Which Functional Groups are the Best Smelling?

In this video, I JUDGE functional groups, and decide which ones smell best and worst!
/ thatchemist
Community Discord - / discord
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Links to articles discussed in this episode:
difluorobenzodioxole paper - www.doi.org/10...
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[@Ceneij]

Love how you seperated amines into three groups only to put all three in F tier.

[@That_Chemist]

Yep!

[@danielaustin7643]

Some primary amines are uniquely bad they have names like putrascine and cadaverine for a reason

[@knutritter461]

@That Chemist I had to work with amines for some time.... I always think of the garbage bin in hot summer when you put fish or prawn remains inside... Yummy! 😂 I washed my hands regularly with citric acid to get rid of that smell. Have you ever wondered why you get slices of citron in hot water in a good restaurant when you eat shellfish? 😂

[@joshua9991000]

Haha, Amines are pretty terrible. I worked with Trimethylamine to make various flavours the odour is so terrible.

[@NormReitzel]

@@knutritter461 Citric acid - hadn't thought of that one. I used ascorbic acid -0 cause I had an 800 lb barrel of it, about half full.

[@JPLYUKI]

Ester synthesis labs are always a fun introduction to the wide world of organic synthesis. Smells great, every reaction is a new experience, and the students learn something very important: you should always waft the smell towards you. One time we did this for a high school class, and one kid placed his nostril over a test tube and took a deep breath of a propanoate ester. He said it felt like a pineapple punched him in the nose.

[@That_Chemist]

Oh no haha

[@sleepyboi2232]

Ah. I have been that kid once. Never again

[@lucassund8605]

Now i really want to try it

[@richardwebb5317]

Ester practicals are a highlight of 16+ courses. The butyrates however are forbidden fruit as most of us do not want butyric acid smells in our labs. Just about thole propionate. Benzoates rule. Methyl Salicate is one I always make sure gets made - a very familiar smell in schools. (That one not S tier!)

[@kevsonkeyboard]

For those who aren't familiar with chemicals and chemisty, please do NOT huff these or any chemicals. always waft the vapors with your hand up towards your nose. Sometimes it's a fast-track ticket to the floor.

[@surkey5055]

Especially with ethers or chloromethanes

[@TheRandomshite123]

We once had a lab where we had multiple beakers at the end, some were organic some were halogenated and no one had labelled their waste, so the lab techs had to go around the fume hoods smelling every beaker to determine which waste it went in

[@AlTheDrummah]

My colleague almost screwed himself with ammonium nitrate (aq) this way

[@tuskedwings7453]

yeah, don’t be a chem sniffer

[@itsovermyhead940]

@TheRandomshite123 I feel like that's genuinely terrifying

[@friedchickenUSA]

in a synthesis exercise i got to smell 2-methylpentanal, which had a strong nutty smell. i think it was nice, but surprising how it overpowered the diethyl ether it was dissolved in. the product was 4-methylheptan-3-ol which i described in my notes as "cut grass vegetable mint soup-tea". had to sniff it for a while to find the right words.

[@That_Chemist]

Interesting!

[@godzillaworks4585]

Homestuck

[@marcopolo8584]

homestuck

[@godzillaworks4585]

@@friedchickenUSA I really don't need to be, homestuck has already ruined my life

[@hailhydrazine4938]

I feel that the smell of a lot of compounds depends entirely on the concentration (?), someone was making some organoselenium compound in the hood next to mine, it first smelled like baked beans, then after a while it smelled like moldy meat, then it smelled like death

[@That_Chemist]

Yeah that’s a valid point

[@waterunderthebridge7950]

Isn’t there also a decomposition/faeces compound (I think skatole) that smells like flowers and nice things in very low concentrations but turns to literal sh*t and death at higher concentration

[@koukouzee2923]

You got a point but I think the tierlist should be based on the smallest concentrations (just wiffs) Mostly because you dont wanna be taking breaths of ethers or those scary fluorine/sulphur compounds

[@eier5472]

Similar with organosulfur compounds. I went from "who brought onions" over "Jesus what did you eat to let out this fart" to "OH SHIT GAS LEAK"

[@hammerth1421]

True. The thresholds also change from person to person. For me, geraniol becomes unpleasant much sooner than it does for the average person which means that many "flowery" perfumes and shampoos smell like the unpleasant "green-ness" of geraniums to me.

[@Mejsiek]

17:57 I totally agree, solid 100% for F-tier also from me. I almost threw up when I worked with cyclopentyl mercaptan which reminded me of rotten onion + chives but surprisingly cyclohexyl mercaptan reminded me of cat urine (just change of -CH2- group). Someone in comments mentioned about concentration - they're absolutely right, benzyl mercaptan in very small concentrations smell like morning coffee, then turns into garlic to finish as burned rubber. I remember, once after work I entered my dad's car and he immediately started panicking because he thought something was burning in the car. There is one unusual exception - although thiophenol reeks, thionaphthol smells like forest edible mushrooms. Maybe it depends on individual perception?

