Mannitol


 * Mannitol ** is a white, crystalline [|[1]]  [|organic compound] with the formula (C 6 H 8 (OH) 6 ). This [|polyol] is used as an [|osmotic diuretic] agent and a weak [|renal] [|vasodilator] . It was originally isolated from the secretions of the [|flowering ash], called [|manna] after their resemblance to the Biblical food, and is also referred to as ** mannite ** and ** manna sugar ** .  [|[2]]  In plants, it is used to induce [|osmotic stress].

Mannitol is a [|sugar alcohol] ; that is, it is derived from a sugar by reduction, with a [|molecular weight] of 182.17 g/mol, [|[3]]  and a [|density] of 1.52 g/mL. [|[4]] Other sugar alcohols include [|xylitol] and [|sorbitol]. Mannitol and sorbitol are isomers, the only difference being the orientation of the hydroxyl group on carbon 2. [|[5]] Aqueous solutions of mannitol are mildly [|acidic] and sometimes such solutions are treated to lower the [|pH]. Chemical Abstracts Registry Numbers for mannitol are 123897-58-5, 69-65-8 (D-Mannitol), 75398-80-0, 85085-15-0, and 87-78-5 (mannitol with unspecified stereochemistry). D-Mannitol (CAS# 69-65-8) has a solubility of 22g mannitol/ 100mL water (25 °C), and a relative sweetness of 50 ( [|sucrose] =100). [|[3]] It melts between 165 and 169 °C (7.6 [|torr] ), and boils at 295 °C at 3.5 torr, indicating a greater boiling point at [|STP] conditions. [|[4]]

Mannitol, [|galactitol] and [|sorbitol] are [|stereoisomers]. All are (C 6 H 8 (OH) 6 ). The only differences in the molecules are the facings of the [|hydroxyl] groups; for example, in sorbitol, the second carbon atom in the chain is [|chiral] like, leading to a physically different molecule.