Bisulfite acid constant

Finally, several equilibrium and kinetic properties of aldehyde-bisulfite adducts were found to be linearly related Taft s a parameter (Betterton et al.t 1988). These compounds, which include a-hydroxymethane sulfonate and other a-hydroxyalkyl sulfonates, may be important reservoirs of S(IV) species inj clouds, fog, and rain. Fairly good relationships were found between equilibrium properties (e.g. acidity constants) and Sir values, but rates constants for) nucleophilic addition of S03 to the aldehydes showed only a crude fit, Similarly, poor results were found in applying a to hydrolysis reactions of] volatile alkyl chlorides (T. Vogel, University of Michigan, personal communh cation, 1989), and this has been shown to be a general characteristic of reactioni of alkyl halides with nucleophiles (Okamoto et al., 1967). 

C. Sodium Hydroxylamine Monosulfonate.—In a 12-I. crock are mixed 5 kg. of shaved ice (Note 6) and 569 g. of sodium nitrite (594 g. of the technical 95 per cent quality). Into this is stirred a suspension of sodium bisulfite containing noo g. of available sulfur dioxide (about 1775 g. of technical bisulfite) in 750 cc. of water. Then, beneath the surface of the solution is added, with constant stirring, 150 cc. of glacial acetic acid... 

In the sulfite pulp process, the digestion fluid is typically made by dissolving sulfur dioxide in water in the presence of limestone until the solution contains 7.0% by weight S02, three-quarters of which is in the form of bisulfite ion. Why is this done In support of your answer to this question, calculate the pH of (a) the digestion solution prepared as above, (b) a hypothetical 7% solution of S02 alone, and (c) an actual saturated solution of S02 alone (2.9% S02), if the first acid dissociation constant of sulfurous acid is 1.7 x 10-2, at ambient temperature and pressure. 

Strictly, SO2 dissolves in water as (S02)aq with little forming sulfurous acid, H2S03(aq>, but it is usual to neglect the distinctions between these two species. The ionization equilibria are typically fast and in the case of the hydration of aqueous SO2 the hydration reaction proceeds with rate a constant of 3.4 X 10 s which allows the formation of the bisulfite anion to be exceedingly rapid. Although H2S03(aq) is a dibasic acid, the second dissociation constant is so small that the bisulfite anion (HSO ) dominates as the subsequent dissociation to the sulfite ion S03(aq> would not be important except in the most alkaline of solutions. At around pH 5.4 in a typical cloud with a gram of liquid water in each cubic meter, SO2 will partition equally into both phases, because of the hydrolysis reactions. 

Sulfopropionic and sulfosuccinic acids were synthesized by addition of bisulfite to unsaturated acids. At pH 5, 55°C, and 0.5 N ionic strength, the second-order rate constants and activation energies for sulfonation of acrylic, fumaric, and maleic acids were, respectively ... 

The lipase from Serratia marcescens has a high enantioselectivity (E = 135) for the (2R,3S)-(4-methoxyphenyl) glycidic acid methyl ester, which acts as a competitive inhibitor. The formed acid (hydrolyzed (+)-methoxyphenylglycidate) is unstable and decarboxylates to give 4-methoxyphenylacetaldehyde this aldehyde strongly inhibits and deactivates the enzyme. It is removed by transfer to the aqueous phase by formation of a water-soluble adduct with sodium hydrogen sulfite added to the aqueous phase. The bisulfite acts also as a buffer to maintain constant pH during synthesis. 

Note the large differenees in the reaction rate constants independent of whether sulfite or bisulfite is the reagent. This makes the overall process strongly dependent on pH. This pH dependence, however, is much more subtle because the sulfur radieals (sulfite, sulfate and peroxomonosulfate) undergo acid-base equilibrium, whieh likely is on the left-hand side because the hydrogenated species are strong acids ... 

Simenson (1940), and the thermodynamic data for the system SO2-H2O are given by Plummer (1950). In water sulfur dioxide exists as the dissolved gas, as undissociated sulfurous acid, H2SO3, as the bisulfite ion, HSOj , and as the sulfite ion, SO3—. Sulfurous acid is a rather weak dibasic acid its first ionization constant is 1.7 X 10 , and the second is 5 X 10 . At 25° C. the corresponding pK values are 1.8 and 5.3, respectively. The calculated distribution of the various ionic species in aqueous solution of sulfurous acid in the range of pH of 0 to 8 is shown in Fig. 1. At pH s over 9.5 only SO3 ions exist, in the range of pH 9.5 to 4.5 both SO3 and HSOs occur, and at pH 4.5 and lower, SO3— no longer exists in appreciable concentrations. 

The equilibrium constants for the equilibrium and velocity of the reaction of glucose with sulfurous acid were first measured by Kerp and his collaborators some forty years ago, but their results are difficult to interpret and apply because pH data are lacking and because most of their data relate to rather dilute solutions of glucose (18% or less) and bisulfite (800 p.p.m. or less). Tomoda and Taguchi (1930), Bianconi and Bianchi (1932), and more recently Vas (1949) investigated this reaction. 

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