Perchloric acid and the perchlorates

The preparation of perchloric acid and the perchlorates.—Perchlorates are produced in a chemical way by the breaking up of a chlorate, and by the direct... 

Xhe existence of chloric(VII), (perchloric), HCIO4, and several periodic(VII) acids has long been established. Bromic(VlI) acid and the bromate(VII) ion have only recently been discovered. 

Practical difficulties in using concentrated (> 72 % perchloric acid) and the fact that the/f function is known only up to 60 % perchloric acid, reduce the value of these media for the study of nitration. 

Other investigations of interest are the studies of the isomeric dihydroderivatives of brucine and strychnine and their reactions, carried out by Leuchs and his collaborators, investigation of the red o-quinone (isolated as the perchlorate, CjiHjoO Ng. HCIO4) formed in the well-known test for brucine with nitric acid, and the examination of the transformation products of oximinobrucine by Wieland et al. ... 

To a suspension of 500 mg of 160i,17a-dihydroxyprogesterone in 25 ml of freshly redistilled acetophenone isadded 0.125 ml of 72% perchloric acid and the mixture isagitated at room temperature for one hour. The clear solution is washed with dilute sodium bicarbonate to remove excess acid and the acetophenone layer, after addition of chloroform is separated from the aqueous phase. The organic layer is dried over sodium sulfate and after removal of the chloroform and acetophenone in high vacuum the residue is crystallized from 95% alcohol. The pure acetophenone derivative has a melting point of about 142° to 144. ... 

To a suspension of 500 mg of 6a-fluoro-triamcinolone in 75 ml of acetone is added 0.05 milliliters of 72% perchloric acid and the mixture agitated at room temperature for 3 hours. During this period the crystals gradually dissolve and the clear solution is neutralized with dilute bicarbonate and the acetone removed in vacuo. The resulting crystalline suspension is filtered and the crystals washed with water. The dried material is recrystallized from 95% alcohol to give the pure acetonide. 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

Derbyshire and Waters192 measured the rates of bromination of sodium toluene-m-sulphonate (in water) and of benzoic acid (in aqueous acetic acid) by hypobromous acid with sulphuric or perchloric acids as catalysts, all at 21.5 °C. No bromination occurred in the absence of mineral acid and the reaction was strictly first-order in aromatic and in hypobromous acid. The function of the catalyst was considered to be the formation of a positive brominating species, according to the equilibrium... 

Phosphoric acid, sulfuric acid, and the hydrogen sulfate ion are members of a group of acids known as oxoacids. An oxoacid has a central atom bonded to a variable number of oxygen atoms and OH groups. Except for the three oxoacids shown in Table (sulfuric acid, nitric acid, and perchloric acid), all of the oxoacids described in this textbook are weak acids. Chapter 17 describes in detail the chemistry of strong and weak acids, including carboxylic acids and oxoacids. 

The British Pharmacopoeia [2] describes a potentiometric titration method for the determination of penicillamine as the pure drug substance. The method is performed by dissolving 100 mg of the substance in 30 mL of anhydrous acetic acid. The mixture is titrated with 0.1 M perchloric acid, and the endpoint determined potentiometrically. Each milliliter of 0.1 M perchloric acid is equivalent to 14.92 mg of C6HnN02S. 

Oxides of chlorine are both more numerous and more useful than those of fluorine. These oxides are the anhydrides of several important acids, and the oxyanions of those acids constitute the hypochlorites, chlorites, chlorates, and perchlorates. The first oxide of chlorine, C120 (m.p. -20 °C, b.p. +2 °C), contains chlorine in the +1 oxidation state. It can be prepared by the reaction... 

The course of acid-catalyzed acetylations with acetic anhydride may depend markedly on the concentration of the acid and the type of acid. Reaction of 7-(3-deoxy-3-nitro-/3-D-galactopyrano-syl)theophylline with acetic anhydride in the presence of one molar equivalent of perchloric acid gave the 2, 4, 6 -triacetate in 89% yield, but, in the presence of only a trace of the acid, 82% of the 4, 6 -diacetate was obtained.93 Treatment of the manno isomer of the nucleoside with acetic anhydride-boron trifluoride gave the 4, 6 -diacetate as a crystalline product (24%), whereas phosphoric acid as the catalyst yielded the 2, 4, 6 -triester (45%). 

An SPE cartridge can be used multiple times, especially after the samples are pretreated with protein precipitation. Bourgogne et al. (2005) quantitated talinolol, a p -adrenoceptor antagonist used to treat arterial hypertension and coronary heart disease, in human plasma. The sample was first precipitated with perchloric acid and the supernatant was injected directly. An Xterra MS analytical column (50 x 4.6 mm, 3.5 [m, Waters) with a C18 recolumn filter (4x2 mm, 3.5 /.mi, Phenomenex) and a C8 EC cartridge were chosen. The cycle time was 4.8 min and linear range was 2.5 to 200 ng/mL. Protein precipitation allowed the SPE cartridge to be used for more than 90 injections. 

Wiersma and Lee [164] determined selenium in lake sediments. The sample is digested with 4 1 concentrated nitric acid 6% perchloric acid and the residue treated with 6M hydrochloric acid then reduced with H PO. The fluorescing agent used was 2,3 diaminonaphthalene. 3 2... 