[@That_Chemist]

Yeah benzyl mercaptan is a perfect example

[@Trifosgene]

Yes cyclohexyl mercaptan smells definitely like cat urine

[@1brytol]

Cold benzaldehyde is like the best smelling compound ever. Key word COLD. I remember my first dibenzylideneacetone synthesis. I didn't use an alcohol to dissolve the benzaldehyde, and it was on excess, so the product dissolved in it. I had to boil it off to recover the product. It basically smelled like rotting, burned, old and potentially toxic cherries. Or if someone took a shit into cherry compot.

[@FUCKTHEBBC]

good for animalic cherry fragrances lol xD

[@IlusysSystems]

I was trying to synthesize benzaldehyde and counted on fact, that people consider it very nice cherry smelling. Well... It's not really at least when not cold and concentrated... it almost smells like chloro toluene with slight cherry undertone. Really awful...

[@jeffhurckes190]

A mine I used to work in used methyl mercaptan as part of their emergency alert system. When there was a situation that required everyone to report into the refuge chambers underground, a 10lb bottle of this stuff was dumped into the fresh air supply for the mine. I felt sorry for the person who had to release it.

[@That_Chemist]

Oh my gosh, that’s brilliant

[@richardwebb5317]

A mercaptan plant blew up once near Paris. The gas company in Southern England was inundated with reports of leaks.

[@ethanreddekopp7256]

2:00 nilered released a video of him making thioacetone back in january or February. He said up close it didnt have a significant smell (the cameraman disagreed) but the farther away he got, the stronger the odor was.

[@Alpha13Wolf]

“Burning fruity skunks” has to be the best and most accurate description of a fragrance ever.

[@YuPuWang]

I have my personal fragrance research going on for a while and have a small collection of aroma chemicals. Personally I think while functional groups do matter a lot, the overall structure, shape, and specific features (like the distance between certain functional groups) are also very important contributors to the odor of a compound. For example, spherical or nearly spherical molecules (or parts of molecules) tend to smell camphoraceous or maybe a bit minty regardless of functional groups. This is probably why tert-butyl or cyclohexyl compounds tend to have such smell though they aren't technically 'functional' groups. I once worked with p-carborane which is an eicosahedral molecule C2H12B10 or (CH)2(BH)10 and was surprised by its scent - strikingly similar to camphor! Also, just think of the wide variety of musky-smelling compounds. Nitroarenes can smell musky (e.g. musk ketone, musk xylene) - the first artificial musks were discovered accidentally in an attempt to make explosives. Polycyclic musks are the most widely used today and they are typically benzo-fused (oxa)cyclopentane/cyclohexane derivatives. And natural musks are usually macrocyclic ketones. My all-time favorite smell is muscenone - such an elegant, sensual, sophisticated, and sweet scent! It can even have floral and woody undertones. Also concentrations matter. While thiols are bad at 'normal' concentrations, trace amounts contribute to the 'natural-ness' of many fruits, vegetables, meats, rosted/baked foods, and even roses! Aliphatic aldehydes while pungent at high concentrations, are important in trace amounts in so-called 'aldehydic' notes in perfumery. Some say they make the floral scents sparkle and some say they make perfumes more 'intimate' or 'sensual' smelling like a real person's skin or hair with some sebum on it. But overdosing them does make that old-person or metallic smell. The same goes for nitriles - people say they typically smell like their aldehyde counterparts but sharper and a bit more metallic. Trace amounts of nitriles are good as aldehyde substitutes in fragrances especially for functional products like detergents due to their greater stability. Back to functional groups - if I have to rank the best smelling functional groups, I'd have lactones separate from esters. If esters are S tier lactones are definitely S++. Gamma-decalactone, undecalactone, and dodecalactone are the soft, fuzzy, and powdery part of peaches. And interestingly enough, according to several Japanese studies, the former two contribute significantly to the natural body scent of young women of 10-30 age. Delta lactones just remind me of tropical paradise - coconuts, fruit cocktails and suntan lotions. Delta-jasmolactone is wonderfully soft, creamy and floral at the same time. And it's hard to forget how good those macrocycic lactones smell like once you take a first whiff of ambrettolide.

[@That_Chemist]

Wow, I wish I could smell all of these!

[@PerfectRodo]

Amazing! Are there commercial fragrances that you would recommend for experiencing lactones?

[@janmelantu7490]

Ester Synthesis was one of our labs in Engineering Chemistry (which is GenChem and OChem crammed into one year) and it was by far the best the lab smelled that year.

[@That_Chemist]

awe yiss

[@owenyoshida9202]

sina toki e toki pona anu seme?

[@InterFelix]

@@owenyoshida9202 what makes you think that?

