- Convenient Synthesis of Symmetrical Polyfluorinated Diphenyl Sulfides
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Abstract: Thermal properties of decafluorodiphenyl disulfide in the pure state and in the presence of copper and iron metals have been studied. A procedure has been proposed for the synthesis of symmetrical poly-fluorinated diaryl sulfides from diaryl dis
- Bredikhin, R. A.,Maksimov, A. M.,Nikul’shin, P. V.,Platonov, V. E.
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p. 1921 - 1930
(2022/01/24)
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- Insight into the Mechanism of Reversible Ring-Opening of 1,3-Benzoxazine with Thiols
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The reversible ring-opening addition and fragmentation reaction of p-cresol-based N-phenylbenzoxazine with aliphatic and aromatic thiols was investigated in solvent-mediated and solvent-free reactions. Independently of the used thiol, N-phenylbenzoxazine and the thiols reacted to equilibrium with comparable amounts of reactants and products in aprotic solvent, whereas in protic solvent almost full conversions were reached. In contrast, thiol reactivity was a crucial factor in solvent-free reactions yielding fast and complete conversions for a more acidic thiol and balanced equilibrium concentrations in case of thiols with high pKa values. The strong influence of thiols with low pKa values emphasizes the relevance of the protonation step in the ring-opening reactions of 1,3-benzoxazines with thiols in absence of solvents where acidity predominates nucleophilicity. The reverse reactions, namely adduct dissociation and benzoxazine recovery, were successfully conducted at elevated temperatures and reduced pressure facilitated by the removal of the formed thiols yielding up to 95% recovered 1,3-benzoxazine. These results provide deeper understanding of the reversible ring-opening reaction mechanism of 1,3-benzoxazine with thiols.
- Urbaniak, Tobias,Soto, Marc,Liebeke, Manuel,Koschek, Katharina
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p. 4050 - 4055
(2017/04/27)
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- Organofluorine sulfur-containing compounds: V. Joint pyrolysis with chlorine or bromine of polyfluoroarenethioles, polyfluorohetarenethioles, and their derivatives
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Joint pyrolysis with chlorine and bromine of polyfluoroarenethiols, -hetarenethiols, and their derivatives at 300-650°C furnished polyfluorocompounds containing chlorine and bromine. 2005 Pleiades Publishing, Inc.
- Platonov,Maksimov,Dvornikova,Nikul'shin
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p. 1647 - 1653
(2007/10/03)
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- 3-Arylthio- and 3-aroxy-1-propynes and their reactions with amines
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3-Arylthio and 3-aroxy-1-propynes can be prepared by reaction of substituted 3-bromo-1-propynes with arylthio- and aroxytrimethylstannanes. Stannylation of 3-arylthio-1-trimethylsilyl-1-propynes with diethyl(trimethylslannyl)amine is accompanied by cleavage of the Si-Csp bond.
- Bogoradovskii,Maksimov,Zubova
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p. 1167 - 1172
(2007/10/03)
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- Elimination reactions of β-Cyano Thioethers: Evidence for a Carbanion Intermediate and a Change in Rate-Limiting Step
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The addition reactions of thiol anions to form adducts with acrylonitrile (1), 1-chloroacrylonitrile (2), and fumaronitrile (3) and the corresponding elimination reactions were examined in aqueous solution, generally containing 8.3percent Me2SO at 25 deg C.Deuterium exchange into the methanethiol and thiosalicylate adducts of 1 is faster than elimination.Deuterium exchange causes biphasic kinetics for elimination reactions in D2O of the p-nitrothiophenol, but not of the pentafluorothiophenol, adducts 1 and 2.The kinetic solvent deuterium isotope effects of knHOH/knDOD = 2.0 for addition of thiosalicylate to form 3 and 1.1-1.2 for addition of β-mercaptoethanol and thioacetic acid anions to form 1 are smaller than the product discrimination isotope effects of kH/kD = 3.2, 2.8 and 3.2 for these reactions.These differences show that the reactions proceed through a carbanion intermediate that is protonated faster than it expels basic thiol anions.These results exclude a concerted mechanism for addition-elimination with a concurrent, separate exchange reaction.The solvent kinetic deuterium isotope effect is 3.9 for the addition of thionitrobenzoate dianion to form 3.Buffer catalysis of elimination becomes more significant with more acidic leaving groups and is larger for 3 than for 1 with a given leaving group.The results show that the rate-limiting step changes from addition-elimination of the thiol anion to proton transfer with decreasing pKa of the thiol; the same change is favored by addition of CN to the α-position for a given thiol.The effect of the α-CN group is attributed to conjugation with the developing double bond in the transition state for elimination.The Broensted slope is β = 0.90 for rate-limiting deprotonation of the pentafluorothiophenol adduct 3 and Broensted-type plots against the pKa of the leaving group have slopes of β1g = -0.25 and -0.54 for predominantly rate-limiting deprotonation and leaving group expulsion, respectively.
