Synthesis of N-and N,N-dialkyl-S-alkylthiolcarbamates by the rearrangement of N-and N,N-dialkyl-O-thioncarbamates

Milosavljević, Milan; Marinković, Dragan; Djordjevic, S Dragan

doi:10.2298/hemind0602027m

Cited by 9 publications

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“…The synthesis of thiocarbamates from thiols and isocyanates can be performed in the presence of catalysts with or without solvents [36]. In addition to the known synthetic methods [37][38][39][40][41], thiocarbamates can also be obtained from sodium or potassium xanthate in aqueous solution and primary or secondary amines, in the presence of elemental sulfur [42]. Thiocarbamates can also be obtained in high yield in the reaction of xanthate and amine in the presence of nickel(II) sulfate heptahydrate as a catalyst [43] or by the oxidation of amine salts of xanthogenic acid with hydrogen peroxide or sodium hypochlorite [44].…”

Section: Introductionmentioning

confidence: 99%

New Facile One-Pot Synthesis of Isobutyl Thiocarbamate in Recycling Solvent Mixture

Milentijević¹,

Marinković

Rančić

et al. 2021

Minerals

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The specific objectives of the presented study were related to the optimization of the production process of N-alkyl-, N,N-dialkyl-, and N-cycloalkyl-O-isobutyl thiocarbamate; trial industrial production of N-ethyl-O-isobutyl thiocarbamate; and the evaluation of flotation efficiency of N-ethyl-O-isobutyl thiocarbamate using a real ore sample. The optimization of thiocarbamate syntheses were performed by varying the molar ratio of isobutyl alcohol, carbon disulfide, potassium hydroxide, reaction time, and reaction temperature. In the first step, one-pot reaction took place to produce alkyl xanthate and was followed with chlorination to give alkyl chloroformate (O-alkyl carbonochloridothioate); finally, thiocarbamates were obtained by the reaction with corresponding amines. N-alkyl-O-ethyl thiocarbamate was synthesized as a comparative flotation agent. The structure of the synthesized compounds was confirmed by IR, 1H and 13C NMR, and MS instrumental methods, and the purity was determined by gas chromatographic method and elemental analysis. The optimized methods gave high-purity products in a significant yield that was also confirmed by semi-industrial production of N-ethyl-O-isobutyl thiocarbamate. The optimized thiocarbamate synthesis, without isolation of intermediates, is of great importance from the aspect of green technologies. Flotation efficiency test results, using real copper and zinc ores, showed the highest activity of N-ethyl-O-isobutyl thiocarbamate. The optimal one-pot thiocarbamate synthesis provides a simple procedure with a high conversion degree, and, thus, offers valuable technology applicable at the industrial scale.

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Section: Introductionmentioning

confidence: 99%

New Facile One-Pot Synthesis of Isobutyl Thiocarbamate in Recycling Solvent Mixture

Milentijević¹,

Marinković

Rančić

et al. 2021

Minerals

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“…1 H NMR spectrum of EMeOT shows clear evidence for the co‐existence of two isomeric forms 74, 75. Each of the types of proton exhibits two signals except the p ‐methoxy group.…”

