Acids pseudo

Typical organic acids contain the --C(0)0H group, but many other acid groupings, e.g. the sulphonic -S(0)20H give acidic properties to organic compounds. Phenols have acidic properties and are classified with enols as pseudo-acids. 

The normal form A can pass by tautomeric change under the influence of alkali into the acidic hydroxy form B, which in turn can 3deld the sodium salt C. Nitroparaffins are therrfore pseudo-acids, and are soluble in alkaline solution. 

The Raman spectrum of the monohydrate, HN03.H20, shows it to exist as the hydroxoni-um salt, H30+N03 13. Also, according to analyses of the Raman spectrum, nitric acid exists in aq solns either as a pseudo-acid, N02.0H or as a true acid, N03".H+. In 10 molar aq soln, both acids are present in equal amounts, being caused by the self-dissociation of nitrogen pentoxide (NjOj), while in a 6 molar soln, the pseudo acid is present only to the extent of 2%. and the more dilute the soln, the less pseudo acid is present. In very coned solns, the true acid is present only in small quantities (Refs 32 33)... 

In 1896 Hantzsch and Schultze obtained the separate nitro and isonitro forms of phenylni-tromethane and studied their properties and their interconversion24. Hantzsch introduced the term pseudo-acid to describe neutral compounds which form alkali metal salts corresponding to their aci forms. 

Some of these refs also described props and uses of HNDPhA. History of its prepn and uses is described in Refs 14 26 HNDPhA is a pseudo-acid which was investigated by Aleksandrov (Ref 8) and Hantzsch St Opolski (Ref 8a)... 

Hexanitrodiphenylamine, Salts of. HNDPhA being a pseudo-acid reacts with oxides, hydroxides and carbonates of metals or of ammonia with formation of salts, most of them explosive... 

Nitroaminoguonidine(NAGu) Salts. As mentioned under nitroaminoguanidine, this compd exists in two forms the normal and the pseudo-acid. The existence of a pseudoacid form explains the possibility of formation of metallic salts... 

Basing his view mainly on the theory of Hantzsch, that suggests that nitric acid at high concentrations exists in the form of the pseudo-acid 02N 0H, Farmer [21]... 

According to A. Hantzsch, while in aq. soln., nitric acid behaves as if it were constituted HO.N02, in alcoholic soln., the hydrogen can be split off by electrolytic dissociation. The optical properties also indicate that under these conditions the constitution may alter to N03.H. He calls the latter a pseudo-acid, meaning an acid which is homopolar with respect to hydrogen, but whose hydrogen atoms do... 

The principle classes of acidic compounds are listed in Table 9.1 (Column 3). The distinction between true acids and the weakly acidic pseudo acids (e.g. phenols, ends, nitroalkanes) should be made by observing the nature of the reaction with sodium hydrogen carbonate. To ensure that evolution of carbon dioxide does not go unnoticed in those cases where reaction appears sluggish, add a solution of the compound in methanol carefully to a saturated solution of sodium hydrogen carbonate solution, when a vigorous effervescence at the interface will be observed. 

Oxidation of 5 - and S/S-3-ketosteroids.6 The oxidation of 3-ketosteroids (1 and 3) involves the enol. The 5oc-ketones are converted into pseudo acids (2) the 5/1-ketones are cleaved at C3-C4 to give mainly keto acids. 

The primary and secondary nitroparaffins are typical pseudo acids, forming metallic salts when treated with bases. 

According to Hantzsch, the structure of a true nitric acid is N03 H+ or N(03)H+. The hydrogen atom is attached by electrostatic force only and that is why it dissociates readily, while the structure of concentrated nitric acid is that of the undissociated pseudo-acid N02.0H or N(02)0H. 

Both forms are in equilibrium. The pseudo-acid form acts as a nitrating and... 

Thus, the addition of sulphuric acid to nitric acid increases the concentration of the pseudo-acid. The sulphuric acid, being the stronger, gives off a proton to pseudo-nitric acid and causes the formation of the following mono- said bivalent... 

In a mixture with 89% sulphuric acid, nitric acid exists in two forms -true nitric acid and pseudo-nitric acid, according to Hantzsch s theory. Only the pseudo-acid form acts as a nitrating agent. On dilution with water the concentration of pseudo-acid falls. 

Jones expressed the view that the identification of 260 mp chromogen with undissociated nitric acid molecule (Hantzsch s pseudo-acid) is largely a speculative hypothesis for which there is insufficient evidence. He suggested that the 260 mp band is produced by the N02+ ion or by the undissociated N205 molecule. The high intensity of this absorption may obliterate the weak absorption of the nitrate ion at 302 mp. 

MelMider points out that unless hydrogen is firmly attached by a covalent bond Mid cmi change its position (as in tautomerism), heavy isotopes react more slowly. The influence of heavy water on the rate of neutralization of a pseudo-acid such as nitroethMie, as observed by Wynne-Jones [89], may be cited as an example. According to him the rate of the reaction involving deuterium loss was about ten times lower than when the proton was lost. 

The two-electron reduction product, fra s-[Rh(en)2(OH)(H)]+ displays a sharp H NMR signal at 30.6 t. The pseudo acid-base equilibrium, represented in equation (164), was proposed to explain the observation that this peak broadens as the pH is raised, disappearing completely by pH 13. 

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