Organic Chemistry
9th Edition
ISBN: 9781305080485
Author: John E. McMurry
Publisher: Cengage Learning
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Chapter 25.SE, Problem 55AP
Interpretation Introduction
Interpretation:
To draw the pyranose form of α-D-galactopyranose, β-D-galactopyranose.
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The C2-epimer of D-xylose is called (blank 1). The enediol rearrangementconverts an aldose into a (blank 2). The aldopentose embedded in RNA is(blank 3). An aldopentose would have (blank 4) possible stereoisomers,of whichBlankwould be D-sugars. An ketopentose would have (blank 4) possiblestereoisomers, of which (blank 5) would be D-sugars
D-Xylose in aqueous solution exists in the pyranose form as a mixture of α and β anomers. Furanose and acyclic forms are present in negligible amounts and can be ignored.
A sample of pure α-D-xylopyranose is dissolved in pure neutral water. The optical rotation is then measured immediately using a polarimeter. The specific rotation [??]?? is +93.6°.
The optical rotation is then observed to decrease with the passage of time, and the solution is allowed to reach equilibrium. Eventually the specific rotation stabilises at [??]?? = +18.8°. The anomeric ratio at equilibrium a : β is 37 : 63. A sample of pure β-D-xylopyranose is not available.
Using this information, predict the specific rotation of pure β-D-xylopyranose. Show how the a and β anomers equilibrate using a mechanism, assuming the presence of a trace amount of base as catalyst.
Like glucose, galactose mutarotates when it dissolves in water. The specific rotation ofa-d-galactopyranose is +150.7°, and that of the b anomer is +52.8°. When either ofthe pure anomers dissolves in water, the specific rotation gradually changes to +80.2°.Determine the percentages of the two anomers present at equilibrium.
Chapter 25 Solutions
Organic Chemistry
Ch. 25.1 - Prob. 1PCh. 25.2 - Prob. 2PCh. 25.2 - Prob. 3PCh. 25.2 - Prob. 4PCh. 25.2 - Prob. 5PCh. 25.3 - Prob. 6PCh. 25.3 - Prob. 7PCh. 25.4 - Prob. 8PCh. 25.4 - Prob. 9PCh. 25.4 - Prob. 10P
Ch. 25.5 - Prob. 11PCh. 25.5 - Prob. 12PCh. 25.5 - Prob. 13PCh. 25.5 - Prob. 14PCh. 25.5 - Prob. 15PCh. 25.6 - Prob. 16PCh. 25.6 - Prob. 17PCh. 25.6 - Prob. 18PCh. 25.6 - Prob. 19PCh. 25.6 - Prob. 20PCh. 25.6 - Prob. 21PCh. 25.6 - Prob. 22PCh. 25.6 - Prob. 23PCh. 25.7 - Prob. 24PCh. 25.8 - Show the product you would obtain from the...Ch. 25.SE - Prob. 26VCCh. 25.SE - Prob. 27VCCh. 25.SE - Prob. 28VCCh. 25.SE - Prob. 29VCCh. 25.SE - Prob. 30MPCh. 25.SE - Prob. 31MPCh. 25.SE - Glucosamine, one of the eight essential...Ch. 25.SE - D-Glicose reacts with acetone in the presence of...Ch. 25.SE - Prob. 34MPCh. 25.SE - Prob. 35MPCh. 25.SE - Prob. 36APCh. 25.SE - Prob. 37APCh. 25.SE - Prob. 38APCh. 25.SE - Prob. 39APCh. 25.SE - Prob. 40APCh. 25.SE - Assign R or S configuration to each chirality...Ch. 25.SE - Prob. 42APCh. 25.SE - Prob. 43APCh. 25.SE - Prob. 44APCh. 25.SE - Prob. 45APCh. 25.SE - Prob. 46APCh. 25.SE - Prob. 47APCh. 25.SE - Prob. 48APCh. 25.SE - Prob. 49APCh. 25.SE - Prob. 50APCh. 25.SE - Prob. 51APCh. 25.SE - Prob. 52APCh. 25.SE - Prob. 53APCh. 25.SE - Prob. 54APCh. 25.SE - Prob. 55APCh. 25.SE - Prob. 56APCh. 25.SE - Prob. 57APCh. 25.SE - Prob. 58APCh. 25.SE - Prob. 59APCh. 25.SE - Prob. 60APCh. 25.SE - Prob. 61APCh. 25.SE - Prob. 62APCh. 25.SE - Prob. 63APCh. 25.SE - D-Mannose reacts with acetone to give a...Ch. 25.SE - Prob. 65APCh. 25.SE - Prob. 66APCh. 25.SE - Prob. 67APCh. 25.SE - Prob. 68APCh. 25.SE - Prob. 69APCh. 25.SE - Prob. 70APCh. 25.SE - Prob. 71AP
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