Hydrolysis in Dilute Acid

The main disadvantage of using dilute acid for hydrolysis is the possibility of anhydride formation, already referred to (p. 16). 

An obvious advantage of using this method of catalyzed hydrolysis is that there will be a minimum of destruction of the amino acids or of any bonds other than the peptide bonds. A disadvantage of the method is the practical difficulty of working with solutions of these strongly surface-active reagents. 

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With dilute alkali, ammonia is evolved. Hydrolysis in dilute acid is slow at room temperature on heating, the amidoxime is rapidly formed. 

Hydrolysis of polynuclear hydroxo-bridged chromium (III) complexes in concentrated solutions of strong acid yields the corresponding mononuclear species. Such cleavage reactions are fast in comparison with the hydrolysis in dilute acid and proceed with retention of configuration of the mononuclear entities. A few representative examples are shown in Eqs. (46)-(49) (40, 42,161, 252). 

Hydrolysis very stable to hydrolysis in dilute acids and alkalis at room temperature (Tomlin 1994). Biodegradation ... 

Hydrolysis in dilute acid under conditions which lead to the preferential rupture of aspartyl bonds may provide an excellent means for specific cleavage of polypeptides and proteins. Of all acid degradative techniques, hydrolysis in dilute acid appears to be the most specific and closely approaches the specificity of certain proteolytic enzymes. This method, however, has not been applied widely to problems on sequence analysis. Ingram and Stretton (1962) hydrolyzed a tridecapeptide from the S-chain of human hemoglobin A2 for 12 hr at 105°C in 0.25 M acetic acid. Prefer-... 

This was first foimd by Sanger et al. (1955) in a peptide from insulin and was observed with other peptides by Hirs et al. (1956) and Smyth et al. (1962). The reaction appears to occur when acidic buffers or dilute acids are employed for isolation of peptides. Conversion of the cyclic pyrrolidone carboxyl residue to a glutamyl residue is obtained on mild hydrolysis in dilute acids or alkalies. The cyclization reaction leads to difficulties when sequence methods are used which proceed from the amino-terminal end of a peptide. In addition, this reaction can occur when an internal glutamine residue becomes amino-terminal in the course of stepwise sequence analysis under acidic conditions, as in the Edman methods. An incorrect sequence for a peptide from ribonuclease was deduced as the result of cyclization of amino-terminal glutamine and acidic destruction of serine and threonine in the same peptide (Smyth et al., 1962). 

This Chapter omits discussion of the acid hydrolysis of anhydro sugars if this reaction gives rise to other anhydro sugars. For example, it has been reported that a number of methyl 2,3-anhydrohexopyranosides give 3,6-anhydrohexoses on hydrolysis in dilute acid. ... 

The particular value of acid hydrolysis is that, used in conjunction with paper chromatography, much evidence may be obtained from very small amounts of compound. As the identification of monosaccharides by paper chromatography is well established, the use of this technique in conjunction with total, acid hydrolysis provides a ready means for identifying, both qualitatively and quantitatively, the monosaccharide components of an oligosaccharide. Acid stability of different glycosidic links differs, and total hydrolysis may require from one to four hours at 100° in N acid even more vigorous conditions may be required when amino sugar or uronic acid residues are present. Very rapid hydrolysis in dilute acid,... 

Most simple oligosaccharides are quantitatively hydrolyzed by boiling dilute acid. Cellulose by contrast is hydrolyzed very slowly, and even on extended hydrolysis at higher temperatures, the maximum yield of recoverable sugar is very low. This was explained by Luers ( ) who showed the cellulose hydrolysis in dilute acid involves consecutive first-order reactions of somewhat similar rates for the production and the decomposition of sugar. This observation formed the basis for the development of the Scholler percolation process. This process, which involves removal of sugar from the digester as it is formed, resulted in twice the yield obtainable by batch hydrolysis. 

The compounds of the III, IV and VI oxidation states are the ones with which the radiochemist deals, and the insoluble compotinds are of primary interest. Of these the insoluble hydroxides, fluorides, and oxalates, phosphates and peroxides of the m and IV states are of major interest in precipitation and co-precipitation reactions and are described in more detail in that section. One of the great complicating factors in Pu chemistry is the formation of a polymeric form by hydrolysis in dilute acid or neutral solutions. The polymeric form can be quite intractable in many reactions, and may be difficult to destroy. The section on hydrolytic reactions of Pu gives details. 

Poor solubility in water (approx. 1 g/litre), very soluble in organic solvents Stable to temperatures up to 285°C stable to hydrolysis in dilute acids and alkalis at room temperature, in the absence of light... 

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