approxiamtely 7.  Therefore they are not acidic in any kind of practical sense.