What molecule am I?
D-Psicose, also widely known as D-allulose, is a natural but rare monosaccharide. It is a ketohexose that has the same empirical formula as common monosaccharides such as glucose and fructose. It is epimeric with fructose at the 3-position. Its enantiomer, L-psicose1, is unknown in nature but has been synthesized.
Known as early as 1915 as D-pseudofructose, German chemists H. Ohle and F. Just determined its structure in 1935 and renamed it D-psicose. In 1942, F. W. Zerban at the New York Sugar Trade Laboratory (New York City) and Louis Sattler at Brooklyn College (NY) . At the time, it was deemed to be unfermentable and therefore of little practical value.
The physical state of D-psicose is variously reported in the literature as a viscous liquid or a white crystalline solid with a melting point of 58 掳C or 109 掳C. These discrepancies are probably attributable to the difficulty of crystallizing the compound. At 鈮�1.0 kg/L, it is extremely soluble in water. (Glucose dissolves at 鈮�900 g/L, fructose at 鈮�4 kg/L.)
D-Psicose is 70% as sweet as sucrose (table sugar), but it has only 鈮�10% of the nutritional energy (calorie) value. As a result, it is under development as a replacement for sucrose and artificial sweeteners. It was originally produced from corn; but this year, food-ingredient startup Bonumose (Charlottesville, VA) and drug-services company Novasep (Lyon, France) teamed up to and fellow low-calorie sugar D-tagatose2 from cellulose, starch, or their derivatives via an enzymatic process.
1. CAS Registry No. 16354-64-6.
2. CAS Registry No. 87-81-0.
D-Psicose听hazard information
| Hazard class* | GHS code and hazard statement |
|---|---|
| Not a hazardous substance or mixture | 听 |
*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals.听
D-Psicose fast facts
| CAS Reg. No. | 551-68-8 |
nomenclature | D-Psicose |
| Empirical formula | C6H12O6 |
| Molar mass | 180.16 g/mol |
| Appearance | White crystals or viscous liquid |
| Melting point | See text |
| Water solubility | 鈮�1.0 kg/L |
MOTW update
Sodium hypochlorite (NaClO) was the Molecule of the Week for June 30, 2008. It is the active ingredient in 鈥渃hlorine bleach鈥�. NaClO has been widely used for >200 years; but until now, the crystal structure of its pentahydrate (the normal solid form) had not been established. Tomislav Fri拧膷i膰 and co-workers at McGill University (Montreal), working at 鈥�100 掳C because NaClO鈥�5H2O liquefies at ambient temperature, determined the , shown. The structure consists of alternating layers of Na+ and ClO鈥� ions 鈥済lued鈥� together by water molecules.
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