4-Hydroxy- and 5-hydroxyaldehydes exist primarily as

What product or products are obtained when d-galactose reacts with each of the following substances? a. nitric acid + \(\Delta\) b. \(\mathrm{Ag}^{+},\ \mathrm{NH}_{3},\ \mathrm{HO}^{-}\) c. \(\mathrm{NaBH}_{4}\), followed by \(\mathrm{H}_{3} \mathrm{O}^{+}\) d. excess \(\mathrm{CH}_{3} \mathrm{I}+\mathrm{Ag}_{2} \mathrm{O}\) e. \(\mathrm{Br}_{2}\) in water f. ethanol + HCl g. 1. hydroxylamine/trace acid 2. acetic anhydride/\(\Delta\) 3. \(\mathrm{HO}^{-} / \mathrm{H}_{2} \mathrm{O}\)

Name the epimers of d -glucose.

Identify the sugar in each description. a. An aldopentose that is not d -arabinose forms d -arabinitol when it is reduced with NaBH 4 . b. A sugar that is not d -altrose forms d -altraric acid when it is oxidized with nitric acid. c. A ketose that, when reduced with NaBH 4 , forms d -altritol and d -allitol

d -Xylose and d -lyxose are formed when d -threose undergoes a KilianiFischer 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?

. Answer the following questions about the eight aldopentoses. a. Which are enantiomers? b. Which are C-2 epimers? c. Which form an optically active compound when oxidized with nitric acid?

What is the coni guration of each of the asymmetric centers in the Fischer projection of a. d -glucose? b. d -galactose? c. d -ribose? d. d -xylose? e. d -sorbose?

The reaction of d -ribose with one equivalent of methanol plus HCl forms four products. Draw the products

Name the following compounds:

A student isolated a monosaccharide and determined that it had a molecular weight of 150. Much to his surprise, he found that it was not optically active. What is the structure of the monosaccharide?

Propose a mechanism for the formation of d -allose from d -glucose in a basic solution.

Treatment with sodium borohydride converts aldose A into an optically inactive alditol. Wohl degradation of A forms B, whose alditol is optically inactive. Wohl degradation of B forms d -glyceraldehyde. Identify A and B.

Treatment with sodium borohydride converts aldose A into an optically inactive alditol. Wohl degradation of A forms B, whose alditol is optically inactive. Wohl degradation of B forms d -glyceraldehyde. Identify A and B.

Draw the mechanism for the interconversion of a - d -glucose and b - d -glucose in dilute HCl.

An unknown b -d-aldohexose has only one axial substituent. A Wohl degradation forms a compound which, when treated with sodium borohydride, forms an optically active alditol. This information allows you to arrive at two possible structures for the b -d-aldohexose. What experiment can you carry out to distinguish between the two possibilities?

The 1 H NMR spectrum of d -glucose in D 2 O exhibits two high-frequency doublets. What is responsible for these doublets?

d -Glucuronic acid is found widely in plants and animals. One of its functions is to detoxify poisonous HO-containing compounds by reacting with them in the liver to form glucuronides. Glucuronides are water soluble and therefore readily excreted. After ingestion of a poison such as turpentine or phenol, the glucuronides of these compounds are found in the urine. Draw the structure of the glucuronide formed by the reaction of b - d -glucuronic acid and pheno

Determine the structure of d -galactose, using arguments similar to those used by Fischer to prove the structure of d -glucose.

A d -aldopentose is oxidized by nitric acid to an optically active aldaric acid. A Wohl degradation of the aldopentose leads to a monosaccharide that is oxidized by nitric acid to an optically inactive aldaric acid. Identify the d -aldopentose.

Draw the mechanism for the formation of b -maltose from a - d -galactose and b - d -glucose in dilute HCl.

Hyaluronic acid, a component of connective tissue, is the l uid that lubricates the joints. It is a polymer of alternating N -acetyld -glucosamine and d -glucuronic acid subunits joined by b@1,3 -glycosidic linkages. Draw a short segment of hyaluronic acid.

In order to synthesize d -galactose, a student went to the stockroom to get some d -lyxose to use as a starting material. She found that the labels had fallen off the bottles containing d -lyxose and d -xylose. How could she determine which bottle contains d -lyxose?

