Comparison with other metals

Comparison with other Metals, Conclusion and Prospects.89... 

Mercuric chloride at low concentration, in comparison with other metal compounds, induced the least DNA repair [257], despite its demonstrated potency in producing DNA lesions, causing equivalently effective breakage in isolated DNA as well as in DNA from cells previously treated with Hg2 +. The degree of modification in DNA repair induced by mercuric chloride may explain why this agent is not severely mutagenic or carcinogenic [253]. 

The normal coordinate analysis also allowed the authors to quantify the relative weakness of the metal-carbon force constant in comparison with other metal-ethylene complexes (0.33 vs 0.58 mdyneA ) . 

Schwarz and coworkers " smdied the reactions of first-row transition-metal ions with different organic molecules and revealed a distinct influence of the individual Met " on the processes occurring in investigated systems. For example, by comparison with other metal ions, the studied closed rf-sheU ions Cu " and Zn+ reacted with 2-methylbutanenitrile... 

Comparisons with Other Metal Systems. Although as complete a series as that reported here is not available for other metal systems, the limited data reviewed in the literature (15, 16, 50) suggest that both steric bulk and electronic effects will influence the M-P bond length. As the bulk of L is changed, the percentage s character in the M-P bond also changes (51, 52). The spectroscopic trends whenX is varied... 

On comparison with other metallic species, we are able to detect areas where efforts are still needed, such as the cycloisomerization of simple nonactivated ene-yne systems, as well as C-H bond activation. 

The interest in assessing the presence of A1 in wines is often motivated by its ability to produce bad taste and clouding effects. In an attempt to improve the sensitivity of ET-AAS instrumentation with end-capped transverse heated graphite tubes (ECTHGTs) for A1 determination in Port wine, Almedia et al. [63] investigated the performance of several chemical modifiers. Compared with other commonly used and recommended chemical compounds, K2Cr207 turned out to be better in terms of sensitivity and reduction of blank levels. The concentrations of Al in real samples were relatively high in comparison with other metals and varied from 273 to 803 pg 1 1. 

Interesting feature Is that oxides are now available with zero points of charge spanning seven or more pH units (see appendix 3, table b). Chemically speaking, this means that oxides are at our disposal with widely differing surface acidity/ basicity. By comparing (T°(pH) curves on chemically different oxides It Is possible to discriminate between oxlde-speclflc and generic double layer features. (For mercury a similar approach Involves comparison with other metals.)... 

Although considered mild in comparison with other metals, copper(I) and (II) Inflates are suitable Lewis acids for affecting Friedel-Crafts alkylation and acylation reactions (Sch. 22). The intramolecular acylaminoalkylation of the indole derivative 88 afforded the cyclized product 89 in high yield [49]. The nitrogen functionality was not a requirement for formation of the benzylic cation, because the benzylic alcohol 90 reacted similarly with 91, even with an electron-withdrawing ester group adjacent to the cationic center. 

Quesnelle, C., lihama, T., Aubert, T., Perrier, H., Snieckus, V. The tert-butyl sulfoxide directed ortho metalation group. New synthetic methodology for substituted aromatics and pyridines and comparison with other metalation directors. Tetrahedron Lett. 1992, 33, 2625-2628. 

Rhodium(II) complexes, e.g.. Rh2(OAc)4, are the mildest and most efficient and versatile catalysts for cyclopropanation, especially with diazo carbonyl reagents5 la 1 31 8S. Side reactions are C-H-insertion and Wolff rearrangement. Intensive mechanistic investigations and a comparison with other metal catalysts have been described10 2. Rhodium catalysts have frequently been used in stereoselective and asymmetric cyclopropanation12. 

PLZT and PNM are, with LiNb03 and LiTa03, the systems related to elec-trooptical ceramics that have been the most studied. Chemical low-temperature routes are particularly attractive for lead-containing materials, since lead oxide is quite volatile in comparison with other metal oxides thus control of the stoichiometry of lead-based materials is tedious. 

Martin, C.J. and Evans, W.j. (1 987) Phytic acid divalent cation interactions. V.Titrimetric, calorimetric, and binding studies with cobalt (II) and nickel (II) and their comparison with other metal ions. Journal of Inorganic Biochemistry 30, 101-119. 

Klofla, T Rieke, P., Unkous, C., Buttner, W.J., Nanthakumar, A., Mewbom, T.D., and Armstrong, N.R. (1985) Tri- and tetravalent phthalocyanine thin film electrodes comparison with other metal and demetaUated phthalocyanine systems. 

Klofta, T., P. Rieke, C. Linkous, W.J. Buttner, A. Nanthakumar, T.D. Mewborn, and N.R. Armstrong (1985). Tri- and tetravalent phthalocyanine thin film electrodes Comparison with other metal and demetallated phthalocyanine systems. J. Electrochem. Soc. 132, 2134-2143. 

The precise structural identities of the high-valent oxo-iron states of heme systems are also of interest. Recent work by Mayer [101] indicates that the Fe =0 bond of an oxo iron (IV) complex is 0.1 A longer than expected in comparison with other metal oxo complexes. The oxygen-binding respiratory proteins hemoglobin and myoglobin will each form a relatively stable derivative... 

Some short-term trials should also be mentioned because they include comparison with other metallic coatings. B. A. Shaw and Moran (1985) found that a zinc-15% aluminum pseudoalloy was best after 6 months of atmospheric, splash, and spray exposure (compared with the pure metals and duplex coatings of two metals), but for some unexplained reason there was flaking and blistering of some of the prealloyed zinc-15% aluminum alloy. 

The mechanism of degradation differs for different types of material, and it is outside the scope of this book to try to compare zinc with plastics, concrete, wood, or other nonmetals. Some comparisons with other metals can, however, usefully be made. 

When there was poor agreement between published values and comparison with other metal ions and ligands did not suggest the best value, the results of more experienced research groups who had... 

In comparison with other metals (ferrous industry), A1... 

In comparison with other metal ions, the stability of BeOH is relatively weak at 25 °C. Polymeric species predominate in acidic solutions at beryllium concentrations above 10 molkg . Consequently, few studies of beryllium hydrolysis have been able to measure the stabUity of BeOH at this temperature. At higher temperatures, the monomers become more stable than the polymers, and, as a result, only monomers have been detected at high temperatures. 

Comparison with Other Metals. Other metals were exposed to the same weathering environments over the same time periods used to evaluate corrosion of aluminum alloys. Comparative corrosion rates (average loss in thickness per side calculated fiom weight losses measured after exposures of 10 and 20 years) are listed in Table 7 for aluminum, copper, lead, and zinc panels. Hgure 2 compares losses in tensile strengths at sevraal weathering sites for unprotected low-carbon steel (0.09C, 0.07Cu) and for aluminum alloys. 

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