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 - Standalone book
- 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.arrow_forwardTreatment 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.arrow_forwardTwo sugars differing in configuration at a single asymmetric carbon atom are known as epimers. D-mannose is a C-2 epimer of glucose (Structure I), while D-galactose is a C-4 epimer of glucose. Structure Il and IIl are H- -OH но- -H H OH HO H но- H HO H H -OH H- -OH HO OH H -OH H- -OH H OH HO. HO, OH II II Which of the following represents an aldopentose? OH H O HO O HO H но н HO H но- HO H HO H HO- H OH H OH H OH H OH OH HO Он of но" HO O OH он III IV These are chemical messengers that are secreted by endocrine glands and carried through the bloodstream to target tissues. prostaglandin deoxysugar glycoside hormones Which of the following is NOT correctly paired? cellulose: beta-1,4-glycosidic linkage amylose: alpha-1,4-glycosidic linkage chitosan: alpha-1,4-glycosidic linkage cellubiose: beta-1,4-glycosidic linkagearrow_forward
- Draw chair conformations for a-d-galactopyranose and b-d-galactopyranose. Label the anomeric carbon in each.arrow_forwardHow many chiral centers are in B-d-glucopyranose and a-D-galactopyranose? How many stereoisomers of these two aldohexoses can theoretically be drawn?arrow_forwardIn the most stable chair conformation of myo-Inositol, how many of the OH groups are axial and how many are equatorial?arrow_forward
- All of the OH groups of the β-pyranose form of d-xylose are equatorial. Which of the following is the β-furanose form of d-xylose?arrow_forward5. Provide suitable responses for questions (a) – (). 6 CH2OH 4 OH OH 3 OH (a) What is the relative configuration of the above monosaccharide? (b) Which labeled carbon is the anomeric carbon? (c) Trace and identify the acetal in the above monosaccharide. (d) Draw the hemiacetal that results from above acetal. (e) Draw the open chain equivalent of the sugar in part (d). (f) Classify the monosaccharide below as a D-sugar or an L-sugar. H. OH O. OH CH,OH OH OHarrow_forward2) a-Draw the proper flat, Haworth form and most stable chair conformation for the B- anomer of L- glucopyranose b- Write the systematic name of this compound O: HO- НО—н НО H FOH HO-H -O- L-Gulosearrow_forward
- Classify below pair of compounds as enantiomers, epimers, diastereomers but not epimers, or constitutional isomers of each other. D-altrose and D-gulosearrow_forwardAll the glucose units in dextran have six-membered rings. When a sample of dextran is treated with methyl iodide and Ag2O and the product ishydrolyzed under acidic conditions, the final products are 2,3,4,6-tetra-O-methyl-d-glucose, 2,4,6-tri-O-methyl-d-glucose, 2,3,4-tri-O-methyl-d-glucose, and 2,4-di-O-methyl-d-glucose. Draw a short segment of dextran.arrow_forwardCH2OH Is this Dor L sorbose? C=0 Is this a ketose or an aldose? H-C-OH 1. Which carbon atoms will cause it to cyclize? но -С -Н Draw the boat conformation of no. 1. H-C-OH Draw the chair conformation of no. 1. CH2OHarrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning