Making a chemical that changes color in different liquids

most chemicals give a pretty consistent color regardless of the solvent that they're dissolved in there are some chemicals though which are so vada chromic meaning that their color changes drastically with different solvents so instead we can get something that looks like this this was a photo that I found on Wikipedia and it shows the color range of a chemical called M OE d or broker's maurice i mean in general i was really interested by this whole concept of self out a chromosome and i wanted to try it out as with most of my projects i plan to make it myself but just out of curiosity i looked online to see how much it would cost the only places that I found selling it were Fisher and alpha and both were insanely expensive alpha was a bit better than Fisher but it was still almost 500 dollars a gram and oddly enough sigma-aldrich didn't even sell it at all this all really didn't matter though because as I said before I plan to make it myself I generally just find it a lot more fun to make the product instead of buying it but now I also had a financial incentive to do it and I was really curious to see how much cheaper I could make it for I looked online for how to make it and it was only really able to find one procedure it unfortunately required a few chemicals that I didn't have on hand but they were all available from Sigma Sigma is generally pretty overpriced when it comes to chemicals but in this case I didn't really mind paying for it because in the end I was going to be saving a lot of money so what I ended up picking up was iota methane for methyl pyridine and for hydroxy benzyl dehyde the other ingredients that I still needed was a hundred percent isopropanol and ethanol piperidine and potassium hydroxide I got the isopropanol from a local dental supply company and I actually made the ethanol myself by fermenting sugar distilling it and then drying it prepare Dean's unfortunately a controlled substance so I didn't really want to buy it or to use it in this prep I instead switched it out for triethylamine which I hoped would work just as well triethylamine is relatively easy to find online and I've bought it before but this bottle in particular was sent to me by a fan a long time ago and the last ingredient was potassium hydroxide which was pretty easy to find online to get started I did 20 mils of cold and dry eyes are propanol to a flask then I turned on the stirring and added nineteen point four mils of the four methyl pyridine it was all quickly mixed together and I moved on to setting up an ice bath I let the solution chill here for about five or ten minutes and then I started to slowly add the iota methane in total I added about twelve and a half mils and I did it over the course of around four or five minutes with each addition it didn't really look like much was happening but it was slowly getting more and more yellow what was happening here was a relatively slow reaction between the four methyl pyridine and the iota methane the major product of this is one for dimethyl pyridinium iodide which has a slight yellow colour the reason I did this in an ice bath and added the iodoethane slowly was just to keep things under control when the aroma things added it can generate some heat and if this was all done at room temperature it might have heated things up a bit too much the original procedure just said to pre chill all the reagents but I found it easier to instead just use an ice bath after everything had been added I let it stir for another five or ten minutes and then I took away the ice bath at this point the reaction had progressed a decent amount but to get it to completion I was gonna have to heat it to do this I needed to set up a reflux but it took me a while to get everything together and in the meantime the reaction kept chugging along even though it was still kind of slow I unfortunately missed it and wasn't able to film it but there was eventually a point at which so much pyridinium iodide was made that it started to separate out this wasn't really an issue though because it was gonna happen anyway so I lowered the flask onto the heating mantle and I turned on the stirring and heating I also of course plugged in my water recirculate er to get the water going through my condenser I let it warm up and it eventually got to a boil but it was way too vigorous so I turned on the heating I adjusted it until the reflux rate was about to drop a second and then I kept it like this for the next two hours the reaction that was happening here was exactly the same as what was happening before I was just using heat to push it to completion at around the hour mark it looked like it was really getting jammed up a lot of solid so I took out the condenser and tried to break it apart it kind of worked and it gave me a more uniform slosh but I don't really think that this was that necessary to do in any case I boiled it for another hour and then I took away the heating mantle as it cooled down the yellow color slowly faded and by the time that it was room temperature it was mostly white I broke it up as best I could with a glass rod and then I transferred it all to a filter funnel it really didn't look like there was much or any solvent left over but it was all still there and it was just stuck to the solid so when it was all added I turned on my vacuum pump and you can see that quite a bit of liquid was pulled out I let