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Questions and Answers
What phenomenon describes the change in optical rotation of glucose until a constant value is reached?
What phenomenon describes the change in optical rotation of glucose until a constant value is reached?
When glucose is oxidized using a weak oxidizing agent like bromine water, which product is formed?
When glucose is oxidized using a weak oxidizing agent like bromine water, which product is formed?
What product results from the reduction of glucose with sodium borohydride?
What product results from the reduction of glucose with sodium borohydride?
What is the final product when glucose reacts with phenylhydrazine?
What is the final product when glucose reacts with phenylhydrazine?
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Which of the following statements about anomers is correct?
Which of the following statements about anomers is correct?
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What is the product formed when glucose undergoes acetylation?
What is the product formed when glucose undergoes acetylation?
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Which reaction converts glucose into glucaric acid?
Which reaction converts glucose into glucaric acid?
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What compound is produced when glucose is reduced?
What compound is produced when glucose is reduced?
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Which compound is formed from glucose when treated with hydroxylamine?
Which compound is formed from glucose when treated with hydroxylamine?
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What is a common feature of the products resulting from glucose reactions?
What is a common feature of the products resulting from glucose reactions?
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What type of glucose linkages are found in glycogen?
What type of glucose linkages are found in glycogen?
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What is the primary component of starch?
What is the primary component of starch?
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Which of the following statements about cellulose is true?
Which of the following statements about cellulose is true?
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What is the repeating disaccharide unit in cellulose?
What is the repeating disaccharide unit in cellulose?
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Which of the following uses of cellulose-based products is accurate?
Which of the following uses of cellulose-based products is accurate?
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What is the molecular formula for heptoses?
What is the molecular formula for heptoses?
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Which of the following sugars is considered a hexose?
Which of the following sugars is considered a hexose?
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What defines a sugar as an aldohexose?
What defines a sugar as an aldohexose?
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What is the significance of D(+) glucose in human blood?
What is the significance of D(+) glucose in human blood?
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How are aldohexoses numbered in the Fischer projection?
How are aldohexoses numbered in the Fischer projection?
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What is the physical state of glucose at room temperature?
What is the physical state of glucose at room temperature?
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In the context of sugars, what does the term 'chiral center' refer to?
In the context of sugars, what does the term 'chiral center' refer to?
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Which of the following sugars can serve as a representative of an aldohexose?
Which of the following sugars can serve as a representative of an aldohexose?
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What characterizes D-sugars in terms of their hydroxyl group configuration?
What characterizes D-sugars in terms of their hydroxyl group configuration?
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In the formation of a ketal, which reactants are involved?
In the formation of a ketal, which reactants are involved?
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What type of ring does D-glucose primarily form in solution?
What type of ring does D-glucose primarily form in solution?
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Which carbon is referred to as the anomeric carbon in sugars?
Which carbon is referred to as the anomeric carbon in sugars?
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What occurs to the specific rotation of D-glucose in water over time?
What occurs to the specific rotation of D-glucose in water over time?
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What is the configuration of the hydroxyl group at the lowest chiral carbon in L-sugars?
What is the configuration of the hydroxyl group at the lowest chiral carbon in L-sugars?
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Which statement is true about the bond angles in a six-membered pyranose ring?
Which statement is true about the bond angles in a six-membered pyranose ring?
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What is the result of chain-ring interconversion involving D-glucose?
What is the result of chain-ring interconversion involving D-glucose?
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Which type of rotation does fructose exhibit in a polarimeter?
Which type of rotation does fructose exhibit in a polarimeter?
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What is the structure of β-D-fructofuranose characterized by?
What is the structure of β-D-fructofuranose characterized by?
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Which of the following products is formed when fructose undergoes reduction?
Which of the following products is formed when fructose undergoes reduction?
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What type of bond is formed between two monosaccharides in a disaccharide?
What type of bond is formed between two monosaccharides in a disaccharide?
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In which of the following polysaccharides are both α(1→4) and α(1→6) linkages found?
In which of the following polysaccharides are both α(1→4) and α(1→6) linkages found?
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What is a characteristic of α-D-fructopyranose?
What is a characteristic of α-D-fructopyranose?
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When fructose is acetylated, what functional group is typically replaced?
When fructose is acetylated, what functional group is typically replaced?
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What is formed as a result of vigorous oxidation of fructose?
What is formed as a result of vigorous oxidation of fructose?
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Which reaction does not occur with fructose?
Which reaction does not occur with fructose?
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What describes the naturally occurring free form of α-D-fructose?
What describes the naturally occurring free form of α-D-fructose?
