4396-19-4

The reductive destruction of poly(methylene sulfides) and poly(methylene polysulfides) in the system hydrazine hydrate - NaOH at 70-115°C involves cleavage of the C-S bond and the formation of sulfide, disulfide and trisulfide unions. Nitrogen and methane

Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(p-Tol) betaine adduct (1a) and its cationic derivatives2aand3aas catalyst precursors for the dichloromethane valorization via transformation into high added value products CH2Z2(Z = OR, SR or NR2). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles Na+Z-(preformed or generatedin situfrom HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity. The reactions are conducted in a multigram-scale under very mild conditions, using dichloromethane both as a reagent and solvent, and very low catalyst loading (0.01 mol %). The CH2Z2derivatives were isolated in quantitative yields after filtration and evaporation, which facilitates recycling the dichloromethane excess. Mechanistic studies for the synthesis of methylal CH2(OMe)2rule out organocatalysis as being responsible for the CH2transfer, and a phase-transfer catalysis mechanism is proposed instead. Furthermore, we observed that1aand2areact with NaOMe to form unusual isoureate ethers, which are the actual phase-transfer catalysts, with a strong preference for sodium over other alkali metal nucleophiles.

The acidity ladder scale in [BMPY][NTf2] was successfully expanded toward the weak acidity region for about five more pK units compared to the previously established one. This allows the acidities of a series of 13 aliphatic and aromatic nitroalkanes to be determined accurately by the UV-vis spectroscopic method. The acidity of nitroalkane in [BMPY][NTf2] covers ～8 pK units and is significantly weaker than those in DMSO and water. The Hammett plot for 4-substituted phenylnitromethanes shows an excellent linearity with a slope of 2.06, which is rather close to that in DMSO but significantly larger than that in water (0.80). The regression analyses reveal that the solvation behavior of [BMPY][NTf2] on the acidic dissociations of C-H acids is similar to that of DMSO.

An investigation into the dependence of the framework formation of coordination architectures on ligand spacers and terminal groups was reported based on the self-assembly of AgClO4 and eight structurally related flexible dithioether ligands, RS(CH2)nSR (L an, R = ethyl group, Lbn, R = benzyl group, n = 1-4). Eight novel metal-organic architectures, [Ag(L a1)3/2ClO4]n (1a), [Ag2(La2)2(ClO4) 2]2 (2a), [AgLa3ClO 4]n (3a), {[Ag(La4) 2]ClO4}n (4a), [AgLb 1ClO4]2 (1b), [Ag(Lb 2)2]ClO4 (2b), {[Ag(Lb 3)3/2(ClO4)1/2](ClO 4)1/2}n(3b) and [Ag(Lb 4)3/2ClO4]n (4b), were synthesized and structurally characterized by X-ray crystallography. Structure diversities were observed for these complexes: 1a forms a 2-D (6,3) net, while 2a is a discrete tetranuclear complex, in which the Ag1 ion adopts linear and tetrahedral coordination modes, and the S donors in each ligand show monodentate terminal and μ2-S bridging coordination fashions; 3a has a chiral helical chain structure in which two homo-chiral right-handed single helical chains (Ag-La3-)n are bound together through μ2-S donors, and simultaneously gives rise to left-handed helical entity (Ag-S-)n. In 4a, left- and right-handed helical chains formed by the ligands bridging Ag1 centers are further linked alternately by single-bridging ligands to form a non-chiral 2-D framework. 1b has a dinuclear structure showing obvious ligand-sustained Ag Ag interaction, while 2b is a mononuclear complex; 3b is a 3-D framework formed by ClO4- linking the 2-D (6,3) framework, which is similar to that of 1a, and 4b has a single, double-bridging chain structure in which 14-membered dinuclear ring units formed through two ligands bridging two Ag 1 ions are further linked by single-bridging ligands. In addition, a systematic structural comparison of these complexes and other reported AgClO4, complexes of analogous dithioether ligands indicates that the ligand spacers and terminal groups take essential roles on the framework formation of the Ag1 complexes, and this present feasible ways for adjusting the structures of such complexes by modifying the ligand spacers and terminal groups.

One-pot synthesis of dithioacetals as well as an efficient method for oxathioacetal is reported. Additionally, some chiral auxiliaries were used to synthesize enantiomerically pure dithioacetals and oxathioacetals.

A convenient preparative synthesis of bis(organylthio)alkanes was developed. It is based on alkylation with dihaloalkanes of solutions of diorganyl disulfides in the basic reductive system hydrazine hydrate-alkali. The generation of organylthiolate anions

Two methods of synthesis of bisethylthiopolymethylene sulfides RS(CH2S)nR (R = Et, n >= 1) are developed. Both approaches are based on the reductive cleavage of the S-S bonds in diethyl polysulfides or a mixture of diethyl polysulfides with elementary sulfur by the system: hydrazine hydrate-base. Subsequent alkylation of the formed thiolate anions with dichloromethane leads to the formation of mixtures of oligomeric bisethylthiopolymethylene sulfides with a predominance of compounds with n = 1, 2.

