Water in hydrolysis

Ozonides undergo hydrolysis in water giving carbonyl compounds... 

For desymmetrization of diesters 3 via their hydrolysis in water, pig Hver esterase [12], o -chymotrypsin [12, 13a], and Candida antarctica Hpase (CAL-B) [14] were successfully used. However, further studies showed that respective anhydrides 5 can be used as substrates for enzyme-catalyzed desymmetrization in organic solvents [15]. The desired monoesters 4 were obtained in high yield in this way, using immobilized enzymes Novozym 435 or Chirazyme L-2 (Scheme 5.3). After the reaction, enzymes were filtered off, organic solvents were evaporated, and the crude products were crystalHzed. This was a much simpler experimental procedure in which control of the reaction progress was not necessary, and aU problems associated with extraction of products from aqueous phase and their further purification were omitted [15]. 

Oxime carbamates are generally stable in aqueous solutions at pH 4-6. Their chemical degradation (hydrolysis) in water depends strongly on pH. Strongly basic conditions... 

For 110a the rate of hydrolysis in water at 35 °C follows the pH profile shown in Fig. 1, i.e. with a pH maximum at 3-4 where the monoanion predominates, while the dianion reacts extremely slowly in principle, 110b behaves analogously but is more reactive than 110a. In contrast, the dianion of 110a is hydrolyzed 16.2 times... 

Hydrolysis of D.F.P. by water. Waters and de Worms1 made a kinetic study of the hydrolysis of D.F.P. in neutral aqueous lolution and in acid solution. They found that the hydrolysis in water was autocatalytic and catalysed by hydrogen ions for the initial rate of hydrolysis (0-6 per cent./hr.) was independent of the initial concentration of D.F.P. The rate-determining stage is not the direct heterolysis of the P—F link, but rather as suggested in schemes (a) or (b) ... 

Bromomethane tends to undergo slow hydrolysis in water, yielding methanol, bromide ion, and hydrogen ion. The rate constant of this reaction has been measured to be about 3x10 /second at 25°C (Castro and Belser 1981), and hydrolytic half- lives may range between 20 and 38 days. 

Nitrobenzoylamino)-2,2-dimethylpropanamide (143 R = Me) reacts in methanol-DMSO solution with sodium methoxide to yield 5,5-dimethyl-2-(4-nitrophenyl)imidazol-4(5//)-one (144 R = Me). The 4-methoxyphenyl derivative and the parent phenyl derivative react similarly, as do compounds in which variation of the 2-substitutent (R = Pr , Ph, 4-O2NC6H4) was made. The mechanism of the cyclization probably involves initial formation of the anion of the alkanamide (145), which adds to the carbonyl group of the benzamido moiety to yield the tetrahedral oxyanion (146) proton transfer and dehydration then yield the heterocycle (144). The kinetics of hydrolysis in water at 70 °C and pH 2-11 of A-glycidylmorpholine (147) have been reported. ... 

Hydrolysis in water is not expected to be signicant because 1-butene is very volatile. 

Chemical/Physical. Under laboratory conditions, methylene chloride hydrolyzed with subsequent oxidation and reduction to produce methyl chloride, methanol, formic acid, and formaldehyde (Smith and Dragun, 1984). The experimental half-life for hydrolysis in water at 25 °C is approximately 18 months (Dilling et al, 1975). 

Walsh, P.R. and Hites, R.A.Dicofol solubility and hydrolysis in water. Bull. Environ. Contam. Toxicol, 22(3) 305-311,1979. Walters, R.W. and Guiseppi-Elie, A. Sorption of 2,3,7,8-tetrachlorodibenzo-/t-dioxin to soils from water/methanol mixtures. 

Stability Indefinite at room temperature (O2/MEHO, etc.) no hydrolysis In water at pH >7... 

Ill) on the contrary is highly soluble (without any hydrolysis) in water, about 100 g/1, and could consequently be used in 0.9% aqueous NaCl solution (saline) as for both the i.p. and the i.v. (intraveinous) route. 

Carbon tetrachloride dissolved in water does not photodegrade or oxidize in any measurable amounts (Howard et al. 1991). The rate of hydrolysis in water is second order with respect to carbon tetrachloride, but is extremely slow, with a calculated half-life of 7,000 years at a concentration of 1... 

Redox Potentials and Rate Constants for the Oxidation of Reduced GO from Aspergillus nicer by Osmium and Ruthenium Complexes at 25 °C and pH 7. Complexes are Shown as Introduced Neglecting Hydrolysis in Water. See Footnote for the Key... 

Hydrolysis. The hydrolysis of dialkyl and monoalkyl sulfates is a process of considerable interest commercially. Successful alkylation in water requires that the fast reaction of the first alkyl group with water and base be minimized. The very slow reaction of the second alkyl group results in poor utilization of the alkyl group and gives an increased organic load to a waste-disposal system. Data have accumulated since 1907 on hydrolysis in water under acid, neutral, and alkaline conditions, and best conditions and good values for rates have been reported and the subject reviewed (41—50). 

Stability-. Stable at room temperature hydrolysis in water is rapid. 

Effect of diffusion and adsorption in methyl and ethyl acetate hydrolysis in water at 40°C... 

The use of formamide as solvent in the ammonolysis of activated aryl chlorides has been recommended when the substrate carries cyano ring substituents which can undergo hydrolysis in water.126... 

There is little need or opportunity to measure BCME in biological samples because of its rapid hydrolysis in water to yield formaldehyde and chloride. The abundance of chloride and, to a lesser extent, of formaldehyde, in biological materials precludes use of these hydrolysis products as an index of exposure to BCME. Therefore, the analysis of BCME in biological samples from exposed humans is virtually impossible. 

Prodrugs are drug substances that are biotransformed in the body to active metabolites and chemotherapeutic agents. Examples include sulfasalazine to sul-fapyridine, phenylbutazone to oxy-phenbutazone, aspirin to salicylate, and heta-cillin to ampicillin. In some cases, such as aspirin (ester) and hetacillin (amide), hydrolysis in water releases the active drug moiety contained within the basic structure of the prodrug. 

Iron dissolves in aqueous HC1, and solids such as [Fe(H20)6]Cl2 and [Fe(H20)4Cl2] can be crystallised. The anhydrous chloride can be obtained by heating the hydrate in a stream of HC1, or by treatment with SOCl2 which reacts with coordinated H20 to give S02 and HC1. Such wet methods are obviously inapplicable to halides which undergo hydrolysis in water, e.g. BeCl2, A1C13. 

White phosphorus can exist in water as dissolved phosphorus in amounts <3 mg/L, in the colloidal state, as large particles of elemental phosphorus at concentrations >3 mg/L, or in the particle-sorbed state (Bullock and Newlands 1969 EPA 1991). Elemental phosphorus can undergo oxidation and hydrolysis in water. The rate of reactions depends on the dissolved oxygen concentration, temperature, state of phosphorus in water (dissolved, sorbed, colloidal, or particle form), and possibly the pH of the solution. The rate of reaction grows faster as the temperature of the water increases (Lai and Rosenblatt 1977a). 

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