Sulphides and sulphones

Whereas oxygen nucleophiles gave poor yields of alkenylated products with alkenyl iodonium salts, the reactions with sulphur nucleophiles proceeded more efficiently, leading to unsaturated sulphides and sulphones. Thus, 4-t-butylcyclohexenyl phenyliodonium salts afforded with sodium thiophenoxide 4-t-butylcyclohexenyl phenyl sulphide (81%) [3] and with sodium phenylsulphinate the corresponding sulphone (29%) in the presence of 18-crown-6, the yield of the latter rose to 80% [45]. jS-Phenylsulphonylalkenyl iodonium salts with sodium phenylsulphinate at 0°C, without any catalyst, afforded Z-l,2-bis(phenylsulphonyl)alkenes, in high yield with retention of the stereochemistry [45] ... 

Quantification. High Pressure Liquid Chromatography. In plasma or urine sulindac and its sulphide and sulphone metabolites, sensitivity 100 ng/ml in plasma, UV detection—B. 

A single dose of 200 mg to 14 subjects produced a mean peak plasma concentration of about 4pg/ml after 1 hour mean peak plasma concentrations for the sulphide and sulphone were about 3 and about 2 pg/ml, respectively, after 2 hours (D. F. Duggan et al., Clin. Pharmac. Ther., 911, 27,326-335). 

Section 15.7 contains tables of magnetic data obtained from anion radicals of compounds fliat don t comfortably fall into any of the previous sections. The subsection on fullerene anion radicals requires a special note as there are several papers of around the same period which vary shghtly in the preparation, solvent or physical parameters of the measurements. As the only data in many cases is the g factor it was decided to include the majority of these entries even though they relate to the same species. The data have been divided into the following subsections sulphides and sulphones, imines and imides, fullerenes, tetracyanoquinodi-methanes, phenylcarbonitriles, phosphaaUcenes and alkylcyclosilanes. Some of these subsections have been further subdivided. 

The first microstnictural issue of linear homopolymer chains that we examine is tacddty, which we illustrate with spectra from two systems from our own work the poly(alkyl <7anoacrylates) [—CHj—QCN)COOR—], which constitute a vinylidene systmn the spectra of which are shown in Figure 1.4, and the polyaJkene sulphides and sulphones [—CHj—CHR—S—] and [—CH2— CHR—SO2—], spectra of which are shown in Figure 1.5. We show tneso or m dyad structures oi two of these polymers in Scheme 4. Note how the two chiral centres of the first polymer appear to be equivalent, but for the second polymer the equivaloice is less immediatdy evident, for the residues contain three bonds... 

Aromatic nitriles are also the products of the base-induced decomposition of a-azido-sulphides and -sulphones and of the elaboration of 2,6-dicyanotoluene by lithiation and subsequent reaction with electrophiles. ... 

Linear Polyarylene Ethers (Oxides), Ether Ketones, Sulphides and Sulphones... 

The presence of the either linkages is sufficient to allow the material to be melt processed, whilst the polymer retains many of the desirable characteristics of polyimides. As a consequence the material has gained rapid acceptance as a high-temperature engineering thermoplastics material competitive with the poly-sulphones, poly(phenylene sulphides) and polyketones. They exhibit the following key characteristics ... 

Crystallisable polymers have also been prepared from diphenylol compounds containing sulphur or oxygen atoms or both between the aromatic rings. Of these the polycarbonates from di-(4-hydroxyphenyl)ether and from di-(4-hydroxy-phenyl)sulphide crystallise sufficiently to form opaque products. Both materials are insoluble in the usual solvents. The diphenyl sulphide polymer also has excellent resistance to hydrolysing agents and very low water absorption. Schnell" quotes a water absorption of only 0.09% for a sample at 90% relative humidity and 250°C. Both the sulphide and ether polymers have melting ranges of about 220-240°C. The di-(4-hydroxyphenyl)sulphoxide and the di-(4-hydroxy-phenyl)sulphone yield hydrolysable polymers but whereas the polymer from the former is soluble in common solvents the latter is insoluble. 

A range of polysulphones has been prepared with a variety of bis-phenols other than bis-phenol A. As might be expected from the discussion in Chapter 4 and from experience with the range of polycarbonates (Chapter 20), replacement of the isopropylidene link with a methylene, sulphide or oxygen link depresses the Tg whilst —C(CgH5)2— and sulphone links raise it. The bis-phenol derived from norcamphor leads to a polysulphone with a Tg of 250°C (195°C for a Udel-type polymer). 

FIGURE 17. The HOMO in trimethylene sulphide, sulphoxide and sulphone, to be compared with the ones for the strained rings (Figure 16) and for the open-chain derivatives (Figures 14 and 15). 

