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March 02, 2008


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a fat chemist

Filling in gaps huh? Well, I find indigo particularly interesting for both chemical, economic, and social reasons. Indigo is an isatin dimer and is constructed from two indole structural units, the same precursors to a number of important natural products such as melanin, melatonin, serotonin, tryptophan, and the indole alkaloids among many others. It is also a convenient starting point for the synthesis of lysergic acid (LSD); however, I won't elaborate any further on that topic.

From a more socioeconomic perspective I find indigo dyes interesting for a couple of reasons. Purple and blue dyes (typically shades of indigo) were restricted to aristocratic classes throughout antiquity, because the pigments were extracted from plants grown in India, southeast Asia, and Africa and very expensive to acquire. The current chemical industry at large was founded on the production of synthetic dye in the late 1800s. Adolf von Baeyer was the first to synthesize indigo in a lab in 1878, with a commercial process to follow from BASF in 1897 (I've pulled these dates from the all-knowing Wikipedia). It's not in the wikipedia article, but if memory serves me correct from an early sophomore organic chemistry lecture, he was researching an alchemy-type reaction (e.g. turning lead into gold) and obtained a black sludge (not a good sign for a chemist). However, when he extracted the material with an organic solvent, he observed the beautiful blue-purple hue of indigo. The impact of this discovery was substantial and immediate. Purple and blue dyes were now attainable by people well outside of the aristocracy, significantly devaluing the symbolic importance of the royal color. The farming of plants for extraction of the dye became unprofitable and subsequently collapsed. Almost all indigo is made synthetically these days.

The commercialization of indigo dyes is one of the very first examples of the power and potential of the modern chemical industry. It demonstrated that valued materials could be made synthetically in a lab, commercialized, and have a huge impact on economic markets.


I love the fact that this discovery was a by-product of attempts at alchemy! I've always found alchemists to be a fascinating subject... I mean, how can you go wrong with a guy named Philippus Theophrastus Aureolus Bombastus von Hohenheim Paracelsus?! They also liked working with piss a lot... not sure why...

a fat chemist

Chemical availability and cost are particularly influencing factors in chemistry. What's more ubiquitous and cheap than urine? It's also rich in nitrogen sources (urea, uric acid, ammonia), which is probably why it was investigated so frequently. Personally, I buy it from a commercial chemical supplier...but I consider myself a pretty rational chem grad student; I can't say the same for everyone.


Fat Chemist has got a point Mark - urea rocks, especially when it comes to dyeing cloth, specifically in direct application of dyes (like making tie-dye or other hand-dyeing processes). It can be synthesized from a natural gas, but it's kind of more festive if it comes from the urine of mammals, don't you think (waste not, want not, right?). It's not used for vat dyeing, but in hand-dyeing it works really well to dissolve more dye in a given amount of water (esp for strong/dark colors) and attracts water (referred to by the cool word "humectant") to keep the fibers you're dyeing damp so the dye will react permanently.

Also C - I certainly didn't mean to suggest all you're good for is the chemistry side of life. Heheheh. It sounds like (as if you don't have enough work to do / stuff to read) you might enjoy looking at Andrew Pickering's article at some point - it's called "Decentering Sociology: Synthetic Dyes and Social Theory" and it was published in _Perspectives on Science_ in Fall 2005.


Well, I'll file all this info away under "cool things I know about urine." Actually, I think I need to make a new file for that... [gets out metaphorical sharpie and blank manila folder]

baju batik

the Three Cats brand comes out of Manchester. The fabric is used for garments in South Africa that are worn by slaves, Khoisan, Sotho, Xhosa, and Voortrekker women.


his post makes me wonder. What essential equipment would you pack with you in your time machine? More importantly, how would you use it? In many cultures, using something as simple as a flashlight could get you burned at the stake!

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