Beiträge zur Kenntnis der Polysulfide I

Abstract

Zum Schluss sollen die wichtigsten Resultate vorstehender Arbeit nochmals kurz zusammengestellt werden: 1. Die Lösliclikeit des Schwefels in Schwefelnatriumlösung ist von der Temperatur zwischen 0° und 50° nahezu unabhängig, sie wird mit steigender Temperatur ein klein wenig geringer. 2. Die Löslichkeit des Schwefels in Schwefelnatriumlösung ist in hohem Grade abhängig von der Verdünnung der letzteren. Sie ist am grössten in der 1/16 normalen Lösung, wo die Zusammensetzung der Lösung der Formel Na2S5.24 entspricht. 3. Es sind Anzeichen dafür vorhanden, dass in den Lösungen nicht einheitliche Verbindungen vorhanden sind, dass vielmehr komplizierte Gleichgewichte zwischen den verschiedenen Stoffen bestehen, von denen sich das Tetrasulfid durch ganz besondere Beständigkeit auszeichnet.

Recent Approaches for the Direct Use of Elemental Sulfur in the Synthesis and Processing of Advanced Materials

“…They can be formed in various ways, including the direct dissolution of elemental sulfur in an aqueous sodium sulfide solution. [52] The terminal sulfide anions are highly nucleophilic, which allows polysulfides to participate in nucleophilic sulfuration reactions and in polycondensations. The preparation, properties, and structure of inorganic polysulfides as well as polysulfide radical anions are discussed in a comprehensive review by Steudel.…”

Mechanisms of the Reaction of Elemental Sulfur and Polysulfides with Cyanide and Phosphines**

“…Similarly, carbon‐based nucleophiles usually provide products with the incorporation of a single sulfur atom, for example in the Gewald [20–22] or Willgerodt–Kindler [23] reactions [24] . Nitrogen‐based nucleophiles are often proposed to open S 8 as part of complex mechanisms, [1,2] oxygen bases generate sulfur radical anions [25,26] or thiosulfate, [27] while hydrogen sulfide and thiols react with sulfur to form complex mixtures of polysulfides [28–32] . In most cases, the opening of S 8 by the nucleophile is believed to be rate‐determining; therefore, the product‐determining steps are kinetically invisible and thus still poorly characterized.…”

“…[24] Nitrogen-based nucleophiles are often proposed to open S 8 as part of complex mechanisms, [1,2] oxygen bases generate sulfur radical anions [25,26] or thiosulfate, [27] while hydrogen sulfide and thiols react with sulfur to form complex mixtures of polysulfides. [28][29][30][31][32] In most cases, the opening of S 8 by the nucleophile is believed to be rate-determining; therefore, the product-determining steps are kinetically invisible and thus still poorly characterized. Indeed, experimental investigations of polysulfide mechanisms are complicated by their thermodynamic instability [33][34][35][36] and recent evidence shows that they interconvert faster than they are trapped by chemical probes.…”

Thermodynamic properties of the aqueous sulfide and bisulfide ions and the second ionization constant of hydrogen sulfide over extended temperatures

“…-Equation 18 which gives the variation of pK20 as a function of temperature was derived by substituting 4500 pK2 = -+ 12.6 log ( /298.15) -1.29 (18) the values of AFd°(25°), ASd°(25°), and £7 (1°| into the equation AFda(T) = AFd°(25°) -ASd°(25°)AT + a(T)ACPi°\¡¡ recognizing that AFd°(T) = 2.303i?2pi£2° (19) Because of the importance of H2S in high-temperature aqueous processes, it is of interest to estimate K2°f or this species above 100°. For the dissociation of HS04-(aq), £7 °was reported not to change very rapidly above 90°.…”

“…The meager data at other temperatures give ~0. 18 (25.2°) and ~0.27 (~-21°). The apparent approximate formation enthalpy and entropy are AH°« -1.6 kcal/mol and 5°« -9 eu.…”