A convenient efficient procedure for the synthesis of thiomethyl sulfides and their reactions with enantiomerically pure (camphorsulfonyl) oxaziridines results in formation of enantioselective monosulfoxides.

Seven aryl-substituted derivatives of bis(ethylsulfonyl)methane have been synthesized and studied thermodynamically and kinetically in aqueous solution with respect to proton abstraction from the central carbon atom.The acidities of the six carbon acids are in the range pKA 10-12.The relaxation times of the reactions were studied by a spectrophotometric temperature-jump technique (hydroxide ion and phenolates as proton acceptors) and are in the microsecond range.The rates of bromination of the various carbanions have also been studied (potentiometrically) and the reactions are shown to be almost diffusion-controlled, with no marked trend with aromatic substituent.A small chemical activation may be due to a steric effect by the two sulfonyl groups.The rates of deprotonation, however, show considerable chemical activation, i.e., intrinsic rates are 3-4 orders of magnitude lower than for normal acids, indicating partial delocalization of the negative charge on the carbanion.This effect is somewhat larger than for cyano-activated carbon acids but considerably smaller than for carbon acids activated by carbonyl or nitro groups.It is concluded that sulfonyl groups interact with carbanions primarily by polar effects, but also, to some extent, mesomerically.The degree of mesomerism is, however, uncertain because part of the intrinsic barrier may derive from steric effects, as is also observed for bromination.

The complexes (M=Cr, R=Et, iPr, t-Bu; M=W, R=Me, Et, iPr, t-Bu) were synthesised.Total bandshape NMR analysis was used to measure energies of inversion of the coordinated S atom in the tungsten complexes. ΔG (298.15 K) values were in the range 34-42 kJ mol-1.An X-ray structure of was obtained.

1,1-Di(alkylthio)alkanes, 1,3-oxathiolanes, 1,3-dithiolanes, and ortho thioesters are cleaved by triethylsilane in the presence of catalytic amounts of zinc iodide or reduced nickel.In the presence of zinc iodide the acyclic dithioacetals and ortho thioester are converted into alkyl sulfides and triethyl(alkylthio)silanes by cleavage of the carbon-sulfur bond.The analogs of the cyclic acetals are cleaved by triethylsilane only in the presence of reduced nickel, while regiospecific cleavage of the heterocycle at the carbon-oxygen bond is observed in 1,3-oxathiolanes.The cleavage of the 1,3-dithiolanes takes place by a more complicated mechanism with the formation of the disilyl ether of ethanediol, hexaethyldisilylthiane, and triethyl(alkylthio)silanes.The cyclic ortho thioester reacts with triethylsilane both at zinc iodide and at reduced nickel with the formation of the products from preferential cleavage of the exocyclic bond.

+ reacts with the ligands L-L and L-L-L to give the cations + (L-L= RS(CH2)nSR, 1,4-dithiane) and + (L-L-L= 1,3,5-trithiane, tris(methylmercapto)methane) containing monodentate coordinated sulfur ligands.In a similar way, sulfur ligand bridged dinuclear dications 2+ and 2+ and trinuclear trications 3+ are formed.Irradiation of the mononuclear cations gives the chelate complexes 2-L-L)>+.

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Under stirred-flow conditions, the title compounds pyrolyze to yield propene and the ethyl, allyl and benzyl dithioformates, respectively, as reaction products.The first order rate coefficients of these unimolecular decompositions followed the Arrhenius equations: 4,6-dithia-1-octene: k(sec-1) = 1010.85+/-0.18exp(-142+/-2kJ/mol RT), 4,6-dithia-1,8-nonadiene: k(sec-1) = 1010.45+/-0.34exp(-132+/-4kJ/mol RT), 4,6-dithia-6-phenyl-1-hexene: k(sec-1) = 1010.09+/-0.43exp(-130+/-5kJ/mol RT).The activation parameters are discussed in relation to those of other allyl sulfides.These suggest that a sulfur atom can stabilize the transition state to the same extent as a ?-electron system.

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Compounds containing a 1,1,1-tribromoethyl group are normally dehydrobrominated by reaction with sodium thiolates.If a 1,1,1-tribromobut-3-ene fragment is present cyclisation to a 2,2-dibromocyclopropylmethyl thioether or rearrangement are also observed.

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Acyclic acetals and 1,1-di(alkylthio)alkanes enter into exchange reactions in the presence of aprotic acids and of the KU-2 cation-exchange resin with the formation of the unsymmetric acetals and 1-alkoxy-1-alkylthioalkanes.In reaction with ethylal di(ethylthio)methane forms 3,5,7-trioxanonane in addition to ethylthioethoxymethane. 2-Methyl-4-thia-2-hexene was found in the products from the reaction of 1,1-di(ethylthio)-2-methylpropane with methylal.

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