Sulfur dioxide synthesis

Catalysis. Catalytic properties of the activated carbon surface are useful in both inorganic and organic synthesis. For example, the fumigant sulfuryl fluoride is made by reaction of sulfur dioxide with hydrogen fluoride and fluorine over activated carbon (114). Activated carbon also catalyzes the addition of halogens across a carbon—carbon double bond in the production of a variety of organic haUdes (85) and is used in the production of phosgene... 

Fluorinated sulflnates are prepared from sodium dithionite and liquid per-fluoroalkyl halides [74] (equation 67). For the transformation of the gaseous and poorly reactive trifluoromethyl bromide, it is necessary to use moderate pressure [75] (equation 68) These reactions are interpreted by a SET between the intermediate sulfur dioxide radical anion and the halide The sodium trifluorometh-anesulfinate thus obtained is an intermediate for a chemical synthesis of triflic acid. 

Cava and Schlessinger have reported the synthesis of 1,2,3-triphenyl-isoindole (65) in 78% yield from 1,3-diphenylisobenzofuran (68) hy reaction with thionylaniline (69) and boron trifluoride. The mechanism proposed for this remarkable transformation involves reaiTangement of the adduct (70) derived from thionylaniline and the isobenzofuran, to the tricyclic intermediate (71). This presumably collapses to the S-sultam (72), which yields the isoindole (65) upon extrusion of sulfur dioxide. Loss of sulfur dioxide, both from S-sultones and unsaturated S-sultams, is well documented. ... 

MLTC bands, S, 575 NMR.5,574 Raman, 5, 575 stereochemistry, 5,538-572 stibine ligands, S, 584 sulfides, S, 584 sulfurdiimine reactivity, 2,194 sulfur dioxide, 5,584 sulfur ligands, 5,584 synthesis, 5,536-538... 

A direct insertion of sulfur dioxide into a C—C bond has been observed under photochemical conditions 3 (equation 72) a related CH insertion followed by an intramolecular sulfinate to carbonyl addition yields the same system 3 (equation 73). A further sulfolene synthesis utilizes a three-component reaction see equation 74 (cf. Section IV below) 35. 

An interesting cycloheptatriene (182) synthesis has been described using thiophene 1, 1-dioxides (180) and cyclopropenes 181 (equation 121)ns. Concerted [4 + 2]cycloaddition and subsequent cheletropic extrusion of sulfur dioxide are suggested by the second-order kinetics (first in each reactant), and by the large negative activation entropy. 

C16-0127. The combustion of sulfur dioxide is one of the steps in the synthesis of sulfuric acid ... 

Since sulfoxides and sulfones are versatile synthetic intermediates, and since in both the thiolene oxide and dioxides the reverse dethionylation" (—SO), and cheletropic extrusion of sulfur dioxide , respectively, readily take place thermally, these cycloadditions are expected to find a useful place in organic synthesis. It should be kept in mind, however, that the retrograde SO-diene reaction and interconversion of the thiolene oxides compete effectively against SO extrusion on heating, and that diene isomerization accompanies the forward reaction (SO -t- diene). 

The synthesis of N-phenyl-1,3,4,6-tetrahydrothieno(3,4-c)-pyrrole-2,2-dioxide (II) was carried out by reacting aniline with 3,4-bis(bromomethyl)-2,5-dihydrothiophene-l,1-dioxide (I). The latter compound was synthesized by the bromination of the cycloaddition product, prepared from 2,3-dimethyl-l,3-butadiene and sulfur dioxide (17). 

The first synthesis of thiepin 1,1-dioxide (131) was performed by Mock in 1967 75>. With exess bromine in chloroform 2,7-dihydrothiepin 1,1-dioxide (129), prepared by 1,6-addition of sulfur dioxide to m-hexatriene, gave a dibromide 130 which, on treatment with two equivalents of triethylamine, afforded 131. Upon catalytic reduction, 131 rapidly absorbed three molar equivalents of hydrogen to yield hexahydrothiepin 1,1-dioxide (132). The 1,1-dioxide 131 is a fairly stable compound ... 

An alternative synthesis of thiepin 1,1-dioxide (131) has also been reported (Paquette, L. A., Maiorana, S. J. Chem. Soc. Chem. Commun. 1971, 313). Thus, the reaction of vinyldiazomethane with sulfur dioxide yields 4,5-dihydrothiepin 1,1-dioxide which was converted to 131 by bromination (NBS) and dehydrobromina-tion (Et3N) sequence. 

Sulfur dioxide has long been used in an industrial synthesis of isothiazole from propene, sulfur dioxide, and ammonia over a catalyst at 200°C.51... 

The sulfoxidation of aliphatic hydrocarbons is the easiest method for the synthesis of alkylsulfonic acids. Their sodium salts are widely used as surfactive reactants in technology and housekeeping. Platz and Schimmelschmidt [1] were the first to invent this synthetic method. Normal paraffins (Ci4-Cig) are used for the industrial production of alkylsulfonic acids [2-4]. Olefins and alkylaromatic hydrocarbons do not produce sulfonic acids under the action of sulfur dioxide and dioxygen and retard the sulfoxidation of alkanes [5-9],... 

One procedure for the synthesis of these title ring systems appeared recently <2003S1079>. Yadav and Kapoor described that the transformation of some oxadiazole and thiadiazole derivatives bearing specially substituted methylsulfinyl side chain 131, when reacted with thionyl chloride, give ring-closed compounds 134. The reaction was carried out in pyridine under reflux conditions in 74-79% yield. As shown in Scheme 25, the authors assume that the first step is the formation of the sulfonium salt 132 which undergoes cyclization with hydrogen chloride and sulfur dioxide elimination to 133 and, finally, demethylation of this intermediate leads to the final product 134. 

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