Dibenzothiophene-5,5-dioxide

The electron-withdrawing property of the sulfonyl moiety in dibenzothiophene-5,5-dioxide 147 is reflected in the more drastic conditions required for the chlorosulfonation of this substrate as compared with those needed for diben-zothiophene 143. It also accounts for the observed orientation of sulfonation in the 3- and 3,7-positions, since these are both meta to the deactivating sulfonyl group and pam to the activating bridge bond. The pattern to sulfonation shoAvn by the dioxide 147 is similar to that of biphenyl (see Chapter 4, p 42). 

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Adapted with permission from Table 1 of F. 6. Dias, S. Pollock, C. Hedley, L. O. Palsson, Andy Monkman, I. I. Perepichka, I. F. Perepichka, M. Tavasli and M. R. Bryce, Intramolecular charge transfer assisted by cx>nformational changes in the excited state of fluorene-dibenzothiophene-5, -dioxide co-oligomers, /. Phys. Chem. B, 110, 19329-19339 (2006). Copyright 2006 American Chemical Society. 

Tellurium replaces sulphur dioxide in dibenzothiophene dioxide," and in thianthrene tetraoxide" and 2,2 -biphenylmercury." ... 

Dibenzotellurophene Tellurium powder (6 g, 47 mmol) and dibenzothiophene S.S -diox-ide (8 g, 37 mmol) are mixed thoroughly, the mixture is carefully heated under an atmosphere of carbon dioxide until evolution of sulphur dioxide commences, and the temperature is then regulated to achieve a steady evolution of sulphur dioxide. From time to time the sublimed dibenzothiophene dioxide is melted and allowed to flow back into the reaction mixture. After 36 h, the mixture is cooled to 20°C and extracted with boiling acetone. The extract is evaporated to dryness, the solid residue is washed several times with cold ethanol, and the washings are collected and evaporated. The residue is steam distilled and the product is recrystallized from light petroleum ether. Yield 1.0 g (10%) m.p. 93°C. 

When the methyl substituted derivatives of u-bis(phenylsulfonyl)benzene (99) are reduced in DMSO, good yields of the intramolecularly coupled products are obtained. These are methyl-substituted dibenzothiophene dioxides (100a), formed after initial cleavage of PhSOo from the radical anion followed by intramolecular attack of the aryl radical on the phenyl group [290] (Scheme 26). 

Poly(dibenzosilole)s are a relatively new class of compounds for the area of organic electronic materials. Poly(dibenzosilole)s are not easily oxidised and have advantages of solubility and processibility over other polyfluorene analogues, such as carbazoles, dibenzophosphole oxides and dibenzothiophene dioxides. Several groups have already incorporated poly(dibenzosilole)s in the latest organic electronic devices such as OLEDs, OFETs and OSCs and have found improved performance over similar polyfluorene-based devices. With continual advancement in their synthesis, dibenzosilole-based polymers are set to match the popularity of polyfluorenes in organic electronic materials. 

Poliak et al. claimed that the reaction of biphenyl 32 with excess chlorosulfonic acid (six equivalents) at 18 °C affords dibenzothiophene-5,5-dioxide-3,7-disulfonyl chloride 34, but more recent attempts to reproduce this result were unsuccessful and only the 4,4 -disulfonyl chloride 33 (80%) was isolated. However, the cyclized product 34 was obtained in good yield (72%) when biphenyl 32 was heated with a large excess of chlorosulfonic acid (20 equivalents) at 150 °C (4 hours) (Equation 11). The reaction presumably involves the formation of the intermediate biphenyl-2,4,4 -trisulfonyl chloride, 35 which subsequently cyclizes with loss of hydrogen chloride to give the dibenzothiophene dioxide 34. Further study of the action of chlorosulfonic acid on biphenyl 32 showed that the optimum yield of the 4-sulfonyl chloride (43%) was derived from treatment of 32 with the reagent (1.5 equivalents) in thionyl chloride as solvent at 0 °C (1 week). The best yield (89%) of the 4,4 -disulfonyl chloride 33 was also achieved by treatment of the hydrocarbon 32 with chlorosulfonic acid (three equivalents) in thionyl chloride at room temperature (1 week). 

H,7Dibenzo[cTJthiocin 6,6-dioxide AG7AG, 7, 707 (75JCS(P1)913) Dibenzothiophene microwave, 4, 5 (70JCS(A)1561)... 

The two principal categories of compounds studied have been diaryl or aryl alkyl sulphones (not dialkyl sulphones, which are polarographically not reducible) and S-dioxides of certain heterocyclic compounds, such as thiophene (also benzo- and dibenzothiophenes) and phenothiazines. The first named have half-wave potentials in the region of — 2.0 V, the thiophene dioxides near — 1.0 V. Some examples of each category may be given. 

Kevan and colleagues69 studied the products of the radiolysis of solid diaryl sulfones at room temperature, such as p,p -ditolyl, diphenyl sulfone and dibenzothiophene-S,S-dioxide. The products found for the first two were S02 and the diaryl hydrocarbon. For p,p -ditolyl sulfone the S02 yield is linear with dose upto about 13 Mrad, above which it falls off considerably from linearity. The initial yields give G(S02) = 0.05, which is equal within experimental error to the yield of p,p -bitolyl. The only another organic product observed had a smaller yield by a factor of 7, and could not be identified. The authors pointed out that no polymeric product was found in contrast to what is known on benzene radiolysis. The mass balance suggests that a simple decomposition as shown by equation 50 is the net consequence of radiolysis. 

