- Thiylation of polyelectrophiles with sulfur in hydrazine hydrate-amine systems
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Thiylation of polyhaloalkanes and Paraform with elemental sulfur activated in hydrazine hydrate-organic amine systems is performed. Monoethanolamine, triethanolamine, and triethylamine were used as amines. The reactions gave thiocols of various structures. The products were characterized by elemental analysis and IR spectroscopy. Reductive cleavage of the synthesized thiocols was performed to obtain di- and polythiols. 2005 Pleiades Publishing, Inc.
- Deryagina,Levanova,Grabel'nykh,Sukhomazova,Russavskaya,Korchevin
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p. 194 - 199
(2007/10/03)
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- Reactions of bielectrophiles (ClCH2CH2)2Y with sulfur in basic reducing systems
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A simple procedure was developed for preparing bis(β-mercaptoethyl) ether and bis(β-mecraptoethyl) sulfide from commercially available chemicals: elemental sulfur, alkali, and bis(β-chloroethyl) ether or sulfide, based on thiylation with elemental sulfur of these substrates in the aqueous system hydrazine hydrate-alkali, with initial formation of the corresponding polysulfide polymers (thiokols). Their reduction with the system hydrazine hydrate-alkali, followed by acidification of dithiolate anions, yields the corresponding dithiols. Thiokols based on bis(β-chloroethyl) ether are soluble in organic solvents; they were studied by 1H NMR.
- Korchevin,Russavskaya,Alekminskaya,Deryagina
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p. 240 - 243
(2007/10/03)
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- Reduction of thiokols in the system hydrazine hydrate-base as a new route to alkanedithiols
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A new procedure for preparative synthesis of alkanedithiols from simple commercially available products is based on reduction of the S-S bond in appropriate polyalkylene disulfides (thiokols) in the system hydrazine hydrate-base. Thiokols were prepared by reaction of dihaloalkanes with Na2S2 or K2S2 generated from elemental sulfur and alkali in aqueous hydrazine hydrate. Reaction of 1,2-dibromocyclohexane with sodium or potassium disulfide yields bis(2-bromocyclohexyl) sulfide as the only product.
- Alekminskaya,Russavskaya,Korchevin,Deryagina,Trofimov
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p. 732 - 737
(2007/10/03)
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- Reduction of thiocols to alkanepolythiols with benzeneselenol
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Heating of benzeneselenol with polymethylene disulfides to 40-120°C results in formation of the corresponding alkanedithiols or alkanetrithiols and diphenyl diselenide. Poly(tetramethylene disulfide) reacts with benzeneselenol to give 1,2-dithiane and diphenyl diselenide. A radical mechanism of this reaction is discussed.
- Shilkina,Papernaya,Deryagina
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p. 263 - 265
(2007/10/03)
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- A general and mild synthesis of thioesters and thiols from halides
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The conversion of a wide variety of halides to thioesters by reaction with potassium thiocetate under mild conditions is described, and the generality of the method is demonstrated.
- Zheng, Tu-Cai,Burkart, Maureen,Richardson, David E.
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p. 603 - 606
(2007/10/03)
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- Photosensitized cleavage of the dithio protecting group by visible light
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Dithio derivatives of aldehydes and ketones have been deprotected under neutral conditions using visible light provided by a 120 Watt spotlight and methylene green as a sensitizer. The key step in the deprotection is apparently an electron transfer from the dithio derivative to the electronically excited visible dye. The resulting dithio radical cation undergoes fragmentation, and the corresponding aldehydes and ketones are isolated in excellent yields.
- Epling, Gary A.,Wang, Qingxi
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p. 5909 - 5912
(2007/10/02)
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- CONVERSION OF CYCLIC TRITHIOCARBONATES TO THIOACETALS, INCLUDING 1,3-DITHIANE, BY REDUCTION WITH DIISOBUTYLALUMINIUM HYDRIDE (DIBAL)
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Cyclic trithiocarbonates can be desulfurized with diisobutylaluminium hydride (DIBAL) to form the corresponding thioacetals.This new synthetic pathway was exploited for the preparation of several Umpolung reagents, including 1,3-dithiane.An efficient isolation of sodium trithocarbonate is described.
- Jordis, Ulrich,Rudolf, Manfred
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p. 279 - 284
(2007/10/02)
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- STUDIES ON THE REACTIONS OF SELENITE ION WITH 1,2-DIMERCAPTOETHANE OR THIOACETIC ACID
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The reactions are reported between selenite and 1,2-dimercaptoethane (DME) or thioacetic acid (TAA) to form moderately stable derivatives having an enhanced absorptions in the 230-360 nm region in combining molar ratios 3:2 and 4:1, respectively.Both reactions invariably yield one product corresponding to the selenium-containing derivative of DME or TAA.The formation of products is a pH dependent process.The equilibrium constants of reactions between selenite and DME or TAA were measured.
