# Name Some Chemical Compounds with Remarkable Colours or Smells
**URL:** https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818
**Category:** Factual Questions
**Created:** [May 31, 2019, 10:21am UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818 "2019-05-31T10:21:12Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Les\_Espaces\_Du\_Sommeil](https://boards.straightdope.com/u/Les_Espaces_Du_Sommeil)
#### Post date: [May 31, 2019, 10:21am UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/1 "2019-05-31T10:21:12Z")
When I was a kid, I wanted to be a scientist. First an astronomer (I had lots of children-friendly books on the subject), then a chemist. It didn’t pan out for several reasons but I’ve kept a distant interest, and sometimes when I’m bored I read Wikipedia pages dedicated to chemical compounds I’m not familiar with, hoping to find some exotic properties. Alas, this is hit or miss and, more often than not, what I stumble on is “colourless” and “odourless”. Boring.
I’m already familiar with [Derek Lowe’s _Things I Won’t Work with_](https://blogs.sciencemag.org/pipeline/archives/category/things-i-wont-work-with) and that blog has filled many of my afternoons with joy, even if some of it is a bit over my head.
So, I turn to you to provide me with examples of chemicals with remarkable properties that people who haven’t done chemistry since secondary school can understand. I’ll post this here since I’m looking for factual answers but it could IMHO.
Bring on the beautiful colours and weird smells !
---
### Author:  [@Sparky812](https://boards.straightdope.com/u/Sparky812)
#### Post date: [May 31, 2019, 10:50am UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/2 "2019-05-31T10:50:07Z")
[Methanethiol (Mercaptan)](https://en.wikipedia.org/wiki/Methanethiol) - The additive to natural gas and propane so you can smell a leak. Also, the one responsible for bad breath, flatus, asparagus pee, swamp gas, pulp mill pollution, etc…
---
### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [May 31, 2019, 10:57am UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/3 "2019-05-31T10:57:26Z")
The gas dinitrogen tetroxide (N[sub]2[/sub]O[sub]4[/sub]) is colorless and odorless… but wait, there’s more. It only exists at low temperatures and/or high pressures; at normal temperatures and pressures it spontaneously converts to two molecules of nitrogen dioxide (NO[sub]2[/sub]), which you’re familiar with if you’ve ever been to Los Angeles: It’s why the air there smells bad and looks brown.
---
### Author:  [@aruvqan](https://boards.straightdope.com/u/aruvqan)
#### Post date: [May 31, 2019, 11:50am UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/4 "2019-05-31T11:50:52Z")
Probably not what you mean, but phosgene has a new mown grassy smell, and a hint of that metallic taste like when you hold a handful of coins in a hot sweat hand … and chlorine gas can be seen as a pale green cloud.
---
### Author:  [@krisolov](https://boards.straightdope.com/u/krisolov)
#### Post date: [May 31, 2019, 11:56am UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/5 "2019-05-31T11:56:18Z")
Acetylene has a smell like rotten garlic. Loads of fun when there’s an acetylene production plant across the parking lot from you.
I worked for a dozen years for a chemical company and the only thing we decided we did NOT want to handle at our facility was Chlorine Trifluoride.
---
### Author:  [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)
#### Post date: [May 31, 2019, 12:22pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/6 "2019-05-31T12:22:18Z")
One of the classic chemicals from the chemistry sets of my youth is _Cobalt Chloride_. As with many chemicals, there is a plain form and not one but at least two hydrated forms. In many cases it’s hhard to transition between the two, but cobalt chloride does so very easily – a change in room humidity can do it. The different hydrates have very different colors. The anhydrous form is blue, the dehydrate is purple, and the hexahydrate is pink. One experiment the chemistry kits had was to make a “weather indicator” by painting a patch of paper with cobalt chloride solution, or soaking a piec of cotton in the solution. In dry weather, it’d be blue. In humid weather, it’d be pink-purple.
> **[Cobalt(II) chloride](https://en.wikipedia.org/wiki/Cobalt(II)_chloride)**
>
> Cobalt(II) chloride is an inorganic compound of cobalt and chlorine, with the formula CoCl2. The compound forms several hydrates CoCl2·nH2O, for n = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed. The anhydrous form is a blue crystalline solid; the dihydrate is purple and the hexahydrate is pink. Commercial samples are usually the hexahydrate, which is one of the most commonly used cobalt compounds in the lab.
> At room temperature, anhydrous cobalt chlor...
