3002-49-1Relevant articles and documents
Efficient method for varying the anions in quaternary onium halides
Jeon, Jong Yeob,Varghese, Jobi Kodiyan,Park, Ji Hae,Lee, Suck-Hyun,Lee, Bun Yeoul
, p. 3566 - 3569 (2012)
Quaternary onium salts of halides can be efficiently converted into the corresponding quaternary onium salts of various anions [NO3 -, BF4-, PF6-, CF 3SO3-, CH3SO3 -, ClO4-, p-CH3C6H 4SO3-, CF3CO2 -, 2,4-(NO2)2C6H3O -] by treating the onium halide with trimethyl phosphate under neat condition in the presence of an equivalent amount of conjugate acid of the desired anion.
Delineation of the Critical Parameters of Salt Catalysts in the N-Formylation of Amines with CO2
Hulla, Martin,Ortiz, Daniel,Katsyuba, Sergey,Vasilyev, Dmitry,Dyson, Paul J.
supporting information, p. 11074 - 11079 (2019/07/17)
N-formylation of amines combining CO2 as a C1 source with a hydrosilane reducing agent is a convenient route for the synthesis of N-formylated compounds. A large number of salts including ionic liquids (ILs) have been shown to efficiently catalyze the reaction and, yet, the key features of the catalyst remain unclear and the best salt catalysts for the reaction remain unknown. Here we demonstrate the detrimental effect of ion pairing on the catalytic activity and illustrate ways in which the strength of the interaction between the ions can be reduced to enhance interactions and, hence, reactivity with the substrates. In contrast to the current hypothesis, we also show that salt catalysts are more active as bases rather than nucleophiles and identify the pKa where the nucleophilic role of the catalyst switches to the more active basic role. The identification of these critical parameters allows the optimum salt catalyst and conditions for an N-formylation reaction to be predicted.
ACID DEACTIVATION OF A NUCLEOPHILE IN THE PHASE-TRANSFER PHENOLYSIS OF CYCLOPHOSPHAZENES AND ITS MECHANISM UNDER HOMOGENEOUS CONDITIONS
Afon'kin, A. A.,Shumeiko, A. E.,Popov, A. F.
, p. 457 - 463 (2007/10/02)
The reactions of tetraalkylammonium salts of 2,4-dinitrophenol (ArO-Q+) with the cyclic trimer of phosphonitrile chloride were studied in a two-phase system of a buffer solution and benzene and in a homogeneous system modeling the conditions of the organic phase. In a two-phase system the aryloxide ion, while being incompletely ionized in the aqueous phase, is extracted into the organic phase together with the neutral form of the phenol, which results in the inhibition of the reaction of monoaryloxyphosphazene formation. The reason lies in the deactivation of the nucleophile as a result of the formation of less reactive complexes with an H bond between the anion and/or the ion pair ArO-Q+ and the proton donor (ROH) contained in the organic phase. On the basis of the kinetic relations and of the results of a study of the equilibrium processes it was found that in the case of strong proton donors (phenols) complexes of the anion and of the ion pair ArO-Q+ with a composition of 1:1 react with the substrate, but in case of weak donors (alcohols) an ion pair not bound into a complex and associations with the anion with compositions of 1:1 and 1:2 react. The reactivity of the complexes of composition 1:1 is thus proportional to the values of the constants of complex formation with ROH, and the inhibiting action of the latter is governed by a single correlation equation without regard to the type of the H-bond acceptor and to the nature of ROH. On the basis of the quantum-chemical calculations it was supposed that the ambiguous effect of ROH on the nucleophilicity of the anions and of the ArO-Q+ ion pairs is determined by the differences in specific solvation between the transition states of the reactions involving these forms of the reagent.
