Glucose: open chain ⇌ α- and β-cyclic (pyranose) formsग्लूकोस: खुली श्रृंखला ⇌ α- और β-चक्रीय (पाइरैनोस) रूपGlucose: open chain ⇌ α- and β-cyclic (pyranose) forms

Class 12 Chemistry · Chapter 10 · interactive diagram

Parts and what they mean

• α-D-(+)-Glucopyranose (α-D-(+)-ग्लूकोपाइरैनोस) — Ring O from C-5 bridges to C-1. Anomeric –OH on the same side as the ring O (right) → α. Crystallises from a concentrated solution at 303 K; m.p. 419 K.
• β-D-(+)-Glucopyranose (β-D-(+)-ग्लूकोपाइरैनोस) — Anomeric –OH on the left, opposite to the ring O → β. Crystallises from a hot saturated solution at 371 K; m.p. 423 K.
• C-1 of α: H left, OH right (α का C-1: H बाएँ, OH दाएँ) — C-1 is now an asymmetric carbon (the anomeric carbon), so two configurations are possible.
• C-1 of β: HO left, H right (β का C-1: HO बाएँ, H दाएँ) — Differs from α only here — α and β are anomers, not mirror images.
• Open-chain D-glucose (structure I) (खुली श्रृंखला D-ग्लूकोस (संरचना I)) — The three forms are in equilibrium in solution. Only a very small amount of free –CHO form is present at any time.
• Ring closure (वलय बनना) — The –OH at C-5 adds across the C=O of C-1, giving a cyclic hemiacetal. This explains no Schiff’s test, no NaHSO₃ adduct, no reaction of the pentaacetate with NH₂OH, and the two crystalline forms.

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake