SYNTHESIS:
Focus on By-Prod ucts Cleaning u p industrial by-products may have to start with the bench chemist, who has been little involved up to now. "It is time for us to teach our students the importance of following the fate of by-products obtained in laboratory synthesis, to consider whether they can be recycled, or modified and used again, or discarded in a manner that is not toxigenic to other living things. We can also reexamine the synthetic process to ascertain whether there is not a more specific, conserving, possibly catalytic method whereby the same conversion can be achieved/' That quote from chemistry professor Nelson J. Leonard of the University of Illinois describes "negative yield" and "reverse synthesis," two concepts he urges in teaching and practicing synthetic chemistry. The occasion of the quote was a luncheon in New York City where he received the Synthetic Organic Chemical Manufacturers Association's medal for creative research in synthetic organic chemistry. SOCMA was recognizing Dr. Leonard for broad contributions in organic chemistry and development of new methods of opening and closing ring structures. He had received ACS's award in Synthetic Organic Chemistry in 1963. Dr. Leonard had industrial application in mind when explaining the importance of negative yield. "I have heard frequent criticism from industrial development groups when their research counterparts have discovered a valuable new product, synthesized it in low yield by a method producing unacceptable waste products, and then passed it along to the development groups for solution of all the problems against a deadline," he says. "We can suggest to our students
Leonard (center) receives award Recognition for creative research 16 C&EN JUNE 22, 1970
that a 90% yield in a synthetic organic reaction really amounts to a negative yield of 10% in terms of the penalty that must be paid for disposal of byproducts. The meaning is dramatized when we ask what this amounts to in a million-time scaleup. By the same factor, the inorganic anions and cations tossed away casually in the laboratory become tons of worry at an industrial level," he says. The award winner points out that an inherent part of synthetic work is to take the problem backwards—to disconnect the molecule at each stage, starting with the full structure. This approach can be modified to degrade organic molecules intentionally. "We can teach our students reverse synthesis, very simply," he suggests, "by examining the functionality (or nonfunctionality) present in the molecule to be destroyed and applying the reactions which, based on experience, theory, or invention, will make it more tractable to further modification." Dr. Leonard feels that instruction could treat as much reverse chemistry as traditional forward chemistry. The concepts, negative yield and reverse chemistry, suggest how the synthetic organic chemist, in improving training and broadening outlook, can make a contribution. He states, "We would like to be certain that while we continue to augment nature in many favorable ways, we do not foul it or disrupt its life-giving cycle."
ORGANICS:
New Search Service A "chicken and egg" situation exists between a list of chemical compounds and possible users of those compounds. This dependence best illustrates a service that will be available this fall. The service will comprise a computerized listing and retrieval of commercially available organic chemicals. Very likely, the number of users and compounds listed will simultaneously increase as suppliers and consumers of chemicals become aware of this worldwide service to be offered by Chemical Systems, Inc., Shreveport, La. The service will determine the availability of chemicals more accurately, faster, and at lower cost than do current methods of searching suppliers' catalogs and general catalogs, calling and writing possible suppliers for information, and, as is done in some cases, making the chemicals themselves, says Dr. L. E. Kidwell, Jr., president of Chemical Systems. Commercially available chemicals are those sold in quantities of 100 grams or more from stock, and including any compound containing carbon. These will be listed by Chemical Systems.
THE CHEMICAL WORLD THIS WEEK The service, when fully operable, will list compounds offered by suppliers as available for six or more months from date of listing. The service will distinguish between manufacturers of chemicals and distributors. It will be available to chemical suppliers and users of chemicals in most countries. The compounds will be listed and retrieved on the basis of functional groups. Alkanes, alkenes, and other classes of compounds without substituents will be in a separate category. The list will include monomers, dimers, and trimerSj where appropriate, but not polymers. Suppliers of chemicals are invited to list their compounds by Oct. 1. Cost will be $3.00 for each compound. Suppliers will be able to revise their listings each month at the same fee for additions or deletions. The cost is $1.00 per month to maintain a listing. People or companies who want to retrieve information are charged a $5.00 enrollment fee, but no other subscription fees. All other costs to retrievers will depend on the amount of searching they want done and on the kind of terminal they have available. Payments are accepted in dollars or in Swiss francs. For example, companies with computer print-out facilities capable of interfacing with computer facilities of University Computing Corp. at several of its U.S. locations and in Europe will have generally lower charges. Small users, however, can obtain the same search and retrieval services from Chemical Systems by mail even though they do not have any kind of computer terminal. Several kinds of searches are available. The simplest is for compounds with a single structural group exclusively such as —OH. Complex systems such as pharmaceuticals can also be handled.
MOSQUITOES:
Breeding Self-Extinction Just a persistent pest in the U.S. but a deadly disease carrier in much of the world, the mosquito may breed itself into extinction. That's the hope of University of Notre Dame biologist Karamjit S. Rai, who has developed a new breed of sterile mosquito by genetic manipulation. The new strain of male Aedes aegypti is normal in every respect, except its translocated chromosomes cause most of its sperm to be sterile. Dr. Rai explains, "70 to 90% of the sperm will not fertilize the female
