Nylon goes green

Simple reaction makes manufacturing produce less greenhouse gas

Whether the world is better off from the invention of panty hose is debatable. But a new route toward making nylon — the polymer of many a sheer stocking — is decidedly better for the planet.

Using ozone bubbles and ultraviolet light, chemists can now make a precursor to nylon without the typical exhaust of greenhouse gas. The finding appears in the Dec. 19 Science.

Nylon is usually made from adipic acid, a zigzag molecule of six carbons bedecked with hydrogens and a few oxygens. To get adipic acid, scientists react hexagon-shaped carbon molecules with corrosive nitric acid. That reaction gives off nitrous oxide, which can harm the Earth’s ozone layer and, molecule-for-molecule, has nearly 300 times the planet-warming capacity of carbon dioxide. Human activity produces more than 8 million metric tons of nitrous oxide each year and up to 8 percent of that comes from making nylon.

To avoid this, chemists Kuo Chu Hwang and Arunachalam Sagadevan of the National Tsing Hua University in Hsinchu, Taiwan, replaced the nitric acid with bubbles of ozone, O3, and ultraviolet light. The ultraviolet light breaks the ozone gas into O2 and a highly-reactive oxygen atom. Lone oxygen atoms then repeatedly attack and latch onto a hexagon-shaped carbon molecule, cyclohexane, until the ring breaks open, forming adipic acid. 

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