(a) Write a detailed mechanism for the isomerization of b-d-fructofuranose fromthe

Chapter 24, Problem 53

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(a) Write a detailed mechanism for the isomerization of b-d-fructofuranose fromthe hydrolysis of sucrose into an equilibrium mixture of the b-pyranose and b-furanose forms.(b) Although fructose usually appears as a furanose when it is part of a polysaccharide, in thepure crystalline form, fructose adopts a b-pyranose structure. Draw b-d-fructopyranose in itsmost stable conformation. In water at 208C, the equilibrium mixture contains about 68% b-dpyranoseand 32% b-d-furanose. (c) What is the free-energy difference between the pyranoseand furanose forms at this temperature? (d) Pure b-d-fructopyranose has [a]d208C 5 2132. Theequilibrium pyranose furanose mixture has [a]d208C 5 292. Calculate [a]d208C for pure b-dfructofuranose.