What is the most advanced chemistry you've done on your own at home or work?

There was one time when I put a mold filled with liquid water in a cold container and made solid water.

that sounds super dangerous!
- Bottles of carbonated beverages can handle up to 150 psi. Semi truck tires are pressurized to 110 psi. Freezing water in a pop bottle can cause it to explode, think about that!

I take in oxygen and turn it into philosophical thought.

Same, except I turn it into farts.
- Basically the same thing, honestly.

Extracted lsa from morning glory seeds in order to make my own knock-off lsd

Yeah, polar/non-polar extractions are about as far as my home chemistry got. But the LSA was good.
- Amen, brother.

I helped create life and It was orgasmic!

Orgasmic chemistry!

baking bread

This one is underrated. That shit is like college-level difficult

Weed science. Not complicated at all, but there's so much bro science out there...

Liquid gas column extraction of organic compounds? I'm told that's something you should definitely do outside!
- Oh no.... Mine is super basic... Flower, everclear, freezer, air fryer.

Eating.

Closest I've come to Mad Scientist was probably yeast ranching to control costs in homebrewing.

sterilize agar media and plates/tubes in poor man's autoclave (pressure coooker) and hood (open oven door and vent fan) - infection rates were surprisingly low with this low-tech approach. I lost maybe 5% of cultures to spurious growth.
streak yeast from $$$ pure liquid cultures, grow, store if successful.
also experimented with yeast suspensions in sterile distilled water based on a 1930s science journal article from a dude in Africa. The suspensions did better in the heat where agar would just remelt....
a few days before needed scrape the streak into a small amount of sterile wort (20ml? on a homemade stirplate (PC fan and HD magnets under an unpended tupperware bowl!), stepping up to pitchable volume coinciding with the batch cooling to pitch temperature....

It was a lot of fun and instead of one 5gal batch of beer from an exotic $20 yeast sample you could get as many as you wanted. In practice I usually did 5-10 cultures from each pure sample. Could do more than that but there was a limit to how much stuff I could sterilize in my "autoclave" at one time.

Edited to add: I successfully cultured yeast from hefeweizen, but since what's in the bottle is typically for secondary/priming rather than primary it was only for fun. I had 100% failure trying to harvest wild yeast from the air or sampled from fruit skins. I couldn't isolate the yeast from other critters.

A lot of those same steps/skills are used in growing magic mushrooms, if you're ever looking for a new hobby

I bake from scratch.

Probably something using dihydrogen monoxide as a solvent for a mixture of organic compounds

For me it has been etching circuit boards and specifically making my own liquid tinning solution at one point. I mostly do hydrochloric acid/hydrogen peroxide on larger stuff and ferric chloride on smaller prototypes.

Steel etching with Winsteard's reagent. It is a bit dangerous because if done wrong it forms explosive dust. It was also long and tedious because the liquid must be near boiling and stirring so it evaporated quickly and has to be topped off and brought back to temperature often. The etch itself requires a long temper of a quenched sample and has an iterative process of etching and back-polishing to gradually remove surface roughness but leave the slightly deeper grain boundaries.

It took several hours of preparation and several hours of active work per sample and even then had a 50/50 success rate. I was professionally trained by a third party who learned this process from the person who perfected it, George Vander Voort.

I'm surprised that nobody has done an extraction of organic/aromatic content in an oil/fat ? Have you never backed some "space cakes" ? I haven't but I've seen people doing it, and it's pretty advanced chemistry when you think well

I don't know if we can call it chemistry but quenching steel.

In high school I was doing blacksmithing and so quenching the blade was part of the process, probably my favorite part.

Heating the blade above 800°C and dipping it in oil, with the oil instantly catching fire was always very dramatic.

Fire is chemistry.

retrobrite of my fridge handles. hydrogen peroxide and uv light to remove yellowing

I got old

I like this answer better than mine.
- hahah, much less explosive. It's a slow burn

I remember we had a lot of fun with Benzene and Benzoates in university, but suspiciously I can't remember details. Hmmm

Extracted lidocaine from butt lube.

Made soap out of lye and a mix of fats and oils.

Stripped a cast iron pan using electrolysis, although that might be more physics than chemistry. I had to add Sodium Carbonate so that's pretty sciencey!

Chemistry is just messy physics.
Biology is just messy chemistry.
Physics is just messy math.
- Your list is in a messy order.

Made pH 14 lye to break down some plant cells and extract stuff. Then putting "surgical spirit" (I hate common english terms) in it to extract it, pipetted it carefully and let it evaporate.

Best DMT you can get :D

Came here for the DMT extraction comments.
Isopropyl alcohol
- No, "Wundbenzin" which is clean "Benzin" which is "Petrol Ether".
  Its really confusing, in german we say "Benzin" to a mix of alkanes that are between Kerosine (really light) and "Petroleum" (pretty heavy, used in lamps) afaik.
  In the US "Benzin" would be "gasoline" or "petrol" which is already so weird. And as that name for alkanes of medium long length is not reused, stuff like "spirit" or "ether" come along which are as far as I know both wrong (not an alcohol or an ether)

Pop Rocks, mouth, coca cola.

Definitely not nitrating cellulose. That would be irresponsible.

Cooking & baking

I don't do that much of that but I hear my guts can do some amazing chemistry on the food all on their own, not to mention the cells themselves.

My great nephew as a teenager ran afoul of an old-school BBS archive website. He was certain it would be good fun to make a few incendiaries, Despite my attempts to dissuade him, he began to hide his enthusiasm, which had me worried he'd do it on his own. I figured it'd be wiser (and safer) to have someone with a bit of chemistry knowledge around when he tried doing dumb things.

We started small. I purchased some dry ice. Thermite was too boring. Elephant toothpaste was cool at first. Some petrol with polystyrene mixed in. Aluminium and acid cleaner. Then onto fertiliser tennis balls.

We eventually worked our way up to the Taj Mahal... Cyclonite. Hexogen. RDX. Unstable as the devil and more volatile than nitrated toluene, or TNT. The chemistry was very simple, but ridiculously foolish. I consider it advanced only due to the difficulty in ensuring we didn't get to visit a hospital or get a visit from the bobbies.

Never again. It took several days because I multiplied the recipe, like a dunce. We should've just made TNT, it would've been safer, but he persisted and I indulged.

The night before the big day. At this point, we'd been faffing around a dangerous line for almost ten months, whenever he managed to wrangle some free time for more mischief. I'd managed to extract a promise, this was to be the last of it until after his national service. He agreed. Keeping it in the boot of the car had me especially anxious,and until we saw the detonation, I felt like a long tailed cat in a room full of rocking chairs. The detonations in a desolate field were gratifyingly lovely though. He got the final trigger on an over sized charge, and his grin was worth the heartache.

He's a pharmacist now.

wow I don't know what most of these are but it sounded risky. I was reading your story hoping it wouldn't end badly.
- It was all in the name of fun... mostly. It was also one of the most memorable teaching experiences.
  I thought I mentioned smoke bombs, but apparently not. They were a good litmus test to see if the boy could keep a secret. Following which were: Dry ice bombs. Thermite, Elephant Toothpaste. Napalm. Hydrogen gas explosions. (If you see a plastic bottle on your lawn filled with blue liquid, do NOT disturb. Call the non emergency police line.) Nitrogen explosions. (See 2020 Beirut explosion for visuals.) And a few other unmentionables that are much too easy to manufacture, one of which I saw in another's answer.
  RDX (Royal Demolition eXplosive) is the oomph behind the plastic explosive C-4. It is slightly more explosive than C-4, because it hasn't been stabilized by anything.
  All ended well and mostly good. Unfortunately I think I assisted the boy is believing breaking the law was fine so long as you don't get caught. Now I can't look at chemical formulae without my heart starting to pick up the pace. However, there were no injuries, no actual close calls except the spilled water when we started the dry ice. Following which the boy sat through several intensive lessons each on operations security, command structure and discipline, distractions, and safety. We learned safely, which is all that matters in the end.

I used to be an industrial chemist. We did esterification reactions to turn chicken fat and laxatives into oil field soaps by the truckload. So I guess mid-level organic chemistry?

Mixtral 8×7B says you were making "sodium alkyl sulfates" for cleaning the unique long chain carbon chemical properties unique to oil drilling rigs and that chicken fat and laxatives were potential sources for the long chain alcohols needed for producing such soaps.
She is pretty good at sexting, but how good is she at cleaning an industrial oil rig as a mid-level chemist? /s
There was also something about a long chain alcohols reacted with a concentrated acid to make carboxylic acids plus heat pressure and water to make soap.
That level of detail is usually not quite right with this kind of LLM, but I'm curious overall how close it got? Duck Duck Go tried to convince me to shop for oilfield bath soap soap on Etsy instead of telling me what an oil field soap is and nothing came up on Wikipedia.
- Soaps are generally speaking, salts of fatty acids not long chain alcohols and strong acids. Dont trust LLMs for anything important.
- We did some sodium salts for personal care, but the chicken fat in this instance is oleic acid, or sometimes soybean or canola oils, and the laxatives are sorbitol or PEGs. Mix and cook them and out comes a surfactant like SMO. We sent it to the midwest to help with fracking.

