By Hydrolysis Reactions

By Hydrolysis Reactions.—Details have appeared of the synthesis of dibenzophosphorin oxides (15) from 5-alkyldibenzophospholes, by reaction with methyl propiolate in the presence of water, and of confirmatory syntheses from phosphinic acid chlorides, as shown below. Evidence for the suggested mechanism of the ring-expansion reaction is presented. The hydrolysis of enamine phosphine oxides is an efficient, although somewhat indirect, method for the preparation of j8-ketoalkylphosphine oxides (16) [see Section 3(iii), for the preparation of enamine oxides]. Reasonable yields (48—66%) of trialkylphosphine oxides (17) have been obtained by the alkaline hydrolysis of the products from the pyrolysis at 220 °C of red phosphorus with alkyl halides, in the presence of iodine. 

The preparation of diphenylphosphine oxide normally involves the controlled hydrolysis of chlorodiphenylphosphine, but the product has a significant amount of diphenylphosphinic acid impurity. This problem 

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Saltlike Carbides. Almost all carbides of Groups 1—3 of the Periodic Table are saltlike. Beryllium carbide and Al C may be considered as derivatives of methane ion) and most carbides having C2 groups, ie, ions, as derivatives of acetylene. This is supported to some extent by hydrolysis reactions ... 

It is interesting to determine which bond (the P—O bond marked a or the O—P bond marked b) is cleaved by hydrolysis (reaction with water). 

The most common sol-gel process employs metal alkoxides of network forming elements (M(0R) where M is Si, B, Ti, Al, etc. and R is often an alkyl group) as monomeric precursors. In alcohol/water solutions the alkoxide groups are removed stepwise by hydrolysis reactions, generally employing acid or base catalysts, and are... 

Because HI is relatively unstable, this method is not appropriate for producing the compound. Instead, as mentioned earlier, HI is better prepared by hydrolysis reactions. If a halide salt is treated with an acid that is an oxidizing agent, a redox reaction occurs in which I2 is produced. 

The sorption processes for cobalt complexes can be complicated by hydrolysis reactions of the complex in solution, surface induced ligand loss processes, sorption of hydrolysis products of either amine, protonated amine, or mixed amine/aquo cobalt complexes, and oxidation/reduction processes associated with cobalt. The principal objective of the XPS studies was to evaluate, the chemical state of cobalt and amine ligands, the surface concentration of the respective elements, and the ligand to cobalt ratio as indicated by the surface nitrogen to cobalt atomic ratio. 

Environmental Fate. The fate of bromomethane in the environment is dominated by rapid evaporation into air, where it is quite stable (EPA 1986b). The rates of volatilization from soil and water have been studied and are known with reasonable precision (although such rates are typically site-specific) (Jury et al. 1984 Lyman et al. 1982). The rates of breakdown by hydrolysis, reaction with hydroxyl radical, and direct photolysis in the stratosphere have also been estimated (Castro and Belser 1981 Davis et al. 1976 Robbins 1976). Further studies to improve the accuracy of available rate constants for these processes would be helpful, but do not appear to be essential in understanding the basic behavior of bromomethane in the environment. 

Their speciation is dominated by hydrolysis reactions. For acids, this is typically represented as a dissociation reaction,... 

Reaction 53 needs to be much faster, k53 > 500 M-1 s-1, to account for the observed 3 2 stoichiometry. The required 50-fold rate acceleration is not unreasonable given that coordination usually causes a great increase in the reactivity of peroxides (213). None the less, the dimerization of N02 followed by hydrolysis, reactions 54-55, cannot... 

In 1995, Tanev and Pinnavaia [1] have reported the synthesis of a new type of mesoporous molecular sieve designated as the hexagonal mesoporous silica (HMS). Instead of using the ionic inorganic precursor and surfactant as in the case of MCM-41 [2], HMS is manufactured by hydrolysis reaction between a neutral inorganic precursor, tetraethyl-orthosilicate (TEOS) and a neutral primary amine surfactant (8-18 carbons). HMS possesses numerous favourable characteristics, but, like MCM-41, its synthesis process can only be concluded by the removal of the surfactant. This was reportedly done either by calcination at 630°C or by warm ethanol extraction [1]. 

On the basis of all the information collected from this MS study, it is possible to propose a mechanism for the formation of silsesquioxane a7bi (Fig. 9.10). Silsesquioxanes with learly stages of the synthesis and react very quickly to form more condensed species. It is assumed that the very reactive a1 bi will not be formed again by hydrolysis reactions of more condensed species this means that the reactions in which albi takes part are effectively irreversible and that the compound will only be available for the reactions in the early stages of the synthesis. Silsesquioxanes with 2react with each other to form the more condensed silsesquioxanes with 4[Pg.226]

We have previously shown that solid particle formation from TTIP in supercritical alcohol occurs at lower temperature than for pure vapor decomposition [1]. This allows us to assume that the first step in Ti02 formation from titanium alkoxide under our experimental conditions is alcohol dehydration followed by hydrolysis reactions. 

In cross-linking studies it is sometimes useful to adopt an exactly opposite approach to cross-link ( vulcanize ) previously prepared linear chains. This process is applied in practice many different ways, mostly in the rubber industry. For study purposes, reversible cross-linking is most suitable because the network can subsequently be destroyed, for example by hydrolysis. Reactions of suitable macromolecules with chelating compounds are interesting from this point of view. 

A major interest, early foreseen [178] of poly(N-acylethyleneimine)s obtained by the cationic polymerization of 2-substituted oxazolines, was their ability to lead to linear polyethyleneimines by hydrolysis reaction. An almost complete basic hydrolysis was performed on polymers prepared using BF3-Et20 catalyst [179]. 

In a general sense, dissolution of feldspars can be viewed as a kind of weathering and can be described by hydrolysis reactions. The exact formulation of these reactions is far from certain, however. In the simplest construction, dissolution of K-feldspar and calcium plagioclase consumes H, the plagioclase consuming slightly more ... 

The use of oxirane together with Na2HP03 to prepare (2-hydroxyethyl)phosphonic acid as its disodium salt is of historical interest. Other poorly exploited, yet interesting and potentially valuable, reactions include the combination of a trialkyl phosphite and dialkyl chlorophosphate with an oxirane to yield O-phosphorylated derivatives of (2-hydrox-yalkyl)phosphonic diesters (reaction 10)" and, following the initial reaction of an a,j8-unsaturated ketone with a phosphorus(III) triester to give the cyclic phosphorane 272, the subsequent further reaction of the latter with an aldehyde followed by hydrolysis (reaction 11)" Dialkyl acetyl phosphites are reported to react with oxirane through anionic intermediate species with the formation, albeit in low yields, of dialkyl (2-acetyloxyethyl)phos-phonates hydrolysable with concentrated HCl, to give (2-hydroxyethyl)phosphonic acid ... 

S. Lee, S. Byeon, Structural and morphological behavior of Ti02 rutile obtained by hydrolysis reaction of Na2Ti307 , Bulletin of the Korean Chemical Society, 25, 1051-1054, (2004). 

We note that in the formal sense, CrO and HCrO are equivalent in that they are simply related by hydrolysis reaction (19), as are HCr04 and Cr207 by equation (20). Nevertheless, the electron distributions within CrO and HCr04... 

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