Chemicals simple

A1 "End of pipe CO2 removal Open/CCGT - Natural ga.s/air LP (chemical) Simple CO2 removal, but large CO2 plant... 

L. B. G. de Morveau made the first table of chemically simple" substances. A. L. Lavoisier used this in his Ttmti EUmentaire de Chinde published in 1789. 

The generalization was based on the introduction of the concept of donor-acceptor pairs into the theory of acids and bases this is a fundamental concept in the general interpretation of chemical reactivity. In the same way as a redox reaction depends on the exchange of electrons between the two species forming the redox system, reactions in an acid-base system also depend on the exchange of a chemically simple species—hydrogen cations, i.e. protons. Such a reaction is thus termed proto lytic. This approach leads to the following definitions ... 

Calcium-sodium-chloride-type brines (which typically occur in deep-well-injection zones) require sophisticated electrolyte models to calculate their thermodynamic properties. Many parameters for characterizing the partial molal properties of the dissolved constituents in such brines have not been determined. (Molality is a measure of the relative number of solute and solvent particles in a solution and is expressed as the number of gram-molecular weights of solute in 1000 g of solvent.) Precise modeling is limited to relatively low salinities (where many parameters are unnecessary) or to chemically simple systems operating near 25°C. 

The immobilization of dissolved chemical species by adsorption and ion exchange onto mineral surfaces is an important process affecting both natural and environmentally perturbed geochemical systems. However, sorption of even chemically simple alkali elements such as Cs and Sr onto common rocks often does not achieve equilibrium nor is experimentally reversible (l). Penetration or diffusion of sorbed species into the underlying matrix has been proposed as a concurrent non-equilibration process (2). However, matrix or solid state diffusion is most often considered extremely slow at ambient temperature based on extrapolated data from high tem-... 

Originally isolated from the prostate gland (hence the name pro sta-gland-in), prostaglandins are chemically simple fatty acid-like molecules (Figure 5.3). Structural differences give rise to several series of structurally different prostaglandins, for example PGE, PGF and thromboxane. 

A formal description of a mineral presents all the physical and chemical properties of the species. In particular, distinctive attributes that might facilitate identification are noted, and usually a chemical analysis of the first or type specimen on which the name was originally bestowed is included. As an example, the complete description of the mineral brucite (Mg(OH)2), as it appears in Dana s System of Mineralogy, is presented as Appendix 3. Note the complexity of this chemically simple species and the range of information available. In the section on Habit (meaning shape or morphology) both acicular and fibrous forms are noted. The fibrous variety, which has the same composition as brucite, is commonly encountered (see Fig. I.ID) and is known by a separate name, nemalite. ... 

Qiloramphenicol inhibits peptide synthetase. It has bacteriostatic activity against a broad spectrum of pathogens. The chemically simple molecule is now produced synthetically. 

As mentioned in part 2.1.3 hydrolytic enzymes are the most frequently used enzymes in organic chemistry. There are several reasons for this. Firstly, they are easy to ttse because they do not need cofactors like the oxidoreductases. Secondly, there are a large amormt of hydrolytic enzymes available because of their industrial interest. For instance detergent enzymes comprise proteases, celltrlases, amylases and lipases. Even if hydrolytic enzymes catalyse a chemically simple reaction, many important featirres of catalysis are still contained such as chemo-, regio- and stereoselectivity and specificity. 

We have already seen in Chapter Nine how James Keir, the translator of Macquer s chemical works, conceived the operational idea of chemical simple body. But no one offered a more explicit definition before the new nomenclature than the Irish chemist Richard Kirwan in 1784 ... 

Olefinic groups in high concentration make up the molecular structure of the chemically simple hydrocarbon, polybutadiene. Moreover, several polybutadienes are available and in commercial use, containing a high fraction of the olefin groups in any one of three isomeric forms. These forms are cis, trans, and side vinyl as shown below. Consequently,... 

There is an old saying that has gotten many people into trouble If one is good, then two is better. And if a statement of the measure of worth of a compound can be made from its potency, then TMA is a step in the right direction. And this was a chemically simple direction to follow further. Looking at mescaline as a compound with no carbons on its side-chain, and TMA as a mescaline molecule with one carbon on its side chain, then what about a compound with two carbons there, or three, or nine carbons ... 

Methadone, like all opiates, is a chemically simple compound that has a variety of effects on those who take it. But while other opiates exert powerful euphoric effects on a person by acting very much like chemicals called endorphins and enkephalins, methadone produces only a mild (or no) euphoria, to which patients quickly become tolerate. Endorphins and enkephalins are naturally produced inside the brain. When released in the brain s reward system, they produce a mind reward and users feel good as a result. Methadone and other opiates mimic these natural brain chemicals, which is why they are so addicting. 

Modern atomic theory received a shot in the arm when it was recognized that the individual atom has light absorption and emission spectra occurring at narrow lines of the spectrum at specific wavelengths, as opposed to the broad bands typical of the polyatomic molecules and compounds. Since the line spectrum of each element is characteristic of that element, atomic spectroscopy can be used for precise elementary analysis of many types of chemically simple and complex materials. These studies make use of the wave character of light, as well as light s particle character. 

Plants (including algae) are uniquely self-sufficient in that they are able to harvest and transform radiant energy into the chemical energy required to transform chemically simple molecules and elements (COz, HzO, and nutrient elements) into substances (including carbohydrates, fats, proteins, alcohols, and hormones) needed for the garden plants to complete their fife cycle, and to produce harvestable products. 

The principles of how chemicals are isolated from plants will be used as an example. Aspirin has been chosen because it is one of the most widely used drugs in the world and it is also one of the most chemically simple, as well as one of the cheapest. 

Previous synthetic routes, although chemically simple, are operationally tedious ... 

For chemically simple molecules such as this, the relative intensities of a multiple are symmetric about their mid-point and are determined by statistical considerations, the intensities being (more or less) proportional to the coefficients of the binomial expansion. In other words, they go as Pascal s triangle, in a doublet 1 1, a triplet 1 2 1, a quartet 1 3 3 1, etc. The spacing between all the split resonances, the triplet for CH3 and the quartet for CH is the same and is independent of the strength of the applied field. This spacing depends on the interaction between the groups and is described in the quantum mechanical treatment by a spin-spin coupling constant, J. 

Silcretes are chemically simple (Summerfield, 1983a,d), usually comprising >90% silica with minor amounts of titanium, iron and aluminium oxides (Table 4.7). As with macromorphology, it is difficult to identify... 

We have chosen the term real samples to describe materials such as those in the preceding illustration. In this context, most of the samples encountered in an elementary quantitative analysis laboratoi course definitely are not real but rather are homogeneous, stable, readily soluble, and chemically simple. Also, there are well-established and thoroughly tested methods for their analysis. There is considerable value in introducing analytical techniques with such materials because they permit you to concentrate on the mechanical aspects of an analysis. Even experienced analysts use such samples when learning a new technique, calibrating an instrument, or standardizing solutions. 

From the chemically simple process of methane or gas oil to carbon black to the first more complex petrochemical process to isopropanol the scope of this industry has expanded to the production of a truly vast range of large-scale chemicals. Here we will cover outlines of representative samples of the more important of these chemicals. For more detailed information consult the items listed in the Further Reading section at the end of this chapter. 

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