The aldonic acid of d -glucose forms a i ve-membered ring lactone. Draw its structure.

The aldaric acid of d -glucose forms two i ve-membered ring lactones. Draw their structures.

Draw the mechanism for the acid-catalyzed hydrolysis of b -maltose.

How many aldaric acids are obtained from the 16 aldohexoses?

A hexose is obtained when the residue of a shrub Sterculia setigeria undergoes acid-catalyzed hydrolysis. Identify the hexose from the following experimental information: it undergoes mutarotation; it does not react with Br 2 ; and d -galactonic acid and d -talonic acid are formed when it reacts with Tollens reagent.

A hexose is obtained when the residue of a shrub Sterculia setigeria undergoes acid-catalyzed hydrolysis. Identify the hexose from the following experimental information: it undergoes mutarotation; it does not react with Br 2 ; and d -galactonic acid and d -talonic acid are formed when it reacts with Tollens reagent.

Draw each of the following compounds: a. b - d -talopyranose b. a - d -idopyranose c. a - d -tagatopyranose d. b - d -psicofuranose e. b - l -talopyranose f. a - l -tagatopyranose

Calculate the percentages of a - d -glucose and b - d -glucose present at equilibrium from the specii c rotations of a - d -glucose, b - d -glucose, and the equilibrium mixture. Compare your values with those given in Section 21.10 . ( Hint: The specii c rotation of the mixture equals the specii c rotation of a - d -glucose times the fraction of glucose present in the a -form plus the specii c rotation of b - d -glucose times the fraction of glucose present in the b -form.)

The specii c rotation of a - d -galactose is 150.7 and that of b - d -galactose is 52.8. When an aqueous mixture that was initially 70% a - d -galactose and 30% b - d -galactose reaches equilibrium, the specii c rotation is 80.2. What is the concentration of the anomers at equilibrium?

An unknown disaccharide gives a positive Tollens test. A glycosidase hydrolyzes it to d -galactose and d -mannose. When the disaccharide is treated with methyl iodide and Ag 2 O and then hydrolyzed with dilute HCl, the products are 2,3,4,6-tetra- O -methylgalactose and 2,3,4-tri- O -methylmannose. Propose a structure for the disaccharide.

Predict whether d -altrose exists preferentially as a pyranose or a furanose. ( Hint: In the most stable arrangement for a i ve-membered ring, all the adjacent substituents are trans.)

Trehalose, C 12 H 22 O 11 , is a nonreducing sugar that is only 45% as sweet as sugar. When hydrolyzed by aqueous acid or the enzyme maltase, it forms only d -glucose. When it is treated with excess methyl iodide in the presence of Ag 2 O and then hydrolyzed with water under acidic conditions, only 2,3,4,6-tetra- O -methyl- d -glucose is formed. Draw the structure of trehalose.

Propose a mechanism for the rearrangement that converts an a -hydroxyimine into an a -aminoketone in the presence of a trace amount of acid (page 1027) .

All the glucose units in dextran have six-membered rings. When a sample of dextran is treated with methyl iodide and Ag 2 O and the product is hydrolyzed under acidic conditions, the i nal 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.

When a pyranose is in the chair conformation in which the CH 2 OH group and the C-1 OH group are both in axial positions, the two groups can react to form 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.

Classify the following monosaccharides:

Problem 2P Draw Fischer projections of L-glucose and L-fructose.

Indicate whether each of the following structures is ?-glyceraldehyde or ?-glyceraldehyde, assuming that the horizontal bonds point toward you and the vertical bonds point away from you (Section 4.6)

a. Are D-erythrose and L-erythrose enantiomers or diastereomers? b. Are L-erythrose and L-threose enantiomers or diastereomers?

Problem 5P a. What sugar is the C-3 epimer of D-xylose? b. What sugar is the C-5 epimer of D-allose? c. What sugar is the C-4 epimer of L-gulose? d. What sugar is the C-4 epimer of D-lyxose?

Problem 6P What are the systematic names of the following compounds? Indicate the configuration (R or S)of each asymmetric center. a. D-glucose b. D-mannose c. D-galactose d. L-glucose

Problem 7P What sugar is the C-3 epimer of D-fructose?

Problem 8P How many stereoisomers are possible for a. a ketoheptose? b. an aldoheptose? c. a ketotriose?

