A sulfur analogues

Thiomahc acid [70-49-5] (mercaptosuccinic acid), C H O S, mol wt = 150.2, is a sulfur analogue of malic acid. The properties of the crystalline, soHd thiomalic acids ate given in Table 6. The racemic acid has the following acid dissociation constants at 25°C pTf i — 3.30 pffc2 — 4.94. 

A sulfur analogue of EC, ethylene sulfite (ES), was proposed as an additive for PC-based electrolytes by Winter and co-workers,apparently because of its structural similarity to EC and its potential, under reductive conditions, to release SO2, a known additive that effectively suppresses PC decomposition. As the voltammetry in Figure 39 shows, ES in only 5% presence successfully eliminated the exfoliation of the graphite anode, whereas 10% SO2 failed. The irreversible process corresponding to the reduction of ES occurred at --"2.0 V, lower than that of SO2 by 0.80 V however, the quantity of charge associated was much lower. According to the authors, the above apparent gap between the reduction potentials of ES... 

This method can be considered as a sulfur analogue of alkene epoxidation. The general principle is that a cycloalkane thiolate is generated, which bears a leaving group at the adjacent position. These precursors can conveniently formed via addition reactions of cycloalkenes. For example, cyclopentene sulfide 87 had been prepared in 58%... 

As it were a two dimensional extension of the no-bond-resonance concept has been synthesized in XVI The structure of this compound has been described as a sulfur analogue of coronene 8) since it comprises a24 ji-electron system. 

Lutke-Eversloh T, Bergander K, Luftmann H, Steinbuchel A (2001) Biosynthesis of poly (3-hydroxybutyrate-co-3-mercaptobutyrate) as a sulfur analogue to poly(3-hydroxybutyrate) (PHB). Biomacromolecules 2 1061-1065... 

A sulfur analogue of pentamethylene ketene 220 has been synthesized via the dehydrochloiination of 2-chlorocarbonyl-l,3-dithiane 219. Numerous spiro l,3-dithiane-2,3 -(5 6 -polymethylene) dihydropyranones 221 were synthesized via the in situ interaction of 2-carbonyl-l,3-dithiane 219 with the 2-(aminomethylene)cycloalkanones 101 (Scheme 69) (1976JHC1105). 

A. Scioscia Santoro, D. Cavallini, A.M. Degener, R. Perez-Ber-coff and G. Rita. Effect of L-aminoethyl-cysteine, a sulfur analogue of L-lysine, on virus multiplication in mammalian cell cultures. Experientia, 1977, 33 451. 

Tiecco et al. have employed a sulfur analogue 476 (5 mol%) which gave the products in high yield and with good ee values (Table 7.33) [318]. 

The thiosulfate ion, 820 is a stmctural analogue of the sulfate ion where one oxygen atom is replaced by one sulfur atom. The two sulfur atoms of thiosulfate thus are not equivalent. Indeed, the unique chemistry of the thiosulfate ion is dominated by the sulfide-like sulfur atom which is responsible for both the reducing properties and complexing abiUties. The abiUty of thiosulfates to dissolve silver haUdes through complex formation is the basis for their commercial appHcation in photography (qv). 

In the period following World War I and during World War II, a wide variety of sulfur analogues of mustard were investigated and many potent vesicants were discovered. Each had two 2-chloroethyi groups attached to a sulfur atom. Examples of such compounds are... 

Amino and sulfur analogues of pyrazolones also yield the aromatic quaternary salt (231 X = NH or S). If the pyrazole bears a substituent with a second pyridine-like nitrogen atom, an intramolecular bridge can be formed by reaction with a dihalogenoalkane. Thus pyrazol-I -ylpyridines react with 1,2-dibromoethane to form (233) (81JHC9). 

Other routes to oxocarbenes are the a-elimination of bromine from a,a-dibromo ketones (73JA2708, 73JA5416), and the elimination of CO2 or COS from dioxolenones (vinylene carbonates) or their sulfur analogues. The former reaction has not been investigated with regard to oxirene involvement the latter is discussed in Section 5.05.6.3.5. The formation of an oxocarbene from a chlorooxirane was mentioned in Section 5.05.6.3.2. 

Any heterocycle containing the OCH=CH moiety can in principle extrude the superfluous fragment and form oxirene, as illustrated for a five-membered ring in Scheme 105. Probably the most propitious AB fragment would be nitrogen, but the required 1,2,3-oxadiazole (123) is unknown (see Chapter 4.21), probably because of ready valence tautomerization to diazoethanal (Scheme 106) (this approach has been spectacularly successful with the sulfur analogue of (2) (8UA486)). The use of (123) as an oxirene precursor is thus closely linked to the important diazo ketone decompositions discussed in Section 5.05.6.3.4(f). 

There are notable differences in both structures and stabilities for binary N-O and S-N anions (Section 5.4). The most common oxo-anions of nitrogen are the nitrite [N02] and the nitrate anion [NOs] the latter has a branched chain structure 1.1. The sulfur analogue of nitrite is... 

Unlike the stable molecule N2O, the sulfur analogue N2S decomposes above 160 K. In the vapour phase N2S has been detected by high-resolution mass spectrometry. The IR spectrum is dominated by a very strong band at 2040 cm [v(NN)]. The first ionization potential has been determined by photoelectron spectroscopy to be 10.6 eV. " These data indicate that N2S resembles diazomethane, CH2N2, rather than N2O. It decomposes to give N2 and diatomic sulfur, S2, and, hence, elemental sulfur, rather than monoatomic sulfur. Ab initio molecular orbital calculations of bond lengths and bond energies for linear N2S indicate that the resonance structure N =N -S is dominant. 

The MS2N2 complexes and their selenium analogues are readily protonated at the nitrogen attached to the metal (Eq. 7.5). Competitive studies show that the selenium complex is a stronger base than its sulfur analogue. 

Diazenes of the type REN=C(R )N=NC(R )=NER have a rich structural chemistry. The selenium derivatives 15.11a,b display a cis,trans,cis conformation with two short l,5-Se N contacts (2.65 A). Several sulfur analogues, e.g., 15.1c, have the same structure, but a different cis,trans,cis conformer 15.12 with two 1,4-S N contacts (2.83 A) has also been characterized. A third type of diazene is the trans,trans,trans isomer 15.13a,b with no intramolecular short contacts. ... 

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