Sucrose in water is dextrorotatory, []D = + 66.4° when boiled with dil. HCl, the solution becomes laevo-rotatory, []D = – 39.9°. In this process the sucrose breaks into

The aqueous solution of sucrose is dextrorotatory having [α]D = + 66.4o. On hydrolysis with dilute acids or enzyme invertase, cane sugar (sucrose) gives equimolar mixture of D-(+)-glucose and D-(-)- fructose. So, sucrose is dextrorotatory but after hydrolysis gives dextrorotatory glucose and laevorotatory fructose. D-(-)-fructose has a greater specific i than D-(+)-glucose. Therefore, the resultant solution is laevorotatory in nature with specific rotation of -39.9o. 12 22 11 6 12 6 6 12 6 HCl 2 o o o D D D C H O C H O C H O cane sugar H O D-glucose + D-fructose [α] =66.4 [α] =+52.5 [α] =-92.4