Reaction with sulphur dioxide

The reaction between SO2 and NO2 was examined by Boreskov and Ilarianov who believed it to be a bimolecular process 

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T.J. Henman, Characterisation of oxidised polyolefines by reaction with sulphur dioxide. In N. Grassie (Ed.), Developments in Polymer Degradation-6, Elsevier Applied Science, Barking, 1985, pp. 107-145. 

Some of the reactions of this novel ring compound are given in Scheme 1. It is to be anticipated that unusual chemical reactivity might be conferred by the presence of a small ring system, but the only comment to this effect concerns its relatively slow reaction with sulphur dioxide and hydrogen chloride. Its i.r. and C1 n.q,r. spectra were also reported. 

In the additions of acetylenedicarboxylic esters to the (penta-l,2,4-trienyl)phosphonic esters 484 (R = Me), both head-to-head and head-to-tail products are formed. The initial reaction is then followed by 1,5-sigmatropic rearrangements to give isomers of benzylic phosphonic diesters, 485 (R = Me) and 486 (R = Me). The trienyl phosphonic esters 487 simi-larly give rise to aromatic phosphonic diesters 488 . The ester 484 (R = Et, R = H) is reactive towards A-phenylphthalimide at room temperature, but the product is not the expected 489 but rather 490, which aromatized on chromatography over alumina . The same trienyl phosphonic diesters undergo Diels-Alder reactions with sulphur dioxide and yield sulpholene adducts 491 and... 

Thiirans, Thietans, and Thiophen Derivatives.— These classes of compounds have been grouped together since very few papers have appeared describing useful synthetic procedures. Apart from exchange reactions from oxirans, thiirans tend to be formed by roundabout routes. The dioxides (204) for instance may be prepared from diazoalkanes by reaction with sulphur dioxide. The reaction produces isomers accompanied by the dihydrothiadiazole dioxides (205). The formation of the thiiran, however, is favoured in polar solvents. 

The dimers of isoprene can be transformed into a great number of terpenoids. For instance, terpene alcohols can be formed by hydrobora-tion [30, 114, 115] and epoxidation [116] reactions. Also the reaction with sulphur dioxide yielding sulfones [117, 118] has been studied. Ploner described the reaction of the 2,7-dimethyl-l,3,7-octatriene with alcohols such as methanol or ethanol [119] yielding terpene ethers which can be used as frangrancies. As catalyst, n H2O or H2lrCl6 proved to be... 

The stereochemistry of iron-carbon bond cleavage by electrophilic attack by mercury(n) chloride or bromine, or by carbon monoxide or sulphur dioxide insertion, has been probed by n.m.r. studies of products derived from /Areo-[Mc3C CHD-CHD-Fe(CO)2(A -C5H5)]. Predominant retention occurs in the reaction with mercury(n) chloride, predominant inversion in the reactions with sulphur dioxide or bromine. It is this last result which is of the most interest, for it affects discussions of the stereochemical course of oxidative additions... 

Differentiation of hydroperoxide groups by reaction with sulphur dioxide... 

Another group of Japanese workers91 found that the sulphoxonium salt, 7, was reducible to sulphoxides with either alkyllithiums or lithium dialkylcuprates, the exact reaction pathway being complicated by halide ions originating from the preparation of the metal alkyls. However, good yields of methyl phenyl sulphoxide were obtained by reduction of 7 with sulphur dioxide or a thiol in pyridine (equation 37). 

Sulphur as well as phosphorus gives highly violent reactions when they are heated with potassium. With carbon disulphide, potassium creates a mixture, which detonates on impact. The same happens by heating. With sulphur dioxide, potassium in the molten state combusts. Finally, the potassium/sulphuric acid mixture gives rise to detonations. 

There is another substitution reaction, not involving transition-metal complexes, namely, reaction of trifluoromethyl bromide with sulphur dioxide anion radicals (165) (Andrieux et al., 1990a) (this is an interesting route... 

James, F. C., J. A. Kerr, and J. P. Simons. Direct measurement of the rate of reaction of the method radical with sulphur dioxide. J. Chem. Soc. Faraday Trans. I. 69 2124-2129, 1973. 

Insertion reactions of sulphur dioxide and nitric oxide have also been observed with [(7i-Cp)2Zr(Cl)Me] and [(rc-CplaZrlCp)]." ... 

Preparation of Hydroxylamine Chloride. Dissolve 7 g of sodium hydroxide in 30 ml of water and saturate the solution with sulphur dioxide to an acid reaction, after which pass the stream of gas through the solution for another five minutes (in a jume cupboard ). Add the solution dropwise with continuous stirring to a solution containing... 

Although there is only one oxidation reaction possible with sulphur dioxide and hence a selectivity problem does not exist, recent results from kinetic research are included in this chapter, since there is a close analogy with other oxidations, especially on V2Os-based catalysts. 

The remaining compounds of bromine and all those of iodine corresponding with thionyl and sulphuryl chlorides and chloros ulphonic acid are cither unknown or their existence is very doubtful. There is no reaction between sulphur dioxide and bromine analogous to that by which sulphuryl chloride is formed from sulphur dioxide and chlorine this is true between 100° and 200° C., both in the dark and under strong illumination, also in the presence of likely catalysts.2... 

Trithionic Acid, H2S3Og.—Formation.—(1) From Thiosulphates Potassium thiosulphate in concentrated aqueous solution reacts with sulphur dioxide forming potassium trithionate 3 the reaction is sometimes represented as... 

The reaction is reversible under the conditions obtaining, but the oxidation may be completed in the presence of excess of sulphur trioxide, the expelled sulphur dioxide being led away and a little oleum containing 80 per cent. S03 added. After cooling, very dilute sulphuric acid (about I per cent.) is added, the solution allowed to settle for 24 hours, and finally filtered. The selenium is then precipitated with sulphur dioxide in the usual manner. 

Disadvantages associated with sulphur dioxide are that some tasters can detect it as an unpleasant banknote or taint and it has a tendency to provoke allergic reactions in some individuals. Asthma sufferers tend to be affected by gaseous sulphur dioxide, small traces of which can promote an asthmatic attack. There is a risk with foods containing sulphites of gas liberation upon swallowing. 

Cone. soln. of two mol. eq. of sodium nitrite and one of sodium carbonate are treated with sulphur dioxide until the mixture has an acid reaction. The sodium salt of hydroxylamine disulphuric acid, H0.N(HS03)s> is formed, and this decomposes on the addition of a little sulphuric acid into the sodium salt of hydroxylamidosulphonie acid, HO-NH.HSO, and sodium hydrosulphate, NaHS04. When the first-named salt has stood a couple of days at 90°-95°, it breaks down still further into hydroxylamine, HO-NHj, and sodium bisulphate. The latter is first crystallized from the soln., and crystals of hydroxylamine sulphate are subsequently separated. Potassium salts do not give so good a yield as the sodium salts. Very little ammonia is formed. W. L. Semon modified this process. 

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