Does pyridine undergo nucleophilic aromatic substitution reactions? If no, why not. If yes, on what position does the substituti
on occur? Use resonance contributors to justify your answer.(15 points) b) Draw the tautomers of 2-hydroxypyridine and 4-hydroxypyridine (5 points)
1 answer:
Explanation:
Part a
Pyridine is an aromatic heterocyclic compound and undergoes nucleophilic aromatic substitution reaction at 2 and 4 positions.
This is because, when a nucleophile attack pyridine at 2 and 4 positions, the anoin formed is stabilized. In the anion formed is tabilized by resonance and also negative charge is present at electronegative atom, nitrogen.
If the nucleophile attack at 3 position, the anion formed is not as stable as anions formed when nucleophile attach at 2 and 4 positions. This is because negative charge is not present at the nitrogen atom.
Part b:
Tautomers are structural isomers of each others formed by migration atom within the molecule. Tautomers exist in equilibrium with each other.
Tautomers of 2-Hydroxypyridine and 4-Hydroxypyrine are given in the attachment.
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Answer : The amount of reactant left in excess is 13.1075 grams.
Explanation : Given,
Mass of = 26.5 g
Mass of = 10 g
Molar mass of = 53.5 g/mole
Molar mass of = 40 g/mole
First we have to calculate the moles of and
.
Now we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,
From the balanced reaction we conclude that
As, 1 mole of react with 1 mole of
So, 0.25 moles of react with 0.25 moles of
From this we conclude that, is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Moles of remaining excess reactant = 0.495 - 0.25 = 0.245 moles
Now we have to calculate the mass of .
Therefore, the amount of reactant left in excess is 13.1075 grams.