Organic Chemistry
9th Edition
ISBN: 9781305080485
Author: John E. McMurry
Publisher: Cengage Learning
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Chapter 25.SE, Problem 54AP
Interpretation Introduction
Interpretation:
Gentiobiose is a disaccharide composed of two units of D-glucose joined with a β(1→6) linkage.
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Ribose, a carbohydrate with the formula shown, forms a cyclic hemiacetal, which, in
principle, could contain either a four-membered, five-membered, or six-membered ring.
When D-ribose is treated with methanol in the presence of an acid catalyst, two cyclic
acetals, A and B, are formed, both with molecular formula C,H,0, These are separated,
and each is treated with sodium periodate (Section 10.8C) followed by dilute aqueous
acid. Both A and B yield the same three products in the same ratios.
он о
CHO
СНО
H+ CH,OH A +B
ÕH
1. NalO,
2. H,0*
НО
CHO + CHOH + CH,OH
ÕH
CH,OH
Isomeric cyclic
acetals with molecular
formula CH12O,
D-Ribose
(C;H1605)
From this information, deduce whether the cyclic hemiacetal formed by D-ribose is four-
membered, five-membered, or six-membered.
b) Disaccharide E is a reducing sugar. It is hydrolyzed by an α-glycosidase enzyme, which means it contains an α-
glycoside link. Treatment of E with Ag2O and excess MeDgives an octamethyl derivative F. Hydrolysis of F in
dilute aqueous acid gives the pair of molecules shown below. Write the structures of E and F. (If the
stereochemistry at a particular carbon is not determined by the above data, indicate this with a wavy line as
shown below.)
HO OMe
OMe
MeO
MeO
OH
OMe
Am OH
OMe
OMe
Aldohexoses A and B both undergo Ruff degradation to give aldopentose C. On treatment with warm nitric acid, aldopentose C gives an optically active aldaric acid. B alsoreacts with warm nitric acid to give an optically active aldaric acid, but A reacts to givean optically inactive aldaric acid. Aldopentose C is degraded to aldotetrose D, whichgives optically active tartaric acid when it is treated with nitric acid. Aldotetrose D isdegraded to (+)@glyceraldehyde. Deduce the structures of sugars A, B, C, and D, and useFigure 23-3 to determine the correct names of these sugars.
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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- An aldose A, is reduced by sodium borohydride to an optically inactive alditol B. The Ruff degredation of A forms C. Oxidation of C by nitric acid generates the optically inactive diacid D. The ruff degreation of C forms D-glyceraldehyde. draw the structures for compounds A through D and discuss a mechanism for the reduction step using sodium borohydridearrow_forwardOne step in the gluconeogenesis pathway for the biosynthesis of glucose is the partial reduction of 3-phosphoglycerate to give glyceraldehyde 3-phosphate. The process occurs by phosphorylation with ATP to give 1,3-bisphosphoglycerate, reaction with a thiol group on the enzyme to give an enzyme-bound thioester, and reduction with NADH. -OPO3²- Enz-SH H-C-OH ATP CH₂OPO3²- 3-phosphoglycerate O 0-0--0 O ADP CH₂CH3 substitute for 1,3-bisphosphoglycerate C H-C-OH CH₂OPO3²- 1,3-bisphosphoglycerate O=C CH3-SH substitute for Enz-SH H H-C-OH | CH₂OPO3²- PO4³- O. S-Enz H-C-OH glyceraldehyde 3-phosphate Propose a structure for the first intermediates in the reaction of 1,3-bisphosphoglycerate with a thiol group on the enzyme to form an enzyme-bound thioester. Assume a basic group on the enzyme catalyzes the formation of this intermediate. To simplify the drawing process, substitute the structures below for the 1,3-bisphosphoglycerate and Enz-SH. CH₂OPO3²- (Enzyme-bound thioester) NADH/H* NAD*,…arrow_forward(a) Which of the d-aldopentoses will give optically active aldaric acids on oxidation with HNO3 ?(b) Which of the d-aldotetroses will give optically active aldaric acids on oxidation with HNO3 ?(c) Sugar 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 X.(d) Even though sugar X gives an optically inactive aldaric acid, the pentose formed by degradation gives an opticallyactive aldaric acid. Does this finding contradict the principle that optically inactive reagents cannot form opticallyactive products?(e) Show what product results if the aldopentose formed from degradation of X is further degraded to an aldotetrose.Does HNO3 oxidize this aldotetrose to an optically active aldaric acid?arrow_forward
- b) Disaccharide E is a reducing sugar. It is hydrolyzed by an α-glycosidase enzyme, which means it contains an α- glycoside link. Treatment of E with Ag2O and excess Mel gives an octamethyl derivative F. Hydrolysis of F in dilute aqueous acid gives the pair of molecules shown below. Write the structures of E and F. (If the stereochemistry at a particular carbon is not determined by the above data, indicate this with a wavy line as shown below.) HO OMe OMe Is is MeO MeO MOH OMe mOH OMe OMearrow_forwardGive me a clear handwritten answer with explanationarrow_forwardPropose a mechanism for this conversion and account for the fact that only the -OH on carbon 1 is transformed into an -OCH3 group.arrow_forward
- Identify A, B, C, and D in the preceding problem if D is oxidized to an optically inactive aldaric acid; if A, B, and C are oxidized to optically active aldaric acids; and if interchanging the aldehyde and alcohol groups of A leads to a different sugar.arrow_forwardAtorvastatin (Lipitor) is used to decrease patient serum cholesterol levels. It works by inhibiting an enzyme called HMG-COA reductase. See"Connections to Biological Chemistry" one synthesis of atorvastatin that produces the desired single enantiomer of the final product, the following reagents are used. Draw the structures of synthetic intermedi- ates A and B. In -Cl NaCN НО. A B DMSO Pyridinearrow_forwardKk.322.arrow_forward
- The chiral hydroxyl compound P, C7H14O contains a five-membered ring and showspositive result in iodoform test. Compound P and sodium bromide can be produced byrefluxing compound Q with aqueous NaOH solution. Compound P is heated withbenzoic acid in the presence of concentrated H2SO4 to form a sweet-smelling product,compound R. Deduce the structure of P, Q and R. PLEASE PROVIDE CLEAR HAND WRITING AND SOLUTIONSarrow_forwardA chiral alkyne A with molecular formula C6H10 is reduced with H2 and Lindlar catalyst to B having the R conguration at its stereogenic center. What are the structures of A and B?arrow_forwardDraw the organic products formed when cyclopentene is treated withfollowing reagent. [1] OsO4 + NMO; [2] NaHSO3, H2Oarrow_forward
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