- The 1,4-dithiin ring opening in 1,4-dithiinodiquinolines as a route to quinoline crown thioethers
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Quinoline crown thioethers (7) and (8) with 8-, 9-, 10-, 11-, 12-, 18-, 20-, 21- and 24-membered macrocyclic thiacrown ring were obtained by the 1,4- dithiin ring opening in 1,4-dithiinodiquinolines (1) and (2) with divalent sulfur nucleophiles followed by S-alkylation with divalent alkylating agents. Thiacrowns (7) and (8) contain two or four quinoline units.
- Pluta, Krystian
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p. 2861 - 2870
(2007/10/03)
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- EFFECT OF VICINAL SUBSTITUENTS ON THE REACTIVITY IN BIMOLECULAR NUCLEOPHILIC SUBSTITUTION AT A SATURATED CARBON ATOM. TWO TYPES OF SUBSTITUENTS II. KINETICS OF THE REACTION OF THIOUREA WITH β-SUBSTITUTED BROMOETHANES IN ETHANOL
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The kinetics of the reaction of thiourea with β-substituted bromoethanes in ethanol were studied by radiochromatography.The rate constants and activation parameters of the reactions were determined.It was shown that an isokinetic relationship is observed for the two types of substituents.The mechanisms of the effect of the vicinal substituents on the reactivity are discussed.
- Ryazantsev, G. B.,Shaposhnikov, A. V.,Fedoseev, V. M.
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p. 1777 - 1782
(2007/10/02)
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- EFFECT OF VICINAL SUBSTITUENTS ON REACTIVITY IN BIMOLECULAR NUCLEOPHILIC SUBSTITUTION AT A SATURATED CARBON ATOM. TWO TYPES OF SUBSTITUENT I. KINETICS OF THE REACTIONS OF THIOUREA WITH β-SUBSTITUTED BROMOETHANES IN DIMETHYLFORMAMIDE
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The kinetics of the reaction of thiourea with β-substituted bromoethanes in DMFA were studied by radiochromatography.It was shown that there is no isokinetic relationship or Taft equation for all the substituents but that there are isokinetic relationships for two separate reaction series, one of which is described satisfactorily by a Taft equation taking account of the inductive and steric effects of the substituents.On the basis of the obtained data it is supposed that there are two types of vicinal substituents, which affect the reactivity of the bromine at the saturated carbon atom by different mechanisms.For the first type of substituent (H, F, Br, CH3, C6H5) the main factors determining the reactivity are the inductive and steric effects of the substituents.Substituents of the second type (COOH, COOC2H5, CN, NH3Br, SC(NH2)2Br) include charged or highly polar substituents, and this makes it possible to expect a field effect, leading to additional stabilization of the transition state.
- Ryazantsev, G. B.,Lys, Ya. I.,Fedoseev, V. M.
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p. 776 - 779
(2007/10/02)
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- ORGANIC SYNTHESIS USING PTC-5: NUCLEOPHILIC AROMATIC SUBSTITUTION UNDER LIQUID-LIQUID AND SOLID-LIQUID PHASE TRANSFER CONDITIONS.
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The reaction of 1-chloro-4-nitrobenzene (1) with dithiols generated in situ from thiouronium salts (2) under PT conditions, which in turn have been procured by the reaction of appropriate α,ω-dibromoalkanes with thiourea have been investigated.The reactions of (1) with various diols have also been investigated and their reaction mechanism is discussed.
- Singh, Paramjit,Arora, Geeta
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p. 2625 - 2632
(2007/10/02)
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- Synthesis of Oxygen and Sulphur Containing Crown Compounds under Solid-Liquid Phase Transfer Catalysis
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Sulphur containing crown compounds and podands have been synthesized by intermolecular nucleophilic displacements of tosylates with thiolate ions generated in situ under solid-liquid phase transfer catalysis.
- Singh, Paramjit,Kumar, Manoj,Singh, Harjit
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p. 861 - 862
(2007/10/02)
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- S-DERIVATIVES OF THIOUREA. XX. REACTION OF THIOUREA WITH TERMINAL DIBROMOALKANES
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The kinetics of the reaction of thiourea with terminal dibromoalkanes Br(CH2)nBr, where n= 1-5, were investigated by radiochromatography.It was established that the reaction of thiourea with 1,4-dibromobutane and 1,5-dibromopentane leads to the formation of only products from substitution of one or two bromine atoms by thiourea.In the case of 1,2-dibromoethane and 1,3-dibromopropane 2-amino-2-thiazoline and 2-amino-5,6-dihydro-4H-1,3-thiazine were found in addition to the analogous substitution products.The rate constants of the individual stages of the processes were determined.A series of S-bromoalkylisothioureas Br(CH2)nSC+.(NH2)2Br-, where n= 2-5, were synthesized.It was shown that the rate of their reaction with thiourea is higher than for terminal dibromoalkanes and (for n= 3-5) alkyl halides Br(CH2)nH.It was found that the reactivity varies irregularly with increases in the length of the polymethylene chain for bromoalkylisothioureas, and this evidently results from the superimposition of several effects from the substituent.
- Tkachenko, S. E.,Sal'nikov, D. I.,Lys, Ya. I.,Fedoseev, V. M.,Zhurilin, V. S.
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p. 878 - 884
(2007/10/02)
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- REACTION OF THIOUREA WITH α-SUBSTITUTED VICINAL DIBROMIDES
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In the reaction of thiourea with vicinal dibromides containing an aryl or carbonyl substituent at the α position to both bromine atoms in the presence of acetone 2,6-diamino-4,4-dimethyl-1,3,5-perhydrothiadiazine dihydrobromide is formed.Substitution of one of the substituents in the dibromide by a nitro group greatly changes the character of the transformations of thiourea.The presence of a carbonyl substituent at only one of the bromine atoms does not prevent retention of the diisothiuronium structure which forms.
- Mizrakh, L. I.,Polonskaya, L. Yu.,Ivanova, T. M.
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p. 240 - 243
(2007/10/02)
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