Perfume and TNT

Perfume and TNT

From A Feast of Science, by Dr. Joe Schwarcz

One of the most fascinating facets of chemistry is the process of discovery. Think of TNT and chances are you think BOOM, not Chanel #5. But rinitrotoluene (TNT) played a major role in thf formulation of one of the most famous fragrances in the world.

Following William Henry Perkin”s 1856 accidental discovery of mauve, the world's first synthetic dye, the chemical industry was hot on the trail of new colorants. It was then that German chemist Joseph Wilbrand synthesized TNT, which never made it is a yellow dye but did announce itself with a bang. At the time, trinitrophenol, commonly known as picric acid, was the most widely used high explosive but was prone to accidental detonation during production and transport. TNT, on the other hand, can be melted and poured into shell or bomb casings with safety. Its detonation requires the use of a more sensitive explosive such as lead azide, which when energetically struck, quickly decomposes to elemental lead and nitrogen gas. The shock wave created by the rapidly expanding nitrogen sets off the TNT. The same chemistry is used in automobile air bags where sodium azide supplies the nitrogen needed to inflate the bag.

When TNT detonates, it also releases nitrogen along with steam and carbon monoxide. It is the rapid production and expansion of thee gases that characterizes an explosion. While TNT never made it as a dye for fabrics, during World War I it did manage to taint the skin of munitions workers, most of whom were women. “Canary girls” these ladies came to be called. Skin discoloration, however, wasn't the only problem. TNT can be absorbed through the skin and cause nausea, loss of appetite, and liver problems. Many workers suffered before it was discovered that application of grease to the skin would prevent absorption.

After the explosive potential of TNT was recognized, chemists went to work trying to get more bang for their buck by attempting to modify the compound's molecular structure. And that is just what Albert Bauer was doing in 1888 when he used the well-known Friedel-Crafts alkylation reaction to add a four-carbon fragment known as a tertiary butyl group to the molecule. As the reaction proceeded, he noted that the lab filled with a decidedly unusual smell. Being a chemist, Bauer was familiar with all sorts of odors, and this one reminded him of the fragrances of musk. That was an exciting observation because at the time musk scent was a much sought-after commodity, highly prized by the perfume industry. Only did it lend a pleasing note to a perfume, but it also acted as a fixative, slowing down the evaporation of all the perfume's components.

Musk scent was very expensive because of the scarcity of its source, the sex glands of the Asian male musk deer. The animal secretes a smelly mixture of compounds from the glands located near its anus to attract the female. In its concentrated form, the scent is decidedly unattractive, but it becomes seductive when diluted. How anyone ever discovered that the dried and then diluted secretions from his inconspicuous little abdominal sac of the male musk deer charmed receptors in our nasal passage remains a mystery. What we do know, however, is that musk fragrance has been used by perfumers since antiquity, with the word “musk” itself deriving from the Sanskrit word for testicle. The ancient Hindus seemingly were better at perfume-making than anatomy since the scent glands are quite distinct from the animal's testes.

As soon as Bauer sniffed the musky aroma of his new compound, he recognized that he was on to something. He quickly filed a patent for Musk Bauer, and proceeded to make other “nitro musks” with even more effective scents. Musk xylene, musk ketone, and musk ambrette revolutionized the perfume industry and made Bauer a rich man. The nitro musks became the cornerstone of the perfume industry, accounting foe the popularity of perfumes such as Chanel #5, introduced in 1921, and L<Air du Temps in 1948. They were mainstays until the 1980s when they were dropped because of concerns about their poor biodegradibility, neurotoxicity, and tendency to cause a skin rash when exposed to sunlight.

Marilyn Monroe apparently wasn't worried about exposure to sunlight in her bedroom. When asked what she wears to bed at night, she famously replied, “Why Channel #5 of course!” Quite an explosive remark in those days.

Marilyn Monroe, Heidi Klum, Farrah Fawcett. Photo by Elena.