Chemist, The

For many chemists, the most familiar IR spectrometer is the dual beam instmnient that covers the region 900-... 

In spite of the importance of reaction prediction, only a few systems have been developed to tackle this problem, largely due to its complexity it demands a huge amount of work before a system is obtained that can make predictions of sufficient quality to be useful to a chemist. The most difficult task in the development of a system for the simulation of chemical reactions is the prediction of the course of chemical reactions. This can be achieved by using knowledge automatically extracted from reaction databases (see Section 10.3.1.2). Alternatively, explicit models of chemical reactivity will have to be included in a reaction simulation system. The modeling of chemical reactivity is a very complex task because so many factors can influence the course of a reaction (see Section 3.4). 

Readers interested in medicinal chemistry can obtain an excellent overview ft om the book The Practice of Medicinal Chemistry, edited by Wermuth [1]. The first edition is nicknamed The Green Bible by medicinal chemists. "The Red Bible written by Bbhm, Klebe, and Kubinyi describes the development of new drugs [2]. An overview of different classes of drugs and their mechanisms of action is given by Mutschler [3]. 

M. S. Tswett, the Polish botanist, in 1906 used adsorption columns in his investigations of plant pigments. It was not untU about 1930 that the method was used extensively by chemists. The most startling results have been obtained in the fields of plant pigments and natural products, but... 

From gadolinite, a mineral named for Gadolin, a Finnish chemist. The rare earth metal is obtained from the mineral gadolinite. Gadolinia, the oxide of gadolinium, was separated by Marignac in 1880 and Lecoq de Boisbaudran independently isolated it from Mosander s yttria in 1886. 

To make her own HBr solution the chemist needs to go down to the local specialty gas supplier. These sorts of businesses sell tanks of oxygen to hospitals, acetylene tanks to welding shops and, yes, HBr to underground chemists. The chemist places 200g of acetic acid in a small PP container or flask and then weighs the flask with its contents. Next, the flask is stirred in an ice bath tray that has just a small amount of ice to keep the contents cool and... 

METHOD 2 This method is a backup use for all that bromo-safrole or phenylisopropyl-bromide that the chemist made. It is the simplest method in the entire book, uses the cheapest most basic ingredients and happens to be the first method that Strike ever studied [59]. Strike does not have many fond reminiscences about this method because it kind of sucks but the chemistry is so basic that it may well serve the most pathetic chemist. The reaction proceeds as follows which uses ammonia to replace the bromine giving MDA or amphetamine directly ... 

Gilbert Newton Lewis (born Weymouth Massachusetts 1875 died Berkeley Califor nia 1946) has been called the greatest American chemist The January 1984 issue of the Journal of Chemical Education contains five articles describing Lewis s life and contributions to chemistry... 

To the synthetic chemist the most important of the reactions m Table 17 1 are the last two the oxidation of primary alcohols to aldehydes and secondary alcohols to ketones Indeed when combined with reactions that yield alcohols the oxidation methods are so versatile that it will not be necessary to introduce any new methods for preparing aide hydes and ketones in this chapter A few examples will illustrate this point... 

Biocatalytic ledox reactions offer great synthetic utility to organic chemists. The majority of oxidase-catalyzed preparative bioconversions are still performed using a whole-ceU technique, despite the fact that the presence of more than one oxidoreductase in cells often leads to product degradation and lower selectivity. Fortunately, several efficient cofactor regeneration systems have been developed (160), making some cell-free enzymatic bioconversions economically feasible (161,162). 

Theories of molecular stracture attempt to describe the nature of chemical bonding both qualitatively and quantitatively. To be useful to chemists, the bonding theories must provide insight into the properties and reactivity of molecules. The stractural theories and concepts that are most useful in organic chemistry are the subject of this chapter. Our goal is to be able to relate molecular stracture, as depicted by stractural formulas and other types of stractural information, such as bond lengths and electronic distributions, to the chemical reactivity and physical properties of molecules. 

