Fundamentals of Organic ChemistryChemistryBiomolecules
What is invert sugar, and why is it so named?
Options
- AThe sugar mixture obtained from the hydrolysis of sucrose; the optical rotation changes from (+) to (-).
- BThe sugar mixture obtained from the hydrolysis of starch; -glycosidic bonds are changed to -glycosidic bonds.
- CThe sugar mixture obtained from the hydrolysis of starch; glucose is isomerised to fructose.
- DThe sugar mixture obtained from the hydrolysis of sucrose; fructose is isomerised to glucose.
Correct answer
A. The sugar mixture obtained from the hydrolysis of sucrose; the optical rotation changes from (+) to (-).
Step-by-step solution
Sucrose is dextrorotatory with a specific rotation of +66.5^ . On hydrolysis, sucrose gives an equimolar mixture of D-(+)-glucose (specific rotation +52.5^ ) and D-(-)-fructose (specific rotation -92.4^ ). Since the levorotation of fructose is greater than the dextrorotation of glucose, the resulting mixture is levorotatory. The process involves a change in the sign of optical rotation from dextro (+) to levo (-). This change in optical rotation is known as the inversion of cane sugar, and the resulting mixture of