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Isomers, and especially stereochemistry, can be tedious and complicated. However, there are huge practical applications of isomers. We have already covered some medicine and fats, but that is just scratching the surface. We'll look at some examples of common isomers and practice along the way.
Glucose and Fructose have the same molecular formula. Glucose (left) is found often in substances like rice, pasta, and breads. glucose provides energy very evenly, and makes you feel full. When you have bloodwork done, and receive a 'blood sugar' reading, you are really seeing your glucose levels. On the other hand, fructose is seen in soda and candy. An overabundance of fructose in a diet can lead to insulin resistance and type 2 diabetes. Fructose absorbs very quickly and is directly metabolized by your liver, which can lead to damage over time. Additionally, they do not make you feel full like glucose.
Galactose, another form of sugar, also has the formula C6H12O6, meaning it is an isomer of glucose and fructose. Try to draw another isomer of fructose and glucose. Then, identify what kind of isomers fructose and glucose are. Check your answer here. (There are many possibilities for a valid isomer)
Vitamin C is extremely important to many bodily functions. It keeps you healthy and helps out your immune system. Chemically, it is known by a different name, Ascorbic acid, with the formula C6H8O6. However, C6H8O6 has four forms that it can take on, which are shown below. The one your body uses is called L-ascorbic acid (Reminder that dashed lines show an atom behind the molecule, and a wedge shows atoms in the front). The L stands for "Levo", which just means left.
L-ascorbic acid is the top left compound
Identify the enantiomer of L-ascorbic acid, and mark any chiral centers in the molecule. Check your answer here.
Stereoisomers play a big role in our sense of smell. In fact, isomers of the same molecule can have very different scents. A chemical called carvone is one of these compounds. It has a formula of C10H14O. It has two enantiomers that give off two different scents. One of them is the chemical that gives scent in spearmint gum, a sort of sweet/mint smell. This is the R enantiomer. However, its other enantiomer gives the smell of carraway, which is a lesser known scent. Carraway is a slightly spicy scent which is found in many oils and fragrances. It is the S enantiomer. Shown below is a diagram of one of these enantiomers. Does this compound smell like spearmint or carraway? (Hint: remember the steps in the R/S system) Check answer here.
There is no quiz for this lesson. Review isomers with the flowchart below, then take the test.
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