Molekulare Zusammensetzung von flüssigem Schwefel. Teil: 3 Quantitative Analyse im Bereich 115–350°C

Molecular Composition of Liquid Sulfur. Part 3: Quantitative Analysis in the Temperature Region 115–350°C Relative concentrations of S₆, S₇, S₈, S_x (x > 8) and S_μ (insoluble sulfur) in equilibrium melts of elemental sulfur have been determined from i. r. and Raman spectra. At the freezing point (115°C) the melt consists of 0.6% S₆, 2.8% S₇, 1.5% S_x, and 95.1% S₈. – The solubility of S₇ in CS₂ has been determined at −77 to −26°C; the solubilities of both S₇ and S₈ in CS₂ are considerably enhanced by the presence of S_x. The thermal decomposition of S₈ and S_μ formation from S₆, S₇, and S_x has been investigated.     

Molekulare Zusammensetzung von flüssigem Schwefel. Teil 2: Qualitative Analyse und Isolierung von S7, S12, α-S18 und S20

Molecular Composition of Liquid Sulfur. Part 2: Qualitative Analysis and Preparation of S₇, S₁₂, α-S₁₈, and S₂₀ from S₈ Raman spectra of sulfur melts (115–300°C), of quenched melts and of CS₂ extracts of quenched melts show besides S₈ the presence of S₆ and S₇. Formation of S₇ from S₈ at 120°C takes more than 8 h; the S₇ equilibrium concentration increases with temperature. Pure crystalline S₇, S₁₂, α-S₁₈ and S₂₀ are prepared on a preparative scale by fractional extraction, crystallization, flotation and precipitation of quenched sulfur melts. Also a mixture of larger rings (S_x; x? = 25) has been isolated. Infrared and Raman spectra of α-S₁₈, S₂₀ and S_x are reported.     

Sulfur Compounds. 164 Thermal Polymerization of the Cyclic Seleniumsulfide 1,2-Se2S5 Studied by DSC,HPLC, Raman Spectroscopy,and X-Ray Diffraction

Solid 1,2-Se₂S₅ polymerizes endothermically at 47°C to give a linear polymer which after stretching and extraction consists of helical molecules similar to those of polymeric sulfur. Heating of the polymer results in slow exothermic depolymerization at 84°C to give a mixture of seven cyclic Se_nS_8–n molecules which melts at 111°C. When the polymeric Se₂S₅ is refluxed with CS₂ the initial depolymerization Products are 1,2-Se₂S₅, SeS₅ and 1,2,3-Se₃S₅ but in addition SeS₇ and 1,2-Se₂S₆ are formed. These results indicate the atomic sequence –Se? S₅? Se– in the polymer. The powder x-ray diffraction pattern and Raman spectrum of the polymer as well as its lattice parameters are reported and the Probable mechanism of its depolymerization is discussed.     

DTA-untersuchung der Umwandlungen des Amorphen Schwefels

DTA was applied to investigate amorphous sulfur samples remelted at different temperaturesT _f. For the sample remelted atT _f<159 °C, an exothermic process I occurs in the range 30–40°C. Transformation of orthorhombic to monoclinic sulfur, melting and polymerization ofS ₈ rings was observed at higher temperatures. For the sample remelted atT _f > 159 °C, a new, fast exothermic process II occurs at ambient temperature, followed by an exothermic process III at slightly higher temperature. The next, also exothermic process IV is detected in the vicinity of the melting point. The heats of the thermal effects for all the above-mentioned processes, and the part of sulfur insoluble in CS₂, were determined. An attempt was made to evaluate the mechanism of the transformations.     

Reaktionen von elementarem Schwefel mit halogenierten Methanen

Reactions of elemental Sulfur with Halogenated Methanes At 250°C a reaction between CCl₄ and sulfur forms S₂Cl₂ and CS₂ (besides small amounts of S₃Cl₂ and S₄Cl₂). CHCl₃ and sulfur above 200°C under catalytic influence of AlCl₃ are forming HCl, S₂Cl₂, and CS₂; CH₂Cl₂ and sulfur also are reacting (with AlCl₃ or AI as catalyst) to CS₂ and HCl. Only at 345°C one gets,CS₂, HCl, and H₂S from CH₃Cl and sulfur. At 160°C forms HBR,BR₂, and CS₂. Aluminium is necessary for the reaction of CH₂Br₂ at 250°C with sulfur, forming CS₂ and HBr. A mixture of products (CS₂,H₂S, HBr, CH₃SCH₃, and (CH₃)₃SBr) results from CH₃ Br and sulfur at 250°C. CH₃I and sulfur produce CS₂,I₂, and H₂S at 145°C. The same products are formed from CH₂I₂ and sulfur with aluminium as catalyst at 175°C.     

