12-5 Odorivectors Description: Samples of various odorivectors can be passed around for the students to smell. Concept

12-5

Odorivectors
Description: Samples of various odorivectors can be passed around for the students to smell.
Concept: There is a relationship between structure of a molecule and its odor. Humans sense of smell depends on a lock and key mechanism. If a person lacks the lock for a particular odor, they will be unable to sense it.
Materials:

• 
  3"x3" sheets of bond paper
  
• 
  Sandwich bags
  
• 
  Vanillin (Fluka Chemika)
  
• 
  Cinnamaldehyde (Fluka Chemika)
  
• 
  Caraway seed (Kroger's)
  
• 
  Vanilla beans (Bloomingfoods)
  
• 
  Spearmint leaves (Bloomingfoods)
  
• 
  Labels for samples
  

Safety: Inform students that there is a danger associated with using the sense of smell with chemicals. Students should be cautious of breathing powder into lungs or exposing themselves to harmful fumes. In lab, when a chemist wants to smell a chemical, she wafts the air from over the open bottle towards her nose. One should never smell directly from the bottle. Assure the students that the chemicals presented to them in class are safe to be smelled.
Procedure:

Place a drop of cinnamaldehyde on each sheet of bond paper and give one sheet to each row of students. Ask students to identify odor. A student who does not detect any odor may have anosmia, which means he/she may be missing the corresponding receptor protein - the "lock" in the lock and key theory.

Pass out pairs of sandwich bags with caraway seed and spearmint leaves. Difference in odor is due to the d and l forms of carvone (See Atkins Molecules pp 133-134).

Compare the odor of vanillin (one odorivector or key) with the rich aroma of vanilla beans (many odorvectors).

Clean-up: Be sure to retrieve all the materials from the students.
Notes: Developed for Prof. Ewing's C100 course.

12-5