In the early chapter and Book I, we have learned several reactions that provide good methods for the preparation of aldehydes and/or ketones, let’s have a review here.

Chapter 1 Review

Oxidation of 1° or 2° Alcohols (1.2.5)

Pyridinium chlorochromate (PCC) is the proper oxidizing reagent to oxidize 1° alcohol to aldehyde, and oxidize 2° alcohol to ketone.

Ozonolysis of an Alkene (10.7.2 in Book I)

 Ozonolysis reaction is the oxidative cleavage of the C=C double bond in the alkene, that produces aldehyde and/or ketone as products. It is a two-step process in which alkene reacts with ozone at a very low temperature (-78 °C) first, then treated with dimethyl sulfide, (CH₃)₂S, (or Zn/CH₃COOH) to give the products. A couple of examples are shown here.

Hydration of an Alkyne (10.8 in Book I)

Starting from terminal alkyne, aldehyde can be prepared by hydroboration-oxidation, and methyl ketone can be prepared by hydration with Hg²⁺ as a catalyst.

For internal alkyne, hydration with Hg²⁺ as a catalyst generates ketone as a product. For synthesis purposes, this method works best with symmetric internal alkyne that gives only one ketone product.

Friedel-Crafts Acylation

Another important reaction that gives ketone as a product is Friedel-Crafts acylation, a type of Electrophilic Aromatic Substitution (EAS) reaction. We will have thorough discussions on EAS and Friedel-Crafts reaction in Chapters 4 and 5. An example is shown here for general purposes.