Molekulare Zusammensetzung von flüssigem Schwefel. Teil 1: Kritische Literaturübersicht

Molecular Composition of Liquid Sulfur. Part 1: Critical Review of the Literature The literature concerning the molecular composition of liquid sulfur is critically reviewed. Experimental data of different authors are compared and in some cases corrected and reinterpreted. At the melting point after equilibration the liquid contains besides S₈ 5% (at 150°C: 8%) π sulfur, while polymeric μ sulfur rises from 1% at 135°C to a maximum of 56% at 250–300°C. The heat of formation of S_π amounts to 22 kJ/mol, the formation of S_μ is also endothermic. It is however concluded that the exact molecular nature of both π and μ sulfur is unknown and both substances are likely to be mixtures. It is shown that all published theories concerning the polymerization of S₈ are in disagreement with well established experimental facts and therefore must be considered unsatisfactory if not wrong.     

Internal rotation around the isopropyl-nitrogen bond and stable conformations of S-methyl-N,N-di-isopropyldithiocarbamate,dichlorotin(IV) bis(N,N-di-isopropyldithiocarbamate) and related compounds

Temperature dependent proton magnetic resonance spectra of dichloro- and dimethyltin(IV) bis(N,N-di-isopropyl-dithiocarbamate) ( 1 and 2 , respectively), dimethylchlorotin(IV) N,N-di-isopropyldithiocarbamate ( 3 ), dimethyltin(IV) bis(N-isopropyldithiocarbamate) ( 4 ), S-methyl-N,N-di-isopropyldithiocarbamate ( 5 ) and S-methyl-N-isopropyldithiocarbamate ( 6 ) were measured in halogenated hydrocarbons or CS₂. The internal rotation around the isopropyl–nitrogen bond of 1, 2, 3 and 5 is restricted below ?30°C, and that of 4 and 6 below ?70°C; 1, 2 and 3 exist as only one conformer in dichloromethane, while 5 exists as two rotational isomers with respect to the isopropyl–nitrogen bond with a mole ratio of about 2·7:1·0 in CS₂ below ?30°C. At this temperature, 6 exists as two stereoisomers in CS₂ with a mole ratio of about 1·2:1·0, although there is no stereoisomer in 4 . From these results, possible conformations of the compounds at low temperature are proposed and the assignments of each proton signal are described.     

THE EFFECT OF S6 AND S7 ON THE POLYMERIZATION OF LIQUID SULFUR1

Abstract

It is shown that the partial polymerization of liquid sulfur which occurs on heating to temperatures above 159°C is initiated by free radicals originating from the homolytic dissociation of the cyclic molecules S₆ and S₇ whose first dissociation enthalpies are calculated from thermodynamic data as 124 and 127 kJ/mol, respectively.     

Die Molekulare Zusammensetzung von erstarrten Phosphor-Schwefel-Schmelzen und die Kristallstruktur von β-P4S6

The Molecular Composition of Solidified Phosphorus-Sulfur Melts and the Crystal Structure of β-P₄S₆ Phosphorus sulfur melts were annealed for one week at 673 K and then quenched in ice water. The solids were dissolved in CS₂ and the concentrations of phosphorus sulfides were determined by ³¹P NMR spectroscopy. Samples containing between 44 and 70 mol% sulfur dissolved completely in CS₂. Between 0 and 42 mol% remains an insoluble residue of red phosphorus. Above 72 mol% it consisted of sulfur chains linked by phosphorus atoms. The solutions contained mainly the congruently melting compounds P₄S₃, P₄S₇, and P₄S₁₀ having maximum concentrations at their stoichiometric compositions. Other compounds P₄S_n (n = 4–9) which decompose on heating, according to the phase diagram, were also found in surprisingly high concentrations. One of these was β-P₄S₆ which crystallizes in the monoclinic space group P2₁/c with the lattice parameters a = 702.4(2), b = 1 205.6(2), c = 1 148.9(6) pm and β = 103.4(2)°. Reaction of white phosphorus with sulfur was also investigated. In contrast to the results of previous authors, who described the system P₄–S₈ below 373 K as eutectic, we found that the elements reacted below this temperature.     

