Refer to the structures shown below. Which of the following is/are true? (Marks will be deducted for incorrect responses). CHO H- H H- H -OH -OH -OH -OH CH₂OH HO HO- HO HO- CHO -H H -H -H CH₂OH 1) They are both hexoses 2) They are enantiomers. The structure on the left is D sugar whereas the one on the right is an L 3) sugar. 4) They are epimers of each other.

Refer to the structures shown below. Which of the following is/are true? (Marks will be deducted for incorrect responses). CHO H- H H- H -OH -OH -OH -OH CH₂OH HO HO- HO HO- CHO -H H -H -H CH₂OH 1) They are both hexoses 2) They are enantiomers. The structure on the left is D sugar whereas the one on the right is an L 3) sugar. 4) They are epimers of each other.

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter25: Biomolecules: Carbohydrates

Section25.SE: Something Extra

Problem 44AP

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D-glucose and L-glucose would be expected to show differences in which of the followingp roperties? (Answer the items as dif erent or not different) a. Solubility in an achiral solvent b. Density c. Melting point d. Solubility in a chiral solvent e. Freezing point f. Reaction with ethanol (achiral compound) g. Reaction with (+)-lactic acid (chiral compound)
A) Draw the structure of any aldohexose in the pyranose ring form. B) Draw the structure of the anomer of the aldohexose you drew above. C) How many asymmetric carbons (chiral centers) does each of these structures have? D) How many stereoisomers of the aldohexoses you drew are theoretically possible?
When a pyranose is in the chair conformation in which the CH2OH group and the C-1 OH group are both in axial positions, the two groups can react to form an acetal. This is called the anhydro form of the sugar (it has “lost water”). The anhydro form of D-idose is shown here. Explain why about 80% of d-idose exists in the anhydro form in an aqueous solution at 100 °C, but only about 0.1% of D-glucose exists in the anhydro form under the same conditions.
How many chiral centers are in B-d-glucopyranose and a-D-galactopyranose? How many stereoisomers of these two aldohexoses can theoretically be drawn?
When a pyranose is in the chair conformation in which the CH2OH group and the C-1 OH group are both in axial positions, the two groups can react toform an acetal. This is called the anhydro form of the sugar (it has “lost water”). The anhydro form of d-idose is shown here. Explain why about 80% of d-idose exists in the anhydro form in an aqueous solution at 100 °C, but only about 0.1% of d-glucose exists in the anhydro form under the same conditions.
Treatment of -D-glucose with methanol in the presence of an acid catalyst converts it into a mixture of two compounds called methyl glucosides (Section 25.3A). In these representations, the six-membered rings are drawn as planar hexagons. (a) Propose a mechanism for this conversion and account for the fact that only the OH on carbon 1 is transformed into an OCH3 group. (b) Draw the more stable chair conformation for each product. (c) Which of the two products has the chair conformation of greater stability? Explain.
a. Pick one of the sugars above you did not find a mirror image for; draw an arrow pointing to that sugar. Next, below this question draw that sugar in the cyclized ring form as a β-pyranose ring b. Show the β(13) linkage between two of the same ring you drew.
The structure of 4 isomers of an aldotetrose carbohydrate are given. 1) select every structure that is a diastereomer of structure D A, B, or C? 2) select every structure that is a enantiomer of structure C D, B, or A? 3) select every structure that is a stereoisomer of structure D A, B, or C
Indicate whether each of the following structures is an enantiomer of, a diastereomer of, or is identical to the structure above.
Without 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)
Without referring to the chapter, draw the chair conformations of(a) b-d-mannopyranose (the C2 epimer of glucose).
Click on all glycosidic bonds in the structure below.