http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Synthesis of Diblock Codendrimers by Fusion of the Fréchet-Type and the PAMAM Dendrons
Lee, Jae Wook,Kim, Jung Hwan,Han, Seung Choul,Kim, Woo Roi,Kim, Byoung-Ki,Kim, Ji Hyeon,Huh, Do-Sung,Shin, Won Suk,Jin, Sung-Ho WILEY-VCH Verlag 2007 Macromolecular symposia Vol.249 No.1
<P>Several diblock dendrimers were synthesized by fusion between the propargyl functionalized Fréchet-type polyether and the azide functionalized Tomalia- type PAMAM dendrons. This was based on the click chemistry protocol, the copper-catalyzed cycloaddition reaction between an alkyne and an azide. The diblock dendrimers were characterized by <SUP>1</SUP>H and <SUP>13</SUP>C NMR spectroscopy, IR spectroscopy, and mass spectra as well as GPC analysis.</P>
Kinetic Evidence for Hypervalent Intermediate in Acid Hydrolysis of N-Arylbenzenesulfinamides
Lee, Jong-Pal,Kim, Woo-Roi,Lee, Yong-Hee,Koo, In-Sun Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.6
Nucleophilic substitution reactions of sulfinic acid derivatives occur with predominent inversion of configuration at sulfur.1 These results are mainly interpreted by an addition elimination mechanism with a trigonal bipyramidal reaction intermediate (sulfurane) and a concerted SN2 displacement mechanism.1,2 The isolation of stabilized bicyclic sulfurances suggests that these species may form as intermediates in nucleophilic substitution reactions of sulfinic acid derivatives.3 However, despite continuing efforts, there are very rare definitive experiments to demonstrate the formation of these intermediates. Some years ago,4 we reported acid catalyzed hydrolysis of some simple sulfinamides. In this report, we found downward breaks in the pH-rate profile for acid catalyzed hydrolysis of sulfinamides having electron donating group in the leaving group, aniline. These data provided the first unequivocal evidence that nucleophilic substitution reaction at sulfinyl sulfur may proceed by a two-step mechanism through a hypervalent reaction intermediate. In this study, we have extended our study to identify the hypervalent intermediate in acid catalyzed reactions of sulfinamides having halide or more stronger electron donating group in the leaving group or the sulfinyl group. So, we have performed the acid catalyzed hydrolyses of N-(3-methyl-5-methoxyphenyl)-benzenesulfinamide (1-a), N-(tolyl)-toluenesulfinamide (1-b), N-(4-fluorophenyl)-toluene-sulfinamide (1-c), N-(4-ethylphenyl)-benzenesulfinamide (1-d) and N-(4-fluorophenyl)-benzenesulfinamide (1-e).