the pump run for a few minutes to dried up as much as possible then I turned it off and I added a small amount of ice-cold 95% ethanol I swirled it around to dissolve any impurities or unreacted starting material and then they turned on the vacuum pump again all the ethanol was quickly pulled away and I left the pump on for another five or ten minutes just to dry it up as much as possible at this point the product was still crude so to clean it up I had to recrystallize it this was quite easy to do and I just had to dissolve it in a minimal amount of boiling 95% ethanol so I added it to a beaker pour it in a small amount of the ethanol and turned on the heating with most recrystallization --zz you have to be pretty careful with the amount of solvent that's used because if you use too much you'll lose a bunch of your product in this case though the solubility of the pyridinium iodide in cold ethanol is so low that I don't think it really matters too much anyway it eventually got to a boil and everything had dissolved so I took it off the hot plate I also put a watch glass on top to prevent the ethanol from evaporating then it took out the stir bar and I waited for it to cool to room temperature I let it sit for about an hour and at this point it was only warm to the touch but no crystals had formed I initially thought that maybe I used way too much solvent but I thought it was more likely that it was just a supersaturated solution so I dipped in a glass rod that still had some crude crystals of the pyridinium iodide on it this provided nucleation sites for the pyridinium iodide in solution to build on and it all started crystallizing out when it looked like it was more or less done I put it in the freezer to drop the solubility even more I left it in there for a few hours and then I filtered it off like before I turned on the vacuum pump and I pulled away as much of the solvent as possible then I washed the beaker and the crystals with a small amount of ice-cold ethanol I left the pump on for about 20 minutes but the crystals were still quite wet so to get it as dry as possible I transferred it back to a beaker and I put it in a vacuum desiccator I filled the bottom of the desiccator with calcium chloride which can form a complex with both water and ethanol and should speed up the process I pulled nearly a full vacuum on it closed the valve at the top and I let it sit for about a day or so then I took it out and this time it was definitely a lot drier my final yield was 33 grams which was a percent yield of about 70 percent okay so what this precursor now made I could move on to building up to the actual mo IDI and to do this I started by adding 14 and a half grams a freshly recrystallized four hydroxy benzyl the hide then on top of this I dumped in twenty eight point four grams of the 1/4 dimethyl pyridinium iodide that I just made the reason they use 28.4 and not the full 33 that I made was just because that's what the procedure called for when they made the pyridinium iodide they got 28 point 4 grams so that's what they just used in the next step in theory I could have just scaled everything up to the full 33 but I decided to follow it with a 28 point 4 and to save the difference I figured that maybe in the future it could be useful for something else so it was worth keeping some around anyway after adding both these chemicals I then poured in a hundred and 50 mils of dry ethanol I let it stir for about 10 minutes but not everything dissolved so I moved on to adding the triethylamine the moment it was added it immediately turned yellow and it also seemed to slowly clear up a bit just like the other reaction to get it really going I had to heat it so I set it up for a reflux as it warmed up the rest of the undissolved stuff eventually disappeared and the colors slowly changed this time-lapse here was taken over the course of about 20 minutes so what should be going on here is a base catalyzed reaction between the pyridinium iodide and the four hydroxy benzyl dehyde this leads to the formation of this intermediate molecule which isn't quite mo Edie and there's still one final step that I need to do anyway this reaction had to be refluxed for 24 hours but after around the hour mark it visually didn't change very much this was what it looked like about 18 hours in and it was just a bit darker when it got to the 24 hour mark I took away the heating mantle and I let it cool overnight and when it came back in the morning I saw that a whole bunch of red solid had formed I scraped it all of the sides and then I dumped it into my vacuum filter then I washed the flask with a small amount of ice-cold ethanol and I added it to the filter I used the glass rod to mix it around a bit and to wash the powder and then I pulled everything through before the washing it was full of impurities so it was just this brownish black powder but afterwards it was this really nice red it still looked like there was a bit of brownish black stuff left so I washed everything with a bit more of the ethanol I left the vacuum on for about 20 minutes to dry it up and then I broke it up into a powder I dumped it all out onto a watch glass and I was honestly really impressed with how rich and nice the color was what didn't impress me though was the yield and I only had nine point two five grams here this was a terrible percent yield of about 22 percent when I think it should have been closer to 80 or 90 in my mind this