Making butadiene into polybutadiene wasn't hard, but butadiene wasn't easy to make. A priest and Notre Dame professor named Father Julius Nieuwland was working on a project that looked like it would have the answer. He had made vinylacetylene. Elmer K. Bolton thought that this might just lead to an easy way to make butadiene, like this:

One of the Carothers team, Gerard Berchet, happened to leave a sample of vinyl acetylene in a jar with hydrochloric acid (HCl) for about five weeks. Then another member of team, Arnold M. Collins happened to look in that jar and found a rubbery white material. The HCl had reacted with the vinylacetylene, making chloroprene, which then polymerized to become polychloroprene.

The new rubber was called "Duprene" at first, but was renamed Neoprene^TM. It was expensive, but resisted oil and gasoline, which natural rubber didn't. It was the first good synthetic rubber.

This was the first discovery made by Purity Hall that could be turned into a profitable product. In some ways it saved "Purity Hall". It also made Carothers famous.

But Carothers never really liked his new synthetic rubber. When he reported its discovery in a memo to his boss, Elmer K. Bolton, he didn't even mention that the material could be used as synthetic rubber, only that it was structurally similar to natural rubber. ^1,2 To Carothers polychloroprene was a lucky accident, not true science. Neoprene^TM was useful, but to him it did not expand his understanding. For Carothers the joy of science was purely reaching new understanding of nature's mysteries. Without that, useful products weren't enough to satisfy him.

"The scientific results were abundant in quantity but perhaps a little disappointing in quality."

- Wallace Carothers^4,5