LETTERS An Organic "Reaction" To the Editor: I read Miles Pickering's provocative opinion "A Physical Chemist Looks a t Organic Chemistry Lab" [1988, 65, 1431 with a vague sense of irritation, similar to what one would feel after reading a diatribe representing surgery as a nonintellectual combination of sewine and butcherv. Part of mv feeling is a reaction to the propensity for some physical chemists to want t o re-derive the world ab initio. I recall a comment at least 30 years ago "Organic chemistry is a fine art, closely related to cookingm-the person who said it was quoting, so the original remark must have been even older. In 1969, Sir Christopher Ingold wrote in the introduction to a lab text, "Gone are the days when a student could (or should) he content to practice a t the bench the art of organic chemistry, aided by a hook of recipes and such empirical experience as he might have built up, hut leaving thought about underlying principles to he pursued, if a t all, as a separate activity elsewhere." The fact that the organic lah is so resistant to change suggests that there is more to the suhject than the critics want to admit. In large part i t reflects the enormous gap between glibly writing and understanding a transformation on oaper and carrvina one out in practice. Pickerina says as m&h; hut while retreading a t Bowdoin he apparentiy limited himself to modifvine the safe, well-developed reactions that appeared in thii ~&rnnl.The real world is not restricted in this way, and some of the simplest reactions on paper can be surprisingly difficult in practice. By trivializing the
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organic lab as a foil for problems that could be done entirely for in class, I think the students will he less well prepared . later challenges. I readily admit that there are some problems with organic lab that are a consequence of changes over the years in the way the lab is conducted. My first experiences with the organic lab course was around 1958 at the University of Michigan, where I worked as a prep person and grader. I recall that students used Bunsen hurners for distillation and that there were rules ahout whether in the event of a fire the oerson with the burner or the flammable liauid (who mieht have been across the aisle) was deemed a t fa&. The lah was interestina. t o say the least. and, without spectral aids. rather challenging. But a student &uld note the difference in the amount of flame necessary to boil, say, ethanol versus hexane, and could relate the experience to heats of vaporization in later courses. The inept were quickly found out, often in dramatic fashion. One finished the organic lab with a genuine sense of accomplishment. Needless to say, I am not suggesting a return to those times. The dangers that a cavalier attitude that one would develop from some of the bygone practices are self-evident. The burners, a t least here, have been replaced with heating mantles and puritanical injunctures against flames of any sort in the lab. In the old days, students got points off if they failed t o exercise care and caused a fire. Today we require them to copy down all of the hazards of the compounds in each experiment and points are deducted if they miss any. From this monotonous and misleading academic exercise the students slowly derive the feeling that chemicals can reach u p and grab you, hut unlike the old days, they don't
reallv have the faintest idea how this can occur. Instead of consiant attention tothedistance between the flameand the flask relative to the position of the front of condensate, they stand around horedkatching distillations on automatic. even tell the students the proper Variac settings for the mantles. In contrast, I remember my heart thumping as I initiated my first Skraup reaction in the basement of our house. In a prearranged scenario I hurriedly put out the propane hurner, unscrewed the clamps, and plunged the 500 mL roundbottomed flask with its violently boiling, black mixture into a bucket of snow and water to moderate the charcteristic, sudden exotherm. I t wasn't very intellectual, I suppose, but I was on mv wav to making a potential anticancer agent. I felt it a worthwhile activity in addition to being enorhous fun. 'I'hedrur companies now design magic bullets with computers, hut they will require someone with the requisite finger skills to synthesize whatever molecules they design. Like farmers, organic chemists will always he needed if not respected. I sense that Pickering's comments about the organic lab reflect an amplification of current public attitude, to wit, that tinkerine with molecules is sort of an ultimate crime against nature. T o counter the popular return to pre-Wohler thinkine. -. we included oreanic lab experiments in which a chemicnl was extracted from natural produrts, such as ipinachor almonds. In the middleof the lab on one occasion, one of the teaching assistants neatly undid my entire effort by barking a t a student, "Take that gum out of your mouth! Chewing gum is almost as bad as chewing organic chemicals!"I am still not sure what she meant by the remark; there are numerous patents on low-molecular-weight copolymers as base stocks for chewing gum. But even venerable DuPout droooed the word chemistrv from their comnanv . . sloean. organic chemists must, I suppose, reel with