was almost definitely because I used the triethylamine I expected the reaction to be hindered a bit but I really didn't think it would be this bad in the future if I ever have to do this reaction again I'll definitely try using a secondary amine like parola diene instead which is structurally very close to piperidine it's also totally legal and relatively cheap from Sigma I really should have just ordered it from the beginning but it's like whatever I still managed to make way more product that I needed and I also learned something in the end so this mistake really didn't bother me that much in any case this still wasn't the final mo edy and I had one last step to do all the nice red powder was dumped into a beaker and I a thermometer then I started adding 500 mils of a dilute potassium hydroxide solution the procedure called for 700 but because my yield was significantly lower I didn't think I needed to use that much I honestly have no idea why I tried going with a black background here because after adding just a small amount I realized the contrast was gonna be horrible so I quickly swapped it out for a white one and continued the addition I brought it up to about the 500 mil mark and then I turned on the hot plate the goal was the heated but not to the boiling point so I brought it up to around 80 C as it warmed up a lot of the solids started dissolving but the most interesting part was the surface of the mixture it had a really interesting pattern to it and I probably stared at it for a little bit too long almost all the solid eventually dissolved and I had this really dark solution when I shot a light through it though I could still see that there was some solid floating around I let it go for another 5 minutes or so but the solid was still there so I just ended up adding about a hundred more mils of the potassium hydroxide solution in hindsight though this probably wasn't necessary and I should have just let it react for a little bit longer so speaking of the reaction what was going on here was an elimination where a double bond was forming and the O H hydroxyl group was getting kicked out and this led to the formation of the final mo II D when everything had dissolved I started my timer and I heated it for 30 minutes then I took it off the hot plate removed the stir bar in the thermometer and I let it cool overnight when I came back the next day there were some really nice crystals that had formed at the bottom and I was kind of sad that I didn't do a time lapse to separate them off I just used my vacuum filter again after the initial liquid had all been pulled through I washed the beaker and the crystals with some ice-cold water I left the pump on for several minutes to get rid of as much water as possible and then I let it dry for about a day or so the final dry result was a bunch of red flaky crystals my yield was kind of terrible though and I only got five point eight grams compared to the amount of precursor that I put into the dehydration reaction though the yield was close to a hundred percent the major loss in this entire prep really came down to my use of triethylamine and my miserable 22 percent yield in the previous step however even with my mistake and my bad yield it was still weight cheaper than buying it this is just a rough estimate of what it cost me for each component so strictly materials it cost me about thirteen dollars and sixty cents to make one gram of mo IDI if I bought the parola ting though and if it worked just as well as the piperidine I could have gotten up to 22 grams and in that hypothetical case I might have been able to make it for about three dollars and 80 cents a gram so in the worst case like I got here it would still be forty five times cheaper than the lowest price that I could find online and in the best case if I got the full 22 grams it could be up to a hundred and sixty two times cheaper considering how straightforward and easy it is to make it I feel like buying it makes absolutely no sense if you guys know of any cheaper and actually reasonable sources though please let me know okay now to test what we actually came here for and to see if it salvado chromic to do this I lined up eight small vials filled each with about 10 milligrams of mo IDI and started adding solvents the first was water than it was methanol ethanol acetic acid isopropanol DMSO acetone and finally DCM with all the solvents added I then tried stirring them to dissolve as much as possible it worked decently well for the first five but the last few were a bit problematic for some reason when I stirred the DMSO the purple would disappear I'm not exactly sure why this happened but eventually it did end up staying purple the he was barely soluble in the acetone and even less so in the DCM the stirring really didn't seem like it was gonna work so instead I just capped all the vials and shook them you I occasionally shook them over the course of the day and I was eventually left with this nice spectrum of colors what was also interesting was that the fluorescence changed as well and this was what it looked like under a UV light the question now though is why does the color change well the common explanation for sivanna chromosome comes down to the polarity of the solvent I don't want to get into too much detail about polarity but in general it has to do with how the electrons are distributed around the molecule this distribution is determined by the geometry and the