Reactions of Carbonyl Compounds

Reactions of Carbonyl Compounds:

Cannizzaro Reaction, Aldol Condensation, Haloform Reaction, Classification Test

Introduction:

The purpose of this experiment is to gain a better understanding of the immense variety of chemistry that can be attributed to the carbonyl group. In order to gain this understanding, we will perform both a Cannizzaro reaction—a reaction where an aldehyde is converted to both a carboxylic acid as well as an alcohol—and an aldol condensation. The cannizzaro reaction will be carried out using p-chlorobenzaldehyde as the reactant, while both p-chlorobenzoic acid and p-chlorobenzyl alcohol will be obtained as the primary products. The aldol condensation will prepare trans-p-anisalacetophenone using the organic reagents of p-anisaldehyde and acetophenone. We will also be able to gain some experience in carrying out small-scale reactions and in effecting purification of small samples in this lab. We will carry out a chromic acid test, a 2,4-Dinitrophenylhydrazine test, and an iodoform test. Lastly, through a combination of classification tests and chemical reasoning and deduction, we will be able to identify an “unknown” alcohol or carbonyl compound.

Main Reaction and Mechanism:

1. Cannizzaro Reaction:

General Cannizzaro Reaction:

Mechanism:

:

2. Aldol Condensation:

General Reaction:

Mechanism:

Table of Reactants:

Compound | Molecular Weight (g/mol) | Amount Used | Density (g/mL) | Moles required (mol) | Theoretical Physical Properties |

(50% solution) KOH | 56.11 | 1.5 mL | 2.04 | 0.055 | Highly corrosive, odorless |

p-chlorobenzaldehyde | 140.57 | 1.0 g | 1.196 | 0.0071 | Pungent odor Combustible Sensitive to air and light |

Methanol | 32.04 | 2.5 mL | 0.791 | | Colorless BP: 64.7°C |

Dichloromethane | 84.93 | | 1.33 | | Colorless Volatile |

acetone in hexane | 144.25 | 2-3 mL | | 2-3 mL | BP: 203.2°C...