Letters

Dropping a grade

U.S. college and university grade inflation is real, and there are many reports and letters discussing the whys, whens, and what to dos ("Grade inflation and scientific literacy," C&EN, Dec. 13, 2004, page 3). I have read about the impact on grade inflation of course content and level, student evaluations of instructor performance, qualitative versus quantitative courses, humanities versus science courses, and so on. However, there has been no discussion on the very real impact on grade inflation of accommodative administrative rules.

Most C&EN readers will recall from their student days that soon after a course started they were either enrolled in a class or not. If they were enrolled, then they did the best they could. Well, this is no longer the case; U.S. students are now often allowed to drop a course up to the last day of class, after the last day of class, and sometimes even after the final exam and grade assignments are completed. So what happens to grade averages when students can drop, late drop, and retroactively drop a course if they don't like their quiz, midterm, or final exam score and grade? You guessed it; they go up irrespective of any other parameter.

Laurence Lavelle
Los Angeles

Uproar over climate change

Chemists who deny the reality of global warming are like biologists who deny the validity of evolution: They are not using scientific reasoning to analyze the evidence that nature presents to us ("Global Climate Change," C&EN, Jan. 24, page 3). In a way, however, those who deny evolution are less dangerous than those who deny global warming. The Earth will continue to evolve whether or not people acknowledge that this is happening. In contrast, we have some ability to ameliorate global warming, should we choose to do so. Unfortunately for our planet's inhabitants, the consequences of failure to act may well be catastrophic.

The reason is that global climate change may involve positive feedback loops. For example, there is evidence that the Gulf Stream--a thermal conveyor belt that warms Europe substantially--abruptly shut down in the not-too-distant past. Computer models indicate that this could happen again, as the result of melting Greenland icepacks.

I don't know if this will happen, but surely it would be prudent to prevent such a shutdown, if we are able to do so. I also do not know if other amplified climate changes caused by global warming will catastrophically modify our environment. I do know, however, that humankind has the capability of ameliorating the effects of global warming, provided we recognize its realities and take appropriate countermeasures. It seems to me that ignoring or denying global warming is the high-risk strategy, while doing what we can to ameliorate climate change is the low-risk strategy.

Thank you, Rudy Baum and Bette Hileman, for keeping C&EN readers alert to the risks that we run when we do not acknowledge that global warming is both real and dangerous.

John Olmsted III
Fullerton, Calif.

I find your stance to be completely close-minded, politically tinged, and unscientific. I base these findings on the following points in your editorial.

◾ You "firmly" believe in anthropogenic global warming. You believe so firmly that you overlook, and refuse to acknowledge, the accumulation of evidence to the contrary. I have addressed this failure to present the contrary evidence several times without success. This is close-minded, not because of my ignored challenges, but because you are by your own admission ignoring a numerous group of the ACS membership.

◾ It becomes apparent that you have politicized your stance on global warming. You see that an Administration which you dislike has taken a position contrary to yours, so you dig in your heels. I am sure politics is not the reason for your firm belief, but it certainly is affecting your response. You must realize that the leader of a nation must look to the best course for the majority and must be sure before he commits to drastic measures, especially those which entail reduction of the gross national product of the nation. Your nonsensical attack on language of politics is childish and comical in a serious periodical. Remember this is about the science; the politics was settled last November.

◾ To be scientific is to present both sides. You and your staff have not done this. It is imperative that you do so, firm belief or not. We do not ask that you change your firm beliefs, we ask only that you present both sides honestly.◾

Anthony J. Di Milo
San Diego

In his letter to the editor, Oswald R. Bergmann refers to "slightly increased CO₂ levels in the atmosphere," and later to "the slight rise in CO₂ in the atmosphere during the past few decades" (C&EN, Jan. 24, page 4).

It has been estimated that atmospheric CO₂ was about 280 ppm in the year 1750; it was found at the Scripps Institute of Oceanography site in Hawaii to be 316 ppm in 1959, and 376 ppm in 2003 (mean annual concentrations). These data imply an increase of CO₂ in the atmosphere of 13% between 1750 and 1959; 19% between 1959 and 2003; and, overall, 34% between 1750 and 2003.

These measured increases are hard numbers, not the results of computer modeling and the like. They are large numbers. They are not "slight."

Charles F. Deck
Trenton, Mich.

Now that I have shoveled 8 inches of northeast Pennsylvania's global warming off my sidewalk, I have time to write about the urgency of doing something about greenhouse gases. Americans must understand that many of the countries that have ratified the Kyoto protocol have no obligations whatsoever to curb their own greenhouse gas emissions, which is prima facie evidence that these countries do not really take the "problem" seriously.

Kyoto is quite simply a scheme for moving the smokestacks, all their carbon dioxide, and the well-paying manufacturing jobs underneath the smokestacks to China and other countries. This is because the treaty will raise energy costs in the U.S. if our Senate is irresponsible enough to ratify it, but will not raise costs in China, which is free to burn as much coal as it wants with no pollution controls whatsoever. Many of the jobs in question are in the energy-intensive chemical process industries.

