Organometallic compounds aryl, hydrolysis

Organometallic compounds can be hydrolyzed by acid treatment. For active metals such as Mg, Li, and so on, water is sufficiently acidic. The most important example of this reaction is hydrolysis of Grignard reagents, but M may be many other metals or metalloids. Examples are SiRs, HgR, Na, and B(OH)2- Since aryl Grignard and aryllithium compounds are fairly easy to prepare, they are often used to prepare salts of weak acids, for example,... 

For the addition of an organometallic compound to an imine to give a primary amine, R in RCH=NR would have to be H, and such compounds are seldom stable (6-13). However, the conversion has been done, for R = aryl, by the use of the masked reagents (ArCH=N)2S02 [prepared from an aldehyde RCHO and sulfamide (NH2)2S02]. Addition of R MgX or R"Li to these compounds gives ArCHR"NH2 after hydrolysis.481... 

Getty, A. D. Goldberg, K. I. Reaction of a Pd(II) complex chelated by a tridentate PNC ligand with water to produce a [(PN)Pd(w-OH)]22+ dimer a rare observation of a well-defined hydrolysis of a Pd(II)—aryl compound. Organometallics 2001, 20, 2545—2551. 

Three classes of hybrid HPA are known to be stable to hydrolysis 1. Organometallic derivatives of the type RM (M = Si, Ge, Sn, Pb and R = alkyl or aryl). 2. Cyclopentadienyl-titaninm derivatives. 3. Zirconium alkoxide or phosphate derivatives, all of which are illustrated in Figure 2. We have tested phenyl model compounds of all of these for stability by boiling them in 6M HCl or H2O2 solution. This study showed that only PhP-O-HPA moieties are stable under conditions likely to be encountered in a fuel cell. Never the less we continue to study model compounds of the type RSi-O-HPA due to the large diversity of available ethoxy- and chloro- silanes. 

In many instances, water is sufficiently acidic to cleave alkyl and aryl transition metal compounds. However, many of these compounds are hydrophobic or insoluble in water and hydrolyze so slowly that the reaction is not detected in a test tube experiment. For example, methylchlorobis(7r-cyclopentadienyl)titanium is reported to be stable to cold water 107) but hydrolyzes rapidly in warm water. Few rate studies have been done in mutual solvents for water and organometallics but hydrolysis rates seem to vary by many orders of magnitude. The effect of hydrogen ion concentration has also received little attention but qualitative observations indicate that hydrolysis proceeds faster in acidic solutions. 

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