Dihydrogen acidity

Table 1.2. Approximate ion-pair pK(HB ) values for cationie dihydrogen acids in CH2CI2.

In the pure acid the dihydrogen sulphate has a proton affinity, so that... 

Hexafluoroarsenic acid [17068-85-8] can be prepared by the reaction of arsenic acid with hydrofluoric acid or calcium fluorosulfate (29) and with alkaH or alkaline-earth metal fluorides or fluorosulfonates (18). The hexafluoroarsenates can be prepared directly from arsenates and hydrofluoric acid, or by neutrali2ation of HAsF. The reaction of 48% HF with potassium dihydrogen arsenate(V), KH2ASO4, gives potassium hydroxypentafluoroarsenate(V)... 

Titanium corrodes very rapidly in acid fluoride environments. It is attacked in boiling HCl or H2SO4 at acid concentrations of >1% or in ca 10 wt % acid concentration at room temperature. Titanium is also attacked by hot caustic solutions, phosphoric acid solutions (concentrations >25 wt%), boiling AlCl (concentrations >10 wt %), dry chlorine gas, anhydrous ammonia above 150°C, and dry hydrogen—dihydrogen sulfide above 150°C. 

Bismuth tribromide may be prepared by dissolving Bi O in excess concentrated hydrobromic acid. The slurry formed is allowed to dry in air, then gendy heated in a stream of nitrogen to remove water, and finally distilled in a stream of dry nitrogen. Bismuth tribromide is soluble in aqueous solutions of KCl, HCl, KBr, and KI but is decomposed by water to form bismuth oxybromide [7787-57-7] BiOBr. It is soluble in acetone and ether, and practically insoluble in alcohol. It forms complexes with NH and dissolves in hydrobromic acid from which dihydrogen bismuth pentabromide tetrahydrate [66214-38-8] H2BiBr 4H2O, maybe crystallized at —lO C. 

Choline Dihydrogen Citrate. This compound [77-91 -8] is a white, crystalline, granular substance possessing an acid taste, mp 105—I07.5°C, and is freely soluble in water, very slightly soluble in alcohol, and practically insoluble in benzene, chloroform, and ether. The pH of a 25% solution is about 4.25. 

In Eq. (6-35), A/Z is the molar heat of ionization of the buffer acid at the conditions (temperature, solvent composition) of the kinetic studies. It happens that for many commonly used acidic buffers this quantity is small. Hamed and Owen give A//2 = —0.09 kcal/mol for acetic acid at 25°C, for example. The very important buffer of dihydrogen phosphate-monohydrogen phosphate is controlled by pK2 of phosphoric acid at 25°C its heat of ionization is —0.82 kcal/mol. 

Figure 6-18 shows a bell-shaped pH-rate profile for the hydrolysis of monomethyl dihydrogen phosphate. Other examples are the hydrolysis of o-carboxyphenyl hydrogen succinate and the hydration of fumaric acid. ... 

Ion exchange on an acid column yields the crystalline dihydrate" H4P2O6.2H2O which is actually the hydroxonium salt of the dihydrogen hypophosphate anion [H30lJl(II0)P(0)2--P(0)2(0H)] " it is isostructural with the corresponding ammonium salt for which X-ray diffraction studies establish the staggered structure shown. 

A mixture of 20 g of 1. [p.((3.diethylaminoethoxy)phenyl]-1,2-diphenylethanol in 200 cc of ethanol containing an excess of hydrogen chloride was refluxed 3 hours. The solvent and excess hydrogen chloride were removed under vacuum, and the residue was dissolved in a mixture of ethyl acetate and methylene chloride. 1-[p-((3.diethylaminoethoxv)phenyl] -1,2-diphenylethylene hydrochloride was obtained, melting at 148° to 157°C. This hydrochloride salt was treated with N-chlorosuccinimide in dry chloroform under reflux. The product then obtained was converted to the free base and treated with citric acid. The dihydrogen citrate salt of 1-[p-((3-diethylaminoethoxy)phenyl]-1,2-diphenylchloroethylene was obtained, melting at 116.5° to 118°C. 

Choline theophyllinate Choline chloride Carbachol Choline salicylate Choline dihydrogen citrate Ferrocholinate Chromic acid... 

Benactyzine hydrochloride Benoxinate hydrochloride Caramiphen edisylate Chloroprocaine HCI Dicyclomine HCI Valethamate bromide 4-( -Diethylaminoethoxy) benzophenone Clomiphene dihydrogen citrate 2-(2-Diethylaminoethyl) acetic acid ethyl ester Chromonar HCI 2-Diethylaminoethyiamine Ambenonium chloride Chlorisondamine chloride Diethylaminoethyl chloride Captodiamine Dlltiazem HCI Flurazepam Penthienate bromide Tiropramide Tripara nol... 

The method may be standardised, if desired, with pure potassium dihydrogen-orthophosphate (see below) sufficient 1 1 hydrochloric acid must be present to prevent precipitation of quinoline molybdate the molybdophosphate complex is readily formed at a concentration of 20 mL of concentrated hydrochloric acid per 100 mL of solution especially when warm, and precipitation of the quinoline salt should take place slowly from boiling solution. A blank determination should always be made it is mostly due to silica. 

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