I have no interest in paying "carbon taxes" on fossil fuels, trading in my eight-cylinder Crown Victoria for a smaller car, or imposing carbon emission limits on U.S. firms so South American Kyoto signatories can keep burning down rain forests to clear land for agriculture while mainland China takes even more manufacturing jobs from the U.S. My only criticism of the Bush Administration's handling of this issue is its failure to openly denounce Kyoto for a scam whose sole purpose is the redistribution of U.S. manufacturing capability to other countries.

William A. Levinson
Wilkes-Barre, Pa.

I work for Climate Solutions, an organization developing practical and economically beneficial solutions to global warming. Your editorial raised the issue of what is the best phrase to describe what is happening to our planet's climate as a result of human activity. Many people who work in this field use the phrase "climate disruption" rather than "climate change" or "global warming" to address many of the issues and problems you noted.

"Disruption" clearly and accurately says that something isn't working the way it's supposed to and that the consequences of that are negative. By contrast, the word "variability," as you pointed out, makes it sound like it's just natural variability and not human caused, not a problem even if human caused, and thus not something to worry or do anything about.

Disruption is also a more accurate description than warming of what people will actually experience. Yes, the global average temperature is increasing, but no individual actually lives in the global average temperature. The local manifestations of global warming might be local warming or local cooling, they might be more severe droughts or more severe flooding, or they might be more frequent hurricanes. All of these are disruptions.

Disruption also implies, again accurately, that something or, in this case, someone is doing the disrupting. Of course there are climatic cycles and natural climate variability; that's fine, but it's the human disruption of relatively small-amplitude long-period natural cycles that is the problem.

So I would offer "climate disruption" as a phrase with greater accuracy and applicability than either "global warming" or "climate change" and less chance of being, intentionally or unintentionally, hijacked or misinterpreted. And I think we can lump "climate variability" in with "Clear Skies," "Healthy Forests," and other Orwellian phrases.

Jabe Blumenthal
Seattle

I agree wholeheartedly with the opinions expressed by Bergmann in his letter. I too have called to your attention the blatant political bias expressed in articles concerning the current Administration's policies. Other than the lack of objectivity in the reporting on these matters, I am upset by the hubris in the text. You may disagree with me as long as you are not disagreeable. You and your colleagues tend to be most disagreeable and churlish.

Charles A. Carroll
Woodcliff Lake, N.J.

While the Bush administration and certain members of the chemistry community may be skeptical over the present and future climate effects of increasing atmospheric CO₂, may I suggest they consider the very real chemical consequences of ongoing anthropogenic CO₂ release.

Because CO₂ forms a weak acid when hydrated, the approximate 7.3 gigatons of excess atmospheric CO₂ that annually diffuses into the ocean leads to the production of roughly 0.15 gigatons of H⁺ per year [Science, 305, 367 (2004)]. It has been shown that if the combustion of fossil fuel continues unabated, the pH of the surface ocean will decline by more than 0.7 units over the next several centuries [Nature, 425, 365 (2003)]. That's more than a fivefold increase in the concentration of H⁺ over current conditions, probably greater acidity than the ocean has experienced in the past 300 million years. Such an increase would likely be catastrophic for certain biogeochemical processes upon which all of us directly or indirectly depend, but the true scope and magnitude of these impacts require further research [http://ioc.unesco.org/iocweb/co2panel/HighOceanCO2.htm; Science, 305, 362 (2004)].

Uncertainty and obfuscation about CO₂ effects on climate can be used by some to impede policies and actions to meaningfully reduce CO₂ emissions. However, business as usual is less easily justified when faced with the inevitable negative ocean impacts of unmitigated fossil fuel use.

Greg H. Rau
Castro Valley, Calif.

Corey and Woodward: Round two

Stu Borman's report about the dispute between Roald A. Hoffmann and Elias J. Corey regarding the origins of the concept of frontier orbital symmetry control in pericyclic reactions (C&EN, Nov. 29, 2004, page 8) was triggered by a recently published letter by Hoffmann [Angew. Chem. Int. Ed., 43, 6586 (2004)].

As Borman reported, this letter details how Corey continues to claim that he invented the concept and on May 4, 1964, communicated it to the late Robert B. Woodward. Borman's conclusion is that this issue is unlikely ever to be resolved. I feel that this conclusion needs revision.

As clearly stated in Hoffmann's recent letter (see page 6589)--but not mentioned in Borman's report--the first, and very explicit, suggestion that frontier orbital symmetry determines the stereochemical course of pericyclic reactions was made by the late L. J. Oosterhoff of Leyden University. This was published by two of his colleagues, E. Havinga and J. L. M. A. Schlatmann [Tetrahedron, 16, 146 (1961)]. This publication, which was correctly cited by Woodward and Hoffmann in their early work on the theory of pericyclic reactions, describes experiments involving thermal and photochemical hexatriene/cyclohexadiene and butadiene/cyclobutene interconversions, a subject at that time undoubtedly of interest to both Woodward and Corey.

