Containing Bivalent Sulphur

Sulphur.—Compounds Containing Bivalent Sulphur. Attempts to oxidize bistrifluoromethyl sulphide (conveniently prepared by pyrolysis of commercial bistrifiuoromethyl disulphide at 425—435 °C) to either the sulphoxide or the sulphone using the reagents ( i-(n C H4-CO)sOa-100°C, NOjCIO, NOa-u.v., or NOa-Oa-350°C have proved unsuccessful fluorination of the monosulphide with hot argentic or cobaltic fluoride gave trifluoromethyl-sulphur pentafluoride, while bis(trifluoromethyl)sulphur difluoride was formed at low temperatures with fluorine itself. Bis(trifluoromethyl)-sulphur difluoride and several other bis(perfluoroalkyl)sulphur difluorides, obtained from the corresponding sulphides and chlorine monofluoride (see p. 162), have been converted into bisperfluoroalkyl sulphoxides  

A series of related alkyl and perfluoroalkyl sulphides and disulphides has been studied by photoionization and mass spectrometric techniques. Bond energies calculated from the data obtained ate listed in Table 2 bistrifluoromethyl disulphide has a particularly low C—S bond energy, and preliminary results have indicated that this compound may be a useful source of trifluoromethyl radicals.  

Parent Bond Parent Bond Parent Bond 

Further interest has been taken in nickel dithiete (71). For example, it has been shown to form semiconducting donor-acceptor complexes with the IT bases pyrene and perylene, to yield a tropylium salt with cyclohepta-triene, and to give cyclo-addition products with norbornadiene [(72) and (73)] and norbornene.  

Transition metal complexes [e.g. (74)] derived from the trifluoromethyl derivatives CFg SX (X = CFj S, MeS, or Cl) have been described.  

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Sulphur—Compounds containing Bivalent Sulphur. The synthesis of sulphides via attack of thiols or thiolates on unsaturated substrates is covered in Chapter 2, and oxidation reactions are dealt with in the next two sections of this chapter a representative selection of information gleaned from patent literature is incorporated in the appendix to this chapter. 

From a graphical study of positional isomers containing bivalent sulphur, it was predicted that (2a) should be more stable than (2b). The former has been synthesized, whereas the latter is not a known compound. 

Sulphur.—Compounds containing Bivalent Sulphur. The use of such compounds in transition-metal chemistry is dealt with in the next chapter. Work on bis(perfluoroisopropylideneimino) disulphide, [(CFj)jC N]2S2, and derived compounds has already been covered (Scheme 20, p. 214 (ref. 137)] so has... 

VI.5 TESTING FOR ANIONS IN SOLUTION ON THE SEMIMICRO SCALE The preliminary tests 7 and 8 with dilute sulphuric acid and with concentrated sulphuric acid will have provided useful information as to many anions present. For more detailed information, it is necessary to have a solution containing all (or most) anions free from heavy metal ions. This is best prepared by boiling the substance with concentrated sodium carbonate solution double decomposition occurs (either partially or completely) with the production of the insoluble carbonates of the metals (other than alkali metals) and the soluble sodium salts of the anions, which pass into solution. Thus, if the unknown substance is the salt of a bivalent metal M and an acid HA, the following reaction will occur ... 

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