Thiacrown compounds: Synthesis and properties. (Review)

Abstract

Data of the last 15 vears on the synthesis and properties o/'vaiVous thiacrown compounds containing 2-8 sttlfttl" atoms in the ring are reviewed.The discovery of interesting and unique complexing charactcristics in crown ethers and their nitrogen and sulfur analogs is one of the most powcrful achievcments of modem organic chemistry. The selectivity of the macrocycle toward the ions of various mctals can be controllcd by the size of the ring, by the type, number, and position of the heteroatoms in the ring, and by the presence of functional groups in the ring and on its periphery. Of the many methods used in the synthcsis of crown ethers and their sulfur analogs (thiacrowns) the most successful is the reaction of dihalogcno dcrivatives with glycols and dithiols, by means of which it is possible to influence positively the main factors determining the selectivity of the macrocycle. Methods have been developed on the basis of this reaction for the synthesis of numerous sulfur-containing heterocyclic compounds.The various types of macrohcterocycles are of great interest as reagents that make it possible to extract metals with the object of separating thcir mixtures and subsequently determining the individual elements. Sulfurcontaining macroheterocycles and their open-chain analogs, called podands, occupy an important position in supramolocular chemistry, having the ability to connect selectively the ions of transition and heavy metals, such as Cu(II). The use of these compounds makes it possible to model the biological systems and processes in which organosulfur compounds participate. The use of macrocycles as the active components in the membranes of ionselective electrodes and molecular receptors has proved very promising.In the present review an attempt is made to summarize comprehensively the achievements of the last 10-15 years in the chemistry of thiacrown compounds containing only sulfur atoms as heteroatoms. The review is not concerned with the extensive material on the synthesis and properties of macroheterocycles containing nitrogen, oxygen, and other heteroatoms.

β-Nitroacrylates and Phenols as Key Precursors of Arenofuran-3-carboxylates

“…Notwithstanding the above-mentioned benefits, the preparation of this specific class of arenofuran derivatives usually requires the use of complex starting materials, 6` b c harsh reaction conditions, 6d e expensive catalysts, 6f multistep approaches, 6g and long reaction times. 6b h i…”

Microwave‐Assisted Synthesis of Aromatic Thiadiazol Crown Ethers and Determination of Complexation Properties with Metal Ions by Application of Job′s Plot Method to Conductometry

“…[8][9][10][11] Crown ethers can be used as metal removal agents because of their stable complexes with metal ions. [12,13] While the apolar outer cavity provides for dispersion in nonpolar environments, the polar inner cavity, which contains oxygen, nitrogen, and sulfur atoms, allows various cations to bind to the ring. [9,14,15] Crown ethers containing oxygen (oxOÀ Crown ether) are to be interested in ions of hard metals, while crown ethers containing sulfur (thiOÀ Crown ether) and nitrogen (aza-crown ether) are interested in ions characterized as soft.…”

“…In complexations, this cavity difference is important [8–11] . Crown ethers can be used as metal removal agents because of their stable complexes with metal ions [12,13] . While the apolar outer cavity provides for dispersion in nonpolar environments, the polar inner cavity, which contains oxygen, nitrogen, and sulfur atoms, allows various cations to bind to the ring [9,14,15] .…”

Determination of crown ether complexation with metal ıons by application Job’s Plot method to conductometry

“…Bu seçimli kompleksleşme metal afinitesi olarak tanımlanmakla birlikte halka üzerindeki S, O ve N atomlarının kombinasyonu ile yumuşak/sert katyonlarını aynı anda seçimli bağlayan sistemler tasarlanabilmektedir [13][14][15][16][17]. Taç eterlerin metallerle olan kararlı kompleksleri taç eterleri metal uzaklaştırma ajanı olarak kullanılabilmesi taç eterlere ayrı bir boyut kazandırmıştır [18]. Kondüktometri çok düşük derişimlerde çalışma, hızlı yanıt süresi, pratik olması gibi imkânlar sunarken potansiyometrik çalışmalara göre çoklu element sistemlerinde kompleksleşme seçiciliğinin belirlenmesine olanak sağlamamaktadır [19,20].…”