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 structure.
Cinnamic acid was used in this lab because as a naturally occurring compound, it has many different uses. It is used as a flavoring, in perfumes, and is a source to a large number of other natural substances. Cinnamic acid is helpful in providing flowers with their bright colors, butterflies with their colorful wings, and gives fall leaves their distinguishable color. These examples reveal the day-to-day uses of cinnamic acid, and shows that the addition of bromide to this particular acid is nothing extremely complex or an uncommon chemical compound, it is easily obtainable.
After the addition of bromine to trans-cinnamic acid, the product is identified by its melting point and infrared spectrum. The product could be erythro-dibromo, threo-dibromo, or a combination of both. Although obtaining a product consisting of both erythro and threo is possible, it results in an impure substance with a broad melting point range that contrasts pure dibromide. These particular compounds of erythro and threo are named as such to distinguish their two chiral centers, but no plane of symmetry. Both of these compounds are derived from simple sugars, erythrose and threose (Figure 1)....
References: 1 Experiment is a modified version of an experiment found in: Lehman, J.W. Operational Organic Chemistry: a problem-solving approach to the laboratory course, 3rd ed., Prentice-Hall, Upper Saddle River, New Jersey, 1999.
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