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Chemistry LibreTexts

Fatty Acids

  • Page ID
    439
  • Fatty acids are merely carboxylic acids with long hydrocarbon chains. The hydrocarbon chain length may vary from 10-30 carbons (most usual is 12-18). The non-polar hydrocarbon alkane chain is an important counter balance to the polar acid functional group. In acids with only a few carbons, the acid functional group dominates and gives the whole molecule a polar character. However, in fatty acids, the non-polar hydrocarbon chain gives the molecule a non-polar character.

    • Hydrogenation of Unsaturated Fats and Trans Fat
      Saturated fats have a chain like structure which allows them to stack very well forming a solid at room temperature. Unsaturated fats are not linear due to double bonded carbons which results in a different molecular shape because the sp2 carbons are trigonal planar. This causes the fat molecules to poorly stack resulting in fats that are liquid at room temperature. Unsaturated fats can be converted to saturated fats via hydrogenation reactions.
    • Introduction to Fatty Acids
      Fatty acids are carboxylic acids with long hydrocarbon chains. There are two groups of fatty acids--saturated and unsaturated. Recall that the term unsaturated refers to the presence of one or more double bonds between carbons as in alkenes. A saturated fatty acid has all bonding positions between carbons occupied by hydrogens. The melting points for the saturated fatty acids follow the boiling point principle observed previously.
    • Prostaglandins
      Prostaglandins were first discovered and isolated from human semen in the 1930s by Ulf von Euler of Sweden. Thinking they had come from the prostate gland, he named them prostaglandins. It has since been determined that they exist and are synthesized in virtually every cell of the body. Prostaglandins, are like hormones in that they act as chemical messengers, but do not move to other sites, but work right within the cells where they are synthesized.

    Thumbnail: A ball-and-stick diagram of arachidonic acid. Image used with permission (Public Domain; SubDural12). Arachidonic acid is a polyunsaturated fatty acid present in the phospholipids of membranes of the body's cells, and is abundant in the brain, muscles, and liver.