[@makylemur7019]

Tributyl phosphite has a skunky odor. Back in the 1970s I was cleaning out a fume hood with a bottle of tributyl phosphite. The bottle was covered with a slime so when I picked it up it slipped out of my hand and fell onto the floor and broke. I then mopped up the spill and put that mess into a sink. Unbeknownst to me all the sinks in Bagley Hall (chemistry building) on the University of Washington were connected to a single trap. So I succeeded in stinking up the entire building leading to an unorganized evacuation of the building. Tributyl phosphite per the poison control center is not significantly toxic. Its only effect is to make anyone who comes in contact with it to stink. Any mild oxidizer will get rid of the stink.

[@That_Chemist]

That sucks so much

[@robertlapointe4093]

Diphenylether has a very potent smell (it is used as a substitute for ambergris in perfume bases) that is somewhere between very unpleasant and suffocating. A production plant where I worked in an earlier job blew a rupture disk one cold January day in Michigan and it actually was snowing diphenylether over the plant site. Our building didn't shut down the air handlers fast enough and most of that day was spent trying not to vomit.

[@That_Chemist]

hahaha that's amazing

[@YuPuWang]

I've worked with diphenyl ether (as a high-temp solvent) a couple of times. To me it smells like the sharpest greenness of geraniums. Not necessarily a bad smell in low concentrations, though.

[@avagadrhoe768]

you're the best smelling functional group in my opinion, joey 😍

[@That_Chemist]

Smh

[@snared_]

I can smell your profile picture sir

[@chrisboyall8602]

Some guy in my undergrad lab project, tried drying (yes drying) ether in the glass drying oven. We found it in time luckily, but safe to say I now hate the smell of ether and I’ve never had a more annoying headache ever. It’s just so intense. So many stories about the same guy

[@That_Chemist]

Haha

[@That_Chemist]

Someone who does one dumb thing often does many dumb things

[@chrisboyall8602]

@@00bean00 diethyl ether does form a hydroperoxide when exposed to UV light, but I’m pretty sure suppliers put stabilisers in to prevent it from happening. I’m sure an increase in temp will speed that up tho. However, the issue was more it was boiling in the oven as it’s boiling point is about ~34°C, and it was just filling the lab which is really dangerous. Also potentially auto igniting is not a pleasant thought.

[@duncanfox7871]

Great video as always! I've done a decent amount of making perfumes and I'd agree there is no place for those compounds you were talking about. I've used lots of esters, benzyl alcohols, aldehydes, longer chain alcohols, allyl compounds, and surprisingly quite a few indole derivatives but those have to be very dilute. They smell very musty and like animals in a bad way above 1-2%, below that they smell very rich and complex

[@That_Chemist]

Interesting!

[@elnombre91]

Definitely agree with alcohols. I prepared a couple of kilos of 3-trifluoromethyl cyclohexanol by hydrogenation of the phenol, it was one of the nicest smelling reactions I've ever done. I made phenylethanol isomers while trialling a Rh catalyst in the hydroboration of styrenes and they definitely smell incredible. Acetophenones are also amazing, 4-fluoroacetophenone smells strongly of bakewell tart to the point that spilling ~1 ml of it in my PhD hood made my lab smell of it for the morning. One final comment, butyric acid is the smell of vomit and rotting dairy products. My lab partner in A-level chem spilled it on my ungloved hand, and that hand smelled of puke for a couple of days.

[@That_Chemist]

That’s awesome - I always forget that you can hydrogenate arenes to make cool Cyclohexane derivatives

[@strangedivine]

About 20 years ago in O Chem we had to extract eugenol from cloves. A drop of it fell on my lab notebook and the smell lasted a surprisingly long time. I love it though. My Biochem prof once shared that when she was in university, someone had dropped I think butyric acid in the vents and the smell stuck to her all day, and had to take public transit to get back home at the end of the day. It was uncomfortable, to say the least.

[@That_Chemist]

I actually hate the smell of cloves - it lasts seemingly forever!

[@Vracaum]

Im currently working with azides, and its really a wheel of fortune smelling game In one hand, I have sodium azide, which (in addition of being dangerous) smells absolutly horrible. In the other hand, I have tetrabutylammonium azide which is a no-odor white powder. Some coworkers said it smells like old books

[@Petemate69]

Wait why are you actively smelling Sodium azide... Sodium azide shouldn't have a smell, you're smelling Hydrazoic acid

[@Vracaum]

@@Petemate69 yeah its hydrazoic acid, but I linked it too much with sodium azide to make a distinction as this point funny thing is that i use sodium azide to make tetrabutylammonium azide in aqueous conditions, and even with 10 equivalents, no smell whatsoever.

