Views : 1,551,245
Genre: Science & Technology
Date of upload: Aug 31, 2018 ^^
Rating : 4.946 (542/39,429 LTDR)
RYD date created : 2022-04-09T18:29:53.639349Z
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Top Comments of this video!! :3
NileRed, regarding Sodium Hydrosulfite (aka Sodium Dithionite), which is an alkali salt itself; from Wikipedia: "It is used as such in some industrial dyeing processes, primarily those involving sulfur dyes and vat dyes, where an otherwise water-insoluble dye can be reduced into a water-soluble alkali metal salt (e.g. indigo dye)" So basically the indigo was being kept water-soluble because it was an alkali metal salt. Adding the acid neutralized the alkali and separated out the indigo dye which then was no longer water-soluble.
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Okay, a couple of things. I've been working with indigo for a few years during my PhD, so there are a few things you could try. For one, as you alluded to, indigo's one characteristic property is its abysmal solubility. Good for a dye, bad for a reagent. Older german papers talk about its solubility in either boiling chloroform, or in neat sulfuric acid, but we have typically used it as a suspension in DMF at around ~260 mg in 40 mL. By itself, it is not very soluble, but a lot of derivatives are considerably more soluble because they typically have less inter/intramolecular hydrogen bonding. Salts in particular have higher solubility (probably why you werent getting anything precipitating before adding acid - indigo is fairly acidic because the N-anion is stabilised), and N-alkyl derivatives are fairly well-behaved (i.e. di-boc indigo will dissolve in hexane). Because of the hydrogen bonding and electronics aspects, a lot of derivatives have different colours. N-acetyl indigos are typically red, mono-N-alkyl derivatives are usually blue, and di-alkyl derivatives are green. The really interesting stuff comes from other modifications of the core ring structure, which is what I've been working on. If you're interested, get in contact and we can talk more about it.
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I love this channel because you do a really good job of talking and explaining your methods, and your production quality has increased tremendously over time. I think I've learned more about chemistry by watching your videos than I ever did in high school. Keep this up and you'll have a golden play button in no-time :)
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I love chemistry and am a horrible test taker. I was getting a 54 in grade 11 chemistry and my teacher saw I wasn’t stupid and asked what the problem was. I told her I loved the class and understood her, just had test anxiety. I showed her one of your videos and said “this is why I took chemistry. I love it and I understand it” she ended up loving your channel and having good conversations with me over them. She passed me with a 70 after the exam. Thanks for your help there 😂. I won’t be continuing chemistry next year but I will be continue watching your videos
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@art_and_sh.t4265
4 years ago
Me, knowing absolutely nothing about chemistry: hehe color
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