Effects of chromium ion on sulfur removal during pyrolysis and hydropyrolysis of coal

The effects of impregnated Cr³⁺ on sulfur removal during pyrolysis and hydropyrolysis of coal were investigated by loading CrCl₃ into raw, demineralized and pyrite removed coal, respectively. The results indicate that Cr has no effect on the removal of pyrite. Cr affects the removal of total sulfur by forming Cr₇S₈ and affecting the removal of organic sulfur. Cr acts as the sulfur removing agent by promoting the decomposition of the unstable organic sulfur at low temperature. However, it behaves to be sulfur fixing agent between 400 and 700 °C so as to inhibit the evolution of H₂S, even in hydropyrolysis. With the increase of temperature from 700 to 1050 °C, a certain ratio of Cr₇S₈ is converted into organic sulfur during pyrolysis; however, almost all the Cr₇S₈ is reduced into Cr at 1050 °C during hydropyrolysis. And Cr significantly promotes the removal of organic sulfur at high temperature within reducing atmosphere. The XPS results indicate that the sulfur is enriched on coke surface by Cr, which is attributable to the formation of Cr₇S₈ as well as the transfer of organic sulfur from bulk to surface during pyrolysis and hydropyrolysis.     

Beiträge zur Chemie des Schwefels. 108. Schmelzwärme und spezifische Wärme des flüssigen Schwefels. Einfluß von Verunreinigungen

Using an adiabatic calorimeter, the heat of transition S_α ? S_β, the heat of fusion of S_β and the specific heat of the liquid had been determined on sulfur samples refined by zone melting and samples doped with chlorine, bromine and iodine. The data obtained from pure sulfur (heat of fusion: 1608 ± 8 J/Tom, specific heat of the liquid at 120°C: 29,4 J/Tom.°C) are about 10% lower than comparable values of other authors. Apparently they represent heat of fusion and specific heat of the pure cyclooctasulfur. The measurements on doped samples (δH_S = 1736 ± 10 J/Tom) are in agreement with the data reported in literature and include a portion of enthalpy from the transition reaction of cycloocta-sulfur (S_λ) to catenaocta-sulfur (S_π), requiring extremly long equilibrium times in pure sulfur. The influence of impurity on the caloric properties of the liquid sulfur is also indicated by the increasing width and decreasing highness of the C_p-maximum at 159°C with increasing amount of halogens. For the heat of transition S_α → S_β, independent of the amount of impurity, the literature data could be confirmed. At the samples doped with iodine there was observed a previously unreported transition near 65,9°C.     

Cs2B2S4 – Ein Salz der dimeren Metathioborsäure

Cs₂B₂S₄ – A Derivative of the Dimeric Metathioboric Acid Cs₂B₂S₄ (structure: I4₁/acd; a = 7.270(1) Å, c = 35.737(7) Å; Z = 8; substructure: I4/mmm; a′ = 5.141(1) Å, c′ = 17.868(4) Å, Z = 2) is prepared by the reaction of cesium sulfide with stoichiometric amounts of boron and sulfur (effective molar ratio M:B:S = 2:2:4) at 600°C and subsequent annealing. The crystal structure contains isolated [B₂S₄]^2? groups consisting of four-membered B₂S₂ rings with two exocyclic sulfur atoms on each of the boron atoms. The cesium cations are nine-coordinate between these rings. The structural feature of two edge-sharing BS₃ groups forming an isolated anion appears for the first time in thioborate chemistry, although it is known as a part of the polymeric network in B₂S₃.     

LiBaBS3 und LiBaB3S6: Zwei neue quaternäre Thioborate mit trigonal-planar koordiniertem Bor

LiBaBS₃ and LiBaB₃S₆: Two New Quaternary Thioborates with Trigonally Coordinated Boron LiBaBS₃ (P2₁/c; a = 7.577(2) Å, b = 8.713(2) Å, c = 8.687(2) Å, β = 116.22(2)°; Z = 4) und LiBaB₃S₆ (Cc; a = 15.116(3) Å, b = 8.824(2) Å, c = 8.179(2) Å, β = 117.46(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of the metal sulfides, boron, and sulfur at 750°C. The anionic part of the structure of the orthothioborate LiBaBS₃ consists of isolated planar [BS₃]^3? anions. The crystal structure of the metathioborate LiBaB₃S₆ contains [B₃S₆]^3? anions formed by six-membered B₃S₃ rings with three exocyclic sulfur atoms. The metal cations are situated between the anion units leading to a ninefold sulfur coordination of the barium atoms and to a fivefold (LiBaBS₃) and fourfold (LiBaB₃S₆) coordination of the lithium atoms.     

