Riedel Crafts Process of Acetylation of Ferrocene

Practical Report Cover Sheet

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University of Zululand

Faculty of Science and Agriculture

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           Department of Chemistry

PRACTICAL REPORT COVER SHEET

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Contents

AIM        3

INTRODUCTION        3

PROCEDURE        5

RESULTS        5

DISCUSSION        6

CONCLUSSION        7

REFERENCES        7

AIM

The aim of this experiment is to prepare Acetylferrocene.

INTRODUCTION

A typical electrophilic substitution is acylation in the presence of a Friedel Craft catalyst a reaction which is more common to both ferrocene and benzene. The acylation of ferrocene is carried out in under mild conditions and the major reaction product is the mono substituted derivative.

Although, the major product of this reaction is the acyl-derivative it is contaminated by unreacted ferrocene and to enable characterization it is necessary to effect separation from the starting material. This separation can be achieved by column chromatography. Due to the stability of the reactants and products in this experiment, it is not necessary to work under inert atmosphere.

In this lab we will be utilizing the Friedel Crafts process of acetylation of ferrocene. Ferrocene is an atom of iron bounded by two aromatic rings. We will use some reagents that will cause the ferrocene to add either one acetyl group to an aromatic ring or add two acetyl groups to each of the aromatic rings. (1)

Acetylferrocene is the organoiron compound with the formula (C5H5)Fe(C5H4COMe). It consists of ferrocene substituted by an acetyl group on one of the cyclopentadienyl rings. It is an orange, air-stable solid that is soluble in organic solvents.

Acetylferrocene is prepared by Friedel-Crafts acylation of ferrocene, usually with acetic anhydride

(Ac2O):

Fe(C5H5)2 + Ac2O → (C5H5)Fe(C5H4Ac) + HOAc

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The experiment is often conducted in the instructional laboratory to illustrate acylation as well as chromatographic separations. Acetylferrocene can be converted to many derivatives, e.g., reduction to the chiral alcohol (C5H5)Fe(C5H4CH(OH)Me) and precursor to vinylferrocene. The oxidized derivative, acetylferrocenium, is used as a 1e-oxidant in the research laboratory.[3]

Column chromatography in chemistry is a chromatography method used to isolate a single chemical compound from a mixture. Chromatography is able to separate substances based on differential adsorption of compounds to the adsorbent; compounds move through the column at different rates, allowing them to be separated into fractions. The technique is widely applicable, as many different adsorbents (normal phase, reversed phase, or otherwise) can be used with a wide range of solvents. The technique can be used on scales from micrograms up to kilograms. The main advantage of column chromatography is the relatively low cost and disposability of the stationary phase used in the process. The latter prevents cross-contamination and stationary phase degradation due to recycling. Column chromatography can be done using gravity to move the solvent, or using compressed gas to push the solvent through the column. A thin-layer chromatograph can show how a mixture of compounds will behave when purified by column chromatography. The separation is first optimized using thin-layer chromatography before performing column chromatography.