Philosophy mechanistic

This book contains what I call an interlude on the logic, the psychology, and the serendipity of scientific discoveries. Readers may wonder what the correlation is between that short Chapter 9 and diazo chemistry. The specific reason for including it was to elucidate the dediazoniation mechanism of aromatic diazonium ions, but I expanded this mechanistic discussion (Sec. 8.3) in the interlude by including general aspects originating in the philosophy of science as developed by Karl Popper and Thomas S. Kuhn, ideas which, in my opinion, should be better known by all scientists working in chemical research. 

But in spite of Theosophical vitalism (to which I shall return below) and the Theosophical attack on mechanistic science and philosophy, the atomic theory Besant and Leadbeater developed in Occult Chemistry and elsewhere was in many ways a mechanical theory involving interactions of ever-more-rarified particles and their vibrations. It adapted many assumptions of Victorian ether mechanics. 

The mechanical philosophy now provided a new justification for the philosophical inability to isolate the elements. Bodies combined with one another because of some kind of attractive force, and the strongest such attraction would be between the two principles which combined to form a mixt. The force between two mixts would be much smaller because much of that attractive force had been used up, so to speak, in forming the mixts themselves. Thus there came to be a rule that the more compounded a body was, the easier it would be to decompound it. Running that rule in the other direction, the simpler a body was, the harder it would be to decompound it further. The only way to decompound a mixt containing only two principles, was to offer another mixt with which the principles in the first could exchange partners. There was nothing that could take one principle from another and leave it in isolated state. Whatever the origin of this idea, it readily served as a mechanistic rationalization for what had been the traditional view from Aristotelian times, that the elements cannot be isolated in material reality. 

The concepts of complexity and emergent properties, discussed here within the context of drug research, must become integral parts of every step in this collective effort as it is practised today and as it evolves to newer methods tomorrow. However, and this remark is so important that it was kept for the end, these new concepts are not meant to replace the traditional mechanistic approaches that have proven so successful in drug research. Rather, the post-Newtonian vision must blend with the Newtonian philosophy to enlarge and enrich our mental world. As so aptly stated by Edward O. Wilson, the father of sociobiology (quoted in Lewin, 1993) ... 

I suggest an initial determination of at least sufficient human evidence, limited human evidence supported by animal or short-term tests, or sufficient animal evidence for a conclusion of probable human carcinogenicity as warranting the most conservative regulatory control philosophy. Limited animal evidence without substantial support from short-term tests or mechanistic data indicative of potential human risk would warrant less heroic controls. Yet, these controls would be more protective than those developed from an ADI determination and sufficient to preclude any significant risk in the event that further studies raised the classification. 

History of physical organic chemistry is essentially the history of new ideas, philosophies, and concepts in organic chemistry. New instrumentations have played an essential role in the mechanistic study. Organic reaction theory and concept of structure-reactivity relationship were obtained through kinetic measurements, whose precision depended on the development of instrument. Development of NMR technique resulted in evolution of carbocation chemistry. Picosecond and femtosecond spectroscopy allowed us to elucidate kinetic behavior of unstable intermediates and even of transition states (TSs) of chemical reactions. 

The premise of this book is based on the presumption that introductory organic chemistry entails very little memorization. As presented in the chapters contained herein, this presumption is valid provided the student adheres to the philosophy that the study of organic chemistry can be reduced to the study of interactions between organic acids and bases. At this point, use of the principles presented in this book, in conjunction with more detailed coursework, allows students a broader understanding of organic chemistry reactions as described using combinations of fundamental organic mechanistic subtypes. 

Within a few hours I accepted the offer and the next day saw Professor Hieber who gave me a cordial welcome and showed me the new lab. He also asked me about the research project for my Habilitation and for a moment I hesitated. It was known that he considered kinetic and mechanistic studies as a type of philosophy which, in his opinion, it was not worth doing.2 Nevertheless, he listened courteously and, after I told him that the class of compounds I was going to use as starting materials for my work were metal carbonyls, he wished me good luck. 

When mechanistic information is available or obtainable for the components of a system, it is possible to develop detailed analyses and simulations of that system. Such analyses and simulations may be deterministic or stochastic in nature. (Stochastic systems are the subject of Chapter 11.) In either case, the overriding philosophy is to apply mechanistic rules to predict behavior. Often, however, the information required to develop mechanistic models accounting for details such as enzyme and transporter kinetics and precisely predicting biochemical states is not available. Instead, all that may be known reliably about certain large-scale systems is the stoichiometry of the participating reactions. As we shall see in this chapter, this stoichiometric information is sometimes enough to make certain concrete determinations about the feasible operation of biochemical networks. 

The basic concept is that estimated results for pesticide movements and exposure levels vary greatly with the model types and modeling philosophy. Before con-dncting a model exercise, a conceptual check of the model is needed to ascertain if the model contains aU relevant routes of exposure. A simple model, such as SCIES, is based on worst-case assumptions, and may be sufficient for inhalation risk assessment. More complicated simulation models, such as CONSEXPO and InPest, provide information on the amounts of pesticides on the room materials, as well as the airborne concentration, and they are appropriate for risk assessment via aU routes. Even in complicated models, each mechanistic model contains assumptions to simplify the process description of the pesticide movement in the real world . The underlying assumptions for each of the models, and the relevant processes they implicate, are criteria to consider when selecting an appropriate model. Therefore, the validity of the assumptions used for the assessment should be considered before using the model, and they should be well documented. A simple phrase such as, we used model xx to estimate an exposure level of yy, is inadequate for documentation purposes. 

Hitherto historians of science have not paid much attention to Boerhaave s religious views and their influence on his natural philosophy. They have mainly emphasised Boerhaave s mechanistic approach to investigating nature and, concerning chemistry, they have praised him for being one of the first to... 

This textbook is not a physical organic chemistry textbook The sole purpose of this textbook is to teach students how to come up with reasonable mechanisms for reactions that they have never seen before. As most chemists know, it is usually possible to draw more than one reasonable mechanism for any given reaction. For example, both an Sn2 and a single electron transfer mechanism can be drawn for many substitution reactions, and either a one-step concerted or a two-step radical mechanism can be drawn for [2 + 2] photocycloadditions. In cases like these, my philosophy is that the student should develop a good command of simple and generally sufficient reaction mechanisms before learning the modifications that are necessitated by detailed mechanistic analysis. I try to teach students how to draw reasonable mechanisms by themselves, not to teach them the right mechanisms for various reactions. 

For both Willis and Lemery, the essential thing was that the principles of matter, if not perhaps the most fundamental reality, were nevertheless basic material substances and not Aristotelian qualities or spiritual presences somehow rooted in matter. Especially Lemery, in this regard, could have his cake and eat it, too. By insisting that chemical principles were sensible and demonstrative, he preserved a traditional way of describing chemical operations in iatrochemical terms (acids and alkalis) while, at the same time, he allowed for the mechanistic and materialistic explanations that Cartesian philosophy demanded (Powers, 1998). That kind of a mixt truth extended also to a mixing of interpretations, both academic and popular, when it came to appraising the further status and reputation of alchemy (Figure 7). 

David Vander Jagt (1942-) received his doctor of philosophy (PhD) in 1967 in synthetic/mechanistic organic chemistry at Purdue University (West Lafayette, Indiana), in the laboratory of the Nobel Laureate H. C. Brown. After Purdue, he took a post-doctoral position at Northwestern University (Chicago, Illinois) in the laboratory of M. L. Bender in bioorganic chemistry/enzymology (1967-1969). When the opportunity came for a joint appointment in the Department of Biochemistry,... 

---