Effects of compound structure

Miller, L. and Weyker, C., Effects of compound structure and temperature on the resolution of enantiomers of cyclopentenones by liquid chromatography on derivatized cellulose chiral stationary phases, J. Chromatogr., 653, 219-228, 1993. 

Admitting the impossibility of calculating absolute rates, we can concern ourselves with the effect of a structural modification to a particular reactant which we take as a point of reference if the rate constant for the reaction involving the modified compound is k, and that for the... 

During the investigation of the effect of the structure of the starting compound on its behavior in this reaction, it was found that N-methylated pyrazolyl ketones 12a-d can also be converted either into the normal products 13a-c, 14a-c via substitution of the carbonyl oxygen by chlorine or into the corresponding a,fi-dichloroethylenes 17a-d in 50-90% yields (76TZV2288) (Scheme 29). 

Why is NaOH a strong base, HNO3 a strong acid, and CH3 OH neither Each of these compounds contains O-H bonds, yet their proton transfer properties are strikingly different. In this section we examine the effect of molecular structure on acid strength. 

Comparative Evaluation of Related Compounds. Structural studies are incomplete, but NMR and gas chromatographic - mass spectroscopic analysis of a component (fraction 7) isolated by HPLC indicated biphenyl characteristics (30). In an attempt to evaluate the cytolytic effect of compounds with similar structure, 4-hydroxybiphenol and 2-hydroxybiphenol were tested for lytic effects on P. brevis. Bioassays of 2- and 4-hydroxybiphenol indicated that both compounds were cytolytic to P. brevis (31). 

A striking illustration of the effect of chemical structure on insecticidal properties is provided by the data given in this paper on compounds related to piperonyl butoxide. According to the above theory, the methylenedioxyphenyl nucleus present in this substance is the toxophore. The materials selected for comparison show the reduction in toxicity produced, first, by modifying the toxophore, and, second, by substituting different groups for the auxotox radical. 

Attack by eCN is slow (rate-limiting), while proton transfer from HCN or a protic solvent, e.g. HzO, is rapid. The effect of the structure of the carbonyl compound on the position of equilibrium in cyanohydrin formation has already been referred to (p. 206) it is a preparative proposition with aldehydes, and with simple aliphatic and cyclic ketones, but is poor for ArCOR, and does not take place at all with ArCOAr. With ArCHO the benzoin reaction (p. 231) may compete with cyanohydrin formation with C=C—C=0, 1,4-addition may compete (cf. p. 200). 

Personov RI, AT shits LA, Bykovskaja LA (1972) The effect of fine structure appearance in laser-excited fluorescence spectra of organic compounds in solid solutions. Opt Commun 6 169-173... 

Cho, H.-H., Park, J.-W., Liu, C.K. (2002) Effect of molecular structures on the solubility enhancement of hydrophobic organic compounds by environmental amphiphiles. Environ. Toxicol. Chem. 21, 999-1003. 

Very little has been done to investigate the effect of the structure of the =SiH compound in determining the structure of the end products of hydrosilation. Examples can be found, in addition to many that have already been mentioned, which indicate that the structure of =SiH com-... 

To probe the effects of HCFC structure on toxicity the metabolism of three penta-haloethanes, HCFC-123, HCFC-124, and HCFC-125 were studied. The three compounds differ one from the other by the number of fluorine atoms present in the /3-carbon (Fig. 4.64). It was found that the enthalpies of activation, AHact, for hydrogen atom abstraction paralleled the rate of trifluoroacetic acid excretion suggesting that the more difficult it was... 

Sorption plays a significant role in the environmental fate and effects of compounds released into the aquatic environment, largely determining their distribution between different environmental compartments. Apart from affecting the mobility, and therefore the potential of a surfactant to reach groundwater and surface water, sorption can affect its toxicity and biodegradation by influencing bioavailability. This process is especially relevant for surfactants, since their molecular structure presents a pronounced tendency to sorb onto interfaces. 

During the course of this study, styrylpyridine based polyesters and polycarbonates as well as their related model compounds were synthesized and characterized by TGA, 01, and UV irradiation to determine the effect of the structure on thermal and UV stability. 

Effect of Ring Structure, Methyl Groups, and Nucleophile on Rates of Lactoni-zation (See Table 3 for Reference Compounds Storm and Koshland, 1972b) at 25° in 20% EtOH-HzO (p = 0-4)... 

The most comprehensive study of lithium cation basicities for organic bases was conducted by Taft, Gal and coworkers who investigated the effect of molecular structure on the gas-phase cation and proton basicities. Taft s LCA scale was revised and extended, and the lithium cation basicity scale now includes over 200 compounds. In the same work the correlations between gas-phase basicities toward lithium cation (LCB) and proton (GB) were examined. Good correlations are obtained provided that separate lines are drawn for homogeneous families and the differences in slopes are traced back to the different sensitivities to structural effects. Large deviations are explained by either a different attachment center for Li+ and H+ or a chelation effect toward Li+. Figure 5 describes three types of interactions that involve chelation of a lithium cation. 

The effects of compound formulations and processing conditions on the structure and properties of extruded EPDM and NR/EPDM blends of tube foams were studied. The characteristics of blends of blowing agents (azodicarbonamide(ADC)/dinilrosopentamethylenelriamine... 

Compared to efficacy, safety is typically more multifactorial, as it is dependent on homeostasis of virtually all cellular processes. A wider number and diversity of potential molecular and cellular effects of compound interactions may affect safety than may affect efficacy or bioavailability. Accordingly, cytotoxicity assessment is less specific, more multi parametric and extrapolatable with less certainty, unless there are specific safety signals indicated by the chemical structure or by its precedents. Extrapolation of safety biomarker data needs a greater foundation of mechanistic understanding of both in vitro and in vivo pathogenesis of toxicities, as well as rigorous, empirical validation of models. 

The effect of certain structural compounds in relation to its activity, duration of action and mechanism can be altered by changing the structure of drugs of known activity. A new product can show different reactions, different relation between the drugs and cell constituents and perhaps even new mechanism of action. 

One investigation 1) sought more definite information on the effect of molecular structure on toxicity. Although it had been well established that aromatic and olefin compounds were toxic as compared to alkanes, it seemed worth while to pursue this study further, with the idea that if some one compound or series of compounds could be identified as the significant factor in toxicity, it could either be isolated by some refining procedure or be synthesized from other substances. 

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