Problem 9P Show how an enediol rearrangement can move the carbonyl carbon of fructose fromC-2 to C-3.

Problem 10P Write the mechanism for the base-catalyzed conversion of D-fructose into D-glucose and D-mannose.

Problem 11P When D-tagatose is added to a basic aqueous solution, an equilibrium mixture of monosaccharides is obtained, two of which are aldohexoses and two of which are ketohexoses. Identify the aldohexoses and ketohexoses.

Problem 12P What products are obtained from the reduction of a. D-idose? ________________ b. D-sorbose?

Problem 13P a. What other monosaccharide is reduced only to the alditol obtained from the reduction of 1. D-talose? 2. D-glucose? 3. D-galactose? b. What monosaccharide is reduced to two alditols, one of which is the alditol obtained from the reduction of 1. D-talose? 2. D-allose?

Problem 14P a. Name an aldohexose other than D-glucose that is oxidized to D-glucaric acid by nitric acid. ________________ b. What is another name for D-glucaric acid? ________________ c. Name another pair of aldohexoses that are oxidized to identical aldaric acids.

Problem 15P What monosaccharides would be formed in a Kiliani-Fischer synthesis starting with each of these compounds? a. D-xylose b. L-threose

Problem 16P What two monosaccharides can be degraded to a. D-ribose? b. D-arabinose? c. L-ribose?

Problem 18P Identify A, B, C, and D in the preceding problem if D is oxidized to an optically inactive aldaricacid; if A, B, and C are oxidized to optically active aldaric acids; and if interchanging thealdehyde and alcohol groups of A leads to a different sugar.

Problem 19P 4-Hydroxy- and 5-hydroxyaldehydes exist primarily as cyclic hemiacetals. Draw the structure of the cyclic hemiacetal formed by each of the following: a. 4-hydroxybutanal b. 4-hydroxypentanal c. 5-hydroxypentanal d. 4-hydroxyheptanal

Problem 20P Draw the following sugars using Haworth projections: a. ?-D-galactopyranose b. ?-D-tagatopyranose c. ?-L-glucopyranose

Problem 21P D-Glucose most often exists as a pyranose, but it can also exist as a furanose. Draw the Haworth projection of ?-D-glucofuranose.

Problem 22P Draw the anomers of D-erythrofuranose.

Problem 23P Which OH groups are in the axial position in a. ?-D-mannopyranose? ________________ b. ?-D-idopyranose? ________________ c. ?-D-aliopyranose?

Problem 24P Draw the products formed when ?-D-galactose reacts with ethanol and HCl.

Problem 25P Why is only a trace amount of acid used in the formation of an N-glycoside?

Name the following compounds and indicate whether each is a reducing sugar or a nonreducing sugar: Solution to \(26a\) The only OH group in an axial position in part a is the one at \(C-3\). Therefore, this sugar is the \(C-3\) epimer of ?- glucose, which is ?- allose. The substituent at the anomeric carbon is in the \(\beta\)-position. Thus, the sugar’s name is propyl \(\beta\)-?- alloside or propyl \(\beta\)-?-allopyranoside. Because the sugar is an acetal, it is a nonreducing sugar. Equation Transcription: Text Transcription: 26a C-3 beta

Problem 27P What is the specific rotation of an equilibrium mixture of fructose? (Hint : The specific rotation of an equilibrium mixture of glucose is +52.7.)

Problem 28P What is the main structural difference between a. amylose and cellulose? ________________ b. amylose and amylopectin? ________________ c. amylopectin and glycogen? ________________ d. cellulose and chitin?

Problem 29P Explain why the C-3 OH group of vitamin C is more acidic than the C-2 OH group.

