The proton-to-deuterium exchange reaction of the hydrogenatom at the 5-position of 15 pyrimidinederivatives has been studied. The exchange proceeds under both acidic and alkaline conditions. Under acidic conditions, the mechanism involves protonation at the 5-position (forming an σ complex), whereas under alkaline conditions the exchange is mainly a result of the formation of a tautomeric equilibrium
BOYD, G. V.;LINDLEY, P. F.;NICOLAOU, G. A., J. CHEM. SOC. CHEM. COMMUN., 1984, N 16, 1105-1107
作者:BOYD, G. V.、LINDLEY, P. F.、NICOLAOU, G. A.
DOI:——
日期:——
Protonation of the Pyrimidine Ring at the C(5) Position: Formation of a Stable Cationic σ-Complex
作者:Ádám Demeter、Csaba Wéber、János Brlik
DOI:10.1021/ja027900v
日期:2003.3.1
NMR studies showed that, in addition to the expected N(1) protonation, 2,4,6-pyrimidinetriamine, N,N,N',N',N',N'-hexamethyl- (1) could also be protonated at the C(5) position in water, leading to an equilibrium between the C(5) and N(1) protonated forms. Analysis of the NMR titration data gives 6.87 and 6.89 for the pK(a) of the C(5) and N(l) protonation equilibria. Moreover, the reaction of 1 with chloroacetyl chloride leads to a novel 1,1-bis(pyrimidin-5-yl)-2-chloroethene type derivative (4) that is, peculiarly, fully monoprotonated at the C(5) position in either of the pyrimidine rings, forming a stable cationic sigma-complex.
Process for Producing Olefin Copolymerization Catalyst and Process for Producing Olefin Copolymer
申请人:NAKAHARA Shinya
公开号:US20080227937A1
公开(公告)日:2008-09-18
A process for producing an olefin copolymerization catalyst, comprising the step of contacting, with one another, (A) a solid catalyst component containing a titanium atom, a magnesium atom and a halogen atom, (B) an organoaluminum compound and/or organoaluminumoxy compound, and (C) a nitrogen-containing aromatic heterocyclic compound, whose one or more carbon atoms adjacent to its nitrogen atom are linked to an electron-donating group, or a group containing an electron-donating group; and a process for producing an olefin copolymer using the an olefin copolymerization catalyst.