Access to Chemistry

Access to Chemistry, by A.V. Jones, and others, expands almost all the topics presented in this CQR by using a tutorial approach for students with limited preparation. Springer Verlag, 29.95. 

A. V. Jones, M. Clement, A. Higton and E. Golding. Access to Chemistry. Royal Society of Chemistry, Cambridge, 1999. 

Whether a mathematical formulation of chemistry (as is now familiar to us) is possible or even desirable has been a controversial subject over the centuries. In 1786 Kant wrote [27] that chemistry will never be a genuine science because it cannot be formulated in mathematical terms. While Gay-Lussac [28] believed in 1808 that in the near future the majority of chemical phenomena will be calculable, Comte [19] in 1830 even went beyond Kant and claimed that mathematics and chemistry are mutually exclusive, and that a - fortunately unlikely -mathematical access to chemistry would imply its decline." ... 

This venerable book was written in 1935, shortly after the birth of modern quantum mechanics. Nevertheless, it remains one of the best sources for students seeking to gain an understanding of quantum-mechanical principles that are relevant in chemistry and chemical physics. Equally outstanding jobs are done in dealing with both quantitative and qualitative aspects of the subject. More accessible to most chemists than Landau and Lifschitz. 

Progress in the theoretical description of reaction rates in solution of course correlates strongly with that in other theoretical disciplines, in particular those which have profited most from the enonnous advances in computing power such as quantum chemistry and equilibrium as well as non-equilibrium statistical mechanics of liquid solutions where Monte Carlo and molecular dynamics simulations in many cases have taken on the traditional role of experunents, as they allow the detailed investigation of the influence of intra- and intemiolecular potential parameters on the microscopic dynamics not accessible to measurements in the laboratory. No attempt, however, will be made here to address these areas in more than a cursory way, and the interested reader is referred to the corresponding chapters of the encyclopedia. 

It was reahzed quite some decades ago that the amount of information accumulated by chemists can, in the long run, be made accessible to the scientific community only in electronic form in other words, it has to be stored in databases. This new field, which deals with the storage, the manipulation, and the processing of chemical information, was emerging without a proper name. In most cases, the scientists active in the field said they were working in "Chemical Information . However, as this term did not make a distinction between librarianship and the development of computer methods, some scientists said they were working in "Computer Chemistry to stress the importance they attributed to the use of the computer for processing chemical information. However, the latter term could easily be confused with Computational Chemistry, which is perceived by others to be more limited to theoretical quantum mechanical calculations. 

More than 10 000 databases exist that provide a small or large amount of data on various topics (including chemistry). The contents in databases are supplied by approximately 3500 database developers (e.g., the Chemical Abstracts Service, MDL Information Systems, etc.). Since there is a variety of topics from economics to science, as well as a variety of structures of the database, only some of the vendors (-2000) offer one or more databases as either local or as online databases (Figure 5-4) [4]. Usually, databases are provided by hosts that permit direct access to more than one database. The search occurs primarily through different individual soft-... 

Aldol condensations are one of the fundamental carbon-carbon bond forming processes of synthetic organic chemistry Furthermore because the products of these aldol con densations contain functional groups capable of subsequent modification access to a host of useful materials is gamed... 

In order to balance public domain science with a high quality commercial software product it has been necessary for us to reimplement almost every aspect of computational chemistry embodied in HyperChem. All HyperChem source code is written in C or C-t-t, specified, designed, and implemented by Hyper-Chem s developers. We have stood on the scientific shoulders of giants, but we have not used their FORTRAN code Thus, although we have had access to MOPAC and other public domain codes for testing and other purposes, HyperChem computes MINDO, MNDO, and AMI wave functions, for example, with HyperChem code, not MOPAC code. We have made the effort to implement modern chemical science in a modern software-engineered product. 

How might we solve equation 6.34 if we do not have access to a computer One possibility is that we can apply our understanding of chemistry to simpKfy the algebra. From Le Chatelier s principle, we expect that the large initial concentration of Pb will significantly decrease the solubility of Pb(I03)2. In this case we can reasonably expect the equiKbrium concentration of Pb to be very close to its initial concentration thus, the following approximation for the equilibrium concentration of Pb seems reasonable... 

The design and manufacture of adsorbents for specific appHcations involves manipulation of the stmcture and chemistry of the adsorbent to provide greater attractive forces for one molecule compared to another, or, by adjusting the size of the pores, to control access to the adsorbent surface on the basis of molecular size. Adsorbent manufacturers have developed many technologies for these manipulations, but they are considered proprietary and are not openly communicated. Nevertheless, the broad principles are weU known. 

Provides access to detailed information on all categories of pesticides including herbicides, fungicides, insecticides, and rodenticides. Included is information on pesticide toxicity, health effects, residual data, efficacy, and other information. NPIC is a cooperative effort of the U.S. EPA and the Oregon State University Department of Agricultural Chemistry. NPIC is staffed from 6 30 a.m to 4 30 p.m. Pacific Standard Time. 

Another tool relates to presentation. We decided to emphasize molecular modeling in the third edition, expanded its usefulness by adding Spartan electrostatic potential maps in the fourth, and continue this trend in the fifth. Molecular models, and the software to make their own models, not only make organic chemistry more accessible to students who are visual learners, they enrich the educational experience for all. 

Snyder has conducted similar chemistry but with the goal of generating carbon skeletons for the total synthesis of alkaloids. Using indole 84 as a dienophile, the canthine alkaloid skeleton 85 was produced. Access to aspidosperma alkaloids was obtained when 86 was transformed into 87. 

The total syntheses of penicillin and cephalosporin represent elegant tours de force that demonstrated once again the power of synthetic organic chemistry. These syntheses, however, had little effect on the course of drug development in the respective fields, since they failed to provide access to analogs that could not be prepared by modification of either the side chains or, as in the case of more recent work, modification of 6-APA and 7-ACA themselves. In order to have an impact on drug development, a total synthesis must provide means for preparing... 

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