Refer to Figure \(21.5\) to answer the following questions: a. People with type O blood can donate blood to anyone, but they cannot receive blood from everyone. From whom can they not receive blood? b. People with type AB blood can receive blood from anyone, but they cannot give blood to everyone. To whom can they not give blood? Equation Transcription: Text Transcription: 21.5

What product or products are obtained when d -galactose reacts with each of the following substances? a. nitric acid + \(\Delta\) d. excess \(\mathrm{CH}_{3} \mathrm{I}+\mathrm{Ag}_{2} \mathrm{O}\) g. 1. hydroxylamine/trace acid b. \(\mathrm{Ag}^{+}, \mathrm{NH}_{3}, \mathrm{HO}\) e. \(\mathrm{Br}_{2}\) in water 2. acetic anhydride/\(\Delta\) c. \(\mathrm{NaBH}_{4}\), followed by \(\mathrm{H}_{3} \mathrm{O}^{+}\) f. ethanol + HCl 3. \(\mathrm{HO}^{-} / \mathrm{H}_{2} \mathrm{O}\) Equation Transcription: Ag+, NH3, HO NaBH4 H3O+ CH3I + Ag2O Br2 HO/H2O Text Transcription: Delta Ag^+, NH_3, HO NaBH_4 H_3O^+ CH_3 I+Ag_2 O Br_2 HO^-/H_2O

Problem 32P Name the epimers of D-glucose.

Problem 33P Identify the sugar in each description. a. An aldopentose that is not D-arabinose forms D-arabinitol when it is reduced with NaBH4. b. A sugar that is not D-altrose forms D-altraric acid when it is oxidized with nitric acid. c. A ketose that, when reduced with NaBH4, forms D-altritol and D-allitol.

Problem 34P 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?

Problem 35P Answer the following questions about the eight aldopentoses. a. Which are enantiomers? b. Which are C-2 epimers? c. Which form an optically active compound when oxidized with nitric acid?

Problem 36P What is the configuration of each of the asymmetric centers in the Fischer projection of a. D-glucose? b. D-galactose? c. D-ribose? d. D-xylose? e. D-sorbose?

The reaction of D-ribose with one equivalent of methanol plus HCl forms four products. Draw the products.

Name the following compounds:

Problem 39P A student isolated a monosaccharide and determined that it had a molecular weight of 150. Much to his surprise, he found that it wasnot optically active. What is the structure of the monosaccharide?

Problem 40P Propose a mechanism for the formation of D-allose from D-glucose in a basic solution.

Problem 41P Treatment with sodium borohydride converts aldose A into an optically inactive alditol. Wohl degradation of A forms B, whose alditolis optically inactive. Wohl degradation of B forms D-glyceraldehyde. Identify A and B.

Problem 42P A hexose was obtained after (+)-glyceraldehyde underwent three successive Kiliani–Fischer synthesis. Identify the hexose from the following experimental information: oxidation with nitric acid forms an optically active aldaric acid; a Wohl degradation followed by oxidation with nitric acid forms an optically inactive aldaric acid; and a second Wohl degradation forms erythrose.

Draw the mechanism for the interconversion of \(\alpha\)-D-glucose and \(\beta\)-D-glucose in dilute HCl.

Problem 44P An unknown ?-D-aldohexose has only one axial substituent. A Wohl degradation forms a compound which, when treated with sodium borohydride, forms an optically active alditol. This information allows you to arrive at two possible structures for the ?-D-aldohexose.What experiment can you carry out to distinguish between the two possibilities?

Problem 45P The 1H NMR spectrum of d -glucose in D2O exhibits two high-frequency doublets. What is responsible for these doublets?

?-Glucuronic acid is found widely in plants and animals. One of its functions is to detoxify poisonous HO-containing compounds by reacting with them in the liver to form glucuronides. Glucuronides are water soluble and therefore readily excreted. After ingestion of a poison such as turpentine or phenol, the glucuronides of these compounds are found in the urine. Draw the structure of the glucuronide formed by the reaction of \(\beta\)-?-glucuronic acid and phenol. Equation Transcription: Text Transcription: beta

Problem 47P Determine the structure of D-galactose, using arguments similar to those used by Fischer to prove the structure of D-glucose.

A D-aldopentose is oxidized by nitric acid to an optically active aldaric acid. A Wohl degradation of the aldopentose leads to a monosaccharide that is oxidized by nitric acid to an optically inactive aldaric acid. Identify the D-aldopentose.

Problem 50P Hyaluronic acid, a component of connective tissue, is the fluid that lubricates the joints. It is an alternating polymer of N-acetyl-D- glucosamine and D-glucuronic acid joined by ?-1,3?-glycosidic linkages. Draw a short segment of hyaluronic acid.

