Sulfite addition

Where sodium sulfite addition is a large contributor to the non-volatiles in the boiler, thermal means of reducing the oxygen can make a significant improvement in the overall operation. 

The semi-batch set-up uses a chemical reaction to immediately remove the absorbed gas from the liquid. In oxygen transfer measurements, sulfite (S032-) or hydrazine (N2H4) have been used to remove the oxygen transferred (Charpentier, pp. 42-49, 1981). For example, the addition rate of the reactant (S032- or N2H4) is adjusted until the system comes to a steady state dissolved oxygen concentration of about 2 mg/L. Then the sulfite addition rate equals the transfer rate. Mass transfer enhancement must be avoided, which is difficult with hydrazine, so that it is rarely used. 

Exercise 16-18 Sodium hydrogen sulfite addition products are decomposed to the parent carbonyl compounds when treated with mild acid or mild alkali. Write equations for the reactions involved and explain why the substances are unstable both in acid and base. ... 

However, it fails to give a hydrogen sulfite addition compound and, although it will react with amines (RNH2), the products are not the expected Schiff s... 

Brouillard, R. and El Hache Chahine, J.M. 1980. Chemistry of anthocyanin pigments. 6. Kinetic and thermodynamic study of hydrogen sulfite addition to cyanin. Formation of a highly stable Meisenheimer-type adduct derived from a 2-phenylbenzopyrylium salt. J. Am. Chem. Soc. 102 5375-5378. 

Sulfite addition to carbonyl Nearing completion Manuscript in preparation... 

Sulfite addition in water can be treated but here it seems necessary to use nine explicit waters solvating the C-O- in the initial product of sulfite addition in order to avoid breakdown of the adduct. Clearly it would be better to include a large number of waters in every case but the cost of the optimizations goes up as the number of waters increases. From a practical perspective it is better to allow a bit of empiricism to find the number of waters needed to reliably give a good result. This reaction is still under investigation as we seek to find a general way to carry out structure optimizations with reaction intermediates that have a lifetime in solution but are unstable in the gas phase unless explicitly solvated. 

Cessation of fermentation is one of the technical problems in botrytized wine production that needs further research and development. Dimethyldicarbonate (DMDC) is now considered a reliable inhibitor which could replace some of the S02. Although DMDC has proven suited for treating wines especially just before bottling, its use in Sautemes production has been investigated (Divol et al., 2005). The results showed that DMDC at a rate of 100-200 mg/1 stopped fermentation but did not replace the antioxidant functions of SO2. Sulfite addition was necessary to limit wine oxidation and yeast reactivation. 

Others recommend treatment to remove the compound. Hydrogen sulfide can be removed or reduced from RO feed water using some iron filters (such as manganese greensand and Filox, see Chapter 8.1.5) or a complicated combination of oxidation, coagulation and filtration, sulfite addition, and rechlorination.9... 

Beside the conversion of endogenic sulfur compounds the addition of S-compounds like sulfite, as an antimicrobial agent, antioxidant and enzyme inhibitor (75) or like thiamine (vitamin Bl), as a nutrient for yeasts, are allowed in the EEC (within defined maximum values). Furthermore chemical reactions like sulfite addition to aldehydes, Maillard reaction or Strecker degradation play an important role with regard to the sulfur chemistry of wines. 

The adducts formed from amine bisulfites and aldehydes are readily purified by crystallization from organic solvents and, like the sodium bi sulfite addition products, are readily decomposed by the action of dilute acids. 

Sulfite Addition to p-Eliminated Antifreeze Glycoprotein at Different pH valuesa,b... 

Rochelle (7) evaluated available kinetic data on sulfite addition to maleic or acrylic acid to give sulfosuccinic or 8-sulfopropicnfc acid. Cavanaugh (14) demonstrated the feasibility of hydrating acrylic acid with H2SO4 catalysis at 100°C to get g-hydroxy-propionic acid. 

This paper reports measuremerts of reaction kinetics for sulfonation of maleic, fumaric, and acrylic acids by sulfite addition and for hydration of acrylic acid with catalysis by H2SO4 or cation exchange resin. The kinetics were measured by sampling of isothermal batch reactors. 

From the data obtained, it is assumed that the active nucleophile is the dianionic sulfite ion. This reaction is typical of conjugate sulfite addition to a,3-unsaturated ketones. It should be inferred that other active nucleophilic agents may behave in a similar manner. 

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