Nowadays they put some in dessicants to indicate if it’s absorbed water or not.
---
### Author:  [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)
#### Post date: [May 31, 2019, 12:37pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/7 "2019-05-31T12:37:44Z")
Dimethyl telluride (CH[sub]3[/sub])[sub]2[/sub]Te smells like garlic and can be smelled in the breath of victims of tellurium poisoning.
---
### Author:  [@MrDibble](https://boards.straightdope.com/u/MrDibble)
#### Post date: [May 31, 2019, 12:51pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/8 "2019-05-31T12:51:19Z")
You need them together, but bromophenols, dimethyl sulfide and dictyopterenes combine to give you the major part of the “smell of the sea”.
Or you can use [Calone](https://en.wikipedia.org/wiki/Calone) (methylbenzodioxepinone), it’s what perfumers use for the same effect.
---
### Author:  [@ftg](https://boards.straightdope.com/u/ftg)
#### Post date: [May 31, 2019, 3:48pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/9 "2019-05-31T15:48:02Z")
**Mrs. FtG** has an aversion to grape-flavored products due to working in labs with [pseudomonas aeruginosa](https://en.wikipedia.org/wiki/Pseudomonas_aeruginosa) which produce the same smell.
The compound is methyl anthranilate.
Fun flavor or infectious agent? Why not both!
---
### Author:  [@mixdenny](https://boards.straightdope.com/u/mixdenny)
#### Post date: [May 31, 2019, 3:48pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/10 "2019-05-31T15:48:14Z")
> [@Chronos](#):
>
> The gas dinitrogen tetroxide (N[sub]2[/sub]O[sub]4[/sub]) is colorless and odorless… but wait, there’s more. It only exists at low temperatures and/or high pressures; at normal temperatures and pressures it spontaneously converts to two molecules of nitrogen dioxide (NO[sub]2[/sub]), which you’re familiar with if you’ve ever been to Los Angeles: It’s why the air there smells bad and looks brown.
Nitrogen tetroxide was used as an oxidizer in some of our exotic engine tests at NASA in the 1960s. When it was vented it made a brown-reddish cloud we had to be on alert for. I only saw it once and we all ran like hell to get back in a building.
They only ran those tests on second shift and we all were issued gas masks to carry around. Actually we had our masks sitting on a curb outside and when the red cloud swept over our building and came towards us our crew chief grabbed them all and yelled, “Run!” We just ducked in the nearest door and shut it.
Ah, the good old times…
Dennis
---
### Author:  [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)
#### Post date: [May 31, 2019, 3:56pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/11 "2019-05-31T15:56:06Z")
[YInMn Blue](https://en.wikipedia.org/wiki/YInMn_Blue) is the name for a new blue pigment that was recently discovered at Oregon State. It’s apparently the first new inorganic blue pigment in about 200 years.
---
### Author:  [@Les\_Espaces\_Du\_Sommeil](https://boards.straightdope.com/u/Les_Espaces_Du_Sommeil)
#### Post date: [May 31, 2019, 4:13pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/12 "2019-05-31T16:13:13Z")
> [@aruvqan](#):
>
> Probably not what you mean, but phosgene has a new mown grassy smell, and a hint of that metallic taste like when you hold a handful of coins in a hot sweat hand … and chlorine gas can be seen as a pale green cloud.
Quite the contrary : it is _precisely_ the sort of things I’m looking for.
Lots of great examples, and the first-hand reports are even better, thanks !
---
### Author:  [@yabob](https://boards.straightdope.com/u/yabob)
#### Post date: [May 31, 2019, 4:24pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/13 "2019-05-31T16:24:14Z")
Look up “esters”, many of which are fruity smelling. Isoamyl acetate smells like bananas.
---
### Author:  [@DPRK](https://boards.straightdope.com/u/DPRK)
#### Post date: [May 31, 2019, 4:27pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/14 "2019-05-31T16:27:46Z")
Benzeneselenol… smellin’ good… (one description: “imagine 6 skunks wrapped in rubber innertubes and the whole thing is set ablaze. That might approach the metaphysical stench of this material.” It’s also toxic, natch.
Colours… how about Tyrian Purple? Got to harvest hundreds of thousands of Murex snails to make that one.
---
### Author:  [@mixdenny](https://boards.straightdope.com/u/mixdenny)
#### Post date: [May 31, 2019, 4:28pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/15 "2019-05-31T16:28:35Z")
There’s always potassium permanganate. The dark powder turns water a deep purple and looks really neat.
