Chemical structures versatility

Polyesters are one of the most versatile classes of polymers ever produced, covering a wide range of properties and applications. Polyesters are present in fibers, engineering thermoplastics, and high-performance polymers as well as in thermosetting resins and elastomers. Table 2.1 lists the chemical structure, abbreviations, and uses of some commercially important thermoplastic polyesters. 

It is difficult to find an industrial sector that does not use alcohol sulfates or alcohol ether sulfates. These surfactants are rendered so versatile in their chemical structure through varying their alkyl chain distribution, the number of moles of ethylene oxide, or the cation that it is possible to find the adequate sulfate achieving the highest mark in nearly every surfactant property. This and the relative low cost are the two main reasons for their vast industrial use. 

This short discussion should provide an indication of the versatility of photochemical reactions. For example it is possible to synthesize, in a simple maimer, complicated ring systems that are difficult to produce by conventional synthetic methods. For these reasons it is only rarely possible to make unequivocal predictions concerning the chemical structures of the products formed particularly if oxygen is present during the course of the reaction. 

Our interest in the past few years has been on biodegradable polymers. We have been evaluating the potential of poly(phosphoesters) as degradable biomaterials (4).We were attracted to this class of polymers because the phosphoester bond in the backbone is cleavable under physiological conditions, the presence of the P-O-C group would facilitate fabrication, and the versatile chemical structure affords a wide... 

Because of their versatility and simplicity, TLC methods have been frequently applied to the separation and semi-quantitative determination of carotenoid pigments in synthetic mixtures and various biological matrices. The retention of pure carotenoid standards has been measured in different TLC systems. Separations have been carried out on silica plates using three mobile phases (1) petroleum ether-acetone, 6 4 v/v (2) petroleum ether-tert-butanol 8 2 v/v, and (3) methanol-benzene-ethyl acetate 5 75 20 v/v. Carotenoids were dissolved in benzene and applied to the plates. Developments were performed in presaturated normal chambers. The chemical structure and the Rv values of the analytes measured in the three mobile phases are listed in Table 2.1. It was concluded from the retention data that mobile phase 3 is the most suitable for the separation of this set of carotenoids [13],... 

Higher olefins are versatile chemical intermediates for a number of important industrial and consumer products, providing a better standard of living with low environmental impact (qv) in many commercial uses. These uses can he characterized by carbon number and by chemical structure. 

Poly(mono-cyclohexylitaconate) (PMCHI) (see Scheme 2.16) is a polymer that present several interesting characteristis. By one hand is a polymer containing a cyclohexyl group what, as it was discussed in previous sections, is a chemical structure that provide several relaxational responses due to the conformational versatility of the saturated cyclic side chain. 

The polymerisation of allene (1,2-propadiene), the simplest cumulene, is of interest not least because polyallene can be considered to be a versatile intermediate polymer blank , if formed with the chemical structure resulting from polymerisation by the scheme... 

Ash, S., M.A. Cline, R. Webster Homer, T. Hurst, and G.B. Smith. 1997. SYBYL Line Notation (SLN) a versatile language for chemical structure representation. J. Chem. Inf. Comput. Sci. 37 71-79. 

The potent and versatile pharmacological activity of natural ergot alkaloids prompted investigations on the relationship between their chemical structure and physiological action. It also caused the natural alkaloids to be modified chemically and the resulting variations of pharmacological and therapeutic action to be studied. 

Hence, this versatility of the Mannich reaction, along with the remarkable possibilities of exploiting the reactivity of Mannich bases in producing further derivatives (Chap. 11), makes it possible to readily attain the most varied chemical structures in conformity with the practical requirements and applications needed in industry (Chap. V). 

As we have seen before (Fig. 3, Chap. I, and Fig. 80, Chap. II), the versatile chemistry of Mannich bases offers many opportunities for creating tailor-made molecular structures suited to different needs by virtue of simple and relatively inexpensive procedures that can be readily carried out in industry. In the present chapter, therefore, we shall examine both the chemical structures that provide the properties required and the synthetic strategies that lead to the products best suited to the desired functions. A survey of the main uses of individual Mannich bases according to the type of application is also included. 

In recent years, the design and synthesis of functional molecular materials is a focus of active research in the fields of chemistry and materials science. Polyoxometalate anions constitute a distinctive class of compounds which are receiving increasing interest in catalysis, medicine and materials science. Their chemical, structural and electronic versatility make them act as electron acceptors and accommodate magnetic transition metal centers in their structures. 

It has been known for many years that surface-free energies of flat solid substrates are determined by atomic-level constitutions of their outermost surfaces as a result, alterations of chemical structures of outermost monoraolecular layers by external stimuli—including pH changes, heat application, photoirradiation, and so on—lead to the modification of versatile interfacial phenomena. Photoirradidation seems to be the most convenient way to manipulate surface properties because of its ability to control them precisely in time and space. In fact, there have been a number of reports... 

Thermal analysis has been and will continue to be widely used for pharmaceutical formulation. due both to its versatility and also the ability to present key information on the physical (and sometimes chemical) structure and behavior. Modem thermal methods tend to be simple to use and. for basic measurements, the amount of training required is often fairly limited. This is clearly an advantage in most respects, although this simplicity of use leads to a danger of underestimating the wealth of information that may be obtained... 

In order to explore whether reactivity properties can be transferred to electrode surfaces it is advantageous, and probably essential, to identify a versatile chemical system. Versatility implies access to a group of related compounds where changes in structure can be made which lead to systematic variations in chemical and physical properties. For our purposes an ideal chemical system should possess as many of the following characteristics as possible ... 

Microporous polymers have been used in the intensification of several processes encountered in nuclear, petroleum, bioconversion, tissue engineering, chemical, and environmental technologies. The advantages of PHP and its metallic form are associated with the accessibility of their pores, controllability of the pore and interconnect structures, versatility of fabrication, and chemical modification of their walls. The structure of these materials is shown in Figs. 6A-C. These polymers can be manufactured over a wide range of pore size (D) (0.5 pm < D < 5000 pm) and interconnect size (D) (0 < d/D < 0.5). 

ACD/Structure Elucidator has matured over the past 6 years to become the most capable commercial CASE system available today. The expert system has been described in detail in previous works." " The first generation system was developed for the elucidation of molecular structures of intermediate-sized organic molecules with 20-25 skeletal atoms using simple ID C NMR spectra. The second pubhcation" " reported on developments allowing the elucidation of structures of large molecules, typical of those found in the world of natural products, and utilizing mainly 2D NMR data as the source datasets. The application and success of the system as a powerful and versatile tool for the structure elucidation of complex chemical structures has been demonstrated in numerous works and will not be discussed in more detail in this review. " " ... 

The chemical structures are the most versatile way, even for nonchemists, to define a chemical. The chemical structure hides or, better, displays all the properties of the compound. The chemical structures may also be written in several ways. It is therefore not a waste of time to leam some examples of chemical formulas for the more important groups of pesticides. 

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