22719-84-2Relevant articles and documents
Concerted mechanisms of the reactions of ethyl S-aryl thiocarbonates with substituted phenoxide ions
Castro,Paves,Santos
, p. 2310 - 2313 (1999)
The reactions of 4-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6- trinitrophenyl O-ethyl thiolcarbonates with substituted phenoxide ions are subjected to a kinetic study in water, 25.0 °C, ionic strength 0.2 M (KCl). By following the reactions spectrophotometrically, pseudo-first-order rate coefficients (k(obsd)) are found under excess of the nucleophile. Plots of k(obsd) vs phenoxide anion concentration at constant pH are linear, with the slope (k(N)) independent of pH. The Bronsted-type plots (log k(N) vs pK(a) of the phenols) are linear with slopes β = 0.92, 0.77, and 0.61 for the reactions of the 4-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6-trinitrophenyl derivatives, respectively. For these reactions, a concerted mechanism is proposed since the slope values are similar to those found in the concerted phenolysis of aryl acetates; the slope magnitudes are not consistent with a stepwise mechanism where the formation of a tetrahedral intermediate is rate limiting. Our results are in line with the finding that the reactions of the 2,4-dinitrophenyl and 2,4,6-trinitrophenyl derivatives with secondary alicyclic amines in water are concerted. In contrast, the reactions of the same substrates with pyridines are stepwise, which means that substitution of a pyridine moiety in a tetrahedral intermediate with a benzenethio group by a phenoxy group destabilizes the intermediate.
Synthesis of organic carbonates with alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates and ROH/AlCl3under ambient condition
Sung, Gi Hyeon,Bo, Ram Kim,Ryu, Ki Eun,Kim, Jeum-Jong,Yoon, Yong-Jin
, p. 2758 - 2764 (2015/04/22)
We demonstrated the synthesis of organic carbonates using alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates and alcohol in the presence of aluminum chloride. Alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates were reacted with alcohol in the presence of AlCl3 in toluene at room temperature to afford the corresponding unsymmetric and symmetric organic carbonates in good to excellent yields. These are efficient and convenient processes. Alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates are solid, stable and non-toxic CO2/CO2R(Ar) source. It is noteworthy that the reaction is carry out under an ambient and acidic conditions, the easy-to prepare and readily available starting materials and the quantitative isolation of reusable 4,5-dichloropyridazin-3(2H)-one.
A new, mild, general and efficient route to aryl ethyl carbonates in solvent-free conditions promoted by magnesium perchlorate
Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Locatelli, Manuela,Marcantoni, Enrico,Melchiorre, Paolo,Palazzi, Paolo,Sambri, Letizia
, p. 4429 - 4434 (2007/10/03)
A new, general and mild method for the direct synthesis of aryl and alkyl ethyl carbonates promoted by a Lewis acid is reported. The reaction proceeds smoothly with diethyl dicarbonate in the presence of Mg(ClO4) 2, a specific activator of 1,3-dicarbonyl compounds, and shows general applicability. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.