[@AJBlueJay]

15:00 Amines tend to smell nasty but some smell nice. Methyl anthranilate smells like flower and grapes. 16:25 If you like cyclohexanes, then you must smell helvetolide and edenolide! 18:00 thiols smell nasty but in traces are important in some flavors, and grapefruit mercaptan smells like grapefruit. 25:30 secondary amides smell nasty but can also smell good. Paradisaide smells fruity. 27:00 Ketones can smell harsh or smell great. Rose ketones smell amazing.

[@That_Chemist]

I will look into this :)

[@BenMurphy-go2ks]

I’m surprised pyridine didn’t get its own mention, it will always be my least favourite chemical, it’s truly disgusting.

[@That_Chemist]

I hate the smell of pyridines

[@YuPuWang]

Pyridine does worth its own place. For me it is like sewer with putrefied dead fish and frogs in it. However, certain alkyl-substituted pyridines - in small concentrations - in addition to being useful as food flavoring, can also add realism to certain types of fragrance notes (e.g. green, aquatic, and gourmand).

[@surkey5055]

Yeah APHP smells like semen, really gross

[@27.minhquangvo76]

@@That_ChemistI haven’t really smelled them, but from this description... easy peasy F tier.

[@oitthegroit1297]

I don't think it really counts as "working" with chemicals, but I absolutely love the smell of allicin and syn-propanethial-s-oxide from "working with" (aka chopping and eating) onions, garlic, and chives. Easy S-tier for me, since they smell delicious and it has an S for sulfur, one of my favourite elements.

[@user-ko7lz3kr1d]

Someone in the lab worked with phenylacetaldehyde and it was the weirdest thing because I would walk past one part of the lab and be like "flowers? in the lab?" and that lasted for about a week until the smell dissipated.

[@That_Chemist]

It’s controversial

[@YuPuWang]

Phenylacetaldehyde has a very powerful smell and trace amounts of it are responsible for the heady green top-note of many flowers. However it is rather unstable toward long-term storage especially in alcohol-based perfumes (forms acetals readily) or acidic/basic media (polymerizes). Therefore the fragrance / flavor industry usually uses its pre-formed acetals like PADMA to get more stable and reproducible effects.

[@user-ko7lz3kr1d]

@@YuPuWang That's cool, I'm interested to learn more about perfume/fragrance chemistry. I just love smelling chemicals.

[@OrbitalSaucer]

@@YuPuWang You should become a content creator.

[@ScienceBang]

I would love to see you formulate a perfume collection with this knowledge and show the process!

[@NormReitzel]

lavor chemists are in high demand, along about end of 2022. Just Sayin.

[@pamesman]

I'd rate ethers higher. Havent smelles tons of them but diethyl ether is generally a enjoyable smell for me and dibuthylether has a nice pineapple smell

[@SMPKarma]

I'm willing to fist fight you! I don't understand why people love ethers. One of my lab colleagues also swears by diethyl ether, saying it smells nice. To me, it smells bad! I'd take acetone, ethanol, isopropanol etc any day of the week over diethyl ether To me it has that sharp sting in the nose and the overall "bouquet" is just not enjoable. Couple that with the fact it's so volatile you always smell a lot of it if you're near, it's bad. Not bad like amines or sulfur compounds, but it has nothing even on simple alcohols E: speaking of sulfur compounds, I'd go so far as to say that hydrogen sulfide smells better than ether. Of course I'd never inhale large concentrations of it because I don't particularly want to inhale a gas as toxic as hydrogen cyanide, at this point in life anyway, but in dilute concentrations it's much less offensive than ether

[@cremebrulee2484]

I remember making esters for the first time a couple months ago. I think it was propyl propanoate I can’t really remember. My friend and I just kept smelling the stuff, it smell like pears but somehow even better, hope there wasn’t any left over sulphuric acid. Funny thing is that a few minutes before I wanted to leave the room because of the smell of the propanoic acid, how can two things that smell so bad make something that smells so good.

[@eier5472]

To me, phenol just smells like old circuit boards, mostly because they contain polymers made with phenol. 1-Naphthol is also... not awful but it's incredibly strong and a bit irritating. I got some on my skin once and could smell it for days, even after multple thorough washings and showerings.

[@That_Chemist]

Wow that is sketchy

[@eier5472]

@@That_Chemist Not as sketchy as my (probably failed) attempt at making isocyanides in the lab. I smelled nothing and no one complained about any smell

[@martinofgliwice1486]

Phenols smell like smoke to me.

[@1mctous]

@@martinofgliwice1486 Probably because Islay malt whiskies mix peat smoke with phenol.

[@martinofgliwice1486]

@@1mctous I never drank whiskey. it is not popular here where I live.

[@AsymptoteInverse]

21:46 I don't know if it was related to allyl groups, but my mother had an almost allergy-type reaction to onions and garlic. She found the smell of both to be quite noxious, and if she actually consumed them, she would get feeling quite sick. It didn't help things that she married a half-Italian man.