- Fishbein, James C.,Jencks, William P.
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p. 5075 - 5086
(2007/10/02)
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- EVIDENCE FOR INTRAMOLECULAR CYCLOADDITION PROCESS IN THE PHOTO-CLAISEN REARRANGEMENT
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Photoreaction of pentafluorophenyl-prop-2-enyl ether in cyclohexane at λ=253.7 nm resulted in intramolecular cycloaddition, forming 2,3,4,5,6-pentafluoro-1,8-epoximethano bicycloocta-2,4-diene, while a similar reaction of the thio analogue led to C - S bond cleavage.
- Sket, Boris,Zupancic, Natasa,Zupan, Marko
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p. 753 - 754
(2007/10/02)
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- HIGH-TEMPERATURE ORGANIC SYNTHESIS. XXVII. REACTIONS OF ALKANETHIONES WITH THE CHLORINE DERIVATIVES OF BENZENE, THIOPHENE, AND NAPHTHALENE
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Alkanethiols react effectively with chlorobenzene, its derivatives, 1-chloronaphthalene, and 2-chlorothiophene at 600-660 deg C with the preferential formation of the corresponding aromatic or heteroatomic thiols.Ethanethiol is most reactive.When it is used instead of hydrogen sulfide in reactions with chlorobenzene or its 4-substituted derivatives, the yield of the aromatic thiols, from which the phenylthiyl radicals are generated with greater difficulty, increases more sharply than the yield of the thiophenols, which generate the more stable 4-XC6H4S radicals.The side products of the reactions are the corresponding diaryl sulfides, thiophene, benzothiophene, and toluene.
- Voronkov, M. G.,Deryagina, E. N.,Sukhomazova, E. N.
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p. 755 - 760
(2007/10/02)
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- REACTION OF AROMATIC COMPOUNDS WITH NUCLEOPHILIC REAGENTS IN LIQUID AMMONIA. II. NUCLEOPHILIC SUBSTITUTION IN NITROHALOGENO AND POLYFLUORINATED AROMATIC COMPOUNDS
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The possibility of aromatic nucleophilic substitution in liquid ammonia was investigated for the case of the reaction of p-nitrochlorobenzene, 2,4-dinitrochlorobenzene, hexafluorobenzene, bromopentafluorobenzene, pentafluorobenzene, and octafluoronaphthalene with a series of charged nucleophiles (potassium hydroxide and sulphite, alcoholates, sodium azide, thiophenolate, phenolate, and sulfide) at -70 to -33 deg C.It was shown that alkyl ethers of p-nitrophenol, phenyl p-nitrophenyl sulfide, 2,4-dinitrophenyl azide, polyfluorinaqted phenols, and their ethers can be obtained with good yields.Comparisons of the results with published data on the rate of the same reactions in other solvents shows that liquid ammonia is highly effective as a solvent for aromatic nucleophilic substitution reactions and in some cases makes it possible to avoid side processes.
- Shtark, A. V.,Kizner, T. A.,Shteingarts, V. D.
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p. 2051 - 2056
(2007/10/02)
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- HIGH TEMPERATURE ORGANIC SYNTHESIS. XIX. MECHANISM OF HIGH-TEMPERATURE REACTION OF AROMATIC CHLORINE DERIVATIVES WITH HYDROGEN SULFIDE
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Quantum-chemical calculations were made in the CNDO/2 approximation for para-substituted chlorobenzene and thiophenol, and the x-ray fluorescence Kα and Kβ spectra of the sulfur in the latter were obtained.The electronic structure parameters of these compounds were compared with their reactivity in high-temperature processess.The reactivity of 4-substituted chlorobenzenes in reaction with hydrogen sulfide in the gas phase correlates with the electron density at the chlorine atom of the chlorine derivative.The direction of this process (the formationof the corresponding thiophenol or diaryl sulfide) is determined by the ability of the thiophenol formed at the first stage to generate sufficiently stable phenylthiyl radicals.The latter are stabilized by a mechanism of ?-conjugation, and the stability increases with increase in the ?-donating character of the para substituent in the aromatic ring. ?-Accepting substituents destabilize the phenylthiyl radicals, increasing the selectivity of the process leading to the production of the respective thiophenol.
- Voronkov, M. G.,Deryagina, E. N.,Dolenko, G. N.,Ivanova, G. M.,Sukhomazova, E. N.,et. al.
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p. 2095 - 2101
(2007/10/02)
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