Coupling agents chromium salts

In this case, the silylation of the metal alkoxide initially formed represents the key step of the overall process which releases the chromium salt from the organic product. The other crucial parameter is the use of the stoichiometric reducing agent for the regeneration of the active Cr" species. Commercial Mn turned out to be particularly well suited, as it is very cheap, its salts are essentially non-toxic and rather weak Lewis acids, and the electrochemical data suggest that it will form an efficient redox couple with Cr . Moreover, the very low propensity of commercial Mn to insert on its own into organic halides guarantees that the system does not deviate from the desired chemo- and diastereoselective chromium path. Thus, a mixture of CrX ( = 2, 3) cat., TMSCl and Mn accounts for the first Nozaki reactions catalytic in chromium [13]. 

As mentioned earlier, these were the original coupling agents for use in polymer composites. Salts of trivalent chromium can be reacted with certain organic acids to produce cyclic complexes, such as shown in Fig. 22.12. If the acid carries a polymer reactive functionality, this can be incorporated into the complex. The reaction between chromium chloride and methacrylic acid is particularly suitable, resulting in a complex with reactive unsaturation. This complex can react with inclusion surfaces through the chromium functionality and with suitable polymers through the unsaturation. 

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