Hydrolytic decomposition

Tribromoacetic acid [75-96-7] (Br CCOOH), mol wt 296.74, C2HBr302, mp 135°C bp 245°C (decomposition), is soluble in water, ethyl alcohol, and diethyl ether. This acid is relatively unstable to hydrolytic conditions and can be decomposed to bromoform in boiling water. Tribromoacetic acid can be prepared by the oxidation of bromal [115-17-3] or perbromoethene [79-28-7] with fuming nitric acid and by treating an aqueous solution of malonic acid with bromine. 

Most chlorofluorocarbons are hydrolytically stable, CCI2F2 being considerably more stable than either CCl F or CHCI2F. Chlorofluoromethanes and ethanes disproportionate in the presence of aluminum chloride. For example, CCl F and CCI2F2 give CCIF and CCl CHCIF2 disproportionates to CHF and CHCl. The carbon—chlorine bond in most chlorofluorocarbons can be homolyticaHy cleaved under photolytic conditions (185—225 nm) to give chlorine radicals. This photochemical decomposition is the basis of the prediction that chlorofluorocarbons that reach the upper atmosphere deplete the earth s ozone shield. 

The principal constituents of rosin (qv) are abietic and related acids. Tall oil (qv) is a mixture of unsaturated fatty and aHcycHc acids of the abietic family. Refined tall oil may be high in rosin acids or unsaturated acids, depending on the refining process. Ethoxylates of rosin acids, eg, dehydro abietic acid, are similar to fatty acid ethoxylates in surfactant properties and manufacture, except for thek stabiHty to hydrolysis. No noticeable decomposition is observed when a rosin ester of this type is boiled for 15 min in 10% sulfuric acid or 25% sodium hydroxide (90). Steric hindrance of the carboxylate group associated with the aHcycHc moiety has been suggested as the cause of this unexpectedly great hydrolytic stabiHty. 

Sta.bilizers. Cyanuric acid is used to stabilize available chlorine derived from chlorine gas, hypochlorites or chloroisocyanurates against decomposition by sunlight. Cyanuric acid and its chlorinated derivatives form a complex ionic and hydrolytic equilibrium system consisting of ten isocyanurate species. The 12 isocyanurate equilibrium constants have been determined by potentiometric and spectrophotometric techniques (30). Other measurements of two of the equilibrium constants important in swimming-pool water report significantly different and/or less precise results than the above study (41—43). A critical review of these measurements is given in Reference 44. 

Lipases are also active during a certain period of the drying step (51), eg, Lipolase displays maximum activity when the moisture content on the fabric is 20—30% by weight. This means that significant decomposition of any residual fatty matter will take place while the laundry is drying. This hydrolytic activity does not result in an immediate advantage in terms of fat removal however, next time the stained fabric is washed the stain will be removed more effectively. 

Subsequent steps of the process involve the decomposition of ammonium peroxometalates, (NH4)3Ta08 and (NH4)3Ta08, which takes place according to a hydrolytic mechanism. Belov et al. [512] presents the following interactions as occurring by different mechanisms in different media. Hydrolysis in acidic media at pH < 3 appears to occur with the separation of oxygen, as shown in Equation (152) ... 

These materials, when exposed to continuous high humidity, especially in the presence of an electrical field, hydrolyze into the acid and alcohol precursors from which they are made. The acid plus water present make a conductive material that will cause the material to short the electrical circuit. The process by which the decomposition of the TS polyester takes place is very gradual at first and then accelerates so that extended testing of the material is necessary to be sure that the particular polyester composition used is resistant to hydrolytic degradation. 

In addition to detergency performance and feedstock economics, other factors related to the processing of these powder formulations must be considered, such as sulfonation/sulfation, crutcher slurry preparation, and spray drying. AS and AES are thermally and hydrolytically less stable than LAS. Care must be taken in spray drying to avoid decomposition and pluming problems. This may place a limitation on the levels of AS and AES in spray-dried laundry powders. 

All of the known rhenium chalcogenide halides are stable in air. With the exception of RegSgCU, they are insoluble in water, acids, and the common organic solvents. They dissolve readily in hot, 50% KOH (263, 264). Re2S3Cl4 is soluble in water, and ethanol, but insoluble in nonpolar organic solvents. With acids, alkalis, or hot water, hydrolytic decomposition takes place. Alkaline solutions can be oxidized to produce perrhenate compounds. 

As discussed earlier the whole process is a redox reaction. Selenium is reduced using sodium borohydride to give selenide ions. In the above reaction, the metal ion reacts with the polymer (PVP or PVA) solution to form the polymer-metal ion solution. Addition of the selenide ion solution to the polymer-metal ion solutions resulted in instantaneous change in the colour of the solutions from colourless to orange (PVA) and orange red (PVP). This indicates the formation of CdSe nanoparticles. The addition of the selenide solution to the polymer - metal ion solution resulted in gradual release of selenide ion (Se -) upon hydrolytic decomposition in alkaline media (equation 4). The released selenide ions then react with metal ion to form seed particles (nucleation). 

These materials are hydrolytically unstable and weaken when stored in water for a week (Bryant Wing, 1976b). Prosser, Groffman Wilson (1982) found that calcium and hydroxide ions and salicylates were released and that the rate of release was controlled by the plasticizer used in the cement formulation. Hydrophilic sulphonamide plasticizers allowed ready ingress of water and promoted decomposition, whereas the hydrophobic hydrocarbon plasticizer repelled water and retarded hydrolytic decomposition. 

Hydrolytic decomposition of these cements is clinically advantageous. Free calcium hydroxide is present in excess so that large amounts of calcium are released which, together with high alkalinity, promotes... 

Hydrolytic decomposition brings disadvantages. There is continued leakage at the margins where complete dissolution can occur (Gourley Rose, 1972) and, indeed, these bases have been observed to disappear entirely (Akester, 1979 Barnes Kidd, 1979). 

Stability of a drug substance and product is monitored throughout the development and clinical phases. This monitoring requires stability-indicating assay methodology, and this is a subject that is separate from performulation per se. In most instances, the major, feasible decomposition products are identified early [51], and as such it is known if the pathways are hydrolytic, oxidative, or photochemical. 

This aromatic alcohol has been an effective preservative and still is used in several ophthalmic products. Over the years it has proved to be a relatively safe preservative for ophthalmic products [138] and has produced minimal effects in various tests [99,136,139]. In addition to its relatively slower rate of activity, it imposes a number of limitations on the formulation and packaging. It possesses adequate stability when stored at room temperature in an acidic solution, usually about pH 5 or below. If autoclaved for 20-30 minutes at a pH of 5, it will decompose about 30%. The hydrolytic decomposition of chlorobutanol produces hydrochloric acid (HC1), resulting in a decreasing pH as a function of time. As a result, the hydrolysis rate also decreases. Chlorobutanol is generally used at a concentration of 0.5%. Its maximum water solubility is only about 0.7% at room temperature, which may be lowered by active or excipients, and is slow to dissolve. Heat can be used to increase dissolution rate but will also cause some decomposition and loss from sublimation. Concentrations as low as 0.125% have shown antimicrobial activity under the proper conditions. 

The mesoionic azolides are reported to be relatively stable toward hydrolytic decomposition, but more reactive against amines than the corresponding imidazo-lides.[194] -Protection of the amino compounds (for example by the Boc group) takes place smoothly at room temperature in about one to five hours and with high yield. The amino acids are introduced as sodium salts in aqueous acetone. 

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