Acids sulfinic

These acids are less stable, less soluble and less acidic than the corresponding sulfonic acids. The conunon impurities are the respective sulfonyl chlorides from which they have been prepared, and the thiolsulfonates (neutral) and sulfonic acids into which they decompose. The first two of these can be removed by solvent extraction from an alkahne solution of the acid. On acidification of an alkahne solution, the sulfinic acid crystallises out leaving the sulfonic acid behind. The lower molecular weight members are isolated as their metal (e.g. ferric) salts, but the higher members can be crystallised from water (made shghtly acidic), or alcohol. 

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Ethyl /m s -2-butenyl sulfone (86) together with some ethyl vinyl sulfone are obtained by the reaction of ethylene and. SO2 in wet benzene using PdCl2. SO2 behaves mechanistically similarly to CO in this reaction[66]. Hydrosulfination of alkenes with SO2 and H2 is catalyzed by the Pd(dppp) complex. The sulfinic acid 87 is a primary product, which reacts further to give the. S-alkyl alkanethiosulfonates 88 as the major product, and 89 and the sulfonic acid 90 as minor products[67]. 

Similar halogenations have been done on 2-lithio-l-phenylsulfonylindole[2], 2-Lithio-l-phenylsulfonylindole is readily converted to the 2-(trimethylsilyl) derivative[2,3]. 2-Trialkylstannylindoles can also be prepared via 2-lithio-indoles[4,5], 2-Sulfonamido groups can be introduced by reaction of a 2-lithioindole with sulfur dioxide, followed by conversion of the sulfinic acid group to the sulfonyl chloride with A-chlorosuccinimide[6]. 

Sulfur Acids. Organic oxy acids of sulfur, that is, —SO3H, —SO2H, and —SOH, are named sulfonic acid, sulfinic acid, and sulfenic acid, respectively. In subordinate use, the respective prefixes are sulfo-, sulfino, and sulfeno-. The grouping —SO2—O—SO2— or —SO—O—SO is named sulfonic or sulfinic anhydride, respectively. 

Salts of thiols (170) or of sulfinic acids (171) react like the alkoxides, giving 4-alkylthio- or 4-alkylsulfono-substituted butyrates. Alkali cyanides give 4-cyanobutyrates (172), hydroxylamine gives a hydroxamic acid (173), and hydra2ine a hydra2ide (174). 

Sulfination. Ben2ene and its homologues react with SO2 iu the presence of AlCl and HCl to form sulfinic acids (146)... 

This Michael-type addition is catalyzed by lanthanum(3+) [16096-89-2] (80). Ethylene glycol [107-21-1] reacts with maleate under similar conditions (81). A wide range of nucleophilic reagents add to the maleate and fumarate frameworks including alcohols, ammonia, amines, sulfinic acids, thioureas, Grignard reagents, Michael reagents, and alkali cyanides (25). 

Other reactions of sulfur dioxide forming sulfinic acids or sulfones have been reviewed (254). 

In the reaction between xanthates and sulfonyl chlorides, the xanthates convert to dixanthogens, and the sulfonyl chlorides reduce to sulfinic acids and other compounds (38) ... 

According to Figure 3, hydroperoxides are reduced to alcohols, and the sulfide group is oxidized to protonic and Lewis acids by a series of stoichiometric reactions. The sulfinic acid (21), sulfonic acid (23), sulfur trioxide, and sulfuric acid are capable of catalyzing the decomposition of hydroperoxides to nonradical species. 

Thiourea dioxide, or formamidine sulfinic acid, is an oxygenated thiourea derivative synthesized by the oxidation of thiourea with hydrogen peroxide. It has the chemical formula (NH2)NHCS02H and is tautomeric. 

Thiourea dioxide, although stable in acidic solutions, decomposes in alkaline solution to urea and sulfinic acid. Unfortunately, the release of urea can create environmental concerns as it is a fertilizer and causes eutrophication when discharged into bodies of water. 

Continuous polymerization in a staged series of reactors is a variation of this process (82). In one example, a mixture of chloroprene, 2,3-dichloro-l,3-butadiene, dodecyl mercaptan, and phenothiazine (15 ppm) is fed to the first of a cascade of 7 reactors together with a water solution containing disproportionated potassium abietate, potassium hydroxide, and formamidine sulfinic acid catalyst. Residence time in each reactor is 25 min at 45°C for a total conversion of 66%. Potassium ion is used in place of sodium to minimize coagulum formation. In other examples, it was judged best to feed catalyst to each reactor in the cascade (83). 

Pyrimidinesulfinic acids are so rare that few reactions are recorded but pyrimidinesul-fonic acids are known to undergo a variety of reactions. The typical sulfinic acid (379 R = SO2H) reacts with ethanolic hydrogen chloride to give 5,6-diaminopyrimidin-4(3ff)-one... 

Thiophene-2-sulfonic acid is a strong acid, similar to benzenesulfonic acid. It forms a sulfonyl chloride with phosphoryl chloride which on reduction with zinc yields thiophene-2-sulfinic acid. 

Carbon-sulfur bonds can be formed by the reaction of elemental sulfur with a lithio derivative, as illustrated by the preparation of thiophene-2-thiol (201) (700S(50)104). If dialkyl or diaryl disulfides are used as reagents to introduce sulfur, then alkyl or aryl sulfides are formed sulfinic acids are available by reaction of lithium derivatives with sulfur dioxide. 

Other interactions of /3-lactams with electrophiles include the oxidative decarboxylation of the azetidin-2-one-4-carboxylic acid (85) on treatment with LTA and pyridine (81M867), and the reaction of the azetidin-2-one-4-sulfinic acid (86) with positive halogen reagents. This affords a mixture of cis- and trans-4-halogeno-/3-lactams (87), the latter undergoing cyclization to give the bicyclic /3-lactam (88) (8UOC3568). 

The intermediate sulfides can be oxidized to the corresponding sulfoxides and sul-fones and then, liberated to give sulfenic and sulfinic acids. 

Benzenesulfinic acid [618-41-7] M 142.2, m 84 , pK 2.16 (2.74). The acid is purified by dissolving the Na salt in H2O, acidifying to Congo Red paper with HCl and adding a concentrated soln of FeCl3 whereby Fe sulfinate ppts. Collect the salt, wash with a little H2O, drain, suspend in H2O and add a slight excess of 1.5M aq NaOH. The Fe(OH)3ppts, it is filtd off, the sulfinic acid in the aq soln is extracted with... 

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