Die Kristallstruktur und das Raman-Spektrum von SbCl3 · S8

Crystal Structure and Raman Spectrum of SbCl₃ · S₈ Contrary to literature data, the reaction of SbCl₅ with CS₂ at 5°C does not yield SbSCl₃ but SbCl₃ · S₈. At room temperature it already decomposes slowly to SbCl₃ and sulphur. The crystalline compound is built up from pyramidal SbCl₃ molecules and S₈ rings; pairs of SbCl₃ molecules form loosely associated dimeric units, furthermore there exist some relatively short Sb…?S contact distances. SbCl₃ · S₈ crystallizes in the space group P1 with the lattice constants a = 805, b = 867, c = 1073 pm, α = 94.9, β = 107.1 und γ = 111.6° (bei ?5°C). The crystal structure was determined with 2032 X-ray reflexions and was refined to a residual index of R = 0.028. The Raman spectrum is reported.     

Na2B2Se7, K2B2S7 und K2B2Se7: Drei Perchalkogenoborate mit neuem polymeren Anionengerüst

Na₂B₂Se₇, K₂B₂S₇, and K₂B₂Se₇: Three Perchalcogenoborates with a Novel Polymeric Anion Network Na₂B₂Se₇ (I 2/a; a = 11.863(4) Å, b = 6.703(2) Å, c = 13.811(6) Å, β = 109.41(2)°; Z = 4), K₂B₂S₇ (I 2/a; a = 11.660(2) Å, β = 6.827(1) Å, c = 12.992(3) Å, β = 106.78(3)°; Z = 4), and K₂B₂Se₇ (I 2/a; a = 12.092(4) Å, b = 7.054(2) Å, c = 13.991(5) Å, β = 107.79(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of sodium selenide (potassium sulfide) with boron and sulfur or of potassium selenide and boron diselenide, respectively, at 600°C with subsequent annealing. The crystal structures consist of polymeric anion chains of composition ([B₂S₇]^2?)_n or ([B₂Se₇]^2?)_n formed by spirocyclically connected five-membered B₂S₃ (B₂Se₃) rings and six-membered B₂S₄ (B₂Se₄) rings. The nine-coordinate alkaline metal cations are situated in between.     

Die Perthioborate RbBS3, TIBS3 und TI3B3S10

The Perthioborates RbBS₃, TIBS₃, and Tl₃B₃S₁₀ . RbBS₃ (P2₁/c, a=7.082(2) Å, b=11.863(4) Å, c=5.794(2) Å, β=106.54(2)°) was prepared as colourless, plate-shaped crystals by reaction of stoichiometric amounts of rubidium sulfide, boron, and sulfur at 600°C and subsequent annealing. TlBS₃ (P2₁/c, a=6.874(3) Å, b=11.739(3) Å, c=5.775(2) Å, β=113.08(2)°) which is isotypic with RbBS₃ was synthesized from a sample of the composition Tl₂S · 2 B₂S₃. The glassy product which was obtained after 7 h at 850°C was annealed in a two zone furnace for 400 h at 400→350°C. Yellow crystals of TlBS₃ formed at the warmer side of the furnace. Tl₃B₃S₁₀ (P1 , a=6.828(2) Å, b=7.713(2) Å, c=13.769(5) Å, α=104.32(2)°, β=94.03(3)°, γ=94.69(2)°) was prepared as yellow plates from stoichiometric amounts of thallium sulfide, boron, and sulfur at 850°C and subsequent annealing. All compounds contain tetrahedrally coordinated boron. The crystal structures consist of polymeric anion chains. In the case of RbBS₃ and TlBS₃ nonplanar five-membered B₂S₃ rings are spirocyclically connected via the boron atoms. To obtain the anionic structure of Tl₃B₃S₁₀ every third B₂S₃ ring of the polymeric chains of MBS₃ is to be substituted by a six-membered B(S₂)₂B ring.     

