Fresh and Clean Perfume
How do perfumers evoke freshness in perfume? What do we mean when we say something smells clean? Let's dive right in.
But first: Imagine for a moment you are doing laundry, I know, exciting stuff right? As you open up the dryer door to remove your warm fluffy clothes, you are enveloped with the delightful aroma of "spring meadow" or "mountain breeze." As consumers, we tend to associate these types of laundry fragrances with the word clean. But why is that? How did laundry care perfumers invent the smell of clean?
It is important to mention that pretty much any fragranced product you use required the formulation expertise of a perfumer. Whether it is a shampoo, a deodorant, or heck, even a scented trash bag! A perfumer was tasked to formulate a fragrance for that very specific application. In the case of your favorite laundry detergent, there are perfumers that specialize in formulating for this very specific product (well...aside for the unscented ones). So how do they do it?
When constructing a fragrance it is very important to understand how the consumer will interact with it. For fine fragrance (perfumes/colognes) that interaction is very straightforward. The user will spray their wrists, neck, perhaps their clothing, and they are on the move! With laundry care fragrances (detergents/softeners/etc.) It is a bit more technical... A detergent fragrance needs to cling to the clothing and withstand the rinse cycle and the high heat output of your dryer.
Here's how it's done:
Aldehydes, Schiff bases, and musks oh my! When it comes to formulating for tenacity, these are the go-to ingredients for laundry care perfumers. An aldehyde is a type of molecule that contains a carbonyl group attached to a hydrogen. It looks like this:
Aldehyde C-12 MNA (2-methyl undecenal)
In the case of Aldehyde C-12 MNA, it has a very fresh sparkling watery aroma. If you have ever smelled the top note of our perfume Mirage, you have without a doubt experienced what this molecule can do when it comes to boosting freshness.
When people smell this molecule for the first time, they often say it reminds them of clean laundry. And this is true! This molecule is used a LOT in laundry... But there is a bit of a caveat. You see, in the world of perfumery, linear chain aldehydes, like the one above, aren't the longest lasting of materials. To improve the substantivity of these compounds, they need a little help. That is where Schiff bases come into play. Quite simply, a Schiff base is a special molecule formed when an aldehyde reacts with a primary amine. In perfumery, that primary amine is ALMOST ALWAYS methyl anthranilate (yes, there are exceptions, but lets move along here!)
Methyl Anthranilate (Methyl 2-Aminobenzoate)
By itself, methyl anthranilate is an immensely important material in perfumery. Smelled in isolation, it smells strongly of concord grapes and orange blossoms. This comes as no surprise as the compound is naturally occurring in both. That's right, methyl anthranilate can be naturally derived or synthetically produced, but either way it is still the same compound. So, when a Schiff base is formed, the two molecules combine to create a much larger molecule that shares the odor characteristics of the starting materials. Not only does this newly formed molecule smell of clean laundry, concord grapes, and orange blossoms, it also lasts a very very long time! This is because the molecular weight is now much larger. Keep in mind that in perfumery, bigger molecules = longer lasting, and vise versa! Molecules like this are used all the time in laundry care, and there are so many different combinations for perfumers to work with. Take for instance hydroxy citronellal, a compound smelling of fresh airy lily of the valley flowers. It too can react with methyl anthranilate to create a Schiff base. As a matter of fact, this reaction produces the most popular Schiff base of them all, it is most often referred to as Aurantiol. The byproduct in this reaction is good ole' H₂O (water), which is then removed to purify the product.
The beauty of Aurantiol is that it smells harmoniously lily of the valley and concord grapes. Even better, it can withstand the wash and dry cycles of your laundry routine, leaving you with fresh smelling clothes even days after you have washed them!
Oh, and a fun fact regarding Schiff bases: Most of them (Aurantiol included) are super vibrant in color. Just a small addition of these compounds to a fragrance formula turns the whole mixture into a neon yellow or orange. Check out this picture below of a fragrance oil I made containing 6% Aurantiol:
And now we move onto our next subject....Musks:
...No, not that one! When we are talking about musks in perfumery, we are talking about the long lasting base notes that anchor compositions down. There are a few categories of musks used in perfumery: Polycyclic musks, macrocyclic musks, alicyclic musks, and nitro musks. (we can address these more exhaustively in another post). Its a bit tricky to describe the smell of musks, but they all lend a unique sensual aspect to compositions. Some people describe musks as smelling of "your skin, but better." Of course, all musks are different; some are a bit waxy, or metallic while others can even be a little animalic.
An example of a very commonly used musk is Ethylene Brassylate. Check out the structure below:
Ethylene Brassylate (1,4-dioxacycloheptadecane-5,17-dione)
Personally, I find that this molecular structure looks like a Wooly mammoth, just sayin'.
Anyway, you will find this ingredient pretty much everywhere; perfumes, hand soap, air fresheners you name it! Musks are useful tools for perfumers as they have the ability to trap and anchor fleeting materials so that they linger longer. For instance, when you smell your favorite laundry detergent, you might notice the fruity banana apple top note. This top note is made up of smaller highly diffusive molecules that are rather short lived. By incorporating musks into a formula, the lifespan of these top notes are effectively increased. Keep in mind, however, that there is no silver bullet for longevity in perfumery. While musks help anchor top notes, its only to a certain extent. It is the perfumers responsibility to select ingredients carefully as a means to best perform in their target application.
If you are interested in taking a look at what a full laundry care fragrance formula looks like, check out the following link to an IFF demonstration formula (page 4 of the PDF):
Thanks for checking out this blog post! Now you know just a little bit more about laundry detergent than the average joe ;) If you like this type of content, be sure to follow me on Instagram and Facebook
As always, if you have any questions or ideas for future content, feel free to post a comment!