Hydrolysis of organometallic

Membranes with extremely small pores ( < 2.5 nm diameter) can be made by pyrolysis of polymeric precursors or by modification methods listed above. Molecular sieve carbon or silica membranes with pore diameters of 1 nm have been made by controlled pyrolysis of certain thermoset polymers (e.g. Koresh, Jacob and Soffer 1983) or silicone rubbers (Lee and Khang 1986), respectively. There is, however, very little information in the published literature. Molecular sieve dimensions can also be obtained by modifying the pore system of an already formed membrane structure. It has been claimed that zeolitic membranes can be prepared by reaction of alumina membranes with silica and alkali followed by hydrothermal treatment (Suzuki 1987). Very small pores are also obtained by hydrolysis of organometallic silicium compounds in alumina membranes followed by heat treatment (Uhlhom, Keizer and Burggraaf 1989). Finally, oxides or metals can be precipitated or adsorbed from solutions or by gas phase deposition within the pores of an already formed membrane to modify the chemical nature of the membrane or to decrease the effective pore size. In the last case a high concentration of the precipitated material in the pore system is necessary. The above-mentioned methods have been reported very recently (1987-1989) and the results are not yet substantiated very well. 

Hydrolysis of Organometallic Compounds Hydro-de-metallation or Demetallation... 

Fukushima, f. (1976) Preparation of BaTiOs films by hydrolysis of organometallic compounds. Am. Ceram. Soc. Bull., 55 (12), 1064. 

This technique produces ceramic materials from a solution. The starting particles are smaller (a few nanometers) than for traditional techniques since the particles are obtained by hydrolysis of organometallic compounds or metallic salts to oxides. The ceramic materials so obtained are more dense with a higher resistance to compression. As a result, imperfections are smaller and less frequent than with other methods. A few cracks of less than 1 pm are formed, while traditional materials can have pinholes of up to 1 mm. 

Hydrolysis of Pb" salts leads to different structures, p. 395.) It seems unlikely that pure Sn(OH)2 itself has ever been prepared from aqueous solutions but it can be obtained as a white, amorphous solid by an anhydrous organometallic method ... 

The Hoch-Campbell aziridine synthesis entails treatment of ketoximes with excess Grignard reagents and subsequent hydrolysis of the organometallic complex. ... 

Arylalkylamines 6 by Addition of Organometallic Reagents to 1,3-Oxazolidines 4 and Oxidative Cleavage and Hydrolysis General Procedure22 ... 

The carboxylic acids of organometallic systems are important synthetic intermediates that have been prepared by many different synthetic methods. Perrocenecarboxylic acid has been studied the most extensively,7 and the best laboratory syntheses previously reported involve hydrolysis of cyanoferrocene [Ferrocene, cyano-]8 or of /S-methylferrocenethiocarbonate [Ferrocene, [(methylthio)thioxo-methyl]-].9... 

An interesting example for the preparation of functional disiloxanes by use of organometallic techniques is the synthesis of l,3-bis(4-hydroxybutyl)t.etramethyl-disiloxane as shown in React ion Scheme VI. The first, part of the reaction is conducted at the reflux temperature of tetrahydrofuran (THF) and methyl iodide is used as catalyst. The ratio of dichlorodimethylsilane to magnesium and to THF affects the yield of the cyclic product very strongly. The disiloxane is obtained in about 70% yield by aqueous hydrolysis of the purified cyclic intermediate under mild conditions and in the presence of a small amount of hydrochloric acid. 

Formation constants for complex species of mono-, di-, and trialkytin(rV) cations with some nucleotide-5 -monophosphates (AMP, LIMP, IMP, and GMP) are reported by De Stefano et al. The investigation was performed in the light of speciation of organometallic compounds in natural fluids (I = 0.16-1 moldm ). As expected, owing to the strong tendency of organotin(IV) cations to hydrolysis (as already was pointed above) in aqueous solution, the main species formed in the pH-range of interest of natural fluids are the hydrolytic ones. ... 

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,... 

Part of this symposium was directed to the synthesis, properties and applications of inorganic and organometallic macromolecules with network structures. The section on organo-oxo macromolecules relevant to sol-gel processing addresses the interesting synthesis and challenging characterization efforts in this area. Brinker (p. 314) outlines the complex chemical and physical factors which affect network formation and structure resulting from the hydrolysis of a tetraalkoxysilane. 

Another synthetic route which gives a good yield of the labelled tin hydride involves the hydrolysis of an organometallic intermediate such as a trialkylstannyllithium46 with deuterated or tritiated water. The trialkylstannyllithium can be prepared by treating the trialkyltin chloride with lithium metal in THF46. This process is shown in equation 42. 

Organotrialkoxysilanes (ArSi(OR)3) were used as organometallic reagents without fluoride additives (Scheme 56).144,144a ArSi(OR)3 was easy to use because of its higher air and moisture stability. Oi and co-workers believed that hydrolysis of the trialkoxysilanes to generate silanetriols was likely occurring prior to transmetallation of the cationic rhodium complex. 

---