Magnesium various halides

Reaction of Various Halides with Activated Magnesium... 

The reactions of Rieke magnesium with various halides and dihalides, some of which react with difficulty under the conditions of normal Grignard preparations, were investigated [58]. The results are summarized in Table 4. The yields obtained by GC after hydrolysis, and the yields of carboxylic acids obtained after CO2 quench are shown. 

Table 4 Reactions of Rieke Magnesium with Various Halides and Dihalides...

Hydroalumination is a less often used reaction but the resulting organoalanes are more reactive than either organosilanes or boranes and less reactive than the traditional organometallic reagents derived from lithium or magnesium. Various aluminum hydrides are commercially available or readily prepared by reduction of aliuninum halides [10]. 

Ultrasound dramatically accelerated the formation of triorganylboranes [36] in a Barbier reaction of an organo halide, magnesium and BF3. etherate. Yields with various halides were... 

Table 4.1 Reactions of activated magnesium with various halides. ...

Methyl steroids (67) are obtained by reaction of an excess of methyl-magnesium halide with various pregnan-20-ones (66). ... 

The fracture mode of stress-corrosion cracks in austenitic stainless steels can be transgranular, intergranular or a mixture of both. One of the earliest environments found to cause problems was solutions containing chlorides or other halides and the data due to Copson (Fig. 8.30) is very informative. The test solution for that data was magnesium chloride at 154°C the alloys contained 18-20alloy with a composition of approximately 18Cr-8Ni has the least resistance to cracking in this environment. 

Metallic tin reacts with methyl halides and 2-halogenopropanoates at 135°, catalyzed by magnesium and butyl iodide in tetrahydrofuran, to give compounds MeSnXjCHgCHgCOjR, from which various other derivatives were prepared (42). 

Taking advantage of the competition principle, Bottini et al. [54] determined relative rate constants (krei) for the interception of 6 by conjugated dienes and styrene. Three precursors of 6 were employed, 32b, 33a and 35 (see Scheme 6.9), and also the solvent and the temperature were varied. If the polymerization of styrene and the dimerization of 1,3-cyclopentadiene are taken into account, the various sets of krei values agree well with each other and indicate the same reactive intermediate 6 under all conditions tried. Obviously, 6 is uncomplexed rather than associated with a metal halide, formed on generation of 6, or magnesium, which is the reagent for the liberation of 6 from 33a. The kre values obtained from experiments with 35 are summarized in Scheme 6.19. 

The catalyst is not necessary either for the electrocarboxylation of aryl halides or various benzylic compounds when conducted in undivided cells and in the presence of a sacrificial anode of aluminum [105] or magnesium [8,106], Nevertheless both methods, i.e., catalysis and sacrificial anode, can be eventually associated in order to perform the electrocarboxylation of organic halides having functional groups which are not compatible with a direct electroreductive process. 

In this section we compare the theory of the preceding two sections with experimental measurements of infrared extinction by small particles. Comparisons between experiment and theory for spheres of various solids, most notably alkali halides and magnesium oxide, have been published in the scientific literature many of these papers are cited in this chapter. In most of this work, however, there is an arbitrary normalization of theory and experiment, which tends to hide discrepancies. For this reason, most theoretical calculations in this section are compared with mass-normalized extinction measurements. The new measurements presented here were made in the Department of Physics at the University of Arizona. A group of solids was selected to illustrate different aspects of surface modes. Results on amorphous quartz (Si02) particles, for example, illustrate the agreement between experi-... 

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