Baking soda and vinegar to clean stuff

Never got why people are so obsessed by combining both which would basically turn it into sparkling water. Individually both have a chemical action, but mixing both wouldn't bring anything
- Pour them down a clogged drain and block it so that the clog gets pushed through.

Mac n cheese

Gold and Tellurium nanoparticle synthesis was the most interesting but I am not sure it qualifies as "complicated" given the procedures we used.

If computational chemistry qualifies, I have run on the order of 5,000 DFT optimizations+freq and of those, the most complicated ones involved metallocarborane clusters. These are composed of Boron, Carbon, a metal and different groups coming off the cluster. The largest one that I worked on took about a week to run the calculations on my home machine.

I once destiled water... from a but less impure water.

I work in a chemistry lab

So you do know what happens when you mix acids and bases.
- for sure
Okay, question, what's the least hazardous reaction you wouldn't want an amateur to ever attempt? Somewhere in between etching art into something and making your own Teflon lives a cutoff line for future shed projects, but I don't know where that would be exactly.
- Anther chemist stepping in here: Anything that produces an off-gas of any kind that does anything other than smell bad should be considered potentially lethal. People have died from working with liquid nitrogen or dry ice without proper ventilation. In addition, a gas explosion can be far worse than any other explosion you are likely to pull off by accident, and if you have a leak somewhere you may have no clue how much explosive gas is in the room with you. Some gases will react and form acid when it gets into your airways, essentially acting as an invisible acid that can jump from the table into your face.
  In short: Stay away from dangerous gases and stuff that makes them, and consider pretty much all gases as dangerous unless you know for a fact that they aren't. Other than that, the potential dangers of backyard chemistry can largely be mitigated by using common sense and working with small amounts of chemicals, good luck :)
- I'd stay away from anything with explosion hazards and toxic gases unless you have a fume hood. Boiling acids too.

Production of chlorine gas

Napalm from petrol and styrofoam

Acid assisted microwave digestion

Extraction and purification of surface residue for triple quadrupole analysis looking for pesticides, or inductively coupled plasma optical emission spectrometry looking for arsenic, but that's practically physics by that level.

I wrote a report on alkali-silica reactivity in concrete.

I used to run a bakery from home. We made pretzels with lye.

Titration of pool water to find its acidity using a commercial kit

And then given the results, Pooli suggested I dump about 5lbs of baking soda in there to neutralize the acidity. Worked like a charm.

Had to do a flame test to identify old fuel for recycling.

Made blue dye from indigo, and red and orange dye from madder, mixing in alum and other things. Making blue is amazing, it comes out green then changes colour all at once. Get the mix wrong and you get the wrong colour.... Also we boiled one batch of madder and got orange instead of scarlet, so even the temperature had to be regulated.

Most recently, been making etched plates from the inside of soft drink cans, etching with copper sulfate (they sell it in Bunnings as a fertiliser). Lots of fun!

So yeah mostly art projects.

That said even baking a cake is pretty fancy chemistry.

I make solder paste stencils from soda cans. What is special about copper sulfate? I typically use hydrochloric acid/hydrogen peroxide just to see the progress better.

Making grain beetles horny for my undergrad organic chemistry degree.

Didn't get to see a train beetle rub one out. Thankfully.

Do they make Kleenex that small?

Please elaborate
- My final year organic chemistry dissertation to make grain beetle pheromone. Very large ring molecule with until then very low yields.
Sounds more like biology.

Does uni count? I synthesised aspirin.

Does biochemistry count? I exponentially copied very specifically selected short fragments of DNA. From 1 to up to 1,099,511,627,776 copies in just 2 hours. I've also very specifically cut and glued together DNA strands.

And at home, I just extracted juice from red cabbage and played with changing its colour by adding lemon juice or baking soda.

I tried a few simple AB extractions long ago in a previous life.

Baking

Colouring hair, baking soda+vinegar (to clean and showoff), crude fuel cell, cleaning a washing machine with borax and something (some soda?)

Crack cocaine

um, Ive nitrated various organic compounds at home as a teenager

Speedballing

My HS chem teacher was a troll; he assigns my group Belousov-Zhabotinsky reactions. Which meant dealing with 1999 internet trying to find resources on it. OTOH, it did make for a very pretty lab demo.