Problem 49P Draw the mechanism for the formation of ?-lactose from ?-D-galactose and ?-D-glucose in dilute HCl.

Problem 51P In order to synthesize D-galactose, a student went to the stockroom to get some D-lyxose to use as a starting material. She found that the labels had fallen off the bottles containing D-lyxose and D-xylose. How could she determine which bottle contains D-lyxose?

Problem 52P The aldonic acid of D-glucose forms a fi ve-membered ring lactone. Draw its structure.

Problem 53P The aldaric acid of D-glucose forms two five-membered ring lactones. Draw their structures.

Problem 54P Draw the mechanism for the acid-catalyzed hydrolysis of ?-maltose.

Problem 55P How many aldaric acids are obtained from the 16 aldohexoses?

Problem 56P A hexose is obtained when the residue of a shrub Sterculia setigeria undergoes acid-catalyzed hydrolysis. Identify the hexose from thefollowing experimental information: it undergoes mutarotation; it does not react with Br2; and D-galactonic acid and D-talonic acid areformed when it reacts with Tollens reagent.

Problem 57P When D-fructose is dissolved in D2O and the solution is made basic, the D-fructose recovered from the solution has an average of1.7 deuterium atoms attached to the C-1 carbon per molecule. Show the mechanism that accounts for the incorporation of these deuterium atoms into D-fructose.

Problem 58P Draw each of the following compounds: a. ?-D-talopyranose b. ?-D-idopyranose c. ?-D-tagatopyranose d. ?-D-psicofuranose e. ?-L-talopyranose f. ?-L-tagatopyranose

Problem 59P Calculate the percentages of ?-D-glucose and ?-D-glucose present at equilibrium from the specific rotations of ?-D-glucose, ?-D-glucose, and the equilibrium mixture. Compare your values with those given in Section 15.9. (Hint: The specific rotation of the mixture equals the specific rotation of ?-D-glucose times the fraction of glucose present in the ?-form plus the specific rotation of ?-D-glucose times the fraction of glucose present in the ?-form.)

Problem 60P The specific rotation of ?-D-galactose is 150.7° and that of ?-D-galactose is 52.8°. When an aqueous mixture that was initially 70%?-D-galactose and 30% ?-D-galactose reaches equilibrium, the specific rotation is 80.2°. What is the percentage of ?-D-galactose and?-D galactose at equilibrium?

Problem 61P An unknown disaccharide gives a positive Tollens test. A glycosidase hydrolyzes it to D-galactose and D-mannose. When the disaccharide is treated with methyl iodide and Ag2O and then hydrolyzed with dilute HCl, the products are 2,3,4,6-tetra-O-methylgalactoseand 2,3,4-tri-O-methylmannose. Propose a structure for the disaccharide.

Problem 62P Predict whether D-altrose exists preferentially as a pyranose or a furanose. (Hint: The most stable arrangement for a five-membered ring is for all the adjacent substituents to be trans.)

Problem 63P Trehalose, C12H22O11, is a nonreducing sugar that is only 45% as sweet as sugar. When hydrolyzed by aqueous acid or the enzymemaltase, it forms only D-glucose. When it is treated with excess methyl iodide in the presence of Ag2O and then hydrolyzed with water under acidic conditions, only 2,3,4,6-tetra-O-methyl- d -glucose is formed. Draw the structure of trehalose.

Propose a mechanism for the rearrangement that converts an \(cx\)-hydroxyimine into an \(cx\)-aminoketone in the presence of a trace amount of acid (page \(1027\)) Equation Transcription: Text Transcription: Cx 1027

When a pyranose is in the chair conformation in which the \(\mathrm{CH}_{2} \mathrm{OH}\) group and the \(C-1\) OH group are both in axial positions, the two groups can react to form an acetal. This is called the anhydro form of the sugar (it has “lost water”). The anhydro form of ?-idose is shown here. Explain why about 80% of ?-idose exists in the anhydro form in an aqueous solution at 100 C , but only about 0.1% of ?-glucose exists in the anhydro form under the same conditions. Equation Transcription: CH2OH Text Transcription: CH_2OH C-1

Problem 65P All the glucose units in dextran have six-membered rings. When a sample of dextran is treated with methyl iodide and Ag2O and the product is hydrolyzed 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.