Every carbohydrate I keep encountering so far has only one hydroxyl (–OH) group attached to every carbon atom in the carbon chain (in Fischer projections): either on the left, or on the right of the carbon, but never both.
This makes me wonder:
Are there any carbohydrates with –OH groups on both sides?
If there aren't, why? Is there any physical or chemical rule that would prevent this?
According to this website:
it seems to be possible for alcohols to have two –OH groups on one carbon:
Many compounds have more than one hydroxyl group; two hydroxyl groups are called "diols". If the hydroxyl groups are on adjacent carbons, then it is called a "glycol." If the hydroxyl groups are on the same carbon, then it is called a "gem" (for geminal, or twin) diol.
so what about carbohydrates?
