The Science of Scented Markers

Children love to color. Getting your first set of markers is almost like a rite of passage. It used to be “cool” just to get have even the plain 8 crayola colors, but now that there are so many types of markers out there, who needs the originals? Continuing with our recent theme if marker-based posts, we are here to talk about the oh so popular Mr. Sketch Markers! So how does the scent of banana, apple, and licorice get into the ink of a marker? It can all be attributed to what chemistry refers to as esters. 4.22

Where did the idea start?

Esters have been around forever. Seriously, forever. Naturally occurring esters can be found in almost every fruit in the world. In fact, perfumes and other fragrance-containing items were used throughout history by royalty before anyone even knew the actual chemistry behind them.

In the early 1800s, scientists finally began to question where the mysterious scent came from, and how they could make it last longer. The first ester was believed to have been synthesized in a laboratory in the 1800s, but information surrounding the event is vague and the name and date of the scientist to do so has been lost.

Later, German chemist Leopold Gmelin was credited with coining the term “esters” in his published paper in 1848. From this point on, esters were more commonly known and produced in laboratory settings for commercial value.

With the aid of technological advances throughout the next century, scientists can currently produce almost every scent known to man using the synthesization reaction use of esters.


How are they made?

Esters are the result of a combination of an alcohol and a carboxylic acid. The science here is mostly classified as organic chemistry because it puts a large focus on functional groups. Functional groups are groups of atoms bonded together in a specific pattern that reveal specific chemical properties. The structure of an ester functional group is shown below. Note the distinct central Oxygen atom, an easy way to categorize the molecule as an ester.

The formation of an ester is a result of a multi step chemical reaction as shown below. For example purposes, the reaction shows an arbitrarily chosen acid and alcohol combination. However, in reality, different combinations of these two requirements will yield different ester scents and characteristics.

As mentioned before, the chemical reaction to form an ester is a result of the combination of an alcohol and carboxylic acid. The conditions for ester formation are very specific. It requires a catalyst of concentrated sulfuric acid and the addition of heat. This means the reaction is endothermic and has a positive change in free energy, or in other words, it has a catalyst and requires an activation energy.

This reaction is also known to be sped along by using LeChatelier’s Principle. By adding excess alcohol or acetate in the formation can aid in pushing the reaction to produce more ester. In addition, a common technique used by manufacturers is to evaporate the water, also forcing the reaction to the right.

By adding the ester solution to the natural dye of the marker, Mr. Sketch is essentially creating a scented ink. So when we draw on paper and smell the result, what we’re really recognizing is the presence of esters.


Where else do we find esters?

Esters have tons of uses that benefit everyone from the prankster to the king. Have you ever smelt a stink bomb? That is an ester. Have you ever smelt perfume? That, too, is made from esters. The wide variety of ester combinations allow for a plethora of smells, both good and bad.

But lets focus on the good. Every scented perfume, shampoo, and creme makes use of esters to produce the smell that we the consumers find so appealing. Lab workers labor tirelessly to mix and combine different ester scents to create newer, better smells every day.

Another, unexpected, use of esters is actually in the production of polymers. Liquid esters of low volatility often serve as softening agents for some resins and plastics. Plexiglass, a solid transparent plastic, is composed of Polymethyl methacrylate, Terylene, Fortrel, and Dacron contain polythylene terephthalate as a film or fiber.


What now?

          As you can there are many wonderful uses for esters in the world around us. As complicated as esters are, there are hundreds of things in your house right now that are made using this process. From cleaners and perfumes, to candy and markers, esters are all around us making our lives smell differently, for better… or worse! Good thing we have Mr. Sketch Markers brighten the day and “make the stench go away”!

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