> **[Potassium Permanganate: 5 Surprising Survival Uses](https://www.primalsurvivor.net/potassium-permanganate-survival/)**
>
> This cheap, readily available chemical has many survival uses. Learn how to use potassium permanganate for purifying water, starting fires, first aid, and more.
Dennis
---
### Author:  [@MrDibble](https://boards.straightdope.com/u/MrDibble)
#### Post date: [May 31, 2019, 4:33pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/16 "2019-05-31T16:33:27Z")
> [@Sparky812](#):
>
> [Methanethiol (Mercaptan)](https://en.wikipedia.org/wiki/Methanethiol) - The additive to natural gas and propane so you can smell a leak. Also, the one responsible for bad breath, flatus, asparagus pee, swamp gas, pulp mill pollution, etc…
It’s just one of the mercaptans. There are others.
IME, the best way to sample the full range of them, as well as a variety of other truly _delightful_ odoriferous compounds? Have a good whiff of[landfill leachate](https://en.wikipedia.org/wiki/Leachate#Composition_of_landfill_leachate).
\
Someone working on leachate for a project opened a container of some in a talk he was giving to our Geochemistry class. People at the \*back \*of the lecture hall (including me) were retching.The faculty was not amused. That was truly the worst thing I’ve ever smelled in my life.
---
### Author:  [@Ynnad](https://boards.straightdope.com/u/Ynnad)
#### Post date: [May 31, 2019, 4:39pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/17 "2019-05-31T16:39:29Z")
> [@mixdenny](#):
>
> There’s always potassium permanganate. The dark powder turns water a deep purple and looks really neat.
>
> [Potassium Permanganate: 5 Surprising Survival Uses](https://www.primalsurvivor.net/potassium-permanganate-survival/)
>
> Dennis
But don’t get any on your fingers. It turns into brown manganese dioxide and it will not come off. You will walk around for a week or two looking like you have poop on your fingers.
---
### Author:  [@am77494](https://boards.straightdope.com/u/am77494)
#### Post date: [May 31, 2019, 4:51pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/18 "2019-05-31T16:51:18Z")
> [@yabob](#):
>
> Look up “esters”, many of which are fruity smelling. Isoamyl acetate smells like bananas.
Yes Esters - the salts of the organic world - they determine the price of wine and spirits.
When fermenting, yeast produce varying amounts of organic acids which taste terrible. Organic acids react with alcohol albeit very slowly to make esters which smell good and taste good. Hence the preference for aged wine and scotch and other liquors.
Wood barrels also have tannins and other acidic components which react with the alcohol to make esters - again sweet smelling / tasting. Hence the aging of alcohol in wood barrels.
---
### Author:  [@am77494](https://boards.straightdope.com/u/am77494)
#### Post date: [May 31, 2019, 4:56pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/19 "2019-05-31T16:56:18Z")
Also :
> [@](#):
>
> Geosmin is an organic compound with a distinct earthy flavor and aroma produced by certain bacteria, and is responsible for the earthy taste of beets and a contributor to the strong scent (petrichor) that occurs in the air when rain falls after a dry spell of weather or when soil is disturbed.
> **[Geosmin](https://en.m.wikipedia.org/wiki/Geosmin)**
>
> Geosmin (/dʒiˈɒzmɪn/ jee-OZ-min) is an irregular sesquiterpenoid, produced from the universal sesquiterpene precursor farnesyl pyrophosphate (also known as farnesyl diphosphate), in a two-step .mw-parser-output .template-chem2-su{display:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em}.mw-parser-output .template-chem2-su\>span{display:block;text-align:left}.mw-parser-output sub.template-chem2-sub{font-size:80%;vertical-align:-0.35em}.mw-parser-output sup.template-chem2-sup{font-siz...
---
### Author:  [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)
#### Post date: [May 31, 2019, 5:02pm UTC](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818/20 "2019-05-31T17:02:17Z")
There are smellier things out there, but the one that I always remembered from my time working in a chemical stockroom was a solvent called pyridine.
That stuff stinks, in a weird nausea-inducing kind of way.
We had a flammable storage cabinet with all kinds of solvents stored within, but the thing always stank of pyridine.
[Next page](https://boards.straightdope.com/t/name-some-chemical-compounds-with-remarkable-colours-or-smells/834818.md?page=2)