Industrial production and purification of <Superscript>32</Superscript>P by sulfur irradiation with partially moderated neutron fluxes and target melting

Target purification of S_α is carried out by distillation at 444±2 °C under N atmosphere and diluting the vapors in CS₂. The solution is filtered through fiberglass, Teflon and cellulose to obtain S_α by CS₂ evaporation. Once 30 g of this target are irradiated with fast neutron fluxes from 4.5 to 7.4·10¹² n·cm⁻²s⁻¹ from 6 to 12 hours, the nuclear reaction ³²S(n,p)³²P takes place. So, the irradiated S_α sample is placed in a Pyrex container situated inside a furnace as the most important piece of equipment in one aluminum and Lucite glove box. The distillation of irradiated sulfur takes place at 444±2 °C under N atmosphere during 1–2 hours. The vapors are connected to a sulfur diluter containing 20% CS₂ aqueous solution, followed by an activated carbon filter and the two similar additional sulfur diluters. Once cooled, the distillation chamber keeps the radioactive, carrier-free ³²P stuck to the wall. Then 25–50 ml of 0.1N HCl acid was injected by suction and heated again at 110±2 °C during 1 hour. The corresponding chemical reaction takes place and the labeled H₃ ³²PO₄ solution is produced. In such a way, industrial production of ³²P labeled molecules has started in Mexico, with an initial production of 3700–5550 MBq per week.     

Li5B7S13 und Li9B19S33: Zwei Lithiumthioborate mit neuen hochpolymeren Anionengerüsten

Li₅B₇S₁₃ and Li₉B₁₉S₃₃: Two Lithium Thioborates with Novel Highly Polymeric Anion Networks Li₅B₇S₁₃ (C2/c; a = 17.304(2) Å, b = 21.922(3) Å, c = 12.233(2) Å, β = 134.91(1)°; Z = 8) and Li₉B₁₉S₃₃ (C2/c; a = 23.669(9) Å, b = 14.361(3) Å, c = 12.237(3) Å, β = 103.77(2)°; Z = 4) were prepared by reaction of stoichiometric amounts of lithium sulfide, boron, and sulfur at 750°C (Li₅B₇S₁₃) and 700°C (Li₉B₁₉S₃₃) with subsequent annealing. The crystal structures consist of interpenetrating, polymeric boron sulfur anion networks which are formed by corner-sharing of B₄S₁₀ and B₁₀S₂₀ units (Li₅B₇S₁₃), or B₁₉S₃₆ units (Li₉B₁₉S₃₃). The lithium cations are situated in between with a strong disorder in Li₉B₁₉S₃₃.     

S‐(4‐Nitrophenyl) 4‐nitrobenzenethiosulfonate

The title compound, C₁₂H₈N₂O₆S₂, (I), is a positional isomer of S‐(2‐nitrophenyl) 2‐nitrobenzenethiosulfonate [Glidewell, Low & Wardell (2000). Acta Cryst. B 56 , 893–905], (II). The most obvious difference between the two isomers is the rotation of the nitro groups with respect to the planes of the adjacent aryl rings. In (I), the nitro groups are only slightly rotated out of the plane of the adjacent aryl ring [2.4 (6) and 6.7 (7)°], while in (II) the nitro groups are rotated by between 37 and 52°, in every case associated with S—S—C—C torsion angles close to 90°. Other important differences between the isomers are the C—S—S(O₂)—C torsion angle [78.39 (2)° for (I) and 69.8 (3)° for (II) (mean)] and the dihedral angles between the aromatic rings [12.3 (3)° for (I) and 28.6 (3)° for (II) (mean)]. There are two types of C—H...O hydrogen bond in the structure [C...O = 3.262 (7) Å and C—H...O = 144°; C...O = 3.447 (7) Å and C—H...O = 166°] and these link the molecules into a two‐dimensional framework. The hydrogen‐bond‐acceptor properties differ between the two isomers.     

Effects of polysulfides on the polymerization of methyl methacrylate

The effect of organic sulfur compounds on the radical polymerization of methyl methacrylate initiated by azobisisobutyronitrile at 50°C. has been studied. The sulfur compounds used were benzene-type polysulfides (C₆H₅CH₂? S_n? CH₂C₆H₅; n = 0–4), benzyl mercaptan, and sulfur (S₈). All sulfur compounds studied, except dibenzyl, dibenzyl monosulfide, and dibenzyl disulfide, were found to behave as retarders under these experimental conditions. Chain-transfer constants of these compounds were determined from rate measurements and from the conventional method based on numberaverage degree of polymerization. Chain-transfer constants of benzyl-type polysulfides were less than those of mercaptan and sulfur and increased with increasing sulfur. The correlation of the reactivities of sulfur compounds as transfer agents and their molecular structures is discussed.