Extra Credit: Briefly explain how dibenzalacetone can potentially work as a sunscreen? How does it differ from Zinc oxide or titanium dioxide? (4 pts) Solution Dibenzylideneacetone is prepared from acetone & benzaldehyde, when acetone is replaced by cyclic ketones.The structural variations in resulting conjugated ketones produces variations in the UV?vis absorption spectra. The choice of the best sunscreen agent based on these variations. The chemical structure of dibenzalacetone makes it highly stable and ideal for use in a compound like sunscreen. Sunscreens use dibenzalacetone because it absorbs UV rays, preventing them from absorbing into the skin itself. There are basically two types of sunscreens i.e. Organic Compounds and Inorganic Compounds. Zinc Oxide or Titanium oxide are inorganic(Having energy gap equivalent to energy of incident UV light) sunscreen. They act as physical barriers which prevent UV rays to come into contact with a user\'s skin. They are more visible(come in a thick whitish paste). Hard to apply and must be applied frequently. On the other hand Dibenzalacetone is an organic(Absorb UV energy to convert into thermal energy) sunscreen. They are unable to provide constant UV protection over a long period due to UV induced degradation. They also have some side effects and can cause skin cancer(due to aromatic rings). .

1. Extra Credit: Briefly explain how dibenzalacetone can potentially work as a sunscreen? How
does it differ from Zinc oxide or titanium dioxide? (4 pts)
Solution
Dibenzylideneacetone is prepared from acetone & benzaldehyde, when acetone is replaced by
cyclic ketones.The structural variations in resulting conjugated ketones produces variations in the
UV?vis absorption spectra. The choice of the best sunscreen agent based on these variations.
The chemical structure of dibenzalacetone makes it highly stable and ideal for use in a
compound like sunscreen.
Sunscreens use dibenzalacetone because it absorbs UV rays, preventing them from absorbing
into the skin itself.
There are basically two types of sunscreens i.e. Organic Compounds and Inorganic Compounds.
Zinc Oxide or Titanium oxide are inorganic(Having energy gap equivalent to energy of incident
UV light) sunscreen. They act as physical barriers which prevent UV rays to come into contact
with a user's skin. They are more visible(come in a thick whitish paste). Hard to apply and must
be applied frequently.
On the other hand Dibenzalacetone is an organic(Absorb UV energy to convert into thermal
energy) sunscreen. They are unable to provide constant UV protection over a long period due to
UV induced degradation. They also have some side effects and can cause skin cancer(due to
aromatic rings).