Sulfite results

Hydrolysis of dialkyl sulfites under acidic and alkaline conditions, which is followed by the use of OH2, proceeds by attack at sulfur to give S—O cleavage (72). The rate of hydrolysis is generally faster for cycHc and aryl sulfites than for dialkyl sulfites (73). Activation parameters of hydrolysis are known for some sulfites, and the increased rate for ethylene sulfite results from a reduced entropy of activation which results from a rigid ring stmcture (74). 

Reaction of the spirocyclic imidazoline 316 with glyoxal and sodium hydrogen sulfite results in hydrolysis of the aminal and subsequent double condensation to give the tetrazolopyridopyrazine 317 (Equation 109) <1999JHC117>. The pyridopyridazinylhydrazine 318 can be cyclized to the fused triazole 319 by reaction with formic acid (Equation 110) <1998SC2871>. 

Presence of oxidizable substances in the sample would interfere in the test, thus giving high results. These include S2. S 0,2. and certain metal ions such as Fe2+ in lower oxidation state. Sulfide should be removed by adding 0.5 g zinc acetate, allowing the zinc sulfide precipitate to settle and drawing out the supernatant liquid for analysis. If thiosulfate is present, determine its concentration in an aliquot of sample by iodometric titration using iodine standard. Subract the concentration of thiosulfate from the iodometric sulfite results to calculate the true value of SO,2. ... 

Derivation Boiling sodium salt of 4-chloro-3-nitro-benzene sulfonate with sodium sulfite, resulting in formation of sodium-2-nitrobenzene disulfonate, which is reduced with iron and acetic acid to aniline-2,5-disulfonic acid. 

Table IV lists the insecticidal activity of cyclic sulfites In this case, the exo cyclic sulfites of 5,6-bis(hydroxymethyl)-7-isopropylidenebicyclo[2.2 l]hept-2-ene [20] was active whereas the corresponding endo Isomer [18] was inactive Monoepoxldation [21 and 22] and diepoxidation [23] of the exo cyclic sulfite resulted in a slight increase in activity Compound 15 was the most active among this series of compounds The LD q value of this compound was estimated to be about 1 pg/fly when topically applied to houseflies without any synergists (data not shown) The C-7 isopropylidene group proved to be unnecessary for high activity by comparison with compound 18. The activity decreased after epoxidation [16] or hydrogenation [17] of the endocyclic double bond The cyclodiene insecticide endosulfan was about 10 times as active as [15] ...

The sulfate co-precipitates with the calcium sulfite, resulting in a mixed crystal (or solid solution) of calcium-sulfur salts. Gypsum is not formed. The relatively high sulfite concentrations in the solution prevent soluble calcium concentrations from reaching the levels required to exceed the gypsum solubility product, and the system operates unsaturated with respect to calcium sulfate. 

The high-molecular-weight solid polysulfide polymer is reduced by sodium sulfite, resulting in splitting of the polymer into segments that are simultaneously terminated by mercaptan groups as follows ... 

Solid or dissolved alkali sulfide or thiosulfate that has been exposed to the air usually contains sulfite resulting from autoxidation. Alkali and ammonium sulfides are particularly prone to suffer from such contamination. The detection of sulfite contamination in such materials is simple and is based on the finding that and are completely eliminated by brief warm-... 

A novel system apt for the simultaneous transformation of inorganic and organic pollutants based on the reaction of sulfite has been reported. UV irradiation of iron(iii) species in the presence of sulfites results in the formation of SO4 and OH radicals, which results consistently better performing than other photo Fenton systems. 

After agitation to promote crystal growth, the precipitate is removed by settling and filtration, and the filtercake is dried and calcined. Calcining of the zinc sulfite results in a gas containing 70% water and 30% sulfur dioxide, which may be cooled, dried, and compressed to produce a nearly pure liquid sulfur dioxide as the final product. Zinc oxide obtained in the calciner is recycled to the process. 

Photolysis of 4-chloro-l-hydoxynaphthalene in an aqueous solution of sodium sulfite results in replacement of chloride with sulfite. This is an example of an SjjjjlAr mechanism. The chain reaction process is illustrated in Scheme 13. ... 

A suspension of 3.90 g (19.6 mmol) of p-(bromomethyl)benzaldehyde (2.8) and 4.00 g (31.7 mmol) of sodium sulfite in 40 ml of water was refluxed for two hours, after which a clear solution was obtained. The reaction mixture was cooled on an ice bath resulting in precipitation of some sodium sulfite. After filtration, the solvent was evaporated. Ethanol was added to the remaining solid and the suspension was refluxed for 10 minutes. After filtering the hot solution, the filtrate was allowed to cool down slowly to -18 °C whereupon sodium (p-oxomethylphenyl)methylsulfonate (2.9) separated as colourless crystals. The extraction procedure was repeated two more times, affording 2.29 g (10.3 mmol, 53%) of the desired product. H-NMR (200 MH D2O) 5(ppm) =4.10 (s,2H) 7.44 (d,2H) 7,76 (d,2H) 9.75 (s,lH). 

