iary in Bhopal, India, and recent chemical leaks at Carbide's Institute plant. At a press conference, the firm revealed the results of the in vestigation of the eruption on Aug. 11 of a reactor being used as a stor age vessel at the Institute plant. Car bide chemists and engineers have concluded that an exothermic de composition of aldicarb oxime was the most likely cause of the erup tion. Of the 3800 lb of material ex pelled, 650 lb was methylene chlo ride solvent, 300 lb was solid resi due in pipes from previous use of the reactor, and only 8 lb was aldicarb oxime itself. Some of the compounds released were foul smelling as well as toxic. Jackson B. Browning, vice president of health, safety, and environmen tal affairs, says that such compounds as methyl mercaptan and dimethyl sulfide and disulfide persisted in the community at concentrations from 3 to 18 ppm for a half hour. Compounds related to aldicarb oxime reached concentrations of 10 ppm. Methylene chloride vapor extend ed beyond the fence limit at 22 ppm for a few minutes, Browning says. As Carbide investigators recon struct the incident, methylene chlo ride was piped into the aldicarb re actor on Aug. 1. Aldicarb oxime (α-thiomethylisobutyraldoxime) was introduced next. A malfunction in a flow meter caused too much ox ime to be let in. Engineers installed a temporary pipeline to pump the solution into another 5000-gal, glasslined reactor that had not been used since November 1984. Unknown to Carbide operators, steam flowed through leaky valves into the jacket of this reactor from Aug. 1 to 7. The heat caused meth ylene chloride (boiling point 104 °F) to boil off from the oxime (boil ing point 410 °F), raising the con centration of oxime from 38% to 81%. Methylene chloride was later found to have condensed in two connected vessels called the knock out pot and the crystallizer. Not realizing that this change had occurred, Carbide operators tried to pump the reactor contents back into the aldicarb reactor on Aug. 7. Af ter two and a half hours, the pump appeared not to be moving any more material, and it was shut off. Oper
ators could not use level indicators to determine that the pumping was incomplete because the remaining 500 gal formed what is called a heel in the convex bottom of the vessel. Steam continued to flow into the reactor jacket, and the temperature rose. To know that this was hap pening, operators would have had to call up the display of the reac tor's condition on the control-room computer. Thinking the reactor emp ty, they did not do this. From laboratory experiments and computer simulations, Carbide in vestigators conclude that on the morning of Aug. 11, the reactor tem perature reached 300 °F. This tem perature initiated exothermic decom position of the oxime. At 9:25 AM, a differential pressure alarm went off, indicating that a safety valve had burst and that a high flow of gas was flowing through the knock out pot and scrubber to the flare tower. An operator entering the con trol room heard a rumbling sound from the reactor. He looked toward
the flare tower and saw a lot of smoke. After four seconds, the dif ferential pressure indicator dropped precipitously, indicating that other release valves had opened. The plant alarm was sounded at 9:26. An opaque, white fume engulfed the yard and the control room, trap ping five operators and their fore man. The men could not see the panels in front of them. At 9:32, the eruption ended. A minute later, the workers were led to safety. At 9:36 county officials were notified. The reactor that erupted had last been used in November 1984 to react 2,4,6-trimethylphenol with methyl isocyanate. Methyl isocyanate was not involved in the incident of Aug. 11. There remained in the piping associated with the reactor a resi due of such methyl isocyanate de rivatives as 1,3-dimethylurea, 1,3,5trimethylbiuret, and trimethyl isocyanurate. These solids (300 lb) were blown out along with aldicarb ox ime decomposition products and methylene chloride. •
Heckert chosen to be next Du Pont chief Du Pont has appointed current vice chairman Richard E. Heckert to a new post of deputy chairman of the board. The move positions Heckert to succeed chairman and chief ex ecutive officer Edward G. Jefferson when Jefferson retires next May 5. As deputy chairman, Heckert, 61, has operating responsibility for all Du Pont units and consolidated subsidiaries. Succeeding Heckert as vice chair man is Edgar S. Woolard Jr., 51, who becomes responsible for Du Pont operations excluding Conoco. Jefferson, who has been chairman and chief executive officer since 1981, says that "by announcing the appointments at this time, we pave the way for an orderly management transition at a time of important changes to improve the competi tive position of our businesses." Be sides the acquisition of Conoco, Du Pont in the past several years has been diversifying itself away from traditional chemicals and becoming more heavily involved in specialty chemical, biomedical, and electron ics businesses.
