Nitration and Purification of Bromobenzene
Nitration and Purification of Bromobenzene
Abstract:
An electrophilic aromatic substitution reaction was performed on bromobenzene with nitric acid producing both 2-bromonitrobenzene and 4-bromonitrobenzene. Products of the reaction were purified through multiple recrystallizations and column chromatography creating multiple crops of a yellow powder. The percent yield of products was determined to be 51%. The melting point of Crop 1 was found to be 110-115 °C, and Crop 2 was found to be 37-90 °C indicating impurity in both crops. TLC analysis shows a less polar compound in Crop 1 than in Crop 2. IR and NMR data provide proof of benzene with a nitro group is present in Crop 1.
Introduction:
In this experiment an electrophilic aromatic substitution is performed. This is done by having the benzene ring attacked by an electrophile creating a carbocation intermediate within the benzene ring that is stabilized by resonance1. During the reaction hydrogen on the benzene ring is replaced with the electrophile used in the reaction1. These reactions are dictated by the functional groups attached to benzene as they direct where the reaction takes place1. Electron-donating groups cause the reaction to take place in an ortho or para position due to having a resonance structure with a positive charge next to an electron withdrawing group as shown in Figure 1.
This resonance structure is not achievable in a meta position making that product unfavorable and thus is not produced1.
In the reaction performed in this experiment both ortho and para products are produced that contain very similar physical properties. In order to separate these two compounds column chromatography can be used to exploit the weaker polarity of 4-bromonitrobenzene. 4-Bromonitrobenzene has a weaker polarity due to its nitro group being in a para position thus lessening the electronegative effects of bromine on the other side of the ring by pulling electron density toward the ring1. Column
Abstract:
An electrophilic aromatic substitution reaction was performed on bromobenzene with nitric acid producing both 2-bromonitrobenzene and 4-bromonitrobenzene. Products of the reaction were purified through multiple recrystallizations and column chromatography creating multiple crops of a yellow powder. The percent yield of products was determined to be 51%. The melting point of Crop 1 was found to be 110-115 °C, and Crop 2 was found to be 37-90 °C indicating impurity in both crops. TLC analysis shows a less polar compound in Crop 1 than in Crop 2. IR and NMR data provide proof of benzene with a nitro group is present in Crop 1.
Introduction:
In this experiment an electrophilic aromatic substitution is performed. This is done by having the benzene ring attacked by an electrophile creating a carbocation intermediate within the benzene ring that is stabilized by resonance1. During the reaction hydrogen on the benzene ring is replaced with the electrophile used in the reaction1. These reactions are dictated by the functional groups attached to benzene as they direct where the reaction takes place1. Electron-donating groups cause the reaction to take place in an ortho or para position due to having a resonance structure with a positive charge next to an electron withdrawing group as shown in Figure 1.
This resonance structure is not achievable in a meta position making that product unfavorable and thus is not produced1.
In the reaction performed in this experiment both ortho and para products are produced that contain very similar physical properties. In order to separate these two compounds column chromatography can be used to exploit the weaker polarity of 4-bromonitrobenzene. 4-Bromonitrobenzene has a weaker polarity due to its nitro group being in a para position thus lessening the electronegative effects of bromine on the other side of the ring by pulling electron density toward the ring1. Column