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Title: Evaluating the Stereospecificity of Electrophilic Addition of Bromine to Green-Stilbene LEARNING OBJECTIVES: - Determine the possible stereochmical outcome of reaction - Devise hypothesis and test its validity experimentally - Propose and perform characterization methods to determine what compound(s) are isolated - Learn the basic format of discussion section of report READING ASSIGNMENT: Recommended Characterization techniques previously covered INTRODUCTION: Stereospecificity of reaction refers to one stereoisomer of reactant giving one stereoisomer of product exclusively. A single stereoisomer giving rise to the major stereoisomer, but also minor one, is stereoselectivity. Stereospecificity of reaction is the result of its mechanism; it is illustrated by the example below. NISH: An example of stereospecific reaction is the bimolecular nucleophilic substitution or S2 reaction. Due to its concerted backside displacement mechanism, each enantiomer of reactant will give specific enantiomer of the product. For example, (R)-2-iodohexane will react with sodium bisulfide to give (S)-2-hexanethiol, while the (S)-2-iodohexane will give only the R product. Stereospecific reaction can give either specific enantiomers or diastereomers of the product depending on the number of chiral centers involved. In bimolecular nucleophilic substitution, the reaction takes place at one chiral center, so enantiomers of the product are possible (though only one actually forms). But if two or more chiral centers are involved, diastereomers can also form. This can complicate the characterization since the stereoisomers of the product formed must be determined. However, diastereomers have distinct physical properties and are easier to separate and determine, while enantiomers have the same properties (in an achiral environment). In today's experiment, you will explore the following aspects of the electrophilic addition of bromine to an alkene: - If the reaction is stereospecific - If the reaction is stereospecific, which stereoisomer(s) of the product form. CHNB, Cco H 1,2-Dihydro-1,1-diphenylbenzene Scheme 2

Title: Evaluating the Stereospecificity of Electrophilic Addition of Bromine to Green-Stilbene

LEARNING OBJECTIVES:
- Determine the possible stereochmical outcome of reaction
- Devise hypothesis and test its validity experimentally
- Propose and perform characterization methods to determine what compound(s) are isolated
- Learn the basic format of discussion section of report

READING ASSIGNMENT:
Recommended Characterization techniques previously covered

INTRODUCTION:
Stereospecificity of reaction refers to one stereoisomer of reactant giving one stereoisomer of product exclusively. A single stereoisomer giving rise to the major stereoisomer, but also minor one, is stereoselectivity. Stereospecificity of reaction is the result of its mechanism; it is illustrated by the example below.

NISH:
An example of stereospecific reaction is the bimolecular nucleophilic substitution or S2 reaction. Due to its concerted backside displacement mechanism, each enantiomer of reactant will give specific enantiomer of the product. For example, (R)-2-iodohexane will react with sodium bisulfide to give (S)-2-hexanethiol, while the (S)-2-iodohexane will give only the R product. Stereospecific reaction can give either specific enantiomers or diastereomers of the product depending on the number of chiral centers involved. In bimolecular nucleophilic substitution, the reaction takes place at one chiral center, so enantiomers of the product are possible (though only one actually forms). But if two or more chiral centers are involved, diastereomers can also form. This can complicate the characterization since the stereoisomers of the product formed must be determined. However, diastereomers have distinct physical properties and are easier to separate and determine, while enantiomers have the same properties (in an achiral environment).

In today's experiment, you will explore the following aspects of the electrophilic addition of bromine to an alkene:
- If the reaction is stereospecific
- If the reaction is stereospecific, which stereoisomer(s) of the product form.

CHNB, Cco H
1,2-Dihydro-1,1-diphenylbenzene
Scheme 2

evaluating the stereospecificity of electrophilic addition of bromine t0 greef stilbene learning objectives detcrmine the possible stcrcochcmical outcome of rcacton devise hypothesis 1nd tes 19571

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