[@quintecence]

As someone who hasn't worked with phosphines but have been in the lab while others have worked with them - I'd put them in F tier.. there's one specific phosphine ligand that triggers migraines for me. It was worse than then getting HCl gas in the eyes. TsCl is a solid D tier imo.. My definitive ranking there lol

[@YuPuWang]

For me, aryl phosphines are fine, it was the alkyl ones that really reek. Especially the small, volatile alkyl phosphines are literally amines on crack. According to S. L. Buchwald, trimethylphosphine is like you take some fish out of your freezer to thaw on the cutting board, and while it is ready to be cooked you got a phone call from friends to help them move. You only return home a week later and open the door, suddenly realizing there's fish from a week ago and it's the middle of August...

[@Petemate69]

My favourite smelling chemical i've made is 1-Deoxymannojirimycin (Imino-sugar) which the freebase has a nice nutty/woody smell. Would make a great cologne i think

[@Jokke13th]

Heyy! Great video as always! I personally have a soft spot for esters, so this topic is really intriguing for me. For the functional groups I know, I'm with your ranking almost always. Maybe great minds do think alike. Have a great one TC! 😎

[@That_Chemist]

Thanks :)

[@mega2codnoob]

Teachers: Dont smell anything in the lab, everything should be in a fume hood! That Chemist: Haha, chemical smell tier list go brrr!

[@iryanmadayana1904]

One group I was kinda expecting was non-aromatic cyclic alkenes. Cyclohexene and cyclopentadiene are classic intense, penetrating, unpleasant smells afterall. A chemical that really surprised me was 2-amino-thiophenol (or 2-mercapto-aniline, same difference). I expected it to smell absolutely awful, but instead it just... smelled like... idk, a greasy rotissery chicken? With only maybe a faint hint of toilet? Smells are hard to describe :Y

[@That_Chemist]

Haha - chicken toilet is a smell I can’t say that I’ve smelled - I’ve worked with 2-aminophenol, but I don’t recall it’s smell

[@MichaelClark-uw7ex]

I think Methanol smells great, it reminds me of my school days. Its the smell of fresh mimeograph copies, everyone huffed them as soon as the teachers handed them out because the smell

[@plutoniumiscool]

I have a small collection of aroma compounds. I really enjoy the smell of fructone, which reminds me of pineapple. Also really like the smell of methyl cinnamate, nerolin and acetanisole. This last one my mom didnt enjoy. Need to get myself some benzaldehyde, anisyl acetate and helional.

[@TimothyReeves]

“Burning fruity skunks” - there’s a unique description!

[@Dangerousbros1]

Story time: the first time I had to work with Mercaptan. As part of a QC job i had I was required to do some regular raw material testing for a flavour lab. That day their lab manager I reported to was with a client so I just grabbed the first work off the top of the todo pile. The sample, already sampled for me awaited in the storage fridge... Around 5ml of a oily clear liquid within a sealed glass vial in plastic bag within a plastic box. Huh seems overkill but oh well I thought. Now I was no stranger to the potency of some of the compounds so I wasn't going to just open the vial on the open bench - for example I previously had to do work on butyric acid (the smell of baby vomit). Taking the sample to our lab upstairs I prepared our FTIR spectrometer within a fumehood (as part of the test I was required to compare the sample spectra to compare to reference spectra). Now here is where the mistake was made... I opened the container to take the sealed vial out on an open bench and left the box open as I took the SEALED vial into the fume hood. However, the compound in question was so potent that just the inside of the box smelled horrifying. Completely obliviously I started testing while people started complaining of a strong gas smell. By the time I had competed testing enough panic has raised that the safety officer was in the lab asking people to leave because of reports of a gas leak. Turns out I had become so desensitised to the stench while working didn't notice the similarity to gas at lower a potency. (to me it just stunk of dog poop?) It was quite embarrassing explaining to people for the rest of the day that the building was safe and it was just me working with thiols.

[@That_Chemist]

Awesome

[@Dangerousbros1]

@@That_Chemist not how I would describe that situation but I'm glad you enjoyed the story! 🤣

[@TNTLuc]

Benzaldehyde S Tier is is relatable. Once during my time in vocational school we did a synthesis with benzaldehyde, afterwards the entire class wanted to go drink some almond liquor afterwards (yes, we were all above legal drinking age, 18 in my country). Was quite a funny day.

[@That_Chemist]

Understandable

[@_iakvb771]

I remember using various phenolic bromides for a synthesis project with varying degrees of ether-ification. All very interesting smells, good and bad but mostly smokey

[@midwestchem368]

I agree benzaldehydes smell good.....well except one I know of. Salicylaldehyde. Just made it and its not exactly what I expected so much so I bought a sample for reference and its the same smell. Phenolic and reminds me slightly of Benzyl alcohol and also the strength of that smell turns me off from it. 2-phenylethanol is really nice when diluted some. I made a scentsy cube or whatever theyre called but i used phenylethanol and helional(i thought helional was going to be a flavoring since i bought it from my flavoring supplier but the bottle said sold for fragrance purposes). I like to use it as it makes me place smell like rosey and fresh like an ocean breeze. You definitely brought some new to me smells that im curious of now though. Great video dude! Always love them!

