Organic Chemistry I For Dummies, 2nd Edition (2014)
Part V. The Part of Tens
Chapter 22. Ten Cool Organic Discoveries
IN THIS CHAPTER
Seeing ten important discoveries in organic chemistry
Recognizing the role that serendipity plays in the discovery process
In this chapter, I cover ten cool discoveries that relate to organic chemistry. One interesting feature of this list is that all these discoveries contain some element of the serendipitous. Although you can never discount hard work and preparation, chance and fortune have played a major role in the big discoveries in organic chemistry (although, as Pasteur would say, luck favors the prepared mind).
Explosives and Dynamite!
Alfred Nobel and his family recognized the potential of nitroglycerin as a commercial explosive — a substance with explosive properties more favorable than gunpowder. In his laboratory, however, his family discovered firsthand how dangerous the substance could be. In a massive nitroglycerin explosion, Alfred’s brother Emil and several co-workers were killed.
After the accident, Alfred worked to make nitroglycerin safer (see Figure 22-1). He noticed that when he mixed the syrupy nitroglycerin with silica powder (diatomaceous earth) he obtained a stable mash that he called dynamite. When he commercialized his discovery — along with blaster caps to safely start the explosion — he became one of the wealthiest men of his time. When he died in 1896, he left his fortune to set up the Nobel Foundation. Each year, the Nobel Foundation grants the prestigious Nobel Prizes, of which, ironically, the Peace Prize is one of the most famous.
FIGURE 22-1: Making dynamite.
No one knows for sure who discovered fermentation, but it was probably first observed many thousands of years ago in caskets of rotting fruit. After being bruised and left out for several weeks, fruit ferments (gets broken down by enzymes in yeasts) to make alcohol, as shown in Figure 22-2. Although this rotting fruit probably didn’t taste very good, someone who drank the juice discovered that it had a potent and pleasurable effect on the body. This likely led to the discovery of wine making, and, some time later, beer making, which uses grains and honey as the source of sugars and carbohydrates rather than fruit.
FIGURE 22-2: Making alcohol.
The Sumerians are the first on record to begin brewing beer, some 6,000 years ago (although beer making probably was going on long before this time). In fact, some historians have suggested that many humans gave up their nomadic lifestyles and became farmers after the discovery of fermentation, just in order to grow crops to make beer. (This suggestion seems to coincide with human nature.)
The Synthesis of Urea
The synthesis of the organic compound urea from an inorganic substance by Friedrich Wöhler was one of the first major breakthroughs in organic chemistry. With this accomplishment, Wöhler showed that organic substances were not held together by a “vital life force,” as had been postulated at the time.
Wöhler had attempted to synthesize ammonium cyanate as a continuation of his studies of inorganic cyanates. He isolated instead a substance that seemed to resemble urea, “a so-called animal substance,” or in modern terms, an organic compound (see Figure 22-3). Comparing the properties of his synthesized compound to those of the pure urea he had extracted from urine, Wöhler found that the properties of the two were identical.
FIGURE 22-3: Wöhler made urea from ammonium cyanate.
The Handedness of Tartaric Acid
The handedness of tartaric acid (shown in Figure 22-4) was discovered by Louis Pasteur. Why was Pasteur studying tartaric acid? As a French chemist, he was studying wine (of course), of which tartaric acid is a component. He noticed that tartaric acid formed into two different crystal shapes. He separated the crystals with tweezers under a microscope, and noticed that crystals of one shape rotated plane-polarized light in one direction, and the other crystals rotated light in the opposite direction. He surmised (correctly) that these different crystals must relate to the handedness of the molecules themselves.
FIGURE 22-4: One of the stereoisomers of tartaric acid.
Two German chemists, Otto Diels and Kurt Alder, discovered the diene synthesis currently known as the Diels–Alder reaction. This reaction is just cool — it forms two carbon-carbon bonds simultaneously, and is extremely useful for the construction of strange-looking bicyclic molecules, like the pesticide Aldrin (shown in Figure 22-5) and various six-membered rings.