The number of reactions that can run away is enormous, Bretherick s Handbook of Reactive Chemical Hazards [1] lists about 4,700 chemicals that have been involved in hazardous reactions of one sort or another, and there are more than 20,000 cross-references to entries involving more than one chemical. It is an essential work of reference for the chemist, the process engineer, and everyone involved in process safety. All I can do here is give a few examples to illustrate the reasons why runaways occur. 

American Council on Science and Health (ACSH), 278 American Crop Protection Association (ACPA), 267, 278 American Cyanamid Agricultural Products Division, See BASF Agricultural Products Group (US), 216 American Fiber Manufacturers Association, hic. (AFMA), 268 American Hydrogen Association (AHA), 268 American Industrial Hygiene Association (AIHA), 278 American Institute of Chemical Engineers (AICHE), 268 American Institute of Chemists, The (AIC), 268 American Methanol Institute (AMI), 268 American Oil Chemists Society (AOCS), 268 American Ordnance LLC, 216 American Pacific Corporation (AMPAC), 216 American Peptide Society (APS), 268... 

I am conscious that I have missed many sets of acronyms from my guided tour of the differential overlap models, and I will just tell you that MINDO, MINDO/1, MINDO/2 all appeared but have now been consigned to oblivion. With MINDO/3, Dewar thought that he had at last developed a reliable model for use by organic chemists. The abstract to the landmark MINDO/3 paper is terse ... 

The actual catalyst is a complex formed from osmium tetroxide and a chiral ligand, e.g. dihydroquinine (DHQ) 9, dihydroquinidine (DHQD), Zj -dihydroqui-nine-phthalazine 10 or the respective dihydroquinidine derivative. The expensive and toxic osmium tetroxide is employed in small amounts only, together with a less expensive co-oxidant, e.g. potassium hexacyanoferrate(lll), which is used in stoichiometric quantities. The chiral ligand is also required in small amounts only. For the bench chemist, the procedure for the asymmetric fihydroxylation has been simplified with commercially available mixtures of reagents, e.g. AD-mix-a or AD-mix-/3, ° containing the appropriate cinchona alkaloid derivative ... 

Though dental afflictions constitute a very significant disease entity, these have received relatively little attention from medicinal chemists. (The fluoride toothpastes may form an important exception.) This therapeutic target Is, however, sufficiently Important to be the focus of at least some research. A highly functionalized piperazine derivative that has come out of such work shows prophylactic activity against dental caries. Condensation of the enol ether 1 of thiourea with ji-pentylisocyanate gives the addition product 1J. Reaction of this with diamine 78, derived from piperazine, leads to substitution of the methylthio moiety by the primary amine, in all likelihood by an addition-elimination sequence. There is thus obtained ipexidine (79). ... 

Various specimens of menthone have been prepared and examined by different chemists, the characters of which Ml within the following limits —... 

Detailed discussions of some of the remaining peaks in Figures 7 and 8 and in the mass spectra of 10a and the D20-exchanged analogs is of more interest to the mass spectrometrist than to the carbohydrate chemist. The probable origins of these peaks will be discussed here, however, because there will be occasions when the carbohydrate chemist must dig into a spectrum in order to satisfy himself that he has interpreted the spectrum in terms of a correct structure. 

G. N. Lewis died March 23, 1946, in the laboratory he loved, surrounded by the beakers and books that were the tools of his trade. He is remembered and respected by chemists the world over. 

We have already seen that the behavior of gases is important to a chemist. The pressure-volume behavior leads to the particle model of a gas. Differences among gases (in properties such as color, odor, and solubility) show that the particles of one gas differ from the particles of another gas. In chemical reactions, the simple combining volume relationships support Avo-gadro s Hypothesis and, hence, give us a way to measure molecular weights. 

You might wish to predict the structure of diborane (which is now known) but do not be discouraged if you are not able to. Its structure, once elucidated, came as quite a surprise to even the most sophisticated chemists. The explanation of the structure is, even today, composed of a large proportion of words and a small proportion of understanding. 

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