First, the complications arising from a multiplicity of propagating species can be reduced considerably if initiators are used which cannot form esters in other words protonic oxo-acids and the mixed anhydrides and salts derived from them, such as triflates and perchlorates, are not useful for attempts to measure kp and k for three reasons ... 

We have shown [1, 2] that, in the polymerisation of styrene by perchloric acid under the conditions reported here, the initiation reaction does not produce carbonium ions and that the monomer is polymerised by non-ionic chain carriers. Since the most likely nonionic reaction product formed from perchloric acid and styrene is the ester 1-phenylethyl perchlorate we attempted its preparation in order to try it as catalyst for the polymerisation of styrene. However, we found this ester to be unstable in methylene dichloride solution. It forms styrene oligomers, polystyryl ions, and perchloric acid, and the preparative technique and the mechanism of the reactions involved will be discussed in a paper dealing with the spectroscopic behaviour of polymerising and polymerised systems. 

According to the Keele theory the primary reaction between the perchloric acid and the monomer is also (1), but thereafter the growth is by a ring-expansion reaction (4) in which no free end is ever formed this goes by way of a four-centred transition state and gives the cyclic product (IV) ... 

The method of Jaacks and his co-workers was used by Firat and Plesch to study the nature of the cations present when DXT, 4-methyl-DXL, and 1,3-dioxepan (DXP) were polymerised by anhydrous perchloric acid in methylene dichloride. They showed that when these polymerisations are done under the most rigorously dry conditions, the concentration of tert.-oxonium ions in the polymerising mixtures is at most close to the limit of detection and much less than the original concentration of perchloric acid and the concentration of ions in the polymerising solution. 

Tetraphenylarsonium pertechnetate is precipitated in the presence of perchlorate as the carrier. The mixed salts are disolved in concentrated sulfuric acid and the solution is electrolyzed at platinum electrodes. The black deposit (TcOj) obtained is dissolved in perchloric acid, technetium heptoxide is distilled out of the solution... 

Thianthrene, 68 X = Y = S, radical-cation is obtained by oxidation in trifluoro-acetic acid containing perchloric acid and the evaporation of the solvent [232], It shows electrophilic behaviour on the sulphur atom. When the electrochemical oxidation of thianthrene is carried out in aqueous acetic acid, the monoxide is obtained... 

Chlorates are reduced to a lower state of oxidation by sulphurous acid, and the soln. then decolorizes indigo while chloric acid does not decolorize this reagent, bromic acid does. Ferrous salts in the presence of dil. sulphuric acid quickly reduce chlorates, but not perchlorates, to chloride KC103+3HoS04+6FeSC>4 =3Fe2(S04)8+3H20+KCl. 

Dry sodium perohlorat, 20 grms., is treated with 25 to 30 c.o. of cono. hydrochloric acid. The sparingly soluble sodium chloride is filtered through an asbestos Alter, and washed with ten 1 c.o. portions of cono. hydrochloric acid. The filtrate contains the aq. perchloric acid and the excess of hydrochloric acid, together with the small amounts of the sodium salts of these acids which are soluble in cone, hydrochloric acid. The mixed filtrate and washings, at 135°, are evaporated on a hot plate to volatilize the hydrochloric acid the soln. of perchloric acid which boils at 205° remains behind. Tho yield is about 95 per cent, of the theoretical. About one per cent, of sodium perchlorate is lost in the sodium... 

The substance (I) was obtained by treating ethylene oxide with 60% perchloric acid, and the compound (II) by acting with 60% perchloric acid on epichlorohydrin. 

The irradiated coal ash samples are digested under reflux with a mixture of hydrochloric, nitric, and perchloric acids. The selenium is then separated by the hydrobromic acid distillation and collected in water at 0°C. Elemental selenium is precipitated from the distillate with sulfurous acid, and the activity of the precipitate is counted. The photopeak arising from the 0.121 and 0.136 MeV y-rays of 75 Se is measured. 

The best known exceptions to the general reluctance of bromine to accept a + 7 oxidation stale are perbroinic acid and the perbromate ion, which were unknown prior to 1968 (see Chapter 17). Their subsequent synthesis has made their nonexistence" somewhat less crucial as a topic of immediate concern to inorganic chemists, but bromine certainly continues the trend started by arsenic and selenium Thus the perbromate ion is a stronger oxidizing agent than either perchlorate or periodate. 

Fig. 4. Analysis of an anion standard solution by IC (a) and CE (b) [48]. IC conditions aVydac 302IC4.6 column, a flow-rate of 2.5 ml/min, an injection volume of 25 xl, an isophthalic acid mobile phase, UV detection at 280 nm. CE conditions an electrolyte of potassium dichromate, sodium tetraborate, boric acid and the DETA (diethylenetriamine) EOF modifier, pH 7.8 65 cmX75 xm I.D. capillary 20 kV indirect UV detection at 280 nm. Anions 1, chloride 2, nitrite 3, chlorate 4, nitrate 5, sulfate 6, thiocyanate 7, perchlorate 8, bromide.

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