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Aromatic Chemistry
Benzene, Aromatic Reactions and Mechanisms.
Question | Answer |
---|---|
What Shape is Benzene: | It is a Planar molecule. |
Why is Benzene more stable than theoretical alternate single and double bonds? | Because it has a Delocalised system of P electrons above and below the ring structure, essentially giving each c-c bond 3 electrons. Making it slightly between a Single and a Double bond. |
What is the bond length in benzene Carbon bonds? | It is an intermediate of the C-C bond which is longer (154pm) and C=C (135pm) of 140pm. This is because of the delocalised electrons present. |
Why does Benzene undergo Electrophilic Substitution rather than addition? | Because the loss of a H+ ion from the Carbocation formed by adding a group to bezene will restore its Aromatic properties by recreating the Cyclic Pi-System of electrons. |
Name two reactions that occur with Benzene required: | Nitration (by Nitronium or Nitryl Ion) of Benzene and Fidel Crafts acylation. |
Give the conditions, name the mechanism for and uses of the products from the Nitration of Bezene: | Conc H2SO4 and HNO3 acids are present to prepare the electrophile, done at under 50degrees C to prevent further substitution of NO2 groups. Electrophilic Substituition. Uses are to form TNT, and Amines. |
Give the conditions, name the mechanism for and uses of the products from the Acylation of Benzene: | Undergoes Electrophilic Substitution. Done with AlCl3 Catalyst and products formed are useful in creating other substituted Aromatic compounds. |
Why is the Hydrogenation of Bezene less exothermic than expected if it was alternate double bonding? | Because the stability of benzene comes from the delocalised Pi System of eletrons, this causes increased stability, thus less energy can be lost when hydrogenated. |