Domanda del libro di testo
Using the Haworth projection, draw the furanose ring that would form between the C5 hydroxyl group and the ketone at C2 for the molecule shown.
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Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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TOC.tableOfContents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases/Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes 1: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes 2: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification 1: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification 2: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution 1: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution 2: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems 1: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems 2: Pericyclic Reactions54
- Ch. 23 - Benzene 1: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene 2: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Non è quello che usi tu?Cambia libro di testo
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Mullins 1st EditionCh. 27 - Carbohydrates, Nucleic Acids, and LipidsProblema 23
Mullins 1st EditionCh. 27 - Carbohydrates, Nucleic Acids, and LipidsProblema 23Capitolo 26, Problema 23
Suggest a mechanism by which α-d-glucopyranose is converted to β-d-glucopyranose in base. [See Figure 27.18.]
Guida verificata passo dopo passo1
Identify the starting material, α-d-glucopyranose, which has the hydroxyl group at the anomeric carbon (C1) in the axial position.
Recognize that the conversion to β-d-glucopyranose involves the change of the hydroxyl group at the anomeric carbon from axial to equatorial position.
Understand that in basic conditions, the hydroxyl group can be deprotonated, forming an alkoxide ion, which is a good nucleophile.
Consider the formation of an open-chain aldehyde intermediate through the cleavage of the hemiacetal linkage, allowing rotation around the C1-C2 bond.
Envision the reformation of the cyclic structure, where the nucleophilic attack by the alkoxide ion occurs from the opposite side, leading to the equatorial position of the hydroxyl group in β-d-glucopyranose.
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Anomeric Carbon
The anomeric carbon is the carbon atom in a sugar molecule that was originally the carbonyl carbon in the open-chain form. In cyclic forms of glucose, it is the carbon bonded to two oxygen atoms. The configuration of the hydroxyl group attached to this carbon determines whether the sugar is in the alpha (α) or beta (β) form, as seen in α-d-glucopyranose and β-d-glucopyranose.
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02:12
Carbonation of Grignard Reagents
Mutarotation
Mutarotation is the process by which an α-anomer of a sugar converts to a β-anomer (or vice versa) in solution, resulting in a change in optical rotation. This occurs through the opening of the cyclic form to the linear form and subsequent reclosure, allowing the hydroxyl group on the anomeric carbon to switch positions. In basic conditions, this process is facilitated, leading to the interconversion of α-d-glucopyranose and β-d-glucopyranose.
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03:06Mechanism
Axial and Equatorial Positions
In cyclic sugar structures, substituents can occupy axial or equatorial positions. Axial positions are perpendicular to the plane of the ring, while equatorial positions are roughly in the plane of the ring. The stability of a sugar molecule can be influenced by these positions, as equatorial positions generally offer less steric hindrance. In the conversion from α-d-glucopyranose to β-d-glucopyranose, the hydroxyl group at the anomeric carbon changes from an axial to an equatorial position, affecting the molecule's stability and reactivity.
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04:02Equatorial Preference
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Suggest a mechanism by which α-d-glucopyranose is converted to β-d-glucopyranose in acid. [See Figure 27.18.]
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