Transalkylation of alkyl aryl sulfides with alkylating agents

The reaction of methyl iodide with tert-butylphenylsulfide in DMF leads to a transalkylation that produces methylphenylsulfide. This transalkylation reaction was further studied by ¹H NMR spectroscopy. The polarity of the solvent, the electron density on the sulfur atom, and the strength of the alkylating agent (MeI, EtI, BuI, dimethyl sulfate, or dimethyl carbonate) played important roles in the reaction. The suggested mechanism of the reaction involves the formation of a dialkyl aryl sulfonium salt that subsequently eliminates the radical. This mechanism was supported by the observation of higher conversion rates for compounds with more branched alkyl groups on the sulfur atom, which may lead to the formation of more stable radicals.     

Oxidative transformations of alkyl caryophyllanyl sulfides

Sesquiterpene sulfoxides and sulfones were synthesized in up to 56 and 74% yields, respectively. The oxidation of sulfides was accompanied by rearrangement of the epoxide fragment to allylic alcohol with subsequent oxidation. The isomerization of 4,5-epoxycaryophyllane-15-thiol afforded for the first time 4,11,11-trimethyl-8-(sulfanylmethyl)bicyclo[7.2.0]undec-3-en-5-ol in 40–45% yield.     

Reactions of alkyl furfuryl ethers and sulfides with n-butyllithium

The direction of the reaction of alkyl furfuryl ethers and sulfides with n-butyllithium is in agreement with the results of basic H-D exchange in the same compounds: In the case of the ethers H-D exchange and metallation take place primarily in the free a position of the furan ring, whereas in the case of the sulfides these reactions take place primarily at the methylene group of the side chain located between the sulfur atom and the furan ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 744–746, June, 1984.     

Differential thermoanalytical studies of frozen ferrous perchlorate solutions

It is inferred from the thermoanalytical data obtained on 0.2–4.0M solutions of Fe(ClO₄)₂ which are frozen under non-equilibrium conditions that the phase containing the solute ions turns into a glassy state below –95°. On the warming of these solutions exothermic and endothermic processes are observed which can be related to the effects observed by the nuclear gamma resonance method.

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Zusammenfassung Es wurde über thermoanalytische Versuche mit gefrorenen Lösungen von Fe(ClO₄)₂ von 0.2 bis 4.0M Konzentration berichtet, die unter Nichtgleichgewichtsverhältnissen zum Einfrieren gebracht worden waren. Es zeigte sich aus den thermoanalytischen Daten, daß die gelöste Ionen enthaltende Phase in einen glasartigen Zustand unter –95° übergeht. Beim Erwärmen dieser Lösungen beobachtete man exothermische und endothermische Vorgänge, die mit den durch Nukleargamma-Resonanz gefundenen Effekten in Einklang gebracht werden konnten.

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Résumé L'étude thermoanalytique de solutions congelées de Fe(ClO₄)₂ montre que pour les solutions dont la concentration du soluté varie de 0.2 à 4.0M, et qui sont congelées sous des conditions de non-équilibre, la phase contenant les ions dissous se transforme en un état vitreux au-dessous de –95°. En chauffant ces solutions, on a observé des processus endothermiques et exothermiques qui peuvent être reliés aux effets mis en évidence par la méthode de résonance nucléaire gamma.

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Fe(ClO₄)₂ 0,2–4,0M. , , , , , –95°C. , , - ( ).

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The authors are indebted to Prof. M. Kaplan (Yale University) and to Dr. L. Keszthelyi for stimulating discussions, and to Mr. I. Klimm, Miss J. Nyeste and Mr. T. Grünstein for their assistance in the measurements.     

Oscillatory behavior during the oxygen oxidation of ascorbic acid

The oscillatory phenomenon was observed in aqueous solution during the oxidation of ascorbic acid by oxygen. Even though the exact number and amplitude of the oscillations could not be exactly duplicated for each and every run, such factors as temperature, concentration of ascorbic acid, cupric ions, and pH affecting the oscillatory behavior were studied, and those regions where oscillations occurred were delineated. A mechanism consistent with the oscillatory behavior is proposed and discussed.     

Selective trifluorination of alkyl aryl sulfides using IF5

In the reaction of IF₅ with alkyl aryl sulfides in heptane under reflux conditions, the arylthio group migrated once and three fluorine atoms were selectively introduced on the alkyl chain. In order to find the reason why the reaction stopped at the trifluorination step, we examined the oxidation potentials of the starting material, a reaction intermediate, and the product, and the time course of the reactions.     

