- Effect of successive increase in alcohol chains on reaction with isocyanates and isothiocyanates
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The reaction of isocyanates and isothiocyanates with long-chain alcohols, e.g. n-hexanol, n-heptanol and n-octanol, exclusively gave N-aryl-O-alkyl carbamates, while N-aryl-O-alkyl carbamates were formed along with symmetrical 1,3-disubstituted ureas and thioureas when the same reactions were carried out with small-chain alcohols at room temperature without using any solvent.
- Perveen, Shahnaz,Yasmin, Arfa,Khan, Khalid Mohammed
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experimental part
p. 18 - 23
(2010/04/23)
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- O,S-Dimethyl carbonodithioate as a phosgene substitute for the preparation of S-methyl alkylcarbamothioates and dialkylcarbamothioates
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O,S-Dimethyl carbonodithioate is proposed as a suitable and safely handled reagent that can be used as a replacement for phosgene in the synthesis of S-methyl alkyl- and dialkylcarbamothioates. The former were obtained by a two-step procedure, which can also be carried out in a one-pot fashion without isolating the intermediates O-methyl alkylcarbamothioates; the overall yields of the pure S-methyl alkylcarbamothioates were 94-98%. Optimal conditions for the synthesis of S-methyl dialkylcarbamothioates involved a one-step procedure in a solvent-free system in the presence of triethyl(methyl)ammonium methyl carbonate as a catalyst; yields of the pure products were 85-98%. A mechanism is proposed for the carbamothioate-formation reaction. Georg Thieme Verlag Stuttgart.
- Degani, Iacopo,Fochi, Rita,Magistris, Claudio
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experimental part
p. 3807 - 3818
(2010/03/30)
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- Identification of new, odor-active thiocarbamates in cress extracts and structure-activity studies on synthesized homologues
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New, odorant nitrogen- and sulfur-containing compounds are identified in cress extracts. Cress belongs to the botanical order Brassicales and produces glucosinolates, which are important precursors of nitrogen- and sulfur-containing compounds. Those compo
- Breme, Katharina,Fernandez, Xavier,Meierhenrich, Uwe J.,Brevard, Hugues,Joulain, Daniel
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p. 1932 - 1938
(2008/02/04)
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- Process to prepare alkyl-ureas from O,S-dimethyl dithiocarbonate
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The present invention relates to the preparation of alkyl-ureas, starting from O,S-dimethyl dithiocarbonate, which provides the following steps: A) causing the O,S-dimethyl dithiocarbonate to react with a primary amine of general formula R1NH2in order to obtain an O-methyl thiocarbamate; B) isomerising the O-methyl thiocarbamate in order to obtain an S-methyl thiocarbamate; C) causing the S-methyl thiocarbamate with a compound of general formula R′R″NH, wherein R′ and R″ may be equal or different one in respect of the other and of R1and may be H, R2or R3, in order to obtain one of the alkyl-ureas of formula (4), (5) or (6).
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Page column 5
(2010/02/06)
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- Process to prepare alkyl-ureas from O,S-dimethyl dithiocarbonate
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The present invention relates to the preparation of alkyl-ureas, starting from O,S-dimethyl dithiocarbonate, which provides the following steps:A) causing the O,S-dimethyl dithiocarbonate to react with a primary amine of general formula R1NH2 in order to obtain an O-methyl thiocarbamate;B) isomerising the O-methyl thiocarbamate in order to obtain an S-methyl thiocarbamate;C) causing the S-methyl thiocarbamate with a compound of general formula R'R"NH, wherein R' and R" may be equal or different one in respect of the other and of R1 and may be H, R2 or R3, in order to obtain one of the alkyl-ureas of formula (4), (5) or (6).
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- Observations on the reactions of isocyanoacetate esters with isothiocyanates and isocyanates
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The reactions of the metal salts of α-isocyanoacetate esters with isothiocyanates and isocyanates were examined. The effects of modifying the reaction parameters on the outcome of the reaction (Scheme I) of methyl α-isocyanoacetate (1a) with phenyl isothi
- Solomon, Daniel M.,Rizvi, Razia K.,Kaminski, James J.
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p. 651 - 674
(2007/10/02)
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- KINETIC ANALYSIS OF COMPETITIVE REACTIONS OF ISOTHIOCYANATES WITH HYDROXYL AND ALKOXIDE IONS
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The reaction of isothiocyanates with hydroxyl and alkoxide ions has been followed spectrophotometrically in alkaline aqueous-alcoholic solutions.Both the nucleophiles are added to the carbon atom of isothiocyanate group in a competition reaction.The effec
- Augustin, Josef,Balaz, Stefan
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p. 443 - 452
(2007/10/02)
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