FIGURE 22-5: Making Aldrin with the Diels–Alder reaction.
Interestingly, in their classic paper describing the reaction, Diels and Alder wrote, “We explicitly reserve for ourselves the reaction developed by us to the solution of such problems [natural product synthesis].” Surprisingly, this “Back off!” warning to other chemists had the desired effect: Other chemists stayed away from this reaction until after World War II was over, and synthetic chemistry in Germany had taken a serious hit. Typically, though, such statements in the literature have the opposite effect of the intended one. Moses Gomberg found this out the hard way in 1900 when he reserved for himself the right to study the triphenyl methyl radical (Ph3C·) — the first radical known to chemists — and chemists trampled over each other to begin their own research on the molecule.
Buckyballs are one of the most recently discovered allotropes of carbon. Allotropes are compounds that contain only a single element — in this case, carbon. Other carbon allotropes include graphite and diamond. Buckyballs, discovered in 1985 by Richard Smalley, Harry Kroto, and Robert Curl, look like molecular soccer balls. Buckyballs were discovered accidentally when these chemists blasted a laser at graphite powder and passed the products through a mass spectrometer. They noticed a peak in their mass spectrum that corresponded to exactly 60 carbons. Using intuition, they surmised that the structure corresponding to this peak must be a spherical molecule (see Figure 22-6). They named this molecule buckminsterfullerene, after Buckminster Fuller, who popularized the geodesic dome; because of their spherical shape, these molecules are often called Buckyballs. Although these molecules haven’t produced any practical applications so far, they’re being studied for use as superconductors, as gasoline markers (so oil spills can be traced back to a specific oil company), and as vehicles for drug delivery.
FIGURE 22-6: Buckyball.
Legend has it that soap was first discovered by Roman women washing their clothes along the Tiber River. They noticed that when they washed their clothes in some places of the river their clothes got cleaner than when they washed them in other places. Apparently, next to the river was a sacrificial site, where, presumably, the animal fat from the sacrifices mixed with the fire ashes (which contain lye, or potassium hydroxide), making soap (see Figure 22-7). The soap then ran down the hill to the river after it rained.
FIGURE 22-7: Making soap.
James Schlatter discovered aspartame by doing something that would make safety experts cringe — he licked his fingers after working in the lab. He found that his fingers tasted very sweet and traced back the sweetness to aspartame (shown in Figure 22-8), the compound he was working on (and he had another taste of his synthetic aspartame just to be sure he was right). And so was born one of the most popular sugar substitutes. NutraSweet and Equal all contain the sugar substitute aspartame, as do many diet soft drinks.
FIGURE 22-8: Aspartame.
The story of penicillin’s discovery is probably the most well-known case of serendipity in the discovery process. Alexander Fleming was doing research on Staphylococcus bacteria, when he noticed that his culture plates had become contaminated by a Penicillium fungus. He discarded the plates into a sterilizing wash but didn’t submerge them properly. When he returned to the lab, he noticed that on the plates where the fungus had grown, the bacteria had been killed. “Something that the fungus is producing must be killing the bacteria,” he thought to himself. That something was penicillin (shown in Figure 22-9), an antibiotic that would eventually save countless lives.
FIGURE 22-9: Penicillin.
Two chemists, James Rebok and Roy Plunkett, who worked for DuPont, discovered Teflon in 1938. Teflon is the polymeric nonstick surface that keeps your eggs, bacon, and pancakes from sticking to your frying pans (see Figure 22-10 for the structure). When they discovered Teflon, Rebok and Plunkett were working with fluorinated hydrocarbon gases kept in large canisters. One day, they opened the valve on what they thought was a full canister of gas, but no gas came forth. At first, they thought that the canister had sprung a leak, until they noticed that the supposedly empty canister had the same weight as a full container. Sawing open the container, they found a sticky white substance had coated the inside of the container — Teflon!
FIGURE 22-10: Teflon.