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Study Notes
Carbohydrates Introduction
- Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketones
- They are large molecules that produce other compounds upon hydrolysis
- Carbohydrates are an important class of naturally occurring organic compounds
- Examples include glucose, fructose, starch, and cellulose
- They are all composed of carbon, hydrogen, and oxygen
- The general formula is Cm(H₂O)m
- Often referred to as saccharides
- Carbohydrates contain alcoholic hydroxyl groups, aldehyde groups, and ketone groups
Classification of Carbohydrates
-
Classified into three major classes based on the number of simple sugar molecules produced by hydrolysis
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1. Monosaccharides (simple sugars):
- Single unit carbohydrates
- Cannot be broken down into simpler carbohydrates upon hydrolysis
- Example: glucose and fructose
- Formula: C₆H₁₂O₆
- No reaction with water
-
2. Oligosaccharides:
- Made up of 2 to 10 monosaccharide units
- Disaccharides contain two monosaccharide units
- Example: sucrose (glucose + fructose)
- Trisaccharides contain three monosaccharide units
- Example: raffinose (glucose + fructose + galactose)
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3. Polysaccharides:
- Contain more than 10 monosaccharide units
- One molecule of starch or cellulose upon hydrolysis yields a large number of glucose units
- Formula: (C₆H₁₀O₅)n +H₂O → nC₆H₁₂O₆
Monosaccharides
- Simplest one-unit sugars
- General formula: CnH₂nOn, where n varies from 3 to 8
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Types: Trioses, tetroses, pentoses, hexoses, heptoses, octoses
- Specific examples given of each type, including their chemical formula and examples
Glucose
- Most common monosaccharide
- Also known as dextrose
- Naturally occurring glucose is D(+) glucose, fructose is D(-) fructose
- Pentahydroxyhexanal
- Essential constituent of human blood
- Normal blood glucose level: 65-110 mg/dL
- In diabetics, the level is higher than normal
- Occurs in abundance as cane sugar and polysaccharides like starch and cellulose
- White crystalline solid
- Soluble in water, sparingly soluble in ethanol
- Optically active
Physical Properties of Glucose
- White crystalline solid, melting point of 146°C
- Soluble in water, sparingly soluble in ethanol
- Optically active
Naming Simple Monosaccharides
- Functional group = aldehyde
- 6 carbons = hexose, 5 carbons = pentose
Aldohexose Sugars
- Lists specific examples of D-sugars like D-allose, D-altrose, D-glucose, D-mannose, D-idose, D-galactose, and D-talose
Numbering Monosaccharides
- Fischer projection
- Arrange the carbon chain vertically
- Aldehyde at top (number 1)
- Ketone next to top (number 2)
Projections for Representing Glucose
- Haworth projection
- Cyclohexane projection
- Fischer projection
Carbohydrate Structure
- D- or L-sugars: indicate stereochemistry of the lowest chiral carbon
- D-sugars: hydroxyl group on the lowest chiral carbon points to the right
- L-sugars: hydroxyl group on the lowest chiral carbon points to the left
Acetal and Ketal Formation
- Ketone + alcohol → hemi-ketal/hemi-acetal → acetal
Ring Formation in Monosaccharides
- The -OH group on C5 is well-placed to react with the C1 aldehyde function
- The resulting 6-membered pyranose ring is relatively unstrained
- -OH groups on C4 and C6 are less favorably oriented
Fischer Projection Form
- Shows different forms of D-glucose (α-D-glucose and β-D-glucose)
- Anomeric carbon: carbon involved in hemiacetal or acetal formation
Chain-Ring Interconversion
- The conversion between chain and ring forms of glucose
α-D-Glucose
- Specific structure details of α-anomer
β-D-Glucose
- Specific structure details of β-anomer
Haworth Projection Formulas for Sugars
- Examples of Haworth projections for sugars
Mutarotation
- Gradual change in specific rotation when glucose is dissolved in water
Monosaccharide Anomers
- Anomeric carbon
- α-anomer: hydroxyl group is down
- β-anomer: hydroxyl group is up
- Anomers undergo mutarotation. Specific examples of α and β forms shown
Chemical Properties of Glucose
-
1. Oxidation
- Glucose oxidized to gluconic acid with a weak oxidizing agent (e.g., bromine water)
- Glucose oxidized to glucaric acid with a strong oxidizing agent (e.g., nitric acid)
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2. Reduction
- Glucose reduced to D-glucitol (sorbitol) with sodium borohydride
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3. Acetylation
- Glucose reacts with acetic anhydride in presence of anhydrous zinc chloride to form penta-acetyl glucose
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4. Reaction with hydroxylamine
- Glucose reacts to form glucose oxime
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5. Reaction with phenylhydrazine
- Excess phenylhydrazine yields glucosazone
Reactions of Glucose
- Includes details on reaction products
- Shows the reaction mechanism with diagrams
Fructose
- Rotates the polarimeter to the left
- Structures of various forms (a-D-Fructose, b-D-Fructose, a-D-Fructofuranose, β-D-Fructofuranose)
- Reactions summary
Reactions of Fructose
- Includes details on reaction products (reduction, mild oxidation, vigorous oxidation)
Glycosidic Bond
- O-glycosidic bond, example diagrams of methyl α-D-glucopyranoside and methyl β-D-glucopyranoside
Disaccharides
- Examples of sucrose, lactose, and maltose
Polysaccharides
- General overview
- Glycogen
- Cellulose
- Starch
- Specific structure details and roles of each type like glycogen, cellulose, amylose, amylopectin are included, with diagrams
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Description
This quiz covers the basic concepts of carbohydrates, including their structure, types, and classification. Learn about monosaccharides, oligosaccharides, and their significance in organic chemistry. Test your knowledge of common carbohydrate examples and their molecular formulas.
