Dibenzyl sulphoxide

N— compounds used as acid inhibitors include heterocyclic bases, such as pyridine, quinoline and various amines. Carassiti describes the inhibitive action of decylamine and quinoline, as well as phenylthiourea and dibenzyl-sulphoxides for the protection of stainless steels in hydrochloric acid pickling. Hudson e/a/. refer to coal tar base fractions for inhibition in sulphuric and hydrochloric acid solutions. Good results are reported with 0-25 vol. Vo of distilled quinoline bases with addition of 0 05m sodium chloride in 4n sulphuric acid at 93°C. The sodium chloride is acting synergistically, e.g. 0-05m NaCl raises the percentage inhibition given by 0-1% quinoline in 2n H2SO4 from 43 to 79%. Similarly, potassium iodide improves the action of phenylthiourea . 

The oldest and generally applied sulphoxide synthesis consists of the oxidation of sulphides to sulphoxides. This reaction was reported for the first time by Marcker9 as early as 1865. He found that treatment of dibenzyl sulphide with nitric acid afforded the corresponding dibenzyl sulphoxide in a high yield. Since that time the oxidation of... 

Strecker153 reported in 1910 that the reaction of thionyl chloride with two equivalents of phenylmagnesium bromide or benzylmagnesium bromide afforded diphenyl or dibenzyl sulphoxides, respectively (equation 49 Table 8). The corresponding sulphides are formed as by-products of this reaction. Recently, other sulphoxides were prepared by this procedure154,155. It should be pointed out that this rather simple approach to the synthesis of symmetrical sulphoxides has not yet found wider application. 

The use of chlorine as an oxidizing agent for the conversion of sulphoxides into sulphones is completely unsuccessful under anhydrous conditions. In aqueous solutions, the sulphone is formed but this is usually part of a complex mixture of chlorinated sulphoxides, chlorinated sulphones and sulphonyl chlorides89, so that the reaction is usually not very useful as a preparative method for alkyl sulphones. Dimethyl sulphone has however been obtained in 70% yield in one isolated case90. In methanol solution dibenzyl sulphoxide is cleanly oxidized to dibenzyl sulphone and benzyl sulphonyl chloride in reasonable overall yield91. 

An early study of the attempted phase-transfer catalysed oxidation of dibenzyl sulphoxide to the sulphone using a variety of conditions and oxygen, periodate, hypochlorate and permanganate as oxidants showed that only potassium permanganate gave any of the required product, albeit in low yields. A further study, using Adogen 464 as... 

An alternative route to sulphones utilizes the reaction of the appropriate activated halide with sodium dithionite or sodium hydroxymethanesulphinite [6], This procedure is limited to the preparation of symmetrical dialkyl sulphones and, although as a one-step reaction from the alkyl halide it is superior to the two-step oxidative route from the dialkyl sulphides, the overall yields tend to be moderately low (the best yield of 62% for dibenzyl sulphoxide using sodium dithionite is obtained after 20 hours at 120°C). The mechanism proposed for the reaction of sodium hydroxymethanesulphinite is shown in Scheme 4.20. The reaction is promoted by the addition of base and the best yield is obtained using Aliquat in the presence of potassium carbonate. It is noteworthy, however, that a comparable yield can be obtained in the absence of the catalyst. The reaction of phenacyl halides with sodium hydroxy-methane sulphinite leads to reductive dehalogenation [7]. 

Stir 2.35 g (0.011 mol) of sodium metaperiodate (Section 4.2.55, p. 454) in 45 ml of a 1 1 mixture of water and methanol held at 0°C. Add portionwise 2.14 g (0.01 mol) of dibenzyl sulphide (Expt 5.204) and continue to stir the mixture at 0 °C for several hours, preferably overnight. Extract the reaction mixture (which contains precipitated sodium iodate) with three 20 ml portions of chloroform. Dry the combined chloroform extracts over magnesium sulphate and remove the solvent on a rotary evaporator. Recrystallise the product from ethanol. The yield of dibenzyl sulphoxide is 2.2 g (96%), m.p. 135 °C. 

Beilstein Handbook Reference) AI3-62190 Benzene, 1,r-(sulfinylbis(methylene))bis- Benzyl sulfoxide BRN 2049262 Dibenzyl sulfoxide Dibenzyl sulphoxide EINECS 210-668-7 NSC 55 Preventol Cl 5 Sulfoxide, dibenzyl Tardiol D. An organic inhibitor for use in cleansing acids and in the surface treatment of metals. Leaflets mp = 134° bpn 210° (dec) Xm = 220, 253, 260, 266, 270 nm (MeOH) insoluble in H2O, soluble in EtzO,... 

Dibenzyl sulphoxide (Benzyl stdphoxide) C,H8CH2SO< Hj-CJE5... 

N— compounds used as acid inhibitors include heterocyclic bases, such as pyridine, quinoline and various amines. Carassiti describes the inhibitive action of decylamine and quinoline, as well as phenylthiourea and dibenzyl-sulphoxides for the protection of stainless steek in hydrochloric acid pickling. Hudson refer to coal tar base fractions for inhibition in... 

The methylene protons in dibenzyl sulphoxide are magnetically equivalent in solvents of low dielectric constant, but non-equivalent in polar solvents. This behaviour is reversed for diphenacyl sulphoxide the non-equivalence arises, on changing solvent, from the downfield shift of one of the methylene protons with increasing polarity. Solvent effects on the deuteriation of... 

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