FIGURE 20. The free surface on the sulphur atom, S, (A2), as a function of ring strain for sulphide, sulphoxide and sulphone molecules. 

Some publications have described studies of sulphones together with representatives of other compound classes, such as sulphoxides, sulphides and ethers. As a rule only those are mentioned in which sulphone examples make up at least about one quarter of the total. 

Popova and colleagues47 carried out TLC of oxidation products of 4,4 -dinitrodiphenyl sulphide (the sulphoxide and sulphone) on silica gel + a fluorescent indicator, using hexane-acetone-benzene-methanol(60 36 10 l) as solvent mixture. Morris130 performed GLC and TLC of dimethyl sulphoxide. For the latter, he applied a 6% solution of the sample in methanol to silica gel and developed with methanol-ammonia solution(200 3), visualizing with 2% aqueous Co11 thiocyanate-methanol(2 1). HPLC separations of chiral mixtures of sulphoxides have been carried out. Thus Pirkle and coworkers131-132 reported separations of alkyl 2,4-dinitrophenyl sulphoxides and some others on a silica-gel (Porosil)-bonded chiral fluoroalcoholic stationary phase, with the structure ... 

Chromic acid oxidation of sulphides to sulphoxides was reported in 1926124. However, this oxidation procedure is not selective and sulphone formation was observed125. When pyridine was used as a solvent the sulphone formation was strongly reduced126. 

Another marked physical difference between sulphides and sulphoxides (or sulphones) is that sulphoxides (and lower alkyl sulphones) are hygroscopic and dissolve quite readily in water or protic solvents such as alcohols, and even more so lower alkyl or alkyl aryl sulphoxides are almost freely miscible with water. This can be accounted for by the formation of the strong hydrogen bond between the S—O bond in the sulphoxides and water molecules. Moreover, lower alkyl sulphoxides and sulphones such as dimethyl sulphoxide (DMSO) or sulpholene can dissolve a number of metallic salts, especially those of alkali and alkaline earth metals, and hence these compounds have been widely utilized as versatile and convenient solvents in modern organic chemistry26 (Table 3). 

TABLE 2. Boiling points and densities of sulphides, sulphoxides and sulphones... 

There are many transition metal ion oxidants used in organic chemistry for the interconversion of functional groups. Those which have been used for the preparation of sulphones from sulphoxides will be discussed below. It is very interesting to note that this type of oxidant often reacts more rapidly with sulphoxides than with sulphides and so sulphoxides may be selectively oxidized with transition metal ion oxidants in the presence of sulphides. This is in direct contrast to the oxidation of sulphides and sulphoxides with peracids and periodate, for example, where the rate of reaction of the sulphide is more than 100 times that for the corresponding sulphoxide. 

If a mixture of diphenyl sulphide and the corresponding sulphoxide are treated with osmium tetroxide in boiling ether for 48 hours the sulphide is unchanged whilst the sulphoxide is converted into the sulphone in 96% yield with concomitant production of osmium trioxide140. It thus seems that this method would be useful synthetically for the preparation of sulphones from sulphoxides containing sulphide functionalities. Ruthenium tetroxide may be used in place of osmium(VIII) oxide148. 

Notwithstanding the forcing conditions required, organic sulphides, sulphoxides and sulphones are analysed quantitatively by their conversion to sulphate. These methods will also be briefly covered in this section. 

TABLE 10. Orbital energies and population analysis (from PP MO calculations) and assumed geometries (see text) for trimethylene sulphide, sulphoxide and sulphone"... 

A determination of dimethyl sulphoxide by Dizdar and Idjakovic" is based on the fact that it can cause changes in the visible absorption spectra of some metal compounds, especially transition metals, in aqueous solution. In these solutions water and sulphoxide evidently compete for places in the coordination sphere of the metal ions. The authors found the effect to be largest with ammonium ferric sulphate, (NH4)2S04 Fe2(S04)3T2H20, in dilute acid and related the observed increase in absorption at 410 nm with the concentration of dimethyl sulphoxide. Neither sulphide nor sulphone interfered. Toma and coworkers described a method, which may bear a relation to this group displacement in a sphere of coordination. They reacted sulphoxides (also cyanides and carbon monoxide) with excess sodium aquapentacyanoferrate" (the corresponding amminopentacyanoferrate complex was used) with which a 1 1 complex is formed. In the sulphoxide determination they then titrated spectrophotometrically with methylpyrazinium iodide, the cation of which reacts with the unused ferrate" complex to give a deep blue ion combination product (absorption maximum at 658 nm). 

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