Molecular vibrations and force fields of alkyl sulfides: Part XV. C-S stretching vibrations of aliphatic alkyl sulfides

The C-S stretching vibrations of 28 aliphatic sulfides including one thiol are summarized, and all of the C-S stretching bands are classified into several groups. An extraordinarily low frequency associated with the ethyl group is discussed briefly.     

Reaction of 2,3-epoxypropyl alkyl sulfides with carboxylic acids and phenol

Russian Chemical Bulletin -     

Acid-catalyzed hydrolysis of alkyl vinyl and propenyl sulfides

The rates of acid-catalyzed hydrolysis of methyl, ethyl, isopropyl, and t-butyle vinyl sulfides have been measured in 10% aqueous acetonitrile. It was found that their reactivities decrease in this order. General acid catalysis was observed. The rate was smaller in a deuterium medium (k_D2O/k_H2O = 0.34). The deuterium exchange between sulfide and solvent was not detected during hydrolysis. Some propenyl sulfides have also been studied, their cis isomers being more reactive than the trans counterparts without geometrical isomerization involved. The reaction mechanism and the substituent effects on the reactivity have been discussed.     

Reaction of singlet oxygen with some benzylic sulfides

Product distribution, total quenching rate (k_T), and rate of chemical reaction (k_r) with singlet oxygen have been determined for some alkyl, benzyl, α-methylbenzyl, and cumyl sulfides. Their contributions depend on the steric hindering around the sulfur atom. In protic solvents, the sulfoxide is the main product via a hydrogen-bonded persulfoxide. In apolar solvents, intramolecular α-H abstraction leads to oxidative C-S bond cleavage, with varying efficiency. The behavior of sulfides is compared to that of alkenes and amines.     

Thallic perchlorate in acid medium as a reagent for oxidimetric determination of ascorbic acid in drugs and fruit

Thallic perchlorate is used for determination of ascorbic acid either by direct titration in acid medium (0.5N) or indirectly by addition of excess of the reagent and iodometric determination of the excess. The method is applicable to fruit juices and vitamin C tablets.     

Reactivity of tert-butoxy radicals towards thiols,alkyl sulfides,and alkyl disulfides

Rate constants for the reactions of tert-butoxy radicals (generated by the thermal decomposition of di-tert-butylperoxyoxalate) with several sulfur containing compounds have been measured at 310 K in benzene. Hexanethiol (k = 6.5 × 10⁷M^?1s^?1) reacts considerably faster than alkyl sulfides and disulfides. For these compounds the reaction rate constants are slightly dependent on the α-hydrogen type, changing (when it is expressed per hydrogen atom) only a factor 5 for sulfides and 3 for disulfides when the α-hydrogen is changed from primary (methyl) to tertiary (isopropyl). The data obtained are compared to those found for the deactivation of the benzophenone triplet. Values of k_tert-butoxy/k_benzophenone range from ca 10^?3 (di-tert-butyl disulfide) to 7.5 (hexanethiol). The results obtained are rationalized in terms of bond strength, steric hindrance, and charge transfer contributions to the critical configuration energies.     

Synthesis of β-phenylvinyl alkyl sulfides from isothiuronium salts

Conclusions A method was developed for the thiylation of phenylacetylene with S-alkylisothiuronium salts, which made it possible to obtain cis--phenylvinyl alkyl sulfides in high yield, in which connection the stereospecificity of the process is independent of the solvating capacity of the solvent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 213–214, January, 1979.     

Biomimetic activation of the C-H bond. 1. Oxygenation of hydrocarbons by atmospheric oxygen in the presence of metal chlorides and ascorbic acid or glucose

Oxygenation of hydrocarbons by atmospheric oxygen is initiated by FeCl₃, CuCl₂, and NaAuCl₄ in aqueous acetonitrile in the presence of ascorbic acid or glucose as the reducing agent. Cyclohexane is oxidized to cyclohexanol and cyclohexanone in the presence of ascorbic acid. Ethylbenzene forms acetophenone and 1-phenylethanol in the presence of ascorbic acid or glucose. Styrene is oxidized to form benzaldehyde in general.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1493–1497, July, 1991.