the punches. A second factor I think has to do with the nature of the students themselves. A generation ago large numbers were from farms or rural areas. Many were used to working hard at chores associated with bad odors and had a sense of a~oreciationfor the effort required to mow a pure crop of &in regardless of the intellekual content of -the process. The job got done even though many important factors, such as the weather, were unforseeable and out of control. Get a group of organic chemists together and you will find them the numerous. essential details of their ~ - - - - -discussine ~ craft, ..."the ehudhoff reaction works best in THF, but doesn't go if there's a nitro group on the molecule. . .no one has been able to duplicate the Selzer synthesis". To mix metaphors, they know the fugue and instantly recognize the sour notes. Scratch a physical chemist and you will find offsnrine of lawvers and the like, who are excited by deterexerted on objects in m i ~ i s t i ~ r e l a t i ohetween & the aclosed room and the temperature of the air. More seriously, I think the growing interrelation of all of the sciences should be an occasion for each subdiscipline to appreciate the contents of the other. The possible benefits of synergism are no better illustrated than with the development of the Woodward-Hoffman rules. Although I now succumb to computer programs to do molecular orbital calculations. I still cannot fathom anvone becoming interested in chemistry by measuring equilib;ium constants and the like. Wibern has suneested in effect that the dullness of contemporary k g h school chemistry texts is due to their excessive content of physical chemistry (2). The one time in the past seven years that I recall the organic lab students showing great interest in an experiment was when they tried to nitrate a sample of cumene that unknowingly contained about 30% cumene hydroperoxide. The reactions overheated and turned all sorts of colors. They were talking about it in the hallways and even in the elevators. The other time the experiments seemed to be appreciated was when they had to develop their own reaction proce~~
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dure, that is, what Pickering spent his summer doing. This invention is a standard experiment in some manuals. The fact that not all the procedures gave the product instilled some degree of respect for the subject. Pickering's drive for intellectual content to simplify the "grammar" of organic chemistry simply doesn't impress me. He realizes in a flash that organic carbonyl chemistry can he explained by nucleophilic attack on carbon followed by loss of water. (Some textbooks present i t this way. Why didn't be look?) Then, I suppose, he heads for the lab to make vinyl bromide by mixing acetaldehyde with aqueous hydrohromic acid, chock full of nucleophilic bromide ions. As with an infant who says he "goed to the store", the successful recognition of general principles does not insure fluency. Literature Clted 1. I8aacs. N. S. Exp~rimentsin Physicai Ormnic 2. Wiborg, K. A c c 1983 16,313.
Chem.Res.
Chmnialry:MacMillan: London, 1969.
G. David Mendenhall Michigan Technological University Houghton, Mi 49931
To the Editor: Professor Mendenhall, you do not have to sell me on the joy of doing organic chemistry. I go a t it with the fervor of a convert. The point of my essay was organic teaching labs are a discredit to thenoble and interesting field of organic chemistry. The average student sees the lab task as "getting through" the preps and unknowns and learns precious little about how organic chemists actually solve problems. Cookbook, cookbook, cookbook.. .how joyless and how unnecessary, considering the real excitement inherent in the field.
Miles Pickerlng Princeton University Princeton. NJ 08544
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A Syllabus for a Two-Semester Chemistry Course for
Health Professions To the Editor: We wish to comment about the paper "A Syllabus for a Two-Semester Chemistry Course for Health Professions" [J.Chem. Educ. 1987 64, 6991. We believe that the main criticism in the proposed program is the lack of a redox section. We consider that the student must know elemental ideas about redox potential, transference of electrons, and oxidized and reduced forms of chemical snecies. because redox reactions are involved in many biological processes. A knowledge of this also seems to he necessary to understand some examples of redox reactions that appear further on in the prorwsed course (sections X11 and XlIlL ~ o r e o i e rwe , disagree with some aspects of section VIII, "Acids, Bases, and Salts". The point l h (2) refers to reactions of arids with metals, whichare not acid-base reartiuns but redox processes. The inrlusion for these electrnn-transfer reactions here will create erroneous concepts for the students. In the same chapter there are two separate blocks, A and B. referine to Arrhenius and Brdnsted theories. respectively. Some topics, such as neutralization processes and titration methods. are listed under Arrhenius theorv, whereas others, such as pH, dissociation constants, and buffers are listed under Rrensted theors. This c c d d lead the student to the erroneous idea that neutralization and titration process-
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Volume 67
Number 6 June 1990
539
