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I Smell Bananas

I Smell Bananas

Credit: oatsy40
Source: http://www.flickr.com/photos/68089229@N06/8462993806
License: CC BY-NC 3.0

Come, Mister tally man, tally me banana,

Daylight come and me wan' go home.

Come, Mister tally man, tally me banana,

Daylight come and me wan' go home.

“The Banana Boat Song” is a traditional Jamaican work song that was performed (among others) by the great calypso singer Harry Belafonte in 1956 and later became a hit single recording. The chorus (quoted above) talks about getting a count of the banana bunches loaded by the singer so he can be paid and go home.

Why It Matters

  • Alcohols and carboxylic acids are two classes of organic compounds that are very versatile starting materials. The alcohol hydroxyl group can be converted into almost every other functional group (including unsaturated derivatives and oxidation products). The carboxylic acid group can also undergo a variety of reactions. When reacted with one another, these two groups will form a class of compounds known as esters.
  • Esters are found throughout nature. Many low-molecular-weight esters contribute to the flavor and odor of plants. Isoamyl acetate plays a dual role. It is the compound responsible for the smell of bananas and it also functions as the alarm pheromone for the honeybee.
  • Credit: Limarie Cabrera
    Source: http://www.flickr.com/photos/limarie/4797925820/
    License: CC BY-NC 3.0

    Esters are commonly used in artificial flavoring for foods like chewing gum [Figure2]

     

  • One class of esters is a health concern. The triglycerides are long-chain esters made up of glycerol (a trialcohol) and three long-chain fatty acids. Triglycerides can easily be found in our favorite burgers or other fatty foods. Those extra pounds that plague many people are due to triglyceride storage in the body. When metabolized, the triglyceride will break down into glycerol and fatty acids which can be used as a source of biochemical energy.
  • Dacron is a synthetic polymer that is composed of the alcohol ethylene glycol and the dicarboxylic acid terephthalic acid. Dacron is a synthetic fiber used in clothing, making up about 50% of all fibers used. When combined with cotton, the fabric no longer requires ironing (or so they say).
  • Watch a video dealing with the synthesis of an ester: https://www.youtube.com/watch?v=h54XyEnYZDA

Use the links below to learn more about these products of alcohols and carboxylic acids, then answer the following questions.

  1. Which ester smells like bananas? Which ester smells like peach?
  2. What carboxylic acid is a component of body odor?
  3. Why should perfume evaporate easily?
  4. Name two esters used as anesthetics
  5. How large are the fatty acids in jojoba esters?

Image Attributions

  1. [1]^ Credit: oatsy40; Source: http://www.flickr.com/photos/68089229@N06/8462993806; License: CC BY-NC 3.0
  2. [2]^ Credit: Limarie Cabrera; Source: http://www.flickr.com/photos/limarie/4797925820/; License: CC BY-NC 3.0

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