Perchloric acid titration

A non-aqueous method for the titration of procaine and other drugs using trifluoromethanesulfonic acid was reported by Zakhari and Kovar [88]. Solutions of procaine hydrochloride in anhydrous acetic acid, acetic anhydride, their mixture, or in acetone, was titrated with an acetic acid solution of 0.1 M trifluoromethanesulphonic acid or 0.1 M perchloric acid. Titration was effected in the presence or in the absence of mercurous acetate. The end point was detected visually (using crystal violet as indicator) or potentiometrically. 

Total Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration... 

Cetyl trimethylammonium bromide-perchloric acid titration method... 

The third method for automatic monitoring of the gel phase synthesis has long been known [ 196] - the perchloric acid titration on polymer — and recently was built into a computer-controlled peptide synthesizer [134]. Here, the results of the analytical determinations are fed back into the monitor system, which is programmed to optimize the course of the synthesis based on the titration data. This example of best realized automatization to date, however, is restricted to acid-tolerant synthesis strategies. The limiting chemical conditions of the analytical principle in use were already discussed on p. 43—44. 

The 4532 cm combination tone is reasonably free of interferences, and can be employed to measure oxirane ring concentrations for epoxy-coating resin systems during synthesis and crosslinking. With the use of low S/N FTIR supported by computer data manipulation, chloroform solutions of five commercially available resins were analysed for epoxide-equivalent weight and correlated with results obtained by perchloric acid titrations. The near-IR technique displays linearity for epoxy concentrations of 3.6-20.7 meq/1. Similar results were obtained via a serial concentration study, indicating that the technique is not strongly affected by matrix effects. 

A comparison of terminal epoxide determinations by the near-IR method and by standard perchloric acid titration showed that the near-IR method is much less affected by interference by solvents and reagents than titration. 

Method Neutralise a suitable volume (about 50 to 80 ml) of glacial acetic acid with O IN perchloric acid using the indicator of choice. Add and dissolve the specified weight of sample, warming and cooling if necessary, and, when the sample is a halide, add 10 ml of a 5 per cent solution of mercuric acetate in glacial acetic acid that has been neutralised, if necessary, to the chosen indicator with 0 1 N perchloric acid Titrate with standard perchloric acid to the colour of the indicator that corresponds to the maximum value of dE/dV (where E is the electromotive force and V the volume of titrant) in a potentiometric titration of the substance being examined. 

American Society for Testing and Materials, Base number of petroleum products by potentio-metric perchloric acid titration, D2896-96. West Conshohocken, PA 19428. 

If carbonyl protonation fails to occur in aromatic amides where extra resonance stabilization of the carbonium ion is possible, one would scarcely think that it would be important for aliphatic amides. However, the data of Martin and Reese (248) show that increased branching of the acyl portion of the molecule (from acetamide to pivalamide) decreases the basicity to perchloric acid titration in acetic acid as would be expected for hyperconjugative stabilization of a carbonium-like species formed by oxygen protonation. Again, solvation may be the deciding factor. In contrast, the stabilities of iodine complexes of a few acyl substituted A, iV-dimethyl acetamides follow inductive rather than hyperconjugative order (97). 

Of more value are the basicities obtained by the effect of water on an indicator titration with strong acid. The original measurement by Hammett and Deyrup (172) in the high dielectric medium formic acid gives a value for the pK of water of —3.43 agreeing roughly with later measurements from perchloric acid titrations in glacial acetic acid where pKa= —2.35 (222,318). 

The alcohols may be expected to have basicities in the range which would make them available for study by perchloric acid titration in... 

For many years fluorine has been deterrnined by the Willard-Winters method in which finely ground ore, after removal of organic matter, is distilled with 72% perchloric acid in glass apparatus. The distillate, a dilute solution of fluorosiUcic acid, is made alkaline to release fluoride ion, adjusted with monochloroacetic acid at pH 3.4, and titrated with thorium nitrate, using sodium a1i2arine sulfonate as indicator. 