In dibenzothiophene-S,S-dioxide the S atom is in a ring, and hence more constrained. The yield of SOz in the radiolysis is linear with the dose to about 13 Mrad after which it levels off as in p,p -ditolyI sulfone. However, the yield of S02 in this case is much lower (a factor of 25) than in the case of p,p -ditolyl sulfone (G = 0.002 compared to G = 0.05). This stability of the dibenzothiophene sulfone could be partially due to back reaction to reform the parent sulfone and partially due to more efficient energy delocalization. The expected biphenylene product was not detected due to limitations of the analytical method. Bowmer and O Donnell70 studied the volatile products in y-radiolysis of dialkyl, alkyl aryl and diaryl sulfones. Table 2 gives the radiolytic yields of S02 and of the hydrocarbon products of the alkyl or aryl radicals. The hydrocarbon products are those obtained either by H atom abstraction or by radical combination. The authors69 suggested the mechanism... 

Of some relevance in this connection is a study216 on the structure of the anion radicals formed when diaryl sulphones react with n-butyllithium in hexane-HMPA solution under an argon atmosphere. Apparently, a dehydrogenative cyclization and a further one-electron reduction occurs to produce the anion radicals of substituted dibenzothiophene-S, S-dioxides. These anion radicals were studied by ESR spectroscopy. 

Dibenzothiophene S-oxide Dibenzothiophene S, S-dioxide Dibenzothiophene S, S-dioxide... 

In contrast with the relatively facile thermal rearrangement of sulfinates to sulfones discussed in the preceding section, the reverse process is relatively, rarely encountered and is usually observed only at elevated temperatures. One of the first thermal sulfone to sulfinate isomerizations has been invoked by Fields and Meyerson to occur during the pyrolysis of dibenzothiophene S, S-dioxide (26) to dibenzofuran, through elimination of sulfur monoxide from the sultine intermediate 27 (equation 27). More recently, the flash vapor-phase pyrolysis of various 2,5-dialkyl and diaryl thiophene-S, S-dioxides has also been shown to involve SO extrusion and formation of the corresponding furans in good yields . 

Ito and Matsuda studied the y-radiolysis of 2-methyltetrahydrofuran (MTHF) solutions of diphenyl sulfone and dibenzothiophene-S,S-dioxide (DBTSD) at 77 K. They found that the radical anions of these sulfone compounds are formed and have intense absorption bands at 1030 nm and 850 nm, respectively. The blue glassy solution of y-irradiated diphenyl sulfone has absorption bands at both 1030 nm and 360 nm while the absorption spectrum of the benzenesulfonyl radical formed by UV irradiation of diphenyl sulfone solution at 77 K showed only a peak at 382 nm. Gamma-irradiated phenyl methyl sulfone solution showed an absorption band only at 385 nm. Consequently the appearance of the absorption bands in 800-1030 nm of diphenyl sulfone and DBTSD may suggest that the unpaired electron is delocalized on two phenyl rings. The same authors studied the radiolysis of MTHF solutions of disulfones (diphenyl and dihexyl disulfones). They found a blue coloring of the solution by the y-radiolysis of diphenyl disulfone and dihexyl disulfone due to absorption peaks at 695 nm and 690 nm respectively, besides smaller absorptions at 300-400 nm. Comparing these results to the previous observation, that phenyl methyl sulfone solution absorbs only at 398 nm, results in the conclusion that the absorption band at 690 nm is due to the linked two sulfone moieties. The authors found that substituents on the phenyl ring lead to shifts in the absorption maxima of the... 

IGTS8 or simply IGTS8. The metabolic pathway in Rhodococcus sp. IGTS8 was delineated in the early 1990s [62], The pathway consists of four enzymes. DBT is converted to 2-hydroxybiphenyl (HBP) and sulfite via a 4-step pathway and the following intermediates DBT sulfoxide (dibenzothiophene-5-oxide, DBTO), DBT sulfone (dibenzothiophene-5,5-dioxide, DBT02) and hydroxyphenyl benzene sulfonate (phenol-phenyl sulfinate, HBPSi). 

The DszC enzyme encoded by the nucleotide sequence of ORF-3 catalyzes the oxidation of dibenzothiophene to dibenzothiophene-5,5-dioxide (dibenzothiophene... 

The phototransformation of l,2-bis(phenylsnlfonyl)-3,4,5,6-tetramethylbenzene into 2,3,4,5-tetramethyldibenzothiophene-S,5 -dioxide on the action of arylthiolates should also be mentioned. The yield of dibenzothiophene-5, S-dioxide is more than 90%. The addition of m-dinitrobenzene prevents the cyclization. The reaction proceeds as shown in Scheme 7.41 (Novi et al. 1982). 

The currently accepted name for (1) in Chemical Abstracts is dibenzothiophene, although biphenylene, diphenylene, or biphenylylene sulfide are still used, especially in the Russian literature. Occasionally 9-thia-fluorene is used and recently, in one instance, dibenzo[6,d]thiophene. An alternative numbering system for (1) is met with on occasions in which C-4 is taken as C-1, as in carbazole. In the absenee of moleeular diagrams this system must be detected by reference to the chemistry described. For example, in a few dyestuff patents 2,7-diaminodibenzothiophene 5,5-dioxide is referred to and this is obviously the 3,7-diamino compound, also known as benzidine sulfone. 

A full iterative analysis of the more-complicated NMR spectra of both dibenzothiophene 5-oxide and 5,5-dioxide has been made. A slight broadening ( 0.05-0.1 Hz) of the lines associated with one of the protons in both compounds was assumed to be due to Jj 9 and this was used to assign peaks in the spectra. ... 

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