Sucrose ([alpha]=+66.5 deg) is hydrolysed completely to a mixture of glucose and fructose. Take [alpha] of D-glucose as +52.7 deg and of D-fructose as -92.4 deg. The specific rotation of the equimolar (and, since both are C6H12O6, equal-mass) product mixture is

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Sucrose ( $[α] = + 66. 5^{\circ}$ ) is hydrolysed completely to a mixture of glucose and fructose. Take $[α]$ of D-glucose as $+ 52. 7^{\circ}$ and of D-fructose as $- 92. 4^{\circ}$ . The specific rotation of the equimolar (and, since both are $C X_{6} H X_{12} O X_{6}$ , equal-mass) product mixture is

A-19.85 $^{\circ}$
B+19.85 $^{\circ}$
C $- 39.7 0^{\circ}$
D $+ 66. 5^{\circ}$

Answer: A

Hydrolysis gives equal moles and equal masses of glucose and fructose, so the specific rotation is the simple mean: (52.7 - 92.4)/2 = -19.85. The sign changes from + to -, which is called inversion.

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Sucrose ([α]=+66.5∘) is hydrolysed completely to a mixture of glucose and fructose. Take [α] of D-glucose as +52.7∘ and of D-fructose as −92.4∘. The specific rotation of the equimolar (and, since both are CX6​HX12​OX6​, equal-mass) product mixture is

Answer: A

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