The lignitic coals of the northern United States tend to have low sulfur contents, making them attractive for boilet fuels to meet sulfur-emission standards. However, low sulfur content coals have impaired the performance of electrostatic precipitators. The ash of these coals tends to be high in alkaline earths (Ca, Mg) and alkaUes (Na, K). As a result, the ash can trap sulfur as sulfites and sulfates (see Airpollution control methods). 

Deficiency or Toxicity in Humans. Molybdenum deficiency in humans results in deranged metaboHsm of sulfur and purines and symptoms of mental disturbances (130). Toxic levels produce elevated uric acid in blood, gout, anemia, and growth depression. Faulty utiH2ation results in sulfite oxidase deficiency, a lethal inborn error. 

Delignification Chemistty. The chemical mechanism of sulfite delignification is not fully understood. However, the chemistry of model compounds has been studied extensively, and attempts have been made to correlate the results with observations on the rates and conditions of delignification (61). The initial reaction is sulfonation of the aUphatic side chain, which occurs almost exclusively at the a-carbon by a nucleophilic substitution. The substitution displaces either a hydroxy or alkoxy group ... 

The absorption of sulfur dioxide in alkaline (even weakly alkaline) aqueous solutions affords sulfites, bisulfites, and metabisulfites. The chemistry of the interaction of sulfur dioxide with alkaline substances, either in solution, slurry, or soHd form, is also of great technological importance in connection with air pollution control and sulfur recovery (25,227,235—241). Even weak bases such as 2inc oxide absorb sulfur dioxide. A slurry of 2inc oxide in a smelter can be used to remove sulfur dioxide and the resultant product can be recycled to the roaster (242). 

Various processes have been disclosed wherein moist soHd sodium pyrosulfite [7681-57-4] is stirred in a steam-heated vessel with sodium carbonate. The exothermic reaction at 80—110°C results in the drying of the product. A lower grade of sodium sulfite is produced commercially in the United States as a by-product of the sulfonation—caustic cleavage route to resorcinol (333). 

In the determination of free formaldehyde in solution, eg, commercial reagents and pad bath formulation, the conditions of analysis allow hydrolysis of the /V-methy1o1 groups, usually between <1% and several percent. The NaOH formed is titrated with hydrochloric acid (82). Because of an incomplete reaction of sulfite with free formaldehyde, these low temperature methods (83) detect only 80—90% of the free formaldehyde present. Skill is important for correct results. 

Structure. The thiosulfate sulfur atoms have been shown to be nonequivalent by radioactive sulfur exchange studies (1). When a sulfite is treated with radioactive sulfur and the resulting thiosulfate decomposed to sulfur and sulfite by acids, the radioactivity appears in the sulfur ... 

Chromium Removal System. Chlorate manufacturers must remove chromium from the chlorate solution as a result of environmental regulations. During crystallization of sodium chlorate, essentially all of the sodium dichromate is recycled back to the electrolyzer. Alternatively, hexavalent chromium, Cr, can be reduced and coprecipitated in an agitated reactor using a choice of reducing agents, eg, sodium sulfide, sulfite, thiosulfate, hydrosulfite, hydrazine, etc. The product is chromium(III) oxide [1333-82-0] (98—106). Ion exchange and solvent extraction techniques have also... 

Reactions between A -(l-chloroalkyl)pyridinium chlorides 33 and amino acids in organic solvents have a low synthetic value because of the low solubility of the amine partner. A special protocol has been designed and tested in order to circumvent this drawback. Soon after the preparation of the salt, an aqueous solution of the amino acid was introduced in the reaction medium and the two-phase system obtained was heated under reflux for several hours. However, this was not too successful because sulfur dioxide, evolved during the preparation of the salt, was converted into sulfite that acted as an 5-nucleophile. As a result, A -(l-sulfonatoalkyl)pyridinium betaines such as 53 were obtained (Section IV,B,3) (97BSB383). To avoid the formation of such betaines, the salts 33 were isolated and reacted with an aqueous solution of L-cysteine (80) to afford thiazolidine-4-carboxylic acids hydrochlorides 81 (60-80% yields). 

A solution of 1.0 g of A -3,11-diketo-20-cyano-21-acetoxy-pregnene in 10 cc of benzene is treated with 1.0 g of osmium tetroxide and 0.43 g of pyridine. After standing at room temperature for 18 hours, the resulting solution is treated successively with 50 cc of alcohol, and with 50 cc of water containing 2.5 g of sodium sulfite. The mixture is stirred for 30 hours, filtered, and the filtrate acidified with 0.5 cc of acetic acid and concentrated to small volume in vacuo. The aqueous suspension is then extracted four times with chloroform, the chloroform extracts are combined, washed with water and concentrated to dryness in vacuo. Recrystallization of the residue from acetone gives 3,11,20-triketo-17(a)-21-dihydroxy-pregnane MP 227° to 229°C. This compound is then treated with acetic anhydride and pyridine for 15 minutes at room temperature to produce 3,11,20-triketo-17(a)-hydroxy-21-acetoxy-pregnane or cortisone acetate. 

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