Hydrogen acid titration

Contaminant by-products depend upon process routes to the product, so maximum impurity specifications may vary, eg, for CHA produced by aniline hydrogenation versus that made by cyclohexanol amination. Capillary column chromatography has improved resolution and quantitation of contaminants beyond the more fliUy described packed column methods (61) used historically to define specification standards. Wet chemical titrimetry for water by Kad Eisher or amine number by acid titration have changed Httle except for thein automation. Colorimetric methods remain based on APHA standards. 

Soluble sulphides. Hydrogen sulphide and soluble sulphides can also be determined by oxidation with potassium iodate in an alkaline medium. Mix 10.0 mL of the sulphide solution containing about 2.5 mg sulphide with 15.0 mL 0.025M potassium iodate (Section 10.126) and 10 mL of 10M sodium hydroxide. Boil gently for 10 minutes, cool, add 5 mL of 5 per cent potassium iodide solution and 20 mL of 4M sulphuric acid. Titrate the liberated iodine, which is equivalent... 

Hydrogen ion titration curves of proteins provide a powerful tool to reveal many aspects of the structures of individual proteins. The characteristic ionization constants of the acidic and basic groups in the amino acids and peptides may be profoundly modified when these groups are incorporated in a protein molecule. An increasing number of proteins have been found in which potentially reactive groups are inaccessible for titration in the native molecule, and become available only after denaturation. Such findings can, in the years ahead, be correlated with detailed knowledge of the three dimensional structure of proteins, as obtained by X-ray diffraction and other methods. The present state of the field is reviewed by Tanford, who has done so much to advance it over the last decade. 

There are two important hydrogenation (or reduction) — titration procedures for the detn of N as ammonia. The Devarda method involves the quant reduction of nitrates to ammonia in alkaline soin using an Al-Cu-Zn alloy. The ammonia evolved is distd into standard sulfuric acid titrated. This procedure is used for K nitrate, nitric acid, nitrites or ammonia (See Vol 6, G107-L Refs3,4,14,17,19,31,34,43 ... 

The atmospheric agents, above all acids formed from carbon dioxide and the oxides of nitrogen and sulfur (carbonic acid, nitric acid, and sulfuric acid), titrate the bases of the minerals, that is, the carbonates, the silicates, and the oxides to form solutes. Depending on whether the end point of the titration is exceeded or not, the residual waters contain alkalinity (excess of bases such as HCO3 ) or acidity (excess of acids, especially hydrogen ions). The interaction of acids with minerals can be formulated as follows (we use carbonic acid, H2CO3) ... 

Given any two of the four quantities SC, Aik, pH, Pcoj/ the other two can always be calculated provided appropriate equilibrium constants are available (the equilibrium constants depend on temperature, salinity, and pressure). The standard analytical technique for the carbonate species in seawater measures alkalinity and total carbon simultaneously in an acid titration. Hydrogen ion concentration can then be determined with the equation ... 

Seventy-seven percent of the benzoyl peroxide formed benzoic acid by hydrogen abstraction. This was done by using styrene as the only monomer and the resultant benzoic acid titrated is due to abstraction of hydrogen by benzoyloxy radical. 

An alternative to the hydrogen peroxide/sulfuric acid titration with alkali is distillation of sulfur dioxide from the acidified sample into excess iodine solution. A proportion of the iodine, equivalent to the amount of sulfur dioxide, is reduced to iodide, and the residual iodine is titrated with sodium thiosulfate using starch as indicator. This more rapid method is suitable for meat products where other volatile sulfur compounds do not interfere, and it has been developed for use with automated distillation systems. 

The bridge hydrogens of a boron hydride are the most acidic, and, in fact, B10H14 is a strong acid. Titration of B10H14 can be performed with a strong base. 

The reaction progress was followed by titrating the unreacted carboxyl groups in samples removed from the reaction mixture at different times of reaction, with a standard methanolic potassium hydroxide solution. The oxirane groups were also titrated in some of the samples, using the hydrogen bromide in glacial acetic acid titration technique (21). 

Three conductometric analysis techniques are mentioned in Analytica-EBC Fourth Edition (1987). The first is a very simple procedure. The hop or hop extract is extracted-dissolved in toluene and the alpha acids are titrated in the same toluene solution. The second is a Verzele procedure which uses a two phase system consisting of toluene and a buffer pH 7, to extract the hops or to dissolve the hop extract. Titration follows in toluene with DMSO added. The third method or Ganziin procedure uses a complex mixture of methanol, diethylether and hydrogen chloride to obtain a suitable solution of the alpha acids. Titration follows in ethanol DMSO solution. 

When we find that aluminum chloride and the proton behave in the same manner in titrations, displacement, and catalysis, as well as in these examples of neutralization, it is clear that we can no longer restrict the name acid to proton donors. To designate acids which owe their acidity to the proton, Lewis sugg ted the term hydrogen acid (or H-acid). 

In what way does a solution of hydrogen peroxide react with (a) chlorine water, (b) potassium permanganate solution, (c) potassium dichromate solution, (d) hydrogen sulphide 50 cm of an aqueous solution of hydrogen peroxide were treated with an excess of potassium iodide and dilute sulphuric acid the liberated iodine was titrated with 0.1 M sodium thiosulphate solution and 20.0 cm were required. Calculate the concentration of the hydrogen peroxide solution in g 1" ... 

As a corollary to the above it should be pointed out that the exchange is in some instances stoichiometric and therefore the amount of cation in solution can be estimated by passage through a hydrogen exchanger as above and subsequent titration of the acid in the effluent. 

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