Answer to Question #338652 in General Chemistry for Austine

Question

9. The antibiotic thiarubin-A was discovered by studying the feeding habits of wild

     chimpanzees in Tanzania. The structure for thiarubin-A is

a. Complete the Lewis structure showing all lone pairs of electrons.

b. Indicate the hybrid orbitals used by the carbon and sulfur atoms in thiarubin-A.

c. How many σ and π bonds are present in this molecule?

Answer 1

a. The only lone pairs on this structure exist on the sulfurs. All of the carbons are are sufficiently bonded to other atoms.

b. Moving from left to right, sp³, sp, sp, sp², sp², sp², sp³, sp², sp³, sp², sp². Atoms connected to four things are sp³, atoms connected to three things are sp2, atoms connected to two things are sp.

c. Every bond (remember to count each individual CH bond) is a sigma bond. All additional bonds are pi bonds. There are 23 sigma bonds and 9 pi bonds.