Organic Chemistry
Organic Chemistry
4th Edition
ISBN: 9780073402772
Author: Janice G. Smith
Publisher: MCG
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Chapter 21, Problem 21.38P
Interpretation Introduction

(a)

Interpretation: The number of stereogenic centers present in α-D-galactose are to be predicted.

Concept introduction: Carbohydrates are naturally occurring compounds. Carbohydrates are polyhydroxy aldehydes and ketones. Galactose is a aldohexose as it contains six carbon atoms as well as an aldehyde functional group. The molecular formula of galactose C6H12O6.

Interpretation Introduction

(b)

Interpretation: The hemiacetal carbon in α-D-galactose is to be labeled.

Concept introduction: Carbohydrates are naturally occurring compounds. Carbohydrates are polyhydroxy aldehydes and ketones. Galactose is a aldohexose as it contains six carbon atoms as well as an aldehyde functional group. The molecular formula of galactose C6H12O6.

Aldehydes or ketones on reaction with one equivalent of alcohol form hemiacetal and on reaction with two equivalents of alcohol it forms acetals. This is nucleophilic addition reaction. These reactions takes place in presence of acids, commonly p-toluenesulfonicacid.

Ethers contain only one alkoxy group on a carbon atom while acetals contain two alkoxy groups on a single carbon atom.

Hemiacetals contains one alkoxy group and one hydroxyl group attached to same carbon atom.

Interpretation Introduction

(c)

Interpretation: The structure of β-D-galactose is to be drawn.

Concept introduction: Carbohydrates are naturally occurring compounds. Carbohydrates are polyhydroxy aldehydes and ketones. Galactose is a aldohexose as it contains six carbon atoms as well as an aldehyde functional group. The molecular formula of galactose C6H12O6.

Interpretation Introduction

(d)

Interpretation: The structure of poly hydroxy aldehyde that cyclizes to α and β-D-galactose is to be drawn.

Concept introduction: Carbohydrates are naturally occurring compounds. Carbohydrates are polyhydroxy aldehydes and ketones. Galactose is a aldohexose as it contains six carbon atoms as well as an aldehyde functional group. The molecular formula of galactose C6H12O6.

Aldehydes or ketones on reaction with one equivalent of alcohol form hemiacetal and on reaction with two equivalents of alcohol it forms acetals. This is nucleophilic addition reaction. These reactions takes place in presence of acids, commonly p-toluenesulfonicacid.

In α-D-galactose, the OH group is in axial position while in β-D-galactose the OH group is in equitorial position.

Interpretation Introduction

(e)

Interpretation: The products formed when α-D-galactose is treated with CH3OH and an acid are to be predicted.

Concept introduction: Carbohydrates are naturally occurring compounds. Carbohydrates are polyhydroxy aldehydes and ketones. Galactose is a aldohexose as it contains six carbon atoms as well as an aldehyde functional group. The molecular formula of galactose C6H12O6.

Aldehydes or ketones on reaction with one equivalent of alcohol form hemiacetal and on reaction with two equivalents of alcohol it forms acetals. This is nucleophilic addition reaction. These reactions takes place in presence of acids, commonly p-toluenesulfonicacid.

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Chapter 21 Solutions

Organic Chemistry

Ch. 21 - Prob. 21.11PCh. 21 - Prob. 21.12PCh. 21 - Prob. 21.13PCh. 21 - Prob. 21.14PCh. 21 - Problem 21.15 Draw the product of each...Ch. 21 - Prob. 21.16PCh. 21 - Prob. 21.17PCh. 21 - Outline a synthesis of each Wittig reagent from...Ch. 21 - Draw the products including stereoisomers formed...Ch. 21 - Prob. 21.20PCh. 21 - Prob. 21.21PCh. 21 - Show two methods to synthesize each alkene: a...Ch. 21 - Problem 21.22 The product formed when reacts with...Ch. 21 - What 1 amine and carbonyl compound are needed to...Ch. 21 - Prob. 21.25PCh. 21 - Prob. 21.26PCh. 21 - Prob. 21.27PCh. 21 - Problem 21.28 Draw a stepwise mechanism for the...Ch. 21 - Problem 21.29 Draw the products of each...Ch. 21 - Problem 21.30 Label each compound as an acetal, a...Ch. 21 - Problem 21.31 Draw a stepwise mechanism for the...Ch. 21 - Problem 21.32 Draw the products of each...Ch. 21 - Problem 21.33 Safrole is a naturally occurring...Ch. 21 - Problem 21.35 How would you use a protecting group...Ch. 21 - Prob. 21.35PCh. 21 - Problem 21.37 Two naturally occurring compounds...Ch. 21 - Problem 21.38 Draw the products of each...Ch. 21 - Prob. 21.38PCh. 21 - Problem 21.40 (a) Give the IUPAC name for A and B....Ch. 21 - 21.41 Rank the following compounds in order of...Ch. 21 - Prob. 21.41PCh. 21 - Give the IUPAC name for each compound. a. d. g. b....Ch. 21 - Give the structure corresponding to each name. a....Ch. 21 - Including stereoisomers, draw the 11 aldehydes...Ch. 21 - Prob. 21.45PCh. 21 - Prob. 21.46PCh. 21 - What alkyl halide is needed to prepare each Wittig...Ch. 21 - 21.46 Draw the products of each reaction. a. e....Ch. 21 - Prob. 21.49PCh. 21 - Prob. 21.50PCh. 21 - Prob. 21.51PCh. 21 - Prob. 21.52PCh. 21 - Prob. 21.53PCh. 21 - Rank the following compounds in order of...Ch. 21 - Which compound forms the higher concentration of...Ch. 21 - Prob. 21.56PCh. 21 - What Wittig reagent and carbonyl compound are...Ch. 21 - Prob. 21.58PCh. 21 - What reagents are needed to convert each compound...Ch. 21 - What reagents are needed to convert each compound...Ch. 21 - Prob. 21.61PCh. 21 - Devise a synthesis of each alkene using a Wittig...Ch. 21 - Devise a synthesis of each compound from...Ch. 21 - Prob. 21.64PCh. 21 - Prob. 21.65PCh. 21 - Prob. 21.66PCh. 21 - Prob. 21.67PCh. 21 - Prob. 21.68PCh. 21 - Prob. 21.69PCh. 21 - 21.64 Draw a stepwise mechanism for the following...Ch. 21 - 21.65 Draw a stepwise mechanism f or the following...Ch. 21 - Prob. 21.72PCh. 21 - 21.67 Draw a stepwise mechanism for each...Ch. 21 - 21.68 Draw a stepwise mechanism for the following...Ch. 21 - Prob. 21.75PCh. 21 - Prob. 21.76PCh. 21 - Prob. 21.77PCh. 21 - Prob. 21.78PCh. 21 - Prob. 21.79PCh. 21 - 21.73 Although the carbonyl absorption of cyclic...Ch. 21 - 21.74 Use the and data to determine the...Ch. 21 - 21.75 A solution of acetone in ethanol in the...Ch. 21 - Compounds A and B have molecular formula ....Ch. 21 - 21.77 An unknown compound C of molecular formula ...Ch. 21 - 21.78 An unknown compound D exhibits a strong...Ch. 21 - Prob. 21.86PCh. 21 - -D-Glucose, a hemiacetal, can be converted to a...Ch. 21 - 21.81 Draw a stepwise mechanism for the following...Ch. 21 - Prob. 21.89PCh. 21 - Prob. 21.90PCh. 21 - Prob. 21.91PCh. 21 - 21.86 Draw stepwise mechanism for the following...
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