acs n e w s
Dow Bromine Process Is Historic Landmark
T
he bustling freeways and urban sprawl of Michigan's lower peninsula obscure its 19th-century history as part of the vast—and mostly e m p t y frontier that stretched west from the Allegheny Mountains. But in the late-19th century, chemical industry pioneers—Herbert H. Dow, especial· ly—began to transform this woodsy outback into a powerhouse for the nation's economic growth and a locus for one of its most continuously successful industries. Drawing on the region's natural resources as well as his own pluck, inventiveness, and dedication to efficiency, Dow reinvented the manufacturing process for bromine and other industrial chemicals. His work
and business acumen allowed him to break the stranglehold of powerful European cartels that dominated world chemical production, and it set the stage for thefledglingU.S. chemical industry to develop, manufacture, and market its own products. Dow's process for producing bromine electrolytically was recently lauded as another of the National Historic Chemical Landmarks designated by the American Chemical Society. The Dow bromine process had been nominated by the ACS Midland Section. At Dow's Midland, Mich., hometown, organizers of the landmark program also held forth with another festive and informative event to commemorate Dow's achievement. ACS President Paul S. Anderson reflected on the significance of hone oring Herbert H. Dow. "It's nice to be here today to honor the work of an industrial chemist," Anderson said. "All members of the chemical community benefit from a creative and profitable chemical industry." Midland, world headquarters for Dow Chemical, is surprising with its frozen-intime Victorian charm and Re-creation of the Evens Mill where Dow started Midland Chemical Co. (left) and replica of lab where Dow carried out the first electrolytic production of bromine. The electrolytic cell Is shown on the tabletop below.
bucolic landscape of parks and quiet, tree-lined streets. Once a neariy forgotten lumbering town, Midland obtained through Herbert Dow a new and lasting prosperity. Evidence of his generosity is seen at practically every street corner. Today, masterfully restored 19thcentury homes blend in with the futuristic look of Frank Iioyd Wright-style houses reflecting the tastes of later generations. Still, at the Herbert H. Dow Museum on the edge of town, it is easy to imagine what Dow first saw in Midland and to imagine also that it still has not changed very much. As a college student at the Case School of Applied Science in Cleveland, Ohio, Dow first became interested in the brine deposits that underlie much of the American Midwest—materials deposited by the evaporation of prehistoric seas. Within these deposits, Dow knew, was an almost inexhaustible supply of valuable chemical materials. One of these chemicals was bromine, which, when converted to a derived product, was salable as a component in patent medicines, as a disinfectant, and as an ingredient in film for the emerging photographic industry. As a student, Dow had already invented an efficient "blowing-out" process for liberating bromine from brine. Instead of boiling a chemically treated brine solution, he trickled it over a burlap curtain and blew a current of air through it. "By passing the bromine-laden air through a body of iron turnings," Dow wrote in his patent, "the bromine and iron will chemically unite, forming a bromide of iron known as ferric bromide." Since the ferric bromide solution was not the form desired by most customers, Dow then converted the bromine into solid products such as zinc, sodium, and potassium bromides. Dow's great innovation, however, involved the first step in this manufacturing process—liberating elemental bromine from brine. The existing chemical process involved adding chemicals such as sulfuric acid and bleaching powder to free the bromine. Next, the brine was boiled until the reddish-brown liquid bromine came off with the steam. Instead of a chemical treatment, Dow used an electric current to oxidize the bromide salts in the brine. Although earlier scientists—Luigi Galvani, Alessandro Volta, Humphry Davy, and Michael Faraday—had pioneered electrochemistry, Dow's electrolytic cell was among the first devoted specifically to chemical manufacture. Successful application of electrochemistry made Dow and his Midland Chemical JULY 7, 1997 C&EN 4 3
acs n e w s Richard M. Gross (left), Dow's Michigan Operation vice president and director, and Anderson with the ACS National Historic Chemical Landmark plaque.
Co. the world's most efficient bromine manufacturer. At the historic chemical landmark event—held on the grounds of the Herbert H. Dow Museum, which includes a replica of theflourmill building and lab-
oratory where Dowfirstimplemented his electrolytic process for bromine—a frequent questionfieldedby museum volunteers was, "Why Midland?" The answer After surveys of many brine wells in Michigan and Ohio, Dow
found the brine in Midland to have the highest concentration of bromine. And tapping brine for bromine led Dow to work out methods for using electrolysis to extract other elements from brine—chlorine, for instance, which could be used to make bleaching powder, a product in high demand by the nation's textile mills. With the success of his bleaching powder product, Dow formed Dow Chemical Co., which eventually incorporated Midland Chemical Co. and its bromine-containing products. In succeeding years, the company made and marketed a growing number of other products derived from the brine stream, ranging from chloroform and sodium benzoate to calcium chloride and Epsom salts. Today, Dow Chemical is the largest chemical company in the U.S. and is still a major producer of chlorine, but it no longer produces bromine or bleaching powder. William Schulz
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