Concept explainers
Interpretation:
The most stable conformation of the
Concept introduction:
A pyranose is a six-membered ring form of a monosaccharide.
The Haworth formula is a representation of carbohydrate in a cyclic form where the substituents point up or down on the ring.
The Fischer projection is converted to Haworth formula by formation of a six-membered hemiacetal between the
The substituents present on the right side in Fischer projection will be drawn on the lower face in Haworth formula. The substituents present on the left side of the vertical line in Fischer projection will be drawn on the upper face in a Haworth formula.
The substituent (alkyl) at equatorial position in chair form is the most stable conformation.
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ORGANIC CHEMISTRY TEXT PACKAGED - 2 YE
- Given D-Mannose (in its Fischer projection) indicate the steps to draw the Haworth projection of beta-D-Mannopyranose and the most stable chair conformation for this anomer.arrow_forwardShow the structures of the following and give their names: C-2 epimer of D-galactose Beta anomer of alpha D-mannopyranose Alpha anomer of beta-D-lyxofuranose Enantiomer of L-ribulose Diastereomer of D-xylulose C-3 epimer of D-tagatose Illustrate what is asked for: Molecular formula of D-erythrulose Fischer projection formula of L-sorbose Haworth formula of alpha-D-idopyranose Number of stereoisomers formed by D-sorbosearrow_forwardd-Xylose and d-lyxose are formed when d-threose undergoes a Kiliani–Fischer synthesis. d-Xylose is oxidized to an optically inactive aldaric acid,whereas d-lyxose forms an optically active aldaric acid. What are the structures of d-xylose and d-lyxose?arrow_forward
- Which of the following is true for structure II? L-ketose D-ketose D-aldose L-aldosearrow_forwardProvide an explanation for the fact that α-D-mannose is more stable thanβ-D-mannose, whereas the opposite is true for glucose.arrow_forwardWithout referring to the chapter, draw the chair conformations of(a) b-d-mannopyranose (the C2 epimer of glucose).(b) a-d-allopyranose (the C3 epimer of glucose).(c) b-d-galactopyranose (the C4 epimer of glucose)arrow_forward
- An important technique for establishing relative configurations among isomeric aldoses and ketoses is to convert both terminal carbon atoms to the same functional group. This can be done either by selective oxidation or reduction. As a specific example, nitric acid oxidation of d-erythrose gives meso-tartaric acid . Similar oxidation of d-threose gives (2S,3S)-tartaric acid. Given this information and the fact that d-erythrose and d-threose are diastereomers, draw Fischer projections for d-erythrose and d-threose. Check your answers against Table 25.1.arrow_forwardd-Altrose is an aldohexose. Ruff degradation of d-altrose gives the same aldopentose asdoes degradation of d-allose, the C3 epimer of glucose. Give the structure of d-altrosearrow_forwardDraw beta-D-galactopyranose and beta-D-mannopyranose in their chair conformations. Label the axial and equatorial positions.arrow_forward
- The most stable conformation of most aldopyranoses is one in which the largest group, the CH2OH group, is equatorial. However, alpha-D-idopyranose exists primarily in a conformation with an axial CH2OH group. Write formulas for the two chair conformations of a-D-idopyranose (one with the CH2OH group axial and one with the CH2OH group equatorial) and provide an explanationarrow_forwardMannose exists in aqueous solution as a mixture of a-d-mannopyranose and b-d-mannopyranose. Draw Haworth projections for these molecules.arrow_forwardArrange the following sugars according to their DECREASING reactivity with Benedict’s reagent. [fructose, starch, maltose, sucrose, glucose]arrow_forward