Heat hydrolysis

Peptide bonds Alkaline pH Acidic pH Aik, heat Hydrolysis N-+0 acyl shift Racemization... 

Properties of PCDEs, including physicochemical ones, are not well known as the literature reviews of PCDEs have shown [4, 11,40,46]. PCDEs resemble PCBs structurally and in their chemical and physical properties, which, like PCDDs, PCDFs, and related compounds, are known to be stable and resistant to breakdown by heat, hydrolysis, bases, and acids. PCBs are also quite stable to oxidation under moderate conditions [3], but there is not much data about PCDEs concerning their stability. There is some evidence that PCDEs are resistant to bases and acids and the occurrence of PCDEs in the environment indicates that PCDEs are persistent and bioaccumulating compounds. The study of Firestone et al. [37] already showed that PCDEs are quite stable, since PCDEs could be measured in chlorophenol extracts after sulfuric acid treatment. Tetra- and octachlorinated PCDE congeners were later proven resistant in treatment with... 

Phenyllithium and p-dimethylaminophenyllithium react with sulfur with the liberation of heat. Hydrolysis of the products by dilute hydrochloric acid gives thiophenol (62%) and p-dimethylaminothiophenol (50%), respectively. The Grignard reagent has been employed in a similar manner. " ... 

If a solution of ammonium molybdate in concentrated nitric acid is added in excess to an orthophosphate solution, a yellow precipitate of ammonium phosphomolybdate is obtained in the cold or with very slight warming (1). No reaction is obtained from pyro or metaphosphates under the same conditions, but, if they are heated, hydrolysis will occur and orthophosphates will be detected. 

Commercial uses of the chlorinated solvents inflict various stresses on the stability of the solvent. The stresses include heat, hydrolysis (reaction with... 

Commercial uses of chlorinated solvents cause serious stresses on the stability of the solvent. These stresses include heat, hydrolysis (reaction with water), metal contact, and air induced oxidation. The addition of selected organic inhibitors (stabilizers) to the solvent helps ensure solvent stability in the most stressful applications. The organic inhibitors used in proprietary chlorinated solvents include antioxidants, acid acceptors, and metal stabilizers. The unsaturated solvents like trichloroethylene and perch loroethylene require amine or phenolic-type antioxidants to minimize the potential oxidative degradation. Acid acceptors are low... 

During grinding and/or subsequent heating hydrolysis occurred under formation of hydroxy iron cations according to Eq. (12). 

The dissolution of uranium oxides Is of considerable Interest since uranium samples prepared as accelerator targets, for neutron Irradiations, or sang>les found In the natural state are frequently In the form of oxides. Also, many compounds of uranium may be transformed to the oxide by heating, hydrolysis, or fusion. All of the oxides, UO, and UOg, are soluble... 

C7H6O5. Colourless crystals with one molecule of water, m.p. 253" C, sparingly soluble in water and alcohol. It occurs free in woody tissue, in gall-nuts and in tea, and is a constituent of the tannins, from which it can be obtained by fermentation or by acid hydrolysis. It gives a blue-black colour with Fe and is used in the manufacture 6f inks. On heating it gives pyrogallol. 

They are formed by heating dibasic acids or their anhydrides with ammonia. The hydrogen atom of the NH group is acidic and can be replaced by a metal. Mild hydrolysis breaks the ring to give the half amide of the acid. See succinimide and phthalimide. 

Prepared by heating p-nitrochlorobenzene with concentrated aqueous ammonia in an autoclave at 170°C. It is also prepared by alkaline hydrolysis of p-nitroacetanilide or by nitrating and hydrolysing benzylideneaniline. 

SNG Substitute natural gas. soaps Sodium and potassium salts of fatty acids, particularly stearic, palmitic and oleic acids. Animal and vegetable oils and fats, from which soaps are prepared, consist essentially of the glyceryl esters of these acids. In soap manufacture the oil or fat is heated with dilute NaOH (less frequently KOH) solution in large vats. When hydrolysis is complete the soap is salted out , or precipitated from solution by addition of NaCl. The soap is then treated, as required, with perfumes, etc. and made into tablets. 

The magnesium ion having a high hydration energy (Table 6.2) also shows hydrolysis but to a lesser extent (than either Be or AF ). The chloride forms several hydrates which decompose on heating to give a basic salt, a reaction most simply represented as (cf. p. 45) ... 

