Extracting the dye in jeans

Nile Red

for some reason, i couldnt find an option anywhere :/

Nile Red

hey, ill look into it! not sure why it isnt an option

Ron Painter

Hi - I noticed that this video doesn't have any captions or auto-captions enabled. I'm deaf, so I need captions to be able to watch your videos. If it's not too much trouble, could you enable the auto-captions for this video? Thanks - as a chemistry teacher, I love your videos!

What if you used a larger (wider) pan for several steps of the reducing solvent along with a rolling pin during each extraction to more effectively force the reductant through the fabric. This could probably really efficiently solubilize the indigo, unless the boiling really is necessary.

To my knowledge, there's no direct prep of skatole from isatin. However, based off of two papers, a simple <a href="https://i.imgur.com/JXjjUeU.jpg" rel="nofollow noopener" target="_blank">two-step synth</a> could be possible: methyl Grignard followed by reductive elimination with BH3•DMS (or BH3•THF). The reductive elimination is to a closely related skatole derivative, but the parent compound should still work, though probably at lower yield than the 90%. I can share the papers if you're interested.

Silviu T

I second the ionic liquid idea. Having experimented a bit with deep eutectic solvents (type 3 only) I can say they have some interesting properties.

Daniel Blake Shoemaker

5-SSA with Isopropanol alc was Purple (Neutral), rusty orange for ph 14, Red for pH 1 and -1 pH it was yellow. 5-SSA is an intersting and cool dye to work with. Have not test ethanol or acetone. Might do that!

Daniel Blake Shoemaker

If you Red Nile want to work with dyes making a simple dye by mixing 5-Sulfosalylic acid with Iron chloride plus solvent works very well. Dependant on solvent and pH it changes many colors. WIth methanol neutral it purple with with some lye it turns orange add way more lye it forms a green precipite. If it is acidic it is brown then turns different colors. I discovered 5 colors for each pH min. When combined with paper and different acids and bases rainbow colors can occur that change over time (pH, vs light maybe).

Isaac Roll

Disclaimer: I'm an engineer, not a very good chemist. Isn't Ethyl Acetate the most polar of the solvents that you used? Would trying a more polar solvent, or perhaps even an ionic liquid, be another way to improve the yield for a simple liquid extraction? Speaking of which, I'd definitely be interested if you could do a video on ionic liquids.

This was super interesting. Definitely excited to see the full pair extraction too!

Nile Red

Yeah, i am definitely going to do it!

Nile Red

If you added just a small amount it would probably just destroy the reducing agent and gently re-oxidize the indigo

Nile Red

Oh wow, i didnt know that purification was in that book. Also, is there a proper procedure for the skatole prep?

Daniel Blake Shoemaker

Wow a yield of 280 mg indigo for 12.8 g. Are you going to try to scale this up with more chemicals, etc to get a better yield Red Nile?

You've independently discovered the standard approach given in Purification of Laboratory Chemicals. Very cool! One final purification step they prescribe is a Soxhlet extraction on the final dried filtrate in chloroform. Oxidizing indigo in nitric acid cleaves it into two equivs of neon orange isatin, essentially a masked indole with an electrophilic handle. From there it would be a short synth to skatole (which I know you've already done) and other indole derivatives.

Would be cool to get an estimate of how much indigo is in a pair of jeans.

Dawnbandit

Would H2O2 have neutralized the reducing agent or would it just destroy the indigo?

Nile Red

True, but I don't have a soxhlet that would easily let me process an entire pair of pants!

Nile Red

Yeah DMSO works well, but it's not easy to get or cheap. Also, it's kind of toxic (allows dissolved stuff to pass through skin easier)

Michael Lang

I'd love to see the full-scale extraction! I think that kind of scaling-up would be an interesting experience in its own right.

Patrick Sweetman

But ... you have a Soxhlet, don't you? If the dye is even only slightly soluble in organic solvent then you can extract it all that way.

I can also confirm that leuko-indigo is yelloy-green.

I'm not through yet, but I'd have recommended DMSO... got a bottle of indigo-in-DMSO here that is very dark from all the indigo in it. At room temperature, and miles ahead of the concentration his first run resulted in.

I like the fact that it's actually a discovery process and not a re-creation of an experiment. Good job

Michael Aichlmayr

This is awesome!! I have a box of denim that has been waiting over six years for this! Thank you!

Brian Reddeman

Unacceptable! I'm withdrawing my Patreon support! I want lots of crap videos! Hey Nurdrage has been spending months on his Sodium project. I'm seeing that Chemistry is either fast and dirty or long, slow with lots of lessons learned along the way. I do kinda like his lab note videos though. :)

The the dilution scene was very visually pleasing! I didn't know you could reverse engineer jeans colorings. You have also discovered the new distressed jeans tlook ☺️ Do any of those chemicals have any effect on the integrity of the fabric? Would it be worth it to use new jeans that haven't been washed by the consumer yet? I'm not sure how someone would go about shredding jeans, but would that increase the amount of indigo you could get out?

Daniel Blake Shoemaker

Interesting extracting Indigo from Jeans.