Glossary of organic molecule smells

[keyestothefuture]

Hey everyone basically this is going to be a thread devoted to cataloguing as many smells for organic compounds as possible, to compile a definitive list. The human olfactory system is incredibly powerful, but it is difficult to put your chemoreceptors to good use without knowing what the various scents represent.

Allow me to start:

Butanal: Rancid butter

Octanal: Citrus (oranges)

Nonanal: Roses

Sorry these aren't more ordered, they're just off the top of my head at the moment. Smell with caution!

[Velocity_Boy]

• Fragrant (e.g. florals and perfumes)

Fruity (all non-citrus fruits)

Citrus (e.g. lemon, lime, orange)

Woody and resinous (e.g. pine or fresh cut grass)

Chemical (e.g. ammonia, bleach)

Sweet (e.g. chocolate, vanilla, caramel)

Minty and peppermint (e.g. eucalyptus and camphor)

Toasted and nutty (e.g popcorn, peanut butter, almonds)

Pungent (e.g. blue cheese, cigar smoke)

Decayed (e.g. rotting meat, sour milk)

[Function]

• The smell of rotting intestine contents (e.g. dissection class went wrong)

Setting up such a list is quite useless: every smell is unique in its own way, and you can try to compare it to known smell, or try to describe it using some adjectives (sweet, ...), but every smell is different and there are probably thousands of different smells we would be able to distinguish.

 

Note that every smell is composed out of combinations of hundreds of different particles, each having their own 'smell', contributing to give rise to a certain scent, and it is thought that every such component would have its olfactory receptor, or to have much more affinity for one receptor than for the other(s). It is thus understandable that, however some scents may be comparable and close to one another, it is useless to make a list of scents, for it would be non-limitative. I don't see the practical use of it.

Edited April 5, 2017 by Function

[keyestothefuture]

@Function I agree such a list would be pointless. I apologise for not being clear with my wording. The purpose was not to simply create a list of scents, but rather to create a list of smells associated with certain molecules. For example, butanal always smells like rancid butter and nonanal always smells like roses. My intent was for users to post scents with an associated molecule. I hope I have made this clearer.

[StringJunky]

Methanethiol (Mercaptan) - Rotting cabbage smell used as an olefactory label in domestic gas.

Citronellol - Lemon

Limonene - Orange

Carvone - Spearmint

Eugenol - Clove
Ethyl Maltol - Caramel

Vanillin -Vanilla

Anisole -Anise

Thymol -Thyme

Trimethylamine - Rotting fish

Putrescine Diaminobutane - Rotting flesh

Cadaverie - Rotting flesh

All from this page: https://en.wikipedia.org/wiki/Aroma_compound

[Velocity_Boy]

 

• The smell of rotting intestine contents (e.g. dissection class went wrong)

Setting up such a list is quite useless: every smell is unique in its own way, and you can try to compare it to known smell, or try to describe it using some adjectives (sweet, ...), but every smell is different and there are probably thousands of different smells we would be able to distinguish.

 

Note that every smell is composed out of combinations of hundreds of different particles, each having their own 'smell', contributing to give rise to a certain scent, and it is thought that every such component would have its olfactory receptor, or to have much more affinity for one receptor than for the other(s). It is thus understandable that, however some scents may be comparable and close to one another, it is useless to make a list of scents, for it would be non-limitative. I don't see the practical use of it.

A list of basic smells is no more useless as is a periodic table of the elements.

 

Sure, there are many smells and most are in fact combinations of two it more basic smells.

 

You know, just like matter is often a combo of elements? LOL there really is little difference.

 

Smell and your olfactory system are incredibly important. Smell has significant impact on your personal well being and mental health. It's used in therapy. It's been used to treat PTSD. It can indeed cause flashback episodes in people suffering from PTSD. It determines how much you enjoy your food. No smell equals no taste, amigo.

 

What is smell? Did you know the only thing that determines odors and the difference in how we perceive them is shape?

 

Yes...The shape of the gaseous molecules emitted from the source.

 

LOL...That's all odor is. The particular shape of molecules when they're detected by your olfactory system.

 

I find this very cool.

 

Hope this helps.

[Function]

You know, just like matter is often a combo of elements? LOL there really is little difference.

 

Smell and your olfactory system are incredibly important. Smell has significant impact on your personal well being and mental health. It's used in therapy. It's been used to treat PTSD. It can indeed cause flashback episodes in people suffering from PTSD. It determines how much you enjoy your food. No smell equals no less taste, amigo.

 

LOL...That's all odor is. The particular shape of molecules when they're detected by your olfactory system.

 

Changed something there, hope you don't mind.

 

So how does that differ from what I said? Eventually receptor affinity is determined by shape (and charge, polarisation, ...)

 

I never argued that smell wasn't important, and I feel sorry for e.g. people with Kallmann syndrome. Yet, at the moment it is - in my most humble opinion - quite indisputable that the way by which the composition of matter by using the periodic table is studied is less diverse (at the moment), more understandable and more important for lots of disciplines: chemistry, physics, pharmacy, medicine, biology, ...

 

There are some more than a hundred elements in the periodic table - there would be hundreds, thousands of different scent particles contributing to a single scent in a more or less way in an olfactory table. Working with it would be impractical, and making it would not be cost-effective.

 

By the way, I found the way you would set up such table rather ambiguous: please describe the "chemical" smell you try to illustrate? If I were to hang my nose above a glass of wather dissolving an effervescent tablet, I'd also describe it as "chemical".

Edited April 6, 2017 by Function

[keyestothefuture]

@Velocity yes I agree. Very cool, which is part of the reason I set up this thread. Especially when you consider that you can smell the difference between a molecule 8 carbons long and a molecule 9 carbons long. Coolest sense, and you have two "classical" senses devoted to it, taste and smell.

@Function obviously smaller simpler compounds such as carbon dioxide don't have a notable scent, but for the more complex ones, they are often the active agents for many of the aromas in everyday life, like the ones that StringJunky posted. So I suppose a better way of phrasing it would be: List the organic compounds responsible for certain scents. As I said before, trying to assign as many smells to as many molecules as possible.

[CharonY]

Well, there is a difference between associating a specific compound with a given smell as compared to odor that are the result of complex compounds or otherwise very unspecific and thus, more of a word association than a categorization.

 

For example, ammonia and bleach smell very different, so giving it the same name ("chemical") is more a word association than what I assume OP is aiming for. Fruits have very different smells, caused by a variety of esters and other compounds.

It would make more sense to call Methyl butyrate "fruity" (or pineapple-y?) and isoamyl acetate banana-like, than call all fruits fruity for example.

[hypervalent_iodine]

A list of basic smells is no more useless as is a periodic table of the elements.

 

...the periodic table is quite a bit more useful / informative than a random and inherently incomplete list of compounds by smell.

 

Also worth noting for the OP that some chemicals that have what would usually be called very distinctive smells can be either not detected or have a completely different smell depending on the person. I can't detect pyridine very well, but I can tell you in a second the identity of many organic solvents by smell. I have another friend who thinks some thiols smell quite pleasant (like gummy bears was his description), whereas most sane people can't stand the odours they give off.

 

Many chemicals also have smells that I would say are very difficult to describe. I've worked with lachrymatory agents extensively in the past, and their smells are very unique, though I could not honestly think of how to explain what it's like. I guess my closest description for those (3- and 4-methoxybenzyl halides) would be, smells like pain and crying, which probably isn't very helpful.