CHEM 3720L Report Sheet – Synthesis of Glucose Pentaacetate – NAME_____________
OAc AcO AcO O H OAc OAc O , ZnCl2 O O HO HO OH O OH OH O O O ,NaOAc AcO AcO OAc O OAc OAc H
D-glucose (mix of α and β-anomers)
1. DataTable: Fill in the appropriate spaces in the data table below. Under the Amount column, use g for solids, mL for liquids. A mmol is 1/1000th of amole. As you performed only one of the two reactions above, use the abbreviation "na" (not applicable) where needed.
Compound D-glucose ZnCl2-Ac2Osolution α-D-glucose pentaacetate acetic anhydride) sodium acetate β-D-glucose pentaacetate FW (g/mol) Amt. used mmol mp (oC) bp (oC) d (g/mL)2. Percent Yield (show calculations on a separate sheet and attach to this page) Percent yield of crude product ___________%
3. Mechanism.Zinc chloride (a Lewis acid) catalyzes the isomerization of β-D-glucose pentaacetate into α-D-glucose pentaacetate. Propose a complete mechanismfor this transformation. Hint: see sections 25.8, 25.13, 25.21 in F. A. Carey, Organic Chemistry, 6th Ed.
OAc AcO AcO O OAc OAc H ZnCl2 AcO AcOOAc O H OAc OAc
4. Question. What is the purpose of sodium acetate in the reactionof D-glucose with acetic anhydride to form β-D-glucose pentaacetate? You may draw partial mechanisms if needed to help explain your answer.
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