Concept explainers
Interpretation:
The structure of the anhydrous sugar (
Concept introduction:
舧 Chair conformations: It is the most stable conformation, which accurately shows the spatial arrangement of atoms.
舧 Equatorial bonds are parallel to the average plane of the ring, while axial bonds are perpendicular to the average plane of the ring.
舧 The conformation having bonds at the equatorial positions are more stable than those with bonds at the axial position.
舧 On flipping the cyclohexane ring, axial bonds become equatorial bonds and equatorial bonds becomes axial bond.
舧 Bulkier group acquires equatorial positions to form stable conformer due to steric factors.
舧 Sugars that have moisture content below 0.5% are said to be anhydrous sugars. They are usually high purity crystalline sugars obtained from
舧 Altrose is an aldohexose sugar with the chemical formula
舧 The most stable configuration of aldopyranoses is when the
舧 Stereochemistry: The equatorial orientation refers to the spatial arrangement of
舧 The anomeric effect is lowest for sugars with equatorial orientation, which results in lower energetic state, and consequently this type of orientation confers higher stability.
舧 The anomeric effect is highest for sugars with axial orientation, which results in higher energetic state, and consequently this type of orientation confers lower stability.
舧 The anhydrous sugar is produced when the axial
舧 Anhydrous sugar is an acetal, it is a nonreducing sugar, and therefore it is called anhydrous non-reducing sugar.
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EBK ORGANIC CHEMISTRY
- Heating D-altrose with dilute acid produces a nonreducing anhydro sugar (C6H1005). Methylation of the anhydro sugar followed by acid hydrolysis yields 2,3,4-tri-O-methyl-D-altrose. The formation of the anhydro sugar takes place through a chair conformation of ẞ- D-altropyranose in which the -CH2OH group is axial. What is the structure of the anhydro sugar? CH3 OH HO OH I H₂C CH3 0. 0 H H H H HO OH OH I CH3 H₂C H H H H CH₂ -OH OH HO eTextbook and Media Explain how is it formed. The anhydro sugar is formed when the axial -CH2OH group reacts with C to form a cyclic SUPF Because the anhydro sugar is (i.e., an internal glycoside), it is a sugar. Methylation followed by acid hydrolysis converts the anhydro sugar to 2,3,4-tri-O-methyl-D-altrose.arrow_forwardAll the glucose units in dextran have six-membered rings. When a sample of dextran is treated with methyl iodide and Ag2O and the product ishydrolyzed 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.arrow_forwardTrehalose, 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_forward
- When an optically active D-aldopentose was subjected to Kiliani-Fischer synthesis, followed by NaBH4/H2O, it produced a mixture of an optically active and an optically inactive alditol. When the same D-aldopentose was subjected to Wohl degradation followed by HNO3 it produced an optically inactive aldaric acid. Provide the structure of this D-aldopentose. Н- НО- н- H -ОН НО -H Н- -Н CH₂OH 1 A) 1 B) II C) III осн H D) IV НО осн -H Н- -OH H- H HỌ CH₂OH П -OH H -OH H Н -H CH₂OH Ш _H -OH HO -OH H- -OH H- осн -H -OH CH₂OH IV -OH CH₂OH Varrow_forwardtrehalose is a disacharide that can be obtained from fungi sea uchins and insects. acid hydrolysis of trehalose yields only D-glucose. trehalose is hydrolysed by a-glucosidase but not b-glucosidase.methylation of trhalose followed by hydrolysis yield two molar equivalents of 2-3-4-6 -tetra-O-methyl-D-glucopyranose. deduce the structure of the trehalose using the experimental dataarrow_forwardMutarotation occurs when the two anomers interconvert in solution. Outline a stepwise mechanism for the acid-catalysed interconversion of glucose anomers by mutarotation. он он H,0* но OH Но Но НО ÓHarrow_forward
- 3 Trehalose is a disaccharide that can be obtained from fungi, sea urchins and insects. Acid hydrolysis of trehalose yields only D-glucose. Trehalose is hydrolysed by α-glucosidase and not by β-glucosidase enzymes. Methylation of trehalose followed by hydrolysis yields two molar equivalents of2,3,4,6-tetra-O-methyl-D-glucopyranose.From the following experimental data, deduce the structure of trehalose.What will be the effect of trehalose on Fehling’s solution?arrow_forwardOne of the later steps in glucose biosynthesis is the isomerization of fructose 6-phosphate to glucose 6-phosphate. Propose a mechanism, using acid or base catalysis as needed.arrow_forwardThe formation of Br2 from NBS first involves the reaction of NBS with HBr to form an iminol intermediate and molecular bromine. The intermediate then undergoes acid-catalyzed tautomerism to form succinimide, the byproduct of the reaction. Propose a curved-arrow mechanism for the conversion of NBS into succinimide that also accounts for the formation of Br2.arrow_forward
- Treatment of -D-glucose with methanol in the presence of an acid catalyst converts it into a mixture of two compounds called methyl glucosides (Section 25.3A). In these representations, the six-membered rings are drawn as planar hexagons. (a) Propose a mechanism for this conversion and account for the fact that only the OH on carbon 1 is transformed into an OCH3 group. (b) Draw the more stable chair conformation for each product. (c) Which of the two products has the chair conformation of greater stability? Explain.arrow_forwardDraw and name the seven aldehydes and ketones with the formula C5H10O. Which are chiral?arrow_forwardIn dilute aqueous base, (R)-glyceraldehyde is converted into an equilibrium mixture of (R,S)-glyceraldehyde and dihydroxyacetone. Propose a mechanism for this isomerization.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage LearningIntroduction to General, Organic and BiochemistryChemistryISBN:9781285869759Author:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar TorresPublisher:Cengage Learning