Section: Methodsmentioning

confidence: 99%

The mechanisms of hydrolysis of N‐alkyl O‐arylthioncarbamate esters

Humeres

Souza

Debacher

2010

J of Physical Organic Chem

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The hydrolysis of N‐ethyl O‐p‐methoxyphenylthioncarbamate (EMeOT) at 50 °C was studied in the range of $H_o^X $ −3.6 to H− 13.7. The pH‐rate profile showed that the hydrolysis occurred through specific acid catalysis at pH <2, spontaneous hydrolysis at pH 2–3, and specific basic catalysis at pH >3. The excess acidity plot against X was linear with slope 0.93, and the Bunnett–Olsen coefficient was 0.07. The acid hydrolysis occurred by an A1 mechanism. The basic hydrolysis of EMeOT can be explained if the mechanism is E1cb. At pH >3 the rate constants increased, reaching a constant value indicating that the expulsion of the aryloxy is not concerted. The neutral species hydrolyzed with general base catalysis with Brønsted β = 0.63 ± 0.07. Water acted as a general base catalyst with (pseudo‐) first‐order rate constant kN = (2.6 ± 0.2) × 10−8 s−1, and inverse kinetic solvent isotope effect of $k_o^D /k_o^H = 2.76$ consistent with a transfer of the proton at a late transition state, as also supported by the highly negative entropy of activation (−31 cal K−1 mol−1). The polynomial expression of the proton inventory curve presented a minimum of the standard deviations that favors the assumption that there are three active protons. The N to O proton transfer to the water molecule forms an incipient hydron. The fractionation factor of the TS of the protons indicated that the hydron is ca. 68% developed at the transition state. Copyright © 2010 John Wiley & Sons, Ltd.

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“…Sinteza tiokarbamata iz tiola i izocijanata se može izvoditi u prisustvu katalizatora sa i bez prisustva rastvarača [10]. Osim poznatih postupaka sinteze [11][12][13][14][15], tiokarbamati se mogu dobiti i reakcijom natrijum-ili kalijum-ksantata u vodenom rastvoru sa primarnim ili sekundarnim aminima i u prisustvu elementarng sumpora [16]. Tiokarbamati se mogu dobiti i reakcijom ksantata i amina u prisustvu nikal(II)-sulfata heptahidrata kao katalizatora [17].…”

Section: Milutin M Milosavljevićunclassified

New method for synthesis of N-alkyl and N,N-dialkyl-O-ethyl and O-isopropylthiocarbamates by oxidation of ammonium salt of xhantogenic acid

Milisavljević¹,

Marinković²,

Milosavljević³

2010

Hem Ind

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A synthesis of N-alkyl and N,N-dialkyl-O-ethyl and O-isopropyl thiocarbamates by oxidation of ammonium salt of ethyl and isopropylxanthogenic acid in a presence of sodium hypochlorite and hydrogen peroxide were performed. Ammonium salt of ethyl and isopropylxanthogenic acid was obtained by the reaction of alkylammonium sulfate and sodium ethyl and isopropyl xanthate. Studies on a dependence of N-ethyl-O-isopropylthiocarbamate yield and purity with respect to reaction parameters (reaction time, molar ratio of oxidant and ethylamonium salt of isopropylxanthogenic acid) were performed. Optimal reaction conditions for synthesis of N-alkyl and N,N-dialkyl-O-ethyl and O-isopropyl thiocarbamates were established. Synthesized compounds have been fully characterized by FTIR, 1H NMR and MS data, while purity has been determined by GC method. A plausible pathway for the N-alkyl and N,N-dialkyl-O-ethyl and O-isopropyl thiocarbamates synthesis, in the presence of the oxidative agents sodium hypochlorite and hydrogen peroxide, was proposed. The presented synthetic methods has been developed at laboratory and applied at semi-industrial level. The developed optimal method provides a powerful and versatile method for the preparation of N-alkyl and N,N-dialkyl-O-ethyl and O-isopropyl thiocarbamates. This new optimized method offer several benefits, namely, simple operation, mild reaction conditions, bypass of hazardous organic solvents, moderately toxic and inexpensive reagents, and also short reaction times and high product yields

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Synthesis of N-and N,N-dialkyl-S-alkylthiolcarbamates by the rearrangement of N-and N,N-dialkyl-O-thioncarbamates

Cited by 9 publications

References 0 publications

New Facile One-Pot Synthesis of Isobutyl Thiocarbamate in Recycling Solvent Mixture

New Facile One-Pot Synthesis of Isobutyl Thiocarbamate in Recycling Solvent Mixture

The mechanisms of hydrolysis of N‐alkyl O‐arylthioncarbamate esters

New method for synthesis of N-alkyl and N,N-dialkyl-O-ethyl and O-isopropylthiocarbamates by oxidation of ammonium salt of xhantogenic acid

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