Amides can be titrated direcdy by perchloric acid ia a nonaqueous solvent (60,61) and by potentiometric titration (62), which gives the sum of amide and amine salts. Infrared spectroscopy has been used to characterize fatty acid amides (63). Mass spectroscopy has been able to iadicate the position of the unsaturation ia unsaturated fatty amides (64). Typical specifications of some primary fatty acid amides and properties of bisamides are shown ia Tables 5 and 6. 

Analytical Methods. The official NIOSH recommended method for determining sulfur dioxide in air consists of drawing a known prefiltered volume of air through a bubbler containing hydrogen peroxide, thus oxidising the sulfur dioxide to sulfuric acid. Isopropyl alcohol is then added to the contents in the bubbler and the pH of the sample is adjusted with dilute perchloric acid. The resultant solution is then titrated for sulfate with 0.005 M. barium perchlorate, and Thorin is used as the indicator. 

UOP Test Method 313 is commonly employed to determine the basic nitrogen content of FCC feed. The feed sample is first mixed 50/50 with acetic acid. The mixture is then titrated with perchloric acid. 

The CH3COOH2 ion so formed can very readily give up its proton to react with a base. A weak base will, therefore, have its basic properties enhanced, and as a consequence titrations between weak bases and perchloric acid can frequently be readily carried out using acetic acid as solvent. 

Acetonitrile (methyl cyanide, cyanomethane) is frequently used with other solvents such as chloroform and phenol, and particularly with acetic acid. It enables very sharp end points to be obtained in the titration of metal acetates6 when titrated with perchloric acid. 

Discussion. Hydroxyl groups present in carbohydrates can be readily acetylated by acetic (ethanoic) anhydride in ethyl acetate containing some perchloric acid. This reaction can be used as a basis for determining the number of hydroxyl groups in the carbohydrate molecule by carrying out the reaction with excess acetic anhydride followed by titration of the excess using sodium hydroxide in methyl cellosolve. 

As the acetonitrile may contain basic impurities which also react with the perchloric acid, it is desirable to carry out a blank determination on this solvent. Subtract any value for this blank from the titration values of the amines before calculating the percentages of the two amines in the mixture. 

The standard or formal potential of ferroin can be modified considerably by the introduction of various substituents in the 1,10-phenanthroline nucleus. The most important substituted ferroin is 5-nitro-l,10-phenanthroline iron(II) sulphate (nitroferroin) and 4,7-dimethyl-1,10-phenanthroline iron(II) sulphate (dimethylferroin). The former (E° = 1.25 volts) is especially suitable for titrations using Ce(IV) in nitric or perchloric acid solution where the formal potential of the oxidant is high. The 4,7-dimethylferroin has a sufficiently low formal potential ( e = 0.88 volt) to render it useful for the titration of Fe(II) with dichromate in 0.5 JVf sulphuric acid. 

Iodide. A 0.01 M solution of potassium iodide, prepared from the dry salt with boiled-out water, is suitable for practice in this determination. The experimental details are similar to those given for bromide, except that the indicator electrode consists of a silver rod immersed in the solution. The titration cell may be charged with 10.00 mL of the iodide solution, 30 mL of water, and 10 mL of the stock solution of perchloric acid + potassium nitrate. In the neighbourhood of the equivalence point it is necessary to allow at least 30-60 seconds to elapse before steady potentials are established. 

Percussion mortar 155 Perchloric acid oxidation with, 112 titration with (nonaqueous), 408 Periodates, D. of as silver iodide, (g) 483 Peroxides analysis of, (ti) 373 Persistent lines 759... 

Barium perchlorate colorimetric titration. This colorimetric titration procedure is used in the determination of inorganic sulfate impurities in complex systems of water-soluble sulfonates and sulfonic acids. Sulfonates are precipi-... 

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