Sulfinic acids formation

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). 

During a study of azonitrones (70), Forrester and Thomson showed that reaction with toluene-p-sulfinic acid resulted in nitrogen evolution and formation of the hydroxamic acid (66) together with the pyrrolidone (71) and the amidine (72). These workers suggested the following reaction course. Although the yield of hydroxamic acid was high, the method is not likely to be of preparative value. 

The formation of diazosulfones and diazosulfonates can also be described as S-coupling. Here the sulfur atom of the sulfinic acid or the sulfite ion, respectively, appears as the basic centre of the nucleophilic component, whereas the oxygen atoms do... 

According to reaction conditions, formation of either the sulfinic acid or the a-thiolated sulfone could be observed (up to 80%) the intermediate a-sulfonylamino sulfone proved to be unstable. 

In the analogous studies of the photolysis of sulfolane (31), the work of Honda and coworkers66 was carried out in the gas phase at 70-130 °C and established the formation of S02, ethylene, cyclobutane and acetylene as the major products, on mercury-sensitized photolysis. In considerable contrast, photolysis of sulfolane at 185 nm in the liquid phase67 produced ethylene( = 0.22), the sultine (32) (parallel experiments on aqueous solutions of sulfolane, a sulfinic acid is also believed to be formed. The authors believe that both four-membered (33) and six-membered (32) sultines may be formed during these photolyses. Further work in this area would appear to be necessary to unravel the full mechanistic details. 

For methyl phenyl sulfoxide it was found that 25% of the adduct decomposes to give phenyl radical and methane sulfinic acid, while 75% of the adduct leads to methyl radical and benzene sulfinic acid. For heavier alkyl groups the formation of the benzene sulfinic acid is even more dominant, 96% for R = Et and 100% for R = C2H4C1 or i-Pr. 

The formation of adduct is followed by fragmentation and subsequent H-atom abstraction reaction from the sulfinic acid produced. Strong acid solutions of aromatic sulfoxides like thianthrene 5-oxide (7) or phenothiazine 5-oxide (8) gives rise to ESR signals, which... 

A very surprising sulfone formation has been investigated by Oae and coworkers . On heating p-toluenesulfinic acid with dimethylaniline in ethanol for 15 h, the reaction mixture shown in equation 100 has been obtained. Obviously, the observed products arise from an equilibrium between the sulfinic acid and its pseudo-anhydride (disulfide trioxide), which is able to attack the amine nitrogen and degrade the tertiary amine corresponding to a Polonovsky reaction . 

No evidence has been obtained as to the source of the sulfur dioxide formed by the action of sulfur and sulfur acids on lemons but tentatively it may be assumed, since sulfur dioxide appears in all the treatments and since it has such a low activity, that it may arise from sulfinic acid in the formation of sulfate or that it is a dismutation product of the protein which disappeared. 

Treatment with alkali removes the various acidic by-products and their salts (acetate, sulfinate, and formate) and also serves to hydrolyze and remove unreacted starting materials. 

Because of its relevance in environmental chemistry the reaction of photochemically excited sulfur dioxide with hydrocarbons in the gas phase has received considerable attention in recent years. In this reaction the principal path for formation of sulfinic acids is believed (Sherwell and Tedder, 1978) to be that shown in Scheme 2. Sherwell and Tedder do not think that abstraction of a hydrogen atom from RH by RS02-, i.e., RS02 + RH - RS02H + R-, occurs to any significant extent in such systems, although a summary of earlier studies of this reaction (Horowitz and Rajbenbach, 1975) shows that such a reaction has been proposed on occasion in the past. 

Equilibrium constants for sulfinyl sulfone formation from aromatic sulfinic acids at 21 °C in acetic acid containing 1 to 5% H20 ... 

Although anhydride formation is more favorable thermodynamically for a sulfinic acid than for most types of acids, it is still true that in media containing any significant amount of-water the equilibrium in (132) for acyclic sulfinyl sulfones lies far to the left, and when placed in such media sulfinyl sulfones are hydrolyzed completely to the corresponding sulfinic acid. Let us now discuss what is known about the mechanism of this hydrolysis reaction. 

However, King et al. (1977) have shown that in some cases one can get abnormal addition and the formation of substituted sulfinic acids (Scheme 4). Abnormal addition, for example, is involved as the first step in the complex pathway (207) by which sulfine [90] is formed from PhCH=S02 when phenylmethanesulfonyl chloride is treated with a tertiary amine in the absence of any of the normal sulfene-trapping reagents (King and Harding, 1976). 

Cycloadditions to a cyano group are comparatively rare. The high-temperature reactions of 1,3-dienes, e.g. butadiene, isoprene and 2-chloro-l,3-butadiene, with dicyanogen, propionitrile or benzonitrile result in formation of pyridines (equation 80)70. Sulfonyl cyanides 147, obtained by the action of cyanogen chloride on sodium salts of sulfinic acids, add to dienes to give dihydropyridines 148, which are transformed into pyridines 149 by oxidation (equation 81)71. 

Enzymes of the pepsin family rarely catalyze the hydrolysis of esters, with the exceptions of, for example, esters of L-/3-penicillactic acid and some sulfinic acid esters. Under suitable conditions, i. e., low pH, high enzyme concentration, and formation of an insoluble peptide, aspartic peptidases are able to catalyze the synthesis of peptides [71] [72],... 

The reaction proceeds by formation of bisformamide 4, which can be isolated but is more typically formed and reacted in situ. The bisformamide 4 is presumably in equilibrium with the corresponding iminium ion 5, which is captured by the sulfinic acid to generate 2. The TMSCI consumes the water of condensation while liberating HCI, which catalyzes the entire sequence. 

Heterolytic scission of the -S-S- bond in which only electrophilic assistance is involved is the exception rather than the rule in reactions involving bond fission of this type. Kice et a/.165,166 have demonstrated that a variety of S-S bond cleavages involve concomitant electrophilic and nucleophilic catalysis including (a) the formation of aryl thiolsulfones from aryl thiolsulfinates and aryl sulfinic acids and (b) the hydrolysis (acetic acid—1% water and 60%... 

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