[@That_Chemist]

interesting!

[@Sinnistering]

Diluted iPrOH actually smells really good. I had an impromptu experiment involving a leaky spray bottle filled with 91% iPrOH and a hot car, and it had this really peculiar, earthy but delicious smell. Delicious in that way that some lip balms are where you know it won't actually taste good but your brain says eat it. That burning, antiseptic harsh smell is only really noticeable at high concentrations imo.

[@That_Chemist]

yeah I agree

[@osmanfb1]

in 1978 I was working with Joel X ray fluorescence spectrometer. Its high voltage transformer was in a box with oil. I was told not to open it, but being in my 20s, I tried to smell it but almost knocked me over. Felt sick for hours. I don't know what it was but to this date was the worst smelling organic liquid.

[@togoth1]

Thing is with diethyl ether is you keep on smelling and it pushes right back into smelling great again!

[@zekayman]

One of my recent organic labs involved getting an unknown carboxylic acid and an unknown alcohol to perform the Fischer esterification. We then had to identify the ester using H-NMR. Turns out I had synthesized benzyl propionate, which has a lovely apple/jasmine smell.

[@lilyp4369]

the smell test would be awesome, looking forward to that possibly happening

[@louiesumrall358]

I want to comment here to say I am an aspiring biochemist and seeing your content here is inspiring! You are putting out such an incredible volume of great quality materials that it is truly impressive!! Keep up the great work!

[@That_Chemist]

Thank you :)

[@punishedexistence]

One of the most pleasant smelling chemicals I've smelled is methyl benzoate. Of course aryl alehydes. Although cinnamaldehyde smells like spit or funky body odors in very high concentrations. But diluted in small amounts, especially with a little vanilla smells awesome. One of the worst was either tritheyl phosphite or pyridine.

[@That_Chemist]

Fun fact - they train drug-sniffing dogs to smell methyl benzoate as an indicator for the presence of cocaine

[@YuPuWang]

@@That_Chemist That methyl benzoate probably comes from self-transesterification of cocaine as it contains both methyl ester and benzoate ester.

[@theta3404]

Love how it gets more yellow-blue as you go down

[@radicalsini]

Aww man, I remember doing alcohol to aldehyde reactions in my chemistry A-Level and I have to say acetaldehyde is one of my favourite smells... it has a smell that nothing else smells like!!! Might have been propanal as well as we used to do ketone reactions too, which needs a secondary alcohol so I assume we also converted a primary propanol!

[@veikkakortelainen7638]

Your voice and delivery makes me think Casually Explained has been secretly studying chemistry!

[@That_Chemist]

Haha

[@florianbeck4283]

Nitroarenes were heavily used in perfumery as so-called “nitro musks”. Most of them have been outlawed for use in perfumery by now, but there’s still some left, e.g. “musk ketone”.

[@empathicwindow]

Small carboxylic acids, like vinegar and formic are interesting but the bigger ones are pretty gross. Phenol itself makes me think “clean”, like antiseptic, but also that it just wiped out the lives of all those little bacteria critters, poor dudes :(

[@taborsmrcna]

I also wanted to make the point that acetic acid is quite ok to smell (in small amounts). Phenol is actually contained in certain whiskeys (like Laphroig) and some people love it while some people hate it.

[@RaunienTheFirst]

I *love* phenols. Related (and missing from your video), Toluene. Absolutely gorgeous. Probably shouldn't breathe it in, but still nice.

[@That_Chemist]

True

[@validpostage]

of course esters are at the top, we all know that "S-tier" got its name from someone mispronouncing "ester"

[@That_Chemist]

Haha

[@enzoruberto]

I’m totally not a chemist so I don’t know what it’s like, but it surprises me that you smell all the chemicals you make. I would think that it’s too risky or bad practice

[@That_Chemist]

usually its inevitable that you smell them - I'm not going HAM and shoving the chemical up my nose, I just gently waft the smell towards my nose

[@OrbitalSaucer]

It seems weird, but an accepted operational mode in organic chem labs to have enough of something in the air that you can smell it while working with it. Just transferring between fume hoods or whatever. That's generally a very low concentration, and if it was dangerous at that low concentration it would be pretty special and special precautions would be taken, or more likely no one would be interested in doing that kind of chemistry, for example nerve agents, one whiff dead. (odourless regardless).

[@satelliteexile2089]

this would have been the prime time to flip S-tier onto the bottom. S for sulfur, S for stinky.

[@Felixkeeg]

I love the smell of TBDMS-groups so much, and how cool is it that you can tell whether your protection worked by smell?