Reflux Distillation Unit. The apparatus shown in Fig. 38 is a specially designed distillation-unit that can be used for boiling liquids under reflux, followed by distillation. The unit consists of a vertical water-condenser A, the top of which is fused to the side-arm condenser B. The flask C is attached by a cork to A. This apparatus is particularly suitable for the hydrolysis of esters (p. 99) and anilides (p. 109), on a small scale. For example an ester is heated under reflux with sodium hydroxide solution while water is passed through the vertical condenser water is then run out of the vertical condenser and passed through the inclined condenser. The rate of heating is increased and any volatile product will then distil over. 

Hydrolysis of Acetoxime. Place about i g. of the recrystallised oxime in a small distilling-flask (50 ml.), add 10 ml. of dilute HjSO, and heat gently until about half the solution has distilled over. Test [a] the aqueous distillate for acetone by the iodoform reaction (p.346), b) the residual solution in the distilling-flask for hydroxylamine by... 

The hydrolysis of as little as 0 5 ml. of the ester can be carried out in the combined reflux-distillation apparatus shown in Fig. 38 (p, 63). Pass a stream of cold water through the vertical condenser. Place in the 10 ml. pear-shaped flask 0 5 ml. of the ester, 5 ml. of 10% NaOH solution and one or two minute fragments of unglazed porcelain and heat the mixture gently for 15 minutes so that the vapours do not rise more than about half-way up the vertical water ondenser. Now run the water out of the ver ical condenser, insert a thermometer at the top, and pass water through the inclined condenser. Heat the flask sufficiently strongly to collect 1--2 ml. of distillate. This is dilute ethanol. 

If the reaction mixture used in the above preparation of formic acid is heated to 190-200°, the glyceryl monoformate which has escaped hydrolysis undergoes decomposition, with the loss of carbon dioxide and water, and the... 

Nitromethane, CH3NO2, the first member of the homologous series, can, however, be readily prepared by a special reaction. When equimolecular amounts of sodium nitrite and sodium monochloroacetate are heated together in aqueous solution, the chlorine in the monochloroacetate is replaced by the nitro group, and the sodium nitroacetate thus formed undergoes hydrolysis follow ed by decarboxylation ... 

Hydrolysis of />-Tolunitrile. As in the case of benzonitrile, alkaline h> drolysis is preferable to hydrolysis by 70% sulphuric acid. Boil a mixture of 5 g. of p-tolunitrile, 75 ml. of 10% aqueous sodium hydroxide solution and 15 ml. of ethanol under a reflux water-condenser. The ethanol is added partly to increase the speed of the hydrolysis, but in particular to prevent the nitrile (which volatilises in the steam) from actually crystallising in the condenser. The solution becomes clear after about i hour s heating, but the boiling should be continued for a total period of 1-5 hours to ensure complete hydrolysis. Then precipitate and isolate the p-toluic acid, CH3CgH4COOH, in precisely the same way as the benzoic acid in the above hydrolysis of benzonitrile. Yield 5 5 g. (almost theoretical). The p-toluic acid has m.p. 178°, and may be recrystallised from a mixture of equal volumes of water and rectified spirit. 

Hydrolysis takes place very slowly, and after heating for some time aniline is liberated. 

Hydrolyses to ethanol and acid on being heated for a few minutes. Cool, add a few ml. of water and then cone. HCl, and cool again. Crystals of benzoic acid separate out. Complete hydrolysis cannot be carried out effectively on a test-tube scale. ( ec p. 355). 

Hydrolysis. Place 2 ml. of the ester in a 50 ml. round-bottomed flask fitted with a reflux water-condenser, or use the reflux-distillation apparatus shown in Fig. 38, p. 63. Add about 20 ml. of 10% aqueous NaOH solution, and some fragments of unglazed porcelain, and reflux gently for 20-30 minutes. (Note that methyl oxalate is hydrolysed rapidly by water alone. Phenyl esters on the other hand hydrolyse comparatively slowly even with hot NaOH solution, and should be heated... 

Place together in a 50 ml. conical flask about 1 g. of the substance and 10 ml. of 10% NaOH solution (or use apparatus in Fig. 38, p. 63)-Add a few pieces of unglazed porcelain, fit a reflux water- condenser, and boil gently for about 20 minutes. Nitriles require longer heating than amides, usually about 30 minutes. The completion of the hydrolysis of an insoluble nitrile ( .g., benzonitrile) is indicated by the disappearance of oily drops in the liquid. Cool the flask, add an excess of dil. H2SO4 and cool thoroughly. 

Hydrolysis by acids. Sucrose is readily hydrolysed by dilute acids. Dissolve 0 5 g. of sucrose in 5 ml. of water, add 2 ml. of dil. H2SO4 and heat in a boiling water-bath for 5 minutes. Cool and show that the solution has reducing properties, and will form glucosazone. Note that the excess of acid must be neutralised before carrying out the reduction tests. 

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