Bisulphite ion

Haight et al. ° have published a detailed account of the kinetics and stoichiometry of the oxidation of buffered bisulphite ion by chromic acid. The reaction is fast and its study requires a rapid mixing technique. The stoichiometry varies from a Cr(VI)/S(IV) molar ratio of 1 2 to 2 3 as the initial concentrations are changed in the range 0.12 < [Cr(VI)]/[S(IV)] < 1.4 and this was explained in terms of competition between two overall reactions... 

Another classic anion reaction is that with bisulphite ion to yield crystalline adducts. The structure of these was long a matter of dispute before it was established that they were indeed salts of sulphonic acids (33), reflecting the greater nucleophilicity of sulphur rather than oxygen in the attacking anion. The effective nucleophile is almost certainly (34) rather than HSO3 (HO + HSO3 H O +... 

Thiosulphate (SzO, ) and sulphite were the principal ions detected by Granger and Warren (1969) in the effluent from their experiment. The stability fields of these labile intermediates are shown in Fig. 8-2. The major relevance of these results to gas geochemistry is the formation of the bisulphite ion, a possible source of SO2 gas ... 

Flowever, bisulphite ions are unstable and in dilute acidic solution the favoured reaction is decomposition by disproportionation ... 

Wedzicha, B.L. and McWeeny, D.J., Non-enzymic browning of ascorbic acid and their inhibition the production of 3-deoxy-4-sulphopentosulose in mixtures of ascorbic acid, glycine and bisulphite ion, J. Sci. Food Agric., 25, 577, 1974. 

Conventional sulphite pulping processes use aqueous solutions of sulphur dioxide at various pH levels. Sulphite solutions differ in their content of sulphur dioxide, bisulphite ions and sulphite ions, as shown in Figure 13.9. At a low pH of between 1 and 2 the sulphite liquor contains about 50% sulphurous acid and bisulphite ions respectively at a pH of 4 to 5 it contains approximately 100% bisulphite ions and at a pH of 8 to 10 it consists almost entirely of sulphite ions. When allowance is made for chemical charge, it is the pH and the relative amounts of bisulphite and sulphite ions that chiefly control the mode of pulping. In the original acid sulphite process... 

In relatively dry atmosphere, it is probable that sulphur dioxide is oxidized by reactions occurring inside water aerosol droplets, frequently with H2O2 as the oxidizing agent. This oxidation process is much faster in the presence of ammonia, which reacts with sulphur dioxide to produce bisulphite ion and sulphite ion in solution ... 

Liquid SO2 reacts with aqueous NR4OH (R = Et, Bu , or n-pentyl) solutions to form the corresponding bisulphite. The bisulphite ion HSO3 in these compounds has essentially symmetry. It was thought that the large cations stabilize the bisulphite ion relative to the SgOf" ion since the lattice energy of the tetra-alkylammonium bisulphite is probably sufiicient to overcome the tendency of the dimeric ion (47) to lose water and form the pyro-sulphite ion. 

In the acid pH range, weakly nucleophilic sites in the aromatic ring of lignin compete with the sulphite and bisulphite ions for the carbonium ion intermediates, forming condensed structures. Such condensation reactions are detrimental to pulp production and can be minimized by a judicious choice of pulping conditions [4]. 

Sulphites exist in the free and bound form in foods (Wedzicha, 1984). The free sulphite consists of sulphite ion, bisulphite ion and sulphur dioxide. Reversibly bound sulphite can dissociate under the right conditions to form free sulphite but irreversibly bound sulphite cannot dissociate. 

The temperature dependence of all the k factors above except for ksA, can be described by the Arrhenius relationship, k = k exp(E/X), with E and k known for each of these reactions. The hydrogen and bisulphite ion concentrations are obtained via electroneutrality arguments combined with the assumption that equilibrium is attained between the SO2 in the vapour and liquid phases. 

Naphthols and the corresponding naphthylamines are interconvertible in aqueous media containing sulphite or bisulphite ion at elevated temperatures . Thus naphthols may be converted to naphthylamines by reaction with ammonia and ammonium sulphite in aqueous solution, usually in the temperature range 90-150 the corresponding dinaphthylamine is sometimes obtained as a byproduct (reaction 15). Monoalkylamines and dialkylamines similarly... 

The volume of HIO3 added to flask B is 10 ml more than that added to flask A and C. Therefore, addition of 10 ml less distilled water to flask B gives same volume of the total solution and hence the same bisulphite ion concentration in all the three flasks. 

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