Organic Chemistry
8th Edition
ISBN: 9781305580350
Author: William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote
Publisher: Cengage Learning
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Chapter 25, Problem 25.27P
Interpretation Introduction
Interpretation:
When the four aldopentoses are reduced by
Concept Introduction:
The reagent
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A D-aldopentose A is reduced to an optically active alditol. Upon Kiliani–Fischer synthesis, A is converted to two Daldohexoses, 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?
Which D-aldopentose is oxidized to an optically active aldaric acid and undergoes the Wohl degradation to yield a Daldotetrose that is oxidized to an optically active aldaric acid?
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.
Chapter 25 Solutions
Organic Chemistry
Ch. 25.1 - Prob. 25.1PCh. 25.2 - Prob. 25.2PCh. 25.2 - Prob. 25.3PCh. 25.3 - Prob. 25.4PCh. 25.3 - Prob. 25.5PCh. 25.3 - Prob. AQCh. 25.3 - Prob. BQCh. 25.3 - Prob. CQCh. 25.3 - Prob. DQCh. 25.3 - How many stereoisomers would result from the...
Ch. 25.4 - Prob. 25.6PCh. 25 - Prob. 25.7PCh. 25 - Prob. 25.8PCh. 25 - Prob. 25.9PCh. 25 - Prob. 25.10PCh. 25 - Prob. 25.11PCh. 25 - Prob. 25.12PCh. 25 - Prob. 25.13PCh. 25 - Prob. 25.14PCh. 25 - Prob. 25.15PCh. 25 - Prob. 25.16PCh. 25 - Prob. 25.17PCh. 25 - Prob. 25.18PCh. 25 - Prob. 25.19PCh. 25 - Prob. 25.20PCh. 25 - Prob. 25.21PCh. 25 - Prob. 25.22PCh. 25 - Prob. 25.23PCh. 25 - Prob. 25.24PCh. 25 - Prob. 25.25PCh. 25 - Prob. 25.26PCh. 25 - Prob. 25.27PCh. 25 - Prob. 25.28PCh. 25 - Prob. 25.29PCh. 25 - Prob. 25.30PCh. 25 - Prob. 25.31PCh. 25 - Prob. 25.32PCh. 25 - Prob. 25.33PCh. 25 - Prob. 25.34PCh. 25 - In making candy or sugar syrups, sucrose is boiled...Ch. 25 - Prob. 25.36PCh. 25 - Prob. 25.37PCh. 25 - Prob. 25.38PCh. 25 - Prob. 25.39PCh. 25 - Prob. 25.40PCh. 25 - Prob. 25.41PCh. 25 - Prob. 25.42PCh. 25 - Prob. 25.43PCh. 25 - Digitalis is a preparation made from the dried...Ch. 25 - Prob. 25.45PCh. 25 - Prob. 25.46PCh. 25 - Prob. 25.47PCh. 25 - Prob. 25.48PCh. 25 - Prob. 25.49PCh. 25 - Prob. 25.50P
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- A D-aldohexose A is formed from an aldopentose B by the Kiliani–Fischer synthesis. Reduction of A with NaBH4 forms an optically inactive alditol. Oxidation of B forms an optically active aldaric acid. What are the structures of A and B?arrow_forwardAn unknown reducing disaccharide is found to be unaffected by invertase enzymes. Treatment with an a@galactosidasecleaves the disaccharide to give one molecule of d-fructose and one molecule of d-galactose. When the disaccharideis treated with excess iodomethane and silver oxide and then hydrolyzed in dilute acid, the products are2,3,4,6-tetra-O-methylgalactose and 1,3,4-tri-O-methylfructose. Propose a structure for this disaccharide, and give itscomplete systematic name.arrow_forwardSugar X is known to be a d-aldohexose. On oxidation with HNO3, X gives an optically inactive aldaric acid. WhenX is degraded to an aldopentose, oxidation of the aldopentose gives an optically active aldaric acid. Determine thestructure of Xarrow_forward
- d-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_forwardRegarding the following monosaccharides, indicate the CORRECT alternative: a) Only Gulosa, Idosa and Mannose can produce alditols because they are aldoses. b) There is only one pair of epimers. c) The reaction of Idosa with HNO3 converts it into a product without optical activity. d) Only two monosaccharides will give a positive result with Fehling's reagent. e) Mutarotation converts D-psychose into an aldose.arrow_forwardAldohexoses A and B are formed from aldopentose C via a Kiliani–Fischer synthesis. Nitric acid oxidizes A to an optically active aldaric acid, B to an optically inactive aldaric acid, and C to an optically active aldaric acid. Wohl degradation of C forms D, which is oxidized by nitric acid to an optically active aldaric acid. Wohl degradation of D forms (+)-glyceraldehyde. Identify A, B, C, and D.arrow_forward
- There are four d-aldopentoses (Table 25.1). If each is reduced with NaBH4, which yield optically active alditols? Which yield optically inactive alditols?arrow_forwardDraw the structure of alpha-d-glucopyranose in straight chain cyclic, Haworth and cyclohexane-chair format. Draw the structures of two aldohexoses which are diastereomers but not epimersarrow_forwarda) Draw Haworth projections of both - and -anomers of D-fructose. Indicate which carbon is the anomeric carbon.b) Sucrose is a disaccharide made up of a molecule of D-fructose and D-glucose. Draw the structure of sucrose clearly indicating the linkage between the two monosaccharides and its biological significance.c) Tollen’s reagent is a very mild oxidizing agent which normally oxidize aldehydes but not ketones. However, both glucose and fructose give positive results with Tollen’s reagent and are classified as reducing sugars. Explain how fructose can also give positive results with Tollen’s reagent (illustrate using structures).arrow_forward
- There are three (3) vials labeled A, B, and C known to contain the following monosaccharides. All three samples reduce Tollens and Fehling. By oxidation with dilute HNO3 an optically active aldaric acid is obtained for sample A and the remaining two give products without optical activity. When the three samples were subjected to an alkaline medium, it was observed that, after a certain time, samples A and C reached the same value of the specific rotation [α]. Select the RIGHT alternative: (a) Sample A is Galactose. (b) Sample B is Alosa. (c) Samples A and C are not related to each other by an epimerization process. (d) Sample C is Talose. (e) Samples B and C are epimers.arrow_forwardHow many stereoisomers are possible for an aldopentose?arrow_forwardDraw the structures of the individual mutarotating a and b anomers of maltose.arrow_forward
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