[@That_Chemist]

well it would be cool, but you could just have TBS-OH and ROH

[@user-yk9qt2cy4j]

What does the Y attached to the cyclohexane and chicken feet stand for? Like it can't be yttrium right?

[@That_Chemist]

Some group, usually indicating another element besides carbon

[@flaplaya]

I will never forget smelling part 2 of old decomposed Marine-Tex epoxy. Methylamine times 100 supposedly the compound is 'Polyamines'. Penetrating toxic evil death fumes, sooo bad.

[@helldad4689]

Mixed organic solvents (essence of solvent cabinet): S+ fight me cowards

[@mixery_dose5435]

I always find Methyl Ethyl Ketone smells somewhat like Acetone, but just a bit different. Like Acetons cousin!

[@That_Chemist]

it has some other vibe going on - its like acetone's hot cousin

[@grebulocities8225]

Acetone with a bit of butterscotch. I kind of like it, in moderation. Like a hot cousin.

[@InterFelix]

Onee rather simple ester smells like superglue. I don't know if I would describe that specific one as S-tier, but most others definitely are.

[@robertb6889]

One of my sleeper favorites is alpha terpineol, though it’s hard to describe. The worst I’ve worked with were adjacent dithiol. Dithiols/dimercaptans in general are bad. 1,4 dithiols smell like skunk and are closely related to actual skunk musk.

[@ethyltryptamine]

I stumbled upon a bunch of silyl ethers that smelled like petrichor but better. I miss them.

[@PepekBezlepek]

OMG yes, do a video of a bunch of ppl smelling compounds ♥ similar to Tom's salt testing vid :D

[@ShouldOfStudiedForTheTest]

When using mesityl bromide, my syringe broke and I got it leaked all over my hand. I expected it to smell stingy or like cancer, but instead it had a very strong lemon smell which took so much soap to get off.

[@That_Chemist]

Interesting! It’s probably still pretty toxic imo

[@janAlekantuwa]

Ethers deserve S tier. Diethyl ether, MTBE, and THF are all three the best smells I've gotten in the lab

[@richardwebb5317]

If you are of a certain age and lived in Somerset, you will know the Bridgwater smell. Came from the British Cellophane factory which like most British factories is no longer there. A bit Carbon disulphideish, I have no idea what it was but it is unforgettable. Fortunately encountered nothing like in the lab. Travelled miles - F Tier!

[@aldenconsolver3428]

I would bring phenols up from D to B, its not any kind of natural good smelling but for a chemical smell its pretty nice.

[@californium-2526]

Chicken feet and difluoromethoxy groups are S+. Thiols, sulfides, selenols, selenides, amines of all kinds, carboxylic acids and their mono- and dithio derivatives, and mono- and dithiocarboxylate esters are F, however.

[@camj4631]

could not agree more about tosyl chloride. Propargyl thioacetate was definitely the worst smelling thing I've made, although I was really shocked by 1-pentyne. thiophenol smells like bacon at really low concentrations strangely enough...

[@VinsCool]

I was honestly expecting chicken feet to smell terrible, surprised it was S tier after all!

[@PancakeInvaders]

Someone should make a molecule out of all these S tier groups

[@That_Chemist]

Figueroa

[@IlusysSystems]

Personally I love smell of acrylates, MEKP also has very nice ozone-y smell to it

[@That_Chemist]

I hate acrylates with a passion

[@Outwhere]

I cannot imagine anyone liking ethyl acrylate, which is just horrendous. Methyl acrylate is not as bad, but more toxic. I like n-butyl acrylate though.

[@spoohable]

Real talk, I keep a little bottle of acetone around to sniff sometimes, smells so good

[@Abedchess]

I really cannot understand how people like the smell of acetone.😂

[@That_Chemist]

Haha

[@yuriikovalov84]

In my 1st year lab I synthesised ester which smelled really nice, just like peach... but I smelled it before evaporating dcm, so ended up being kinda high for some time

[@That_Chemist]

sounds pleasant :)

[@Tuxedosam.]

Next episode... The forbidden tier list - Best tasting chemicals

[@That_Chemist]

Maybe someday ;)

[@darkfexthefirst]

A former colleague once made 1,3,5-norcaratriene (basically benzene with a cyclopropane fused to it). That stuff smells awful down to very low concentrations and I have no clue why.

[@That_Chemist]

weird!

[@sandman0123]

"...smell like burning, fruity skunks..." "...garbage or unclean bottom..." 😟... 🤣🤣🤣 Thanks for making me laugh so hard, all the way through the video!

[@1mctous]

I share your dislike of diacetyl. Certain British ales (Bass) contain some diacetyl from fermentation by-products and I tend to avoid them. I also make my own popcorn from kernels and oil for the same reason.

