Bromination Of Arenes Lab Report
al Chain Reactions: Bromination of Arenes
Introduction The purpose of the bromination of arenes was to determine the different reactivities of different hydrocarbons with different hydrogen atoms when reacted with bromine under free-radical substitution. The time it took for the bromine color to disappear was used to determine the order of reactivity of the different hydrocarbons.
Data and Results The data of the 10 hydrocarbon tubes and the 2 control tubes with bromine and dichloromethane in the two different conditions is listed below in Table 1. As a result, the hydrocarbon tubes in light reacted and lost the bromine color quicker than the tubes not in light. Not all of the hydrocarbons observed a full disappearance in the bromine color, but did observe a color change. The control tube had …show more content…
The more selective a radical is the least reactive is. Since the chlorine radical is more reactive than the bromine radical, the bromine is more selective than chlorine. Using Hammond’s Postulate, since bromine radicals are lower in energy, less reactive, and endothermic it has a late transition state. Therefore, the transition state resembles the products over the reactants, the energy difference is large, and the bromine radical is more selective. Since bromine is more selective, it is used in most experiments.
Conclusion The predicted reactivity of the five hydrocarbons in free-radical chain bromination in increasing order was ethylbenzene (9), toluene (8), methylcyclohexane (13), cyclohexane (12), and tert-butylbenzene (11). This hypothesis was a result of the fact that benzylic hydrogen atoms react faster than aliphatic hydrogen atoms and aliphatic hydrogen atoms react faster than aromatic hydrogen atom atoms. The hypothesis was in fact correct and the reaction times of each hydrocarbon with different hydrogen atoms in the bromination experiment support
Introduction The purpose of the bromination of arenes was to determine the different reactivities of different hydrocarbons with different hydrogen atoms when reacted with bromine under free-radical substitution. The time it took for the bromine color to disappear was used to determine the order of reactivity of the different hydrocarbons.
Data and Results The data of the 10 hydrocarbon tubes and the 2 control tubes with bromine and dichloromethane in the two different conditions is listed below in Table 1. As a result, the hydrocarbon tubes in light reacted and lost the bromine color quicker than the tubes not in light. Not all of the hydrocarbons observed a full disappearance in the bromine color, but did observe a color change. The control tube had …show more content…
The more selective a radical is the least reactive is. Since the chlorine radical is more reactive than the bromine radical, the bromine is more selective than chlorine. Using Hammond’s Postulate, since bromine radicals are lower in energy, less reactive, and endothermic it has a late transition state. Therefore, the transition state resembles the products over the reactants, the energy difference is large, and the bromine radical is more selective. Since bromine is more selective, it is used in most experiments.
Conclusion The predicted reactivity of the five hydrocarbons in free-radical chain bromination in increasing order was ethylbenzene (9), toluene (8), methylcyclohexane (13), cyclohexane (12), and tert-butylbenzene (11). This hypothesis was a result of the fact that benzylic hydrogen atoms react faster than aliphatic hydrogen atoms and aliphatic hydrogen atoms react faster than aromatic hydrogen atom atoms. The hypothesis was in fact correct and the reaction times of each hydrocarbon with different hydrogen atoms in the bromination experiment support