A Cis to Trans Conversion

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Maleic acid and Fumaric acid are both compounds belonging to the carboxylic acids class. In this experiment, we formed the two isomers of 1,2-ethylenedicarboxylic acid and tested the solubility and melting points of both of these products. Both of these compounds involve a carbon-carbon double bond that is composed of one σ bond and one π bond. The overlap of sp2 hybrid orbitals forms the σ bond, and one empty p orbital forms the π bond. This process is illustrated in the figure below: Sp2 hybrid orbitals:Unhybridized p orbital:

(3 σ bonds)(1 π bond)
_1 _1 _1_1
Molecules with double bonds are alkenes, and they have restricted rotation around the double bond so they tend to form the cis and trans geometric isomers. While both of these isomers have the same molecular formula, they usually vary in many physical features. Cis isomers have two identical groups located on the same side of the double bond, while trans isomers have the two groups on opposing sides of the molecule. Trans isomers are usually more stable than cis isomers because there is no steric interaction, or repulsion, between the carboxyl groups of the molecule. The more negative heat of formation value of trans alkenes also show that these compounds are more stable than cis alkenes. In the first part of this experiment, we formed maleic acid from maleic anhydride by adding the maleic anhydride to boiling water and then filtering the product using a Buchner funnel. We then mixed the filtrate with HCl and boiled it to form fumaric acid in the second part of the experiment. RESULTS

A clear and oily substance appeared while boiling the maleic anhydride in water and a precipitate started to form during cooling. After filtering with the Buchner funnel, a solid white crystal-like product remained and the filtrate was a clear liquid. The following Table 1 describes observations made during the first part of the experiment, and the theoretical yield of the product formed....
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