Concept explainers
a)
Interpretation:
The configurational stereochemistry of the molecules to be determined.
Answer to Problem 26VC
The Fischer projection follows as
It is D sugar the molecule is a retrose. Elclose or eldotetrose, is 4-carbon elclose.
Explanation of Solution
Concept strategy: The Fischer projection of the given monosaccharide is drawn vertically, by rotating the molecule anticlockwise 90° so that the carbonyl
Review from front side C-3-OH is to the right By convention the molecule has the C-3 hyduxyl at the right. So it is D sugar the molecule is a retrose. Elclose or eldotetrose, is 4-carbon elclose.
Based on the Fischer projection formula for the given sugars it is a B-D-glucopyranose monosaccharide.
b)
Interpretation:
The configurational stereochemistry of the molecules to be determined.
Answer to Problem 26VC
The given model is the cyclic structures of an aldohexose in six membered pyranose form.
Strategy: We redraw the model as
Explanation of Solution
By convention, the terminal -CH2OH group is on the top of the chair Pyranose structure. Thus it is a D sugar. The molecule is an aldohexose is B-D-glucopyranose, all the –OH groups are equatorial (and more stable due to minimum repulsion) conformation.
Based on the Fischer projection formula for the given sugars it is a B-D-glucopyranose monosaccharide.
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Chapter 25 Solutions
ORGANIC CHEMISTRY-EBOOK>I<
- Trehalose, C12H22O11, is a nonreducing sugar that is only 45% as sweet as sugar. When hydrolyzed by aqueous acid or the enzyme maltase, it formsonly d-glucose. When it is treated with excess methyl iodide in the presence of Ag2O and then hydrolyzed with water under acidic conditions, only2,3,4,6-tetra-O-methyl-d-glucose is formed. Draw the structure of trehalose.arrow_forwardThe first step in the metabolism of glycerol, formed by digestion of fats, is phosphorylation of the pro-R—CH2OH group by reaction with adenosine triphosphate (ATP) to give the corresponding glycerol phosphate plus adenosine diphosphate (ADP). Show the stereochemistry of the product.arrow_forwardWhat aldoses are formed when the following aldoses are subjected to the Kiliani–Fischer synthesis: (a) d-threose; (b) d-ribose; (c) D-galactose?arrow_forward
- (d) Draw the structure of the expected product when monosaccharide B undergo mutarotation upon dissolving in water in the presence of Tollens reagent (AGNO3, NHẠOH). он OH O. OH OH OH monosaccharide Barrow_forwardThe anticoagulant heparin is a polysaccharide that contains alternating residues of -D- glucuronic acid-6- sulfate and N-sulfo-D-glucosamine-6sulfate connected by (1 B 4)- glycosidic linkages. Draw a part of heparin that shows one each of the two residues.arrow_forwardDraw the product of the mutarotation of the monosaccharide shown below. ОН CH₂OH ОН ОН H3O+ ОН of вarrow_forward
- An aldohexose (e.g., Glucose) can occur in three forms: two cyclic forms and one open-chain structure in aqueous solution. 5. H-C-OH H (a) н-сто (b) (c) CH₂OH OH ОН aldotriose H H-C=O H-C-OH H-C-OH H-C-OH CH₂OH OH OH OH OH aldopentose Draw the corresponding structures of aldohexoses (c.f., aldotriose and aldopentose). aldohexose Draw the reaction forming two cyclic forms from the open-chain structure How many asymmetric carbon atoms (chiral centers) are there in three forms, respectively?arrow_forwardA D-aldopentose A is reduced to an optically active alditol. Upon Kiliani–Fischer synthesis, A is converted to two D-aldohexoses, B and C. B is oxidized to an optically inactive aldaric acid. C is oxidized to an optically active aldaric acid. What are the structures of A–C?arrow_forwardTreatment with NaBH 4 converts aldose U into an optically inactive (meso) alditol V. Ruff degradation ofU gives W, whose alditol is optically inactive. Ruff degradation of W forms D-glyceraldehyde, thesimplest aldose. Upon Kiliani-Fischer synthesis, U is converted to two aldoses, X and Y. X is oxidized toan optically active aldaric acid Z. Y is oxidized to an optically inactive aldaric acid. Draw the structuresof D-glyceraldehyde, V, W, X, Y, and Z. Structure of compound U is shown below.arrow_forward
- Draw α-l-tagatopyranose :arrow_forwardDraw α-d-tagatopyranose :arrow_forward1. Draw Haworth projections of B-D-arabinofuranose and a-L-mannopyranose. 2. Consider the structure of the disaccharide drawn at right: НО `CH2 В ОН (a) Give the names and D/L designation for the two monosaccharides linked together. H,C-O OHO „OH OH А: НО НО A В: ОН (b) In the structure, circle the anomeric carbon of each saccharide. (c) Is each saccharide present in its a or ß anomer? Specify both A and B (d) Would this disaccharide undergo mutarotation? Why or why not? (e) Would this disaccharide react with Tollens and/or Benedicts reagent? Why or why not? (f) There are two reasons this is very unlikely to be a naturally occurring disaccharide. What about its structure suggests this is true? Give both reasons.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning