In Dr Stone, the main character makes aniline by rinsing coal tar with HCl, then mixing in ethyl acetate. See the image below. Is a method like this possible? What is occurring here?
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1$\begingroup$ It's extraction, not synthesis; and seems reasonable. $\endgroup$– MithoronCommented Oct 12, 2019 at 18:13
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3$\begingroup$ Actually he's getting anilinium hydrochloride $\endgroup$– WaylanderCommented Oct 12, 2019 at 18:38
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1$\begingroup$ @Waylander Sure, but extraction with acetate suggest not mentioned neutralization step. $\endgroup$– MithoronCommented Oct 12, 2019 at 20:32
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1 Answer
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Believe it or not, aniline was actually isolated from coal tar way back in 1834. A chemist called Friedlieb Runge isolated aniline along with phenol from coal tar. He discovered that aniline produced a beautiful blue color when treated with chloride of lime (calcium hypochlorite). He named it cyanol/kyanol and that was the birth of the first aniline dye but it was made a dye by the exhaustive work of another chemist, William Perkin.
Perkin distilled the components of coal tar like benzene, aniline, toluene, anthracene, phenol, naphthalene and other aromatic hydrocarbons. He first worked around toluene to make allyl toluidine which he then transform to quinine by oxidizing it with a mixture potassium dichromate and sulfuric acid. He was left with a useless reddish-black powder. He then took aniline and repeated the experiment. He was left with a black gooey substance. Disappointed by the results, he took the test tube and washed it off but then came out a beautiful looking purple residue which hung off at the wiping cloth. He named the dye "mauveine". Perkin was so amazed by the result that he started working with other distilled products hoping to make other dyes$\ce{^{[4]}}$ . His discovery revolutionized the dye industry. Perkin proposed the following statement:
Benzene, toluene, and other components of coal tar were colorless because they absorbed ultraviolet light undetectable by the human eye. But if those aromatic hydrocarbons were treated with an acid to create aniline or another amine, after some additional steps the newly synthesized molecules very efficiently absorbed light particles from specific wavelengths in the visible spectrum.
So, Senku (the main character of Dr. Stone) being well-versed in chemistry knows what he's talking about.
Notes and references
- https://trc-leiden.nl/trc-needles/materials/dyes/aniline
- https://www.scientificamerican.com/article/toms-river-excerpt-on-aniline-dye/
- https://www.cavemanchemistry.com/cavebook/chtar.html
- Magentas from toluene, reds from anthracene, pinks from phenol, and indigos from naphthalene.
- Dr. Stone is an amazing anime. I recommend fellow readers to check it out.
answered Jun 19, 2020 at 14:19
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$\begingroup$ My recollection is that Hofmann, Perkin's teacher, put him up to the task of synthesizing quinine based solely on formulas. I don't believe he every succeeded in his goal. $\endgroup$ Commented Jun 19, 2020 at 18:36