- Czauderna, Marian,Samochocka, Krystyna
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p. 2421 - 2423
(2007/10/02)
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- A Kinetic Study of the Soft Metal Ion-promoted Hydrolyses of Some S-Acetals
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The S-acetals (III)-(VII) hydrolyse readily in aqueous ethanol or in aqueous dioxan solutions containing an excess of Tl3+ or Ag+ ions to give benzophenone and the appropriate sulphide.The hydrogen-ion catalysed hydrolyses are very slow by comparison and the supposedly soft ions Cd2+ and Cu2+ have even less effect than H3O+.Kinetic and spectroscopic studies of the hydrolyses, mainly at 25 deg C, show that the Tl3+-promoted reactions occur via the rapid formation of a 1 Tl3+ : 1-S-acetal adduct.This adduct is formed stoicheiometrically with (IV), (V), and(VII), but in small amounts with (III) and (VI).The tripositive adduct probably reacts with water in the slow step of the overall hydrolysis.This adduct can also lose charge by proton dissociation from hydroxy groups in the bound S-acetal, or from thallium-bound water.The resulting dipositive adducts, however formed, hydrolyse much less rapidly than the tripositive adducts.The (chelated) dipositive adduct from (V) is sufficiently stable for contributions to hydrolysis from a 4+ adduct to be detected.The Ag+-promoted hydrolyses proceed principally via small amounts of rapidly formed dipositive 2 Ag+ : 1-S-acetal adducts.For (V), where loss of a carboxy proton can occur, the formation constant of the monopositive + adduct is very large (K ca. 107 l mol-1) but that of the dipositive adduct is small, as for the other S-acetals.With (V) and (VI) the 1 Ag+ : 1-S-acetal adduct is formed stoicheiometrically and with (IV) its formation constant is large (K ca, 900 l mol-1).For (III), (IV), (VI), and (VII) these 1:1 adducts contribute significantly to the hydrolysis at low silver ion concentrations.For both the Tl3+-and the Ag+-promoted reactions the effects of ionic strength are consistent: where more charged adduct can form an increase in ionic strength increases the reaction rate; where adduct formation is complete, changes in ionic strength have little effect on the rate.The S-acetals display wide (up to 105-fold) differences in reactivity towards hydrolysis and their sequence of reactivity alters markedly with the promoting ion.With both ions (VI) hydrolyses relatively slowly.For all the substrates Tl3+ is a better promoter than Ag+.Exact comparisons of reactivity are impossible owing to the differences in mechanistic detail and in solvent.In view of its soft acid character Tl3+ is surprisingly more acidic towards the O-containing acetals than towards those having just two S atoms.For (IV) and Ag+ the establishment of the pre-equilibrium giving the 1 Ag+ : 1-S-acetal adduct is slow enough at 25 deg C to be followed by stopped-flow spectroscopy.
- Satchell, Derek P. N.,Weil, Thomas J.
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p. 1191 - 1200
(2007/10/02)
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- Novel polytriazine compounds
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Novel tetraalkyl piperidine radical containing polytriazine compounds are produced by reacting a dihalogen-triazine with a bifunctional compound containing amine, alcohol, mercaptan or phenol groups at least one of the bifunctional compounds containing a tetraalkyl piperidine radical. The compounds are valuable light stabilizers for synthetic polymers, particularly polyolefin in the form of fibers or films.
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- Ethylenic silicon compounds and thermoplastic elastomers obtained therefrom
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The invention provides organosilicon compounds of the formula: STR1 in which: N IS 1, 2 OR 3; Each R, which may be identical or different, is a monovalent organic group which contains a carbon-carbon double bond and from 2 to 10 carbon atoms; Each R1, which may be identical or different, is a straight or branched alkyl radical optionally substituted by one or more halogen atoms or cyano groups; an aryl radical or an alkylaryl radical optionally substituted by one or more halogen atoms; R2 is a straight or branched divalent alkylene or alkylidene radical possessing up to 4 carbon atoms; X is a divalent radical consisting of, or containing, at least one hetero-atom selected from oxygen, sulphur and nitrogen atoms, the radical being attached to the radical R2 via a said hetero-atom; G is an organic radical of valency (m+ l) possess from 1 to 30 carbon atoms; m is 1, 2 or 3; And each Y, which may be identical or different, is a functional group selected from: --NO2, STR2 --COOM (where M represents a sodium, potassium or lithium atom); --COOR4 ; STR3 --COCl; --OH; --OR4 ; STR4 --SH; --SR4 ; STR5 --CONH2 ; --CSNH2 ; --CN; --CH2 --NH2 ; --CHO; STR6 --NCO; STR7 wherein R3 represents a hydrogen atom or a straight or branched alkyl radical possessing up to 6 carbon atoms and R4 represents an alkyl radical possessing up to 4 carbon atoms, with the proviso that two Y groups can together constitute an imide group STR8 wherein R5 represents a hydrogen atom or a straight or branched alkyl radical possessing up to 4 carbon atoms. These are useful intermediates in the preparation of disilanes and silicon polymers, in particular of polyethylenic silicon compounds which can be polymerized with an α, ω-dihydrogenopolysiloxane to give thermoplastic elastomers.
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- Pesticidal compositions containing phosphoric esters and divalent sulphur compounds
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Pesticidal composition comprising: a pesticidal, phosphoric ester the molecule of which has at least one alkyl group of 1 to 3 carbon atoms, 0.05 to 10% of an agent stabilizing the said ester against decomposition by protonisation, together with adjuvants characterized in that the stabilizing agent comprises at least one sulphur compound containing per molecule at least one divalent sulphur atom of which one valence is bonded to an atom chosen from sulphur, carbon, nitrogen, hydrogen, and metals capable of giving a salt, the other valence being bonded to an atom chosen from hydrogen, the carbon atom already noted, a second carbon atom, the nitrogen atom already noted, a second nitrogen atom, the metal atom already noted in the case of a metal of valence greater than one, a second atom of metal and oxygen when the first valence is not attached to an atom of hydrogen, the proportion of sulphur calculated with reference to the weight of the sulphur compound being between 5 and 99%. Process for stabilizing a phosphoric ester of which the molecule possesses at least one alkyl group containing 1 to 3 carbon atoms characterized in that there is added to the phosphoric ester or to a mixture which contains it, 0.05 to 10% calculated on the weight of the phosphoric acid ester of an agent capable of stabilizing the said phosphoric ester against protonisation and comprising at least one sulphur compound such as that defined thereupon.
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