Q47 / 180 · KCET 2014 · Chemistry
The statement that is NOT correct is
- ACarbohydrates are optically active,
- BLactose has glycosidic linkage between \( C_{4} \) of glucose and \( C_{1} \) of galactose unit.
- Correct answerCAldose or ketose sugars in alkaline medium do not isomerism.
- DPentaacetate of glucose does not react with hydroxylamine.
Solution
Aldose or ketose sugars in alkaline medium isomerize. For example; on heating with conc. solution of \( \mathrm{NaOH} \) glucose
(aldose) first turns yellow and then brown and finally resinifies with dilute solution of \( \mathrm{NaOH} \) glucose (aldose) undergoes a
reversible isomerization and is converted into a mixture of D-glucose, D-maltose and D-fructose. This reaction is known
as lobry de Bruyn-van Ekenstein rearrangement.
(aldose) first turns yellow and then brown and finally resinifies with dilute solution of \( \mathrm{NaOH} \) glucose (aldose) undergoes a
reversible isomerization and is converted into a mixture of D-glucose, D-maltose and D-fructose. This reaction is known
as lobry de Bruyn-van Ekenstein rearrangement.
Hence, the correct answer is option: 'C'.