S2 CARBON DISULFIDE

ZrSe [12166-53-9] and ZrTe [39294-10-5] (138). Zirconium disulfide [12039-15-5] is made from the elemental powders and by the action of carbon disulfide on zirconium oxide above 1200°C (139) some ZrOS [12164-95-3] is usually also obtained. The higher sulfides disproportionate at ca 700°C synthesis reactions at 900—1000°C with S Zr ratios between 0.2 and 2.3 produced crystals that were identified as Zr S2 [12595-12-9] ... 

Sulfur vapor is an equiUbrium mixture of several molecular species, including Sg, S, and S2. The equiUbrium shifts toward S2 at higher temperatures and lower pressures. The overall reaction is endothermic and theoretically consumes 1950 kj/kg (466 kcal/kg) of carbon disulfide when the reactants are at 25°C and the products are at 750°C. Most of the heat input goes into dissociation of sulfur vapor to the reactive species, S2. Equation 25 is slightly exothermic when the reactants are at a constant temperature of 750°C. 

Fig. 1. Use of the SUFIR method in extreme conditions the two spectra correspond to S and S2 (see text) of a dilute species (1 mg of the Ceo fullerene dissolved in 1 ml of carbon disulfide) possessing an unusually long relaxation time. The SUFIR sequence was repeated...

The absorption of ultrasonic energy is also influenced by relaxation effects. At the frequencies of near 100 MHz that are employed, the relaxation times are of the order of ns, rather than the ps for dielectric relaxation. The relevant quantity is the absorption coefficient, a, divided by the square of the frequency, f2. Values of a//2 in 10-15 s2 nr1 have been measured for many solvents near 25 °C at the frequency of 104 to 107 MHz (Heasall and Lamb 1956 Krebs and Lamb 1958) and are shown in Table 3.10, being considered accurate within 2%. For a few solvents the ratio a//2 depends strongly on the frequency as it decreases somewhat for all solvents, e g., for carbon disulfide a//2/ (10-15 s2 nr1) = 2068 at 104 MHz and 776 at 189 MHz and for dichloromethane it decreases from 779 at 107 MHz to 550 at 193 MHz... 

The products of the oxidation of carbon disulfide include SO2, S2O, CO2, CO, OCS, and sulfur. SO and CS intermediates have been observed in the cold flame " Kondratiev reported the yields of SO2, CO, OCS, and S2 as functions of the initial [O2] [CS2] ratio in flames. At a ratio of 2.5 1, the products were almost exclusively SO2 and CO in a ratio of 2 1, suggesting that the bulk of the reactants obeyed the stoichiometry... 

When diatomic sulfur (S2) is dissolved in a polar solvent like methanol or acetonitrile, an equilibrium is established in which 1% of the sulfur exists as the S6 and S7 ring forms. Since these are much more reactive than the normal S8 rings, they may provide a pathway for the reactions of sulfur in polar solvents. Cyclic sulfur allotropes also dissolve in carbon disulfide, benzene and cyclohexane. Sulfur reacts with amines, e.g. piperidine, giving coloured solutions containing polythiobisamines (1) (Scheme 1). 

These S8 molecules are present also in solutions of sulfur in solvents such as carbon disulfide and chloroform, and in sulfur vapor at a moderate temperature. Sulfur vapor also contains S6 molecules and S2 molecules, in amounts increasing with increase in the temperature. 

Example 4-3 The homogeneous reaction between sulfur vapor and methane has been studied in a small silica-tube reactor of 35.2 ml volume. In a particular run at 600°C and 1 atm pressure the measured quantity of carbon disulfide produced in a 10-min run was 0.10 g. Assume that all the sulfur present is the molecular species S2. The sulfur-vapor (considered as S2) flow rate was 0.238 g mole/hr in this steady-state run. 

The production of carbon disulfide from methane and sulfur vapor can be carried out homogeneously or with a solid catalyst. Also, some solid materials act as a poison, retarding the reaction. The following data were obtained on a flow basis at a constant temperature of 625°C and with an initial reactants ratio of 1 mole of CH4 to 2 moles of sulfur vapor (considered as S2). The first set of data was obtained with the reactor empty (effective volume 67.0 ml), and the second set was obtained after packing the reactor with a granular material (7 mesh) which reduced the void volume to 35.2 ml. 

The greater hydrogen adsorption reported in Table II compared with that listed in Table I is explained by the authors as being due to a better clean-up of the catalyst before measurement in this particular series of determinations. From the measurements, it can be seen that only hydrogen, carbon disulfide, and sulfur dioxide show appreciable activated adsorption on a Ni S2 catalyst. 

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