Jan W. Verhoeven
Amsterdam

I was interested to read the article concerning priority for inventing the Woodward-Hoffmann rules. When I first arrived at the University of Cambridge in 1966, I heard a lecture by Christopher Longuett-Higgins, in honor of my supervisor J. W. Linnett's getting the Chair of Physical Chemistry, on the role of symmetry in the photolysis of organic molecules. Clearly Longuett-Higgins already had an extensive theoretical basis for this kind of reaction at the time he gave his lecture. Several years later, I heard the opinion expressed by an American chemist from Temple University working at the University of Sussex, where I then was, that Longuett-Higgins deserved a Nobel Prize for his work.

Simon J. Fraser
Toronto

C&EN described the controversy surrounding the question of priority in formulating orbital symmetry as the explanation for the occurrence, and outcome, of chemical reactions. On the question of priorities, one of the parties claims precedence by virtue of having used the concept, in 1964, to explain the course of an interesting, and then puzzling, chemical reaction.

Your readers may find these points relevant to reaching a decision concerning the question of credit, or lack thereof, in this historically significant development of modern chemistry.

In 1960, Leslie E. Orgel, a fellow of Peterhouse College at the University of Cambridge, published a seminal monograph titled "An Introduction to Transition-Metal Chemistry--Ligand Field Theory" (London: Methuen & Co. Ltd.) On pages 26–39, he presents one of the clearest, most simply worded, descriptions of - and -bonding available in those days. More important, the emphasis from the start is on orbital symmetry and its consequences for reaction pathways and subsequent bonding results. "Our rule about the matching of symmetry properties of molecules shows ...," he writes. I believe most undergraduates of that time read that sentence, and got the message.

Sometime between 1960 and 1964, Orgel lectured at Harvard University's chemistry department, where such ideas were presented and discussed. The university's records will surely provide the exact dates, if need be.

Is it my claim that Orgel deserves credit for the subsequent developments? No. However, my point is that the importance of orbital symmetry, and matching thereof, was already known there and then, and that those ideas were known to a significant portion of the people at the forefront of chemistry and stereochemistry. Orgel's book leaves no doubt that orbital symmetry was the foundation upon which we needed to formulate a theory of chemical reactions and of mechanistic chemistry.

Isaac Newton once said, famously, "because I stood on the shoulders of giants." The fact that the seeds of the oak were sown by Newton's predecessors does not mean that he was not the one that put it all together and changed the face of physics. Nor, for example, does Hendrik A. Lorentz deserve to be credited with the discovery of relativity. He investigated the effect of motion on the science of measurement. Einstein saw the rest. There is nothing new about this. The moral of the story is that the ones who put it together are the ones who deserve the credit--in this case, Hoffmann and Kenichi Fukui, no more, no less than in other examples of the history of intellectual achievements.

Reading C&EN's report reminded me of claims made that Einstein's wife was the genius of the family and the one who did all of his mathematical work. Perhaps, but we will only know for sure when we reach the pearly gates--and, by that time, the point will be moot.

Ivan Bernal
Houston

I wish to remind readers that besides Elkan Blout, Frank H. Westheimer, a longtime colleague of both Woodward and Corey's at Harvard and a true giant in the field of chemistry, has also mentioned Corey's "undeniable" contributions in the "conception" of the idea by Woodward. In the biography "Robert Burns Woodward: Architect and Artist in the World of Molecules" (Benfey & Morris, editors, Philadelphia: Chemical Heritage Foundation, 2001), in Chapter 3, Westheimer writes: "In addition to his great contribution to rational synthesis, he and Roald Hoffmann, after a conversation with E. J. Corey, formulated the principles of the conservation of orbital symmetry, a set of principles that for example, control the formation and cleavage of rings."

Mukund M. Mehrotra
San Francisco

SAFETY LETTER

Lithium 2,6-Difluoroanilide Decomposition Hazard

The title compound, which we prepared from 2,6-difluoroaniline and n-butyllithium in diethyl ether solution, is a touch-sensitive explosion hazard. While transferring the vacuum-dried yellow solid from a glass fritte (inside a nitrogen-atmosphere glove box), a sudden, violent decomposition occurred in two stages, scattering pea-sized pieces of glass and sooty black powder throughout the glove box. Fortunately, the student conducting these operations was not injured, and no additional problems were encountered upon cleanup.

Although we are keenly aware that fluorinated aryllithium and alkyllithium compounds can be treacherously unstable, we did not find lithium fluoroanilides or lithium fluorophenoxides mentioned in Bretherick's "Handbook of Reactive Chemical Hazards" (6th Edition). Moreover, several fluorinated lithium anilide etherates have been crystallographically characterized. Nevertheless, we must concur with Peter Urben's cautionary advice [C&EN, July 8, 1996, page 3] against isolating, free of solvent, any compounds containing both C–F and highly reactive metal-nonmetal bonds.

Paul A. Deck
Blacksburg, Va.