How many sigma/pi bonds are in the aspirin structure?

1 Answer
Truong-Son N.
May 1, 2016

Aspirin is the brand name for acetylsalicylic acid, which is the common name for 2-(acetyloxy)benzoic acid. This compound looks like this:

https://upload.wikimedia.org/

In a single bond, you have a single #sigma# bond.

In a double bond, there is one #pi# bond in addition to the single #sigma# bond that constituted the single bond.

Thus, if we treat each double bond as a single bond on this structure, we count up the #sigma# bonds as:

  • 5 #"C"-"O"# #sigma# bonds (2 from the carboxylic acid group, and 3 from the acetate group)
  • 2 non-aromatic #"C"-"C"# #sigma# bonds (1 from the carboxylic acid group, and 1 on the acetate group)
  • 6 aromatic #"C"-"C"# #sigma# bonds (on the benzene ring)

Then, in accounting for the particular bonds that are double bonds, the remaining #pi# bonds are from:

  • 2 #"C"-"O"# #pi# bonds (1 from the carboxylic acid group, and 1 from the acetate group)
  • 3 aromatic #"C"-"C"# #pi# bonds (on the benzene ring)

Thus, we have 5 + 2 + 6 = 13 #\mathbf(sigma)# bonds and 2 + 3 = 5 #\mathbf(pi)# bonds.

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