Bromination of trans-cinnamic acid Essay

692 Words May 7th, 2014 3 Pages
Abstract The bromination of trans-cinnamic acid was completed to determine dibromide’s stereochemical structure and its mechanism. After the addition of bromine to trans-cinnamic acid, the product was identified by its melting point and infrared spectrum resulting in erythro-2,3-Dibromo-3-phenylpropanoic acid after comparing similar properties.
Introduction
In this lab, the bromination of trans-cinnamic acid was completed to determine dibromide’s stereochemical structure, and from there determine whether the reaction is carried out by the usual bromonium ion mechanism or a different mechanism. This is important in the determination of dibromide’s stereochemical structure, as a mechanism can be affected by changing a reactant’s
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Results and Discussion
Melting Point: The melting point was determined to be 202°C, which is extremely close to the literature value of erythro-2,3-Dibromo-3-phenylpropanoic acid, 204°C. This is the first indicator that the product obtained possess a stereochemical structure resembling erythro-2,3-Dibromo-3-phenylpropanoic acid.
Infrared Spectrum: The Infrared Spectrum’s collected from the starting material and the product look almost identical, with functional groups C=O(1700 cm-1), O-H(3300-2600 cm-1), and C=C (1680-1640 cm-1) present.
Mechanisms:
Although a variety of mechanisms can be suggested for the addition of bromine to an alkene, the addition of bromine to the C = C in our final product illustrates an anti-addition.

Experimental The reaction was done in the fume hood with proper safety gloves on throughout the entire experiment. 10.0 mmol of trans-cinnamic acid was combined with 6.0 mL of glacial acetic acid with a stirbar in a 50 mL round-bottom flask. The round-bottom flask was placed on a magnetic stirrer with a separatory funnel over the flask with the stopcock closed. 8.2 Ml of 1.25 M solution of bromine in acetic acid was poured into the separatory

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