Hydrolytic behaviour

The kinetics of alkaline hydrolysis of a series of eleven vinylsulphone reactive dyes fixed on cellulose have been investigated at 50 °C and pH 11. Bimodal hydrolytic behaviour was observed under these conditions, the reaction rates being rapid at first but becoming slower as the concentration of fixed dye remaining gradually decreased. These results were attributed to differences in the degree of accessibility of the sites of reaction of the dyes within the fibre structure [87]. 

An interesting legal case ensued in the English High Court [87], where Ethicon (Johnson Johnson) maintained, among other things, that the formation and hydrolytic behaviour of polyglycolide fibres were already known and that it was therefore obvious to use the material as an absorbable suture. The outcome was basically favourable to American Cyanamid. 

As trivalent americium has a smaller ionic potential than the ions of plutonium it hydrolyses to a much lesser extent than the various plutonium ions. However, like Pu3+, hydrolytic reactions and complex formation are still an important feature of the aqueous chemistry of Am3+. Starik and Ginzberg (25) have shown that Am(III) exists in its ionic form from pH 1.0 to pH 4.5 but above pH 4.5 hydrolysis commences and at pH 7.0 colloidal species are formed. The hydrolytic behaviour of Cm(III) resembles that of Am(III). 

The hydrolytic behaviour of Ag1 in solution has been critically reviewed by Baes and Mesmer.221 The addition of alkali to Ag+ solutions produces a dark brown precipitate, Ag20, which is more soluble in highly alkaline solutions than in water. Even under these conditions, only the mononuclear species AgOH and Ag(OH)2 are produced and claims of polynuclear species have not been substantiated. At 25 °C and 7 = 0, the equilibrium constants for the formation of AgOH and Ag(OH)J were determined to be -12.0 3(log/8i) and — 24.0 0.1(log/32).221... 

Levenfeld, B. San Roman, J. Bunel, C. Vairon, J.P. Polymers with pharmacological activity, 5. Hydrolytical behaviour of poiymethacrylic hydrogels bearing Paracetamol side groups. Makromol. Chem. 1991, 192, 793-803. 

Examinations with PA-6 from different producers led to contradictory results and this formed the basis for the following investigation concerning the reason for the different hydrolytic behaviour. 

Table 6 shows the effect of traces of mineral acid concerning the hydrolytic behaviour of PA-6 during processing. Active mineral acids catalyse the hydrolysis. It is assumed for sample 4 and 8 that during the water treatment, traces of phosphoric acid were absorbed by PA-6, which then became active during processing. If bases (NaHCOs) were added for neutralisation and deactivation of the acid... 

Interestingly, the cyclic ester (73) does not rearrange. A comparison of the hydrolytic behaviour of the esters (74) and (75) has shown that the presence of the triple bond generally increases the rate of hydrolysis under basic conditions. The hydrolysis of the fluorides R R P(0)F (R and R are alkyl or alkoxy) has been examined for both alkaline and neutral aqueous solutions. For the amides Ph2P(0)X (X = NMe2 or NHC6H4NO2-4), the increase in the rate of acid-catalysed hydrolysis in acetonitrile with decreasing concentration of water has been ascribed partly to an increase in the basicity of the substrate under the same conditions. ... 

Baes and Mesmer s [1976BAE/MES] comprehensive survey and critical review of the hydrolysis of cations is the most frequently cited standard book on metal ion hydrolysis and widely accepted to represent the state of the art for long time after its publication. The authors have in most cases made their own analysis of previously published data and tested a number of different equilibrium models. The choice of models is based on the standard deviation of the experimental average number of coordinated hydroxide ions 0H However, one should complement this method by a calculation of the speci-ation in the various test solutions as done in the present review. Species that occur in low concentrations should be looked upon with suspicion as gradual changes in diffusion potentials and changes in the ionic medium may be erroneously interpreted as minor complexes. The discussion of the hydrolytic behaviour of thorium(IV) is based on the following potentiometric titration studies which are also included in the data evaluation of the present review ... 

Milic [1981MIL2] and Suranji and Milic [1981SUR/MIL], [1982SUR/MIL] investigated the hydrolytic behaviour of thorium(IV) in various aqueous chloride media at 25°C. These papers are discussed together, cf. Appendix A review of [1981MIL2]. 