[@chrisgeroleto2211]

I kinda disagree with Aldehydes being in the D Tier, but only from a Perfume standpoint. In Lab they might really smell pleasant and/or meh, but in Perfumery Aldehydes are very common in use and even made Channel No.5 so crazy famous, the Aldehyde 2-Methylundecanal, I would love to see a Video of you reviewing Perfumery Chems.

[@miriamg3689]

yeah but chanel no 5 literally smells like an old person

[@defenestrated23]

One time a chemist dropped a liter glass bottle of (iirc) pyrrolidone. The whole building smelled like...I don't know how to phrase this politely... it smelled like baby batter for over a week.

[@That_Chemist]

:(

[@yeoldebaccyfarm3081]

Tosyl chloride doesnt bother me. I kind like a lot of the "bad " smelling sulphur compounds anyways. Surpricing variety of aromas in those too outside generic surphury smells.

[@xECxMONEYx]

If you have alcohols in A tier you’ve never smelled fusel oil (mix of butanols/pentanols) that stuff is FOUL

[@GerinoMorn]

Also I do use isopropanol extensively and tbh I only avoid breathing it in because of metabolites, the smell is pretty nice, perfume like :D

[@oliviersmith6977]

How about a forbidden "best tasting functional groups" for the next video

[@That_Chemist]

Haha

[@penteractgaming]

volatile compounds with SeH and SeR groups from locoweed plants smelled like gunpowder so not horrible like thiols and mercaptans but not pleasant either

[@SMPKarma]

I actually don't entirely agree about thiols. As far as I know, they are added to fuel gases such as propane/butane and methane to make sure people smell it if there's a leak, and those smell good! In fact, I've read that fried onions' smell is partially due to thiols. Double-in fact, I'd rate some thiols even above ethers and alcohols (except Bn alcohols), because I really like that musky onion smell. Disclaimer: I haven't worked with any particular thiols, so I can't associate the smell with structure, but based on what I've read and experienced, I'd say *some* thiols can be aight E: you didn't talk about protective groups like chloroformates. One I actually like is Z chloride. It's that sort of fresh flowery smell, but it's also very toxic, so it's kind of a "forbidden fruit" for me. Whenever I've used it, one of my lab colleagues would be very upset about smelling it, but not because of how the smell feels. You feel bad about smelling it, but simply because you know it's bad. Otherwise it smells good

[@morgan0]

chem noob here, what’s the difference between R, R’, and Ar? im guessing Ar isn’t argon since it doesn’t tend to react much, and my guess for R and R prime is mirrored versions or stuff that’s completely different, but i have no clue what the difference between R/R’ and Ar is. also Y.

[@That_Chemist]

R and R' just means "some thing, usually a carbon" and R' just means it can be a different thing than R is - Ar means aryl, and it just means some benzene ring with various substituents

[@morgan0]

@@That_Chemist cool, thanks for the explanation

[@goda743]

I definitely love the smell of ethers, and how dare you say that isopropanol and ethanol smell bad! (I definitely never played around with isopronal/dry ice for hours)

[@justinedward9243]

what about thiourea?

[@DIGITALVHS]

Nitro-toluene has a strong benzaldehyde mixed with sickly sweet cancer smell mixed in.

[@NormReitzel]

Let me recommend "Common Fragrance and Flavor Materials: by Bauer, Garbe, and Surburg. (Wiley)

[@bachvaroff]

I used to prepare ~100ml batches of Ar-N+≡C- via the :CCl2 process, splashing the product here and there, then having fun watching the horrified passers-by :). IT'S A TRAP!!! Nope, 't'ain't a trap, 'tis intentional :).

[@sorlag_x]

I got to work with the bromine analog of mace and it just smelled like cherries/red hots to me, vaguely spicy but mostly fruity, I wasn't sticking my nose in it though so maybe it's not a fair assessment

[@Kall1208E]

I see your ethers in D and raise you vinylethers. They smell like the essence of glue to me and i love it xD

[@That_Chemist]

vinyl ethers smell bad

[@SeekingTheLoveThatGodMeans7648]

Talking about foot smell, and maybe popcorn smell, the paws of dogs (and I have checked out cats and gotten it) are said to smell like Fritos... what chemical is that? It isn't a people foot smell.

[@That_Chemist]

Yeah triethyl orthoacetate smells EXACTLY like what you’re describing

[@That_Chemist]

Like the smell of rice cooking

[@129140163]

I’ve never smelled any of these, not that I know of/am aware of/remember. Two questions: 1. Would methyl salicylate (wintergreen flavoring, my personal favorite, smell-wise) fall in any of these categories? 2. I’ve seen a few comments praising benzaldehyde. What does it smell like?

[@That_Chemist]

Methyl salicylate is great - it is both a methyl benzoate as well as a phenol - it is nice but it can be toxic in high enough doses. 2. Benzaldehyde is the typical almond/cherry flavour

[@NitronNeutron]

Esters, aldehydes ord terpenes (not really a functional group I know.)