Benzene and Benzene Compounds

Question 1

What is the molecular formula of benzene?

Answer 1

C6H6

Question 2

What was Kekulé’s structure like?

Answer 2

a ring structure with alternating single and double bonds

Question 3

What would be the IUPAC name for Kekulé’s structure of benzene?

Answer 3

cyclohexa-1,3,5-triene

Question 4

Did Kekulé’s structure turn out to be correct or incorrect?

Answer 4

incorrect

Question 5

What evidence is there that Kekulé’s structure is incorrect?

Answer 5

1, If benzene consisted of alternating single and double bonds, then it would react like a typical alkene. Benzene does not react by electrophilic addition. Therefore, benzene does not give a positive test for alkenes with bromine water. So this tells us benzene does not contain double bonds.
2, We can use X ray diffraction to measure the lengths of chemical bonds. In benzene the carbon to carbon bonds are all the same length whereas C-C bonds are measured to be longer than C=C bonds.
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