chemical makeup of the molecule and it's different for each one when it's uneven and asymmetrical like with water we hit areas with high concentrations of electrons and other areas with a relatively low concentration this causes there to be a partial negative over the oxygen and a partial positive over the hydrogen's and the molecule is said to be polar however in other cases like with pentane the electrons are spread out very evenly and there's little to no charge separation molecules like this are said to be nonpolar so when it comes to solvents polarity is important because it gives us an idea of what it should be able to dissolve in general polar solvents like to dissolve polar molecules and the non-polar solvents prefer the non-polar ones anyway with that being said why does polarity affect the color of the mo Edie from what I found it seems like the exact details are quite complicated but the general idea of it is relatively simple mo Edie exists as an equilibrium between two molecules which I'll just refer to as a and B in solution the a form has a yellow color and the B is closer to blue or violet both forms exist at any given time and the color that the solution takes on is due to a balance of the two different solvents will favor one over the other and therefore cause the color to change in general the more polar solvent is the more it'll favor the charged a form so this would be Y in highly polar solvents like water we get an orange a yellow color however as we move across the solvents and things get less and less polar the amount of the B form increases this causes the color to change and we eventually get to a very nice violet or blue color at first glance this seems like a decent explanation but there's one major problem with it it doesn't explain the two major anomalies here which are the acetic acid and the D meso acetic acid is definitely less polar than water but color wise it looks like it should go before it the DMSO seems to be placed quite well but it should actually go just after the water because it's more polar than all the alcohols the reason for this is that because on top of polarity we also have to consider whether the solvent is protic or aprotic solvent setter protic have a labile H+ ion either because they're acids or because they're hydrogen bond donors solvents that are hydrogen bond donors have at least one hydrogen that's attached to a much more electronegative atom like nitrogen or oxygen examples of solvents like this are water and all of the alcohols that are used these solvents can partially donate a hydrogen which can help stabilize the negative charge on the oxygen of the a form and between polarity and hydrogen bonding they really tip the balance towards the a form in the case of DMS so it can act as a hydrogen bond donor and it relies only on its polarity and because of this even though it's technically more polar than the alcohols it still can't stabilize the a form as well and it gets shifted more towards violet the acetic acid is just the extreme form of a protic solvent where instead of just stabilizing and partially donating a hydrogen it can just flat-out give one away so with the mo edy it just throws a proton onto the oxygen and kind of locks it in the a form I think this over power is almost any effect by polarity and just completely shifts it over to being yellow as an extra little test I dissolved more of the mo IDI in acetone and I added several drops of acid and that's I more or less expected the violet color very quickly disappeared so to sum this all up the color of the mo ad depends mostly on the polarity and whether or not the solvent is protic when I first started this project I thought that the color would correspond directly to a specific polarity but that clearly wasn't the case here this might be true for other salvado chroma chemicals though and I plan to explore this in future videos now before I go this is just one last thing that I wanted to show which i think is pretty cool this is a photo of the solid mo e and you can see that it's both red and blue at the same time I think this is because as it crystallized it did so in both the a and B form which reflect like differently anyway I think that's about it for this project I honestly had a lot of fun messing around with the mo Edie and in the future I definitely want to try making some other salvado chromic chemicals for now though I think I've been doing way too much stuff with dyes and I'm gonna try something a little bit different for the next video for the past couple months I've been messing around with liquid rocket propellants and I think I want to show you some of the stuff that I've found I know I've been kind of slow with videos lately and I'm not gonna promise when this one will be released but it should be within the next week or so as usual a big things goes out to all my supporters on patreon everyone who supports me can see my videos at least 24 hours before I post them to YouTube also everyone on patreon can directly message me and if you support me with five dollars or more you'll get your name at the end like you see here [Music]

Channel: NileRed

Views: 1,123,970

Rating: 4.9567266 out of 5

Keywords: nile, red, science, chemistry, moed, brookers merocyanine, solvatochromism, colors, change, solvent, synthesis, organic, organic chemistry, nile red, nilered, liquids, color

Id: RGG2GNvpwA4

Length: 22min 41sec (1361 seconds)

Published: Sun Sep 23 2018