Stilbene Dibromide Lab Report
The purpose of this experiment was to successfully produce stilbene dibromide by using a more sustainable approach, which would prevent less environmental issues. This was done by brominating trans-stilbene and then using the elimination process on the dibrominated product. This process is considered “greener” compared to the original bromination procedures.
In order to create the alkyl halides, which are able to undergo chemical transformations more readily than the carbon-carbon double bond, onto the trans-stilbene the addition process of halogenation in needed. The typical reagents that are used, such as elemental bromine and liquid bromine, are dangerous and highly corrosive, so this experiment used an alternative method of bromination.
Instead, pyridinium tribromide can be used because it gradually releases bromine into the reaction. Another reason this reagent is useful is that it can be measure more accurately in it’s solid form, compare to measure a liquid reagent. But this reagent is still corrosive and damaging to the lab equipment. Also, this reagent still creates a wasteful bi-product. The alternative “greener” reagent of Hydrogen peroxide and HBr, was used in this experiment to brominate the trans-stilbene. The reason this reagent was selected was because this reagent does not create any wasteful bi-product and is less hazardous to use in a lab setting. Instead of using Br2 directly, Br2 is generated in “situ” in this reaction. Situ is a latin phrase, meaning “on-site” or “in-place”, so Br2 is created safety within the apparatus and under the fume hood. Also, for this reaction potassium hydroxide was used as a base and ethylene glycol (1,2-dihydroxyethane) was used as a high-boiling solvent. It was necessary to use this solvent because it requires a lot of energy to proceed with the second elimination reaction of the alkene and HBr. Bromination process is one of the techniques altered to become less hazardous and safer to use in a lab setting.
In order to create the alkyl halides, which are able to undergo chemical transformations more readily than the carbon-carbon double bond, onto the trans-stilbene the addition process of halogenation in needed. The typical reagents that are used, such as elemental bromine and liquid bromine, are dangerous and highly corrosive, so this experiment used an alternative method of bromination.
Instead, pyridinium tribromide can be used because it gradually releases bromine into the reaction. Another reason this reagent is useful is that it can be measure more accurately in it’s solid form, compare to measure a liquid reagent. But this reagent is still corrosive and damaging to the lab equipment. Also, this reagent still creates a wasteful bi-product. The alternative “greener” reagent of Hydrogen peroxide and HBr, was used in this experiment to brominate the trans-stilbene. The reason this reagent was selected was because this reagent does not create any wasteful bi-product and is less hazardous to use in a lab setting. Instead of using Br2 directly, Br2 is generated in “situ” in this reaction. Situ is a latin phrase, meaning “on-site” or “in-place”, so Br2 is created safety within the apparatus and under the fume hood. Also, for this reaction potassium hydroxide was used as a base and ethylene glycol (1,2-dihydroxyethane) was used as a high-boiling solvent. It was necessary to use this solvent because it requires a lot of energy to proceed with the second elimination reaction of the alkene and HBr. Bromination process is one of the techniques altered to become less hazardous and safer to use in a lab setting.