WCTS, now a division of IT Analytical Services, has been a leader in analytical chemistry for the past seventeen years. We continue to set the standard for excellence in the chemical testing profession.
Complete Environmental Laboratory Services Environmental analyses is one of our specialties. Whatever the problem may be, from trace organics to trace metals in media such as air, water, sludge, or tis sue, we can provide you with fast, accurate results. Our services include NPDES Priority Pollu tants, Drinking Water, Pesticides & Herbicides, Hazardous Wastes, and Wastewater Analyses.
GC/MS Analyses WCTS was the first lab in the country to offer commercial GCMS analyses. Today, not only are we equipped with state-of-the-art instruments, but we have the many years of experience necessary to handle your unique problem or routine analysis.
Newest Procedures WCTS was recently awarded contracts by the EPA for the anal ysis of soil and water samples taken in and around chemical dump sites. Newest EPA proce dures call for pre-screening by gas chromatography for priority and other hazardous pollutants. We are now offering this highest quality analysis to our industrial clients. For copies of our Catalog and Fee Schedule, please circle the reader service number or contact: WCTS, 17605 Fabrica Way, Cerritos, CA 90701 ; (213) 921 -9831.
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66 C&ENNov. 15, 1982
Technology tor, which has been the focus of gov ernment experimental programs for coal combustion, cannot achieve that level of carbon combustion, Green says. However, the semientrained flow combustor (also called a circu lating fluidized-bed reactor), which possesses high heat- and masstransfer effectiveness and hence high combustion efficiency, can achieve better than 98% combustion. Green described a 2-MW pilot plant in Helsinki, Finland, built by H. Ahlstrom Co., that burns a variety of low-grade fuels with up to 80% ash content. T h a t semientrained flow combustor burns 98.5% of the carbon in the fuel. Full-scale versions of that plant are available commercially, and he estimates that such units likely achieve even higher rates of carbon combustion. Green concludes that cogeneration of electric power and process heat at coal preparation facilities—most of which are owned by coal com panies—represents an opportunity for a symbiotic relationship between coal producers and processors and electric utilities. D
Professor John C. Sheehon ι To Receive the 2nd Annuol Oesper Aword Professor John C. Sheehan of the Massachusetts Institute of Technology has been named as the recipient of the 2nd Annual Oesper Award. Professor Sheehan will receive the award at the Oesper Memorial Award Banquet on Tuesday, November 16, 1982 at the University of Cincinnati. The Oesper Award is designated to recognize scholarly activities of scientists in their field of endeavor. The speakers for the evening will be Dr. Murray Goodman, University of California, San Diego, "Penicillins and Pep tides: Modern Chemical Mir acles — a tribute to John C. Sheehan" and Robert W. Parry, President American Chemical Society "John C. Sheehan: Ma nipulator of Molecules, large and small." 2nd Ralph E. Oesper and Helen W. Oesper Memorial Lecture Honoring Professor John C. Sheehan Massachusetts Institute of Technology
Science
Method finds carbonyl acidity, enol content A method to determine acidities and enol contents of simple carbonyl compounds simply and reliably has been developed by chemists at the University of Toronto [J. Am. Chem. Soc. 104, 6122 (1982)]. Their achievement may aid studies of the fundamental natures of aldehydes and ketones. Until now, the only compounds for which acidities and enol contents could be determined reliably have been those like /3-diketones, which can have relatively large enol contents. Enolization is a chemical reaction that all carbonyl compounds undergo in which the hydrogen atom on a carbon adjacent to the carbonyl car bon is transferred to the carbonyl oxygen. A double bond forms between the former carbonyl carbon and the adjacent carbon. Thus, isobutyraldehyde molecules constantly interconvert with 2-methyl-l-propen-l-ol molecules. In simple carbonyl com pounds the equilibrium usually lies overwhelmingly on the side of the keto form. Organic chemistry professor A. Jerry Kresge approached the problem by finding rate constants of conver-
Wednesday, November 17, 1982 University of Cincinnati Great Hall, Tangeman University Center
I I I I I I I I I I I I I I I I I I I I I I I I I I I ^
8:55- 9:00 - Opening remarks by R. Marshall Wilson, University of Cincinnati 9:00- 9:50 - Dr. William G. Dauben, University of California, Berkeley, "Organic Synthesis at High Pressure" 9:50-10:40 - Dr. Barry M. Trost, University of Wisconsin, Madison "Selectivity in Organic Synthesis" 11:00-11:50-Sir Derek Barton, Institut De Chimie Des Substances Naturelles, "Recent Progress in Natural Products Chemistry" 1:20- 2:10-Dr. Burton G. Christensen, M ere Κ Sharp and Dohme, "The Use of Total Synthesis in the Design of B-Lactam Analogues" 2:10- 3:00 - Dr. Murray Goodman, University of California, San Diego, "Topochemical Analogues of biologically Active Peptides" 3:20- 4:10 - Dr. Konrad E. Bloch, Harvard University, "Steroid Structure, Evolution and Membrane Function" 4:10- 5:00 - Dr. John C. Sheehan, Massachusetts Institute of Technology, "Judging Science: The Gray Area"
Science sions from enol to keto forms, k K . The keto-enol equilibrium constant, K E , would then be kpJ^Ky where kE is the rate constant for conversions of keto to enol forms. Values of kE are readily available by such methods as mea suring rates of scavenging of enols by iodine. Working with his wife, research associate Y. Chiang Kresge, and postdoctoral fellow Peter Walsh, Kresge made trimethylsilyl enol ethers and reacted these with butyllithium in tetrahydrofuran to get lithium enolates. Addition of lithium enolate solutions to large excesses of water produced enols, which changed only slowly to keto forms. The To ronto workers found rates of ketonization of enols by following a strong ultraviolet absorption for enols near 200 nm. Their work was supported by the Natural Science & Engineering Research Council of Canada and the Petroleum Research Fund, adminis tered by the American Chemical So ciety. Kresge's group used the technique to get a kx for acid-catalyzed ketonization of the enol of isobutyraldehyde of 0.59 L per mole-second. Iodine scavenging yielded a ks of 4.7 X 10~ 5 L per mole-second. After correcting their k^ for competing hydrate for mation, the researchers calculated a keto-enol equilibrium constant K E of 1.28 Χ 10" 4 and a pK E of 3.90. They used this value of the pK E of isobutyraldehyde for their next goal, which was determination of the acidity of the «-hydrogen of the keto form in aqueous solution. They rea soned that the pK a (carbon) for ion ization of this proton would be the sum of the P K E , already determined, and the pK a (enol) of the enol form. Kresge and his coworkers used rate studies of ketonization of the enol to find pK a (enol). The first step in base-catalyzed ketonization of enols is reaction of the enol with the base to form enolate ion and the conjugate acid. In the second step, a proton from the conjugate acid adds across the enol double bond to give the ketone and regenerate the base. At high pH, Kresge points out, catalysis becomes saturated, and rates of ketonization can be used to estimate pK a (enol) from the first step. Kresge's group found pK a (enol) to be 11.63. Combining this with the previously determined P K E , they derived a pK a (carbon) of 15.53. Says Kresge, "The result is, to our knowledge, the first accurately de termined, empirically founded acidity constant of a simple carbonyl com pound in aqueous solution." D
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