Organic chemistry with biological applications

John E. McMurry

ISBN #9781285842912

3rd Edition

1,528 Questions

13,325 Students Helped

Homework Questions

Summary

Learning Objectives

Key Concepts

Example Problems

Explanations

Common Mistakes

Summary

Aldehydes and ketones serve as vital intermediates in organic synthesis due to their highly reactive carbonyl groups. Their chemistry is dominated by nucleophilic addition reactions, which can be fine-tuned under various conditions to yield a wide array of products such as alcohols, imines, acetals, and alkenes via the Wittig reaction. Spectroscopic techniques such as IR, NMR, and mass spectrometry are essential tools for characterizing these compounds. A deep understanding of reaction mechanisms, including direct versus conjugate addition, helps in designing selective synthetic strategies, including protecting group chemistries and enantioselective reactions.

Learning Objectives

Key Concepts

CONCEPT

DEFINITION

Definition: The study of molecular reactivity via polar covalent bonds where differences in electronegativity create dipole moments, guiding acid–base behavior.

The study of molecular reactivity via polar covalent bonds where differences in electronegativity create dipole moments, guiding acid–base behavior. •

Example Problems

Example 1

Name the following aldehydes and ketones:

Example 2

Draw structures corresponding to the following names: (a) 3-Methylbutanal (b) 4-Chloropentan-2-one (c) Phenylacetaldehyde (d) cis-3-tert-Butylcyclohexanecarbaldehyde (e) 3-Methylbut-3-enal (f) 2 -(1-Chloroethyl)-5-methylheptanal

Example 3

How would you prepare pentanal from the following starting materials? (a) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ (b) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CH}_{2}$ (c) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{CH}_{3}$ (d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CH}_{2}$

Example 4

How would you carry out the following reactions? More than one step may be required. (a) Benzene $\rightarrow m$ -Bromoacetophenone (b) Bromobenzene $\rightarrow$ Acetophenone (c) 1-Methylcyclohexene $\rightarrow$ 2-Methylcyclohexanone

Example 5

Treatment of an aldehyde or ketone with cyanide ion $(-: \mathrm{C} \equiv \mathrm{N})$, followed by protonation of the tetrahedral alkoxide ion intermediate, gives a cyanohydrin. Show the structure of the cyanohydrin obtained from cyclohexanone.