Circobiphenyl and the attempted synthesis of 1:14, 3:4, 7:8, 10:11-tetrabenzoperopyrene

A reducing condensation of naphthanthrone (2) gave the isomeric dinaphthoperopyrenes 3, 4 and 5, besides (circobiphenyl (7). Tetrabenzoperopyrene (1) was not formed. An attempt to synthesize it from 2,5-dimethylterephthalic acid failed.     

Frederick Thomas Trouton: The Man, the Rule, and the Ratio

Trouton was a multifaceted theoretician and experimentalist who left his name in several fields. Here, his many contributions to science are described and analyzed with particular emphasis on Troutons rule and its further development, his contributions to rheology (Troutons ratio), and the famous Trouton—Noble experiment, which is related to the absolute movement of the Earth through the æether.Chemists and chemical engineers are familiar with Trouton through the rule that carries his name. Troutons rule states that at the normal boiling temperature the entropy of vaporization is constant. They are generally unaware of his rich contributions in other scientific areas, such as rheology, osmotic pressure, and physics. Here we describe his personal life and career, his scientific achievements, and, in particular, how his rule has been further developed by others.     

Polyelectrolyte networks: elasticity,swelling, and the violation of the Flory-Rehner Hypothesis

This paper discusses the elastic behaviour of polyelectrolyte networks. The deformation behaviour of single polyelectrolyte chains is discussed. It is shown that a strong coupling between interactions and chain elasticity exists. The theory of the complete crosslinked networks shows that the Flory-Rehner Hypothesis (FRH) does not hold. The modulus contains contributions from the classical rubber elasticity and from the electrostatic interactions. The equilibrium degree of swelling is estimated by the assumption of a c1-network.     

Studies toward the synthesis of pinnatoxins: the B,C,D-dispiroketal fragment

A stereoselective synthesis of the tricyclic B,C,D-dispiroketal fragment of pinnatoxins is described. Both products of an efficient enzymatic resolution reaction are used to set the stereochemistry of C12 and C23, which have opposite configuration. The configuration of the ketal centers is established upon an optimized thermodynamically controlled spiroketalization.     

The mass spectrum of 1:12, 2:3, 4:5, 6:7, 8:9, 10:11-hexabenzocoronene

The mass-spectra of 1:12, 2:3, 4:5, 6:7, 8:9, 10:11-hexabenzocoronene and the isomer 1:2, 3:4, 5:6, 7:8, 9:10, 11:12-hexabenzocoronene have been examined. The former is typically that of an aromatic conjugated hydrocarbon and is sparse, the latter is more intense. It is conjectured that the former may be found in interstellar space.     

Revisiting the Chemistry of Vinylpyrazoles: Properties,Synthesis, and Reactivity

Vinylpyrazoles, also known as pyrazolyl olefins, are interesting motifs in organic chemistry but have been overlooked. This review describes the properties and synthetic routes of vinylpyrazoles and highlights their versatility as building blocks for the construction of more complex organic molecules. Concerning the reactivity of vinylpyrazoles, the topics surveyed herein include their use in cycloaddition reactions, free-radical polymerizations, halogenation and hydrohalogenation reactions, and more recently in transition-metal-catalyzed reactions, among other transformations. The current state of the art about vinylpyrazoles is presented with an eye to future developments regarding the chemistry of these interesting compounds. Styrylpyrazoles were not considered in this review, as they were the subject of a previous review article published in 2020.     

Biocatalysis,sustainability, and industrial applications: Show me the metrics

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Nitrous Oxide: Production,Application, and Protection of the Environment

Russian Journal of General Chemistry - Natural and anthropogenic sources of nitrous oxide were considered, and their contribution to environmental pollution was determined. The effect of N2O on...     

How chemistry shifts horizons: element, substance, and the essential

In 1931 eminent chemist Fritz Paneth maintained that the modern notion of “element” is closely related to (and as “metaphysical” as) the concept of element used by the ancients (e.g., Aristotle). On that basis, the element chlorine (properly so-called) is not the elementary substance dichlorine, but rather chlorine as it is in carbon tetrachloride. The fact that pure chemicals are called “substances” in English (and closely related words are so used in other European languages) derives from philosophical compromises made by grammarians in the late Roman Empire (particularly Priscian [fl. ~520 CE]). When the main features of the constitution of isotopes became clear in the first half of the twentieth century, the formal (IUPAC) definition of a “chemical element” was changed. The features that are “essential” to being an element had previously been “transcendental” (“beyond the sphere of consciousness”) but, by the mid-twentieth century the defining characteristics of elements, as such, had come to be understood in detail. This amounts to a shift in a “horizon of invisibility” brought about by progress in chemistry and related sciences. Similarly, chemical insight is relevant to currently-open philosophical problems, such as the status of “the bundle theory” of the coherence of properties in concrete individuals.