Synthesis of 3-Nitrobenzaldehyde Essay

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This experiment is about the synthesis of 3-nitrobenzaldehyde through nitration. The nitration of benzaldehyde is an example of an electrophilic aromatic substitution reaction, in which a proton of an aromatic ring is replaced by a nitro group. Many aromatic substitution reactions are known to occur when an aromatic substrate is allowed to react with a suitable electrophilic reagent, and many other groups besides nitro may be introduced into the ring. Although the reaction produced a low yield at the end, the yield is calculated from the reaction and limiting reagent.
Keywords: electrophilic aromatic substitution, nitration, aldehyde, nitrating group

Electrophilic substitution happens in many of the …show more content…

Stage 1 of the mechanism of nitration

As the NO2+ ion approached the delocalised electrons in the benzene, those electrons were strongly attracted toward the positive charge.
Two electrons from the delocalised system were used to form a new bond with the NO2+ ion. Because those two electrons aren't a part of the delocalised system any longer, the delocalisation was partly broken, and in the process the ring gained a positive charge.
Stage two

Figure 2. Stage 2 of the nitration mechanism
The second stage involved a hydrogensulphate ion, HSO4-, which was produced at the same time as the NO2+ ion. This removed a hydrogen from the ring to form sulphuric acid - the catalyst had therefore been regenerated. The electrons which originally joined the hydrogen to the ring were now used to re-establish the delocalised system.
Table 1. Observations from the experiment proper

89 mL conc. H2SO4
Clear solution
+ 45 mL fuming HNO3
Clear solution
+ 10.2 mL benzaldehyde
Solution turns yellow if stirred continuously while adding benzaldehyde. But solution will produce red orange fumes and increase heat.
+ ice
White fluffy precipitate
After vacuum filtration
White gum-like precipitate
+ 125 mL diethyl ether
Precipitate dissolves and solution turns into pale yellow color
+ 125 mL 5% NaHCO3
Immiscible with solution. Golden yellow in color.

While the experiment was being executed,

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