Heckert, who joined Du Pont as a research chemist in 1949, has been a director and member of the exec utive committee since 1973. In 1981, when Jefferson became chairman of Du Pont, Heckert was made presi dent and chief operating officer of
Heckert: appointed to new post September 2, 1985 C&EN
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News of the Week the company. Later that year, after the acquisition of Conoco, to make room for its management his title was changed to vice chairman, and he had responsibility for n o n Conoco operations. Conoco chair man Ralph E. Bailey was appointed vice chairman with responsibility for Conoco operations. Woolard has been an executive vice president, a director, and mem ber of the executive committee since 1983. He joined Du Pont in 1957 as an industrial engineer. D
Trade bill would do more harm than good A bill that would impose counter vailing duties on lower-priced im ported products made with alleged ly subsidized n a t u r a l resources might save the U.S. chemical in dustry a few thousand jobs, but it probably would cost the overall U.S. economy a few hundred thousand jobs. That's the asessment of Bruce R. Lippke, president of Wharton Econometric Forecasting Associates, Philadelphia, who spoke last week at a meeting of the World Trade Writ ers Association in New York City. The bill, introduced by Rep. Sam Gibbons (D.-Fla.), just missed be coming law last year. It passed the House, but died in an l l t h - h o u r conference session struggling to push through the Trade & Tariff Act of 1984. Gibbons reintroduced a slightly modified version this year. Lippke says the Gibbons bill would do more harm than good to the U.S. chemical industry and to the entire U.S. economy. If passed, it would save a maximum of about 7000 jobs in affected industries, he says, split almost evenly between the chemical and the lumber and wood products industries. But Wharton's econometric mod el of the U.S. economy predicts that, by the end of 1994, the price of saving those 7000 jobs would be the loss of 385,000 jobs in other industries. Meanwhile, the federal debt would rise $33.3 billion, per sonal disposable income would drop $59 billion, and gross national prod uct would suffer a $113 billion loss. That's a high price to pay, says 8
September 2, 1985 C&EN
Lippke, for 3857 chemical industry jobs saved in the 1986-94 period. The chemical industry has been split over the problem of foreign subsidized natural resources ever since the problem first surfaced. An ad hoc committee of domestic ni trogen producers tried to get coun tervailing duties slapped on Mexican ammonia. The Commerce Depart ment dismissed the complaint, rul ing that although natural gas prices in Mexico were lower than the prices of Mexican gas exports, those lower prices were available to all Mexican industries, not just ammo nia producers. Other U.S. chemical companies, with extensive foreign investments or exports, fear retaliation by for eign countries if the U.S. places im port duties on products made with
their lower-priced natural resources. Those countries consider their re sources a natural advantage, not an unfair advantage. Lippke agrees that a successful Gibbons bill would invite retalia tion. It is one of the basic assump tions in Wharton's study, which was done for the Promote America Trade group. Wharton looked at the im pact on four selected industries that would be affected by the legisla tion—petrochemicals (plastics), fer tilizer (ammonia), carbon black, and softwood lumber. Particularly hard hit, says Lippke, would be the U.S. farm sector, for which higher fertil izer prices would raise production costs, hurt exports, and cost 52,000 agricultural jobs. Had the study cast a wider net, the impact would have been even greater. D
Herbicide-resistant corn nearer to market A genetic engineering company, a chemical company, and a seed com pany have joined forces to bring herbicide-resistant corn varieties close to marketing. First commer cial results of the venture could ap pear by 1991. Molecular Genetics Inc., Minnetonka, Minn., identified and isolat ed genes conferring resistance to a new class of herbicides developed by American Cyanamid, then in corporated the genes into corn plants. Cyanamid, which funded the MGI work, holds an exclusive li cense to the genes. Now Cyanamid has licensed Pioneer Hi-Bred Inter national, Des Moines, to breed the genes into other corn "inbreds" for testing and perhaps for use in com mercial hybrids. The new herbicides belong to a class k n o w n as i m i d a z o l i n o n e s (C&EN, Sept. 27, 1982, page 33). They work by inhibiting certain en zymes, are effective at low dose rates, and so far appear to be rela tively nontoxic and environmentally benign. Two types are on the mar ket. Arsenal, which is nonselective, is licensed for "industrial weed con trol." Scepter, selective against a broad spectrum of broadleaf weeds, received a permit for emergency use on soybeans this year, and Cyana mid expects to receive registration
soon for its r o u t i n e use on soy beans. According to Charles Muscoplat, president of MGI, the herbicide re sistance was imparted by dosing corn-cell cultures with imidazo linones and then growing the sur viving cells—containing the pre sumably mutant gene that conveyed tolerance—into whole corn plants. The resistant plants contain a dif ferent form of acetohydroxy acid synthase, the enzyme that is nor mally blocked by the herbicide. Those first plants, although herbi cide resistant, d i d n ' t give good yields. So now Pioneer, the U.S.'s largest producer of hybrid seed corn, will incorporate the resistance gene into its proprietary inbreds and also into selected "public" lines (non proprietary varieties developed at universities), using classic crossing and back-crossing techniques. The eventual aim is to produce highyielding hybrids, with yields further enhanced by the ability to use the herbicide to minimize competition from broadleaf and grassy weeds. Meanwhile, others pursue simi lar goals. For example, Calgene Inc., Davis, Calif., is using recombinant DNA techniques to insert genes conveying resistance to Monsanto's Roundup (glyphosate) into various crop plants. Π