Salts of [0s(N02)5] have long been reported in the literature" with sodium, potassium, ammonium, magnesium, calcium, strontium and barium cations, but the anion in these salts is now known to be trflns-[0s(N0)(0H)(N02)4] ." The potassium salt, made from [OsCl ] " and excess KNO2," is a useful starting material for other nitrosyl complexes since the NO groups are easily displaced. The X-ray crystal structure of the anion is discussed below (p. 548). The anion exhibits a complex hydrolytic behaviour, alledgedly in accordance with the trans effect of the nitrosyl Ugand." ... 

A calorimetric study of the hydrolysis of the esters (117 R = Me or Et) and of dimethyl 2-hydroxyethyl phosphate (and also of the phostonic esters (118 R = Me or Et) and comparison of their hydrolytic behaviour with that of dialkyl (2-hydroxyethyl)phosphonates) has been carried out so allowing a full analysis of thermodynamic aspects of the hydrolysis processes7 ... 

As regards solubility, the reaction of chemical warfare agents with water depends on hydrolysis. This reaction leads to new compounds with properties different from those of the chemical warfare agents. In addition, they are less toxic or no longer toxic. The following discussion addresses the hydrolytic behaviour of the chemical warfare agents concerned. 

The monosaccharides found in living systems are mostly mono- and di-phosphate esters. Of greatest importance in animal metabolism are the three esters (10.11), which also occur in plant life, particularly fruit (Chapter 12.3). They have high water solubilities and high acid strengths (Table 5.26). Individual glucose phosphates vary greatly in their hydrolytic behaviour (Chapter 5.6). 

In general, the hydrolytic behaviour of the actinides is very complicated and, in spite of much effort, is still poorly understood with respect to both thermodynamic and kinetic factors (Waters et al. 1991). The presence of mixed hydroxy-carbonate-actinide species has been shown in solutions from which carbon dioxide has not been excluded and so there is a strong possibility that some equilibrium hydrolysis data has been contaminated by the presence of carbonate (Bernkopf and Kim 1984, Kim 1986). For certain of the actinides, particularly uranium, it is probable that ternary hydroxy-carbonate species exist in vivo (Bulman 1980b). 

The hydrolytic behaviour of etho)yphosphazenes (156) was studied. It was revealed that the hydrolytic sensitivity of the ethoxy phosphazene units was so pronounced that even hydrophobic or bullqr O-linked... 

Neptunium, like uranium, can occur in aqueous solution in four oxidation states trivalent, tetravalent, pentavalent and hexavalent. The most studies have been conducted on the hydrolysis and solubility of neptunium(V) species and phases. There are much fewer studies on the hydrolysis and solubility of neptu-nium(IV). Not many studies are available that have determined the solubility or stability constants of neptuniumfVI). However, it is clear from the studies that have been undertaken that the hydrolytic behaviour of neptunium(VI) is quite similar to that of uraniumfVI). There is only a single study that has determined stability constants for the hydrolytic species of neptunium(III). 

Kraus, K.A. and Dam, J.R. (1949a) Hydrolytic behaviour of plutonium(III). Acid-base titrations of plutonium(III), in The Transuranium Elements (eds G.T. Seaborg, J.J. Katz, and W.M. Manning), McGraw-Hill, New York, pp. 466-477. 

Kraus, K.A. and Nelson, F. (1948) The Hydrolytic Behaviour of Uranium and the Transuranic Elements. Technical Report AECD-1864> National Laboratory Oak Ridge, TN, 12 pp. 

Moskvin, A.I. and Zaitseva, V.P. (1962) Hydrolytic behaviour of plutonyl in aqueous solution. Radiokhimiya, 4, 63-70. Moutte, A. and Guillaumont, R. (1969) Complexes citriques d actinium et de curium. Rev. Chim. Miner, 6, 603-610. 

Danesi, P.R., Magini, M., Margherita, S., and D Alessandro, G. (1968) Hydrolytic behaviour of concentrated thorium nitrate and perchlorate solutions. Energy Nucl.,... 

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