HOCHCHOH

HOCHCHOH is a shorthand notation used in organic and carbohydrate chemistry to denote a vicinal diol unit, that is, two adjacent carbon atoms each bearing a hydroxyl group. It is not a single defined compound, but a structural motif that appears in many molecules and reaction schemes. In schematic representations, the motif is often shown as HO-CH-CH-OH to indicate the presence of two neighboring hydroxyl groups, with the exact stereochemistry varying with the specific molecule.

This diol motif is common in sugars and polyols. For example, many carbohydrates contain multiple 1,2-diols in their linear or cyclic forms, and polyols such as glycerol feature several adjacent hydroxyl-bearing carbons. The term HOCHCHOH is most useful as a generic descriptor rather than a fixed chemical entity.

Properties of the vicinal diol motif include strong polarity and the ability to participate in extensive hydrogen bonding, which influences solubility and conformational preferences. The 1,2-diol unit is also a site of characteristic reactivity: it can be protected as acetals or ketals, used in boron-diol complexation, or cleaved oxidatively by periodate oxidation to yield carbonyl fragments.

In summary, HOCHCHOH denotes a flexible, widely encountered diol fragment rather than a single compound. Its significance lies in the role such vicinal diols play in the structure and chemistry of carbohydrates and polyols, as well as in common protective and oxidative transformations in organic synthesis.