Preparation of alkyl fluorides and carbonates via divergent dehydroxyfluorination and carbonation of alcohols with trifluoromethyl trifluoromethanesulfonate (CF3SO2OCF3) is described. The reactions performed with BTMG in THF provided alkyl fluorides in good yields, whereas those of two different alcohols with Et3N in DCM formed asymmetric carbonates in moderate to excellent yields. CF3SO2OCF3 was demonstrated
描述了通过使用三氟甲磺酸三氟甲酯 (CF 3 SO 2 OCF 3 )对醇进行不同的脱羟基氟化和碳酸化来制备烷基氟化物和碳酸酯。在 THF 中使用 BTMG 进行的反应以良好的收率提供烷基氟化物,而在 DCM 中使用 Et 3 N 的两种不同醇的反应以中等到极好的收率形成不对称碳酸酯。CF 3 SO 2 OCF 3通过改变碱基,在反应中被证明是“F”或“CO”试剂,允许从相应的醇中高效地选择性构建烷基氟化物和碳酸酯。值得注意的是,该方法综合制备了其他方法难以合成的含氟不对称碳酸酯,在学术和工业领域都具有巨大的应用潜力。
A Structural Equation Model of Parental Involvement, Motivational and Aptitudinal Characteristics, and Academic Achievement
作者:Julio Antonio Gonzalez-pienda、Jose Carlos Nunez、Soledad Gonzalez-pumariega、Luis Alvarez、Cristina Roces、Marta Garcia
DOI:10.1080/00220970209599509
日期:2002.1
The authors used the structural equation model (SEM) approach to test a model hypothesizing the influence of parental involvement on students' academic aptitudes, self-concept, and causal attributions, as well as the influence of the 3 variables on academic achievement. The theoretical model was contrasted in a group of 12- to 18-year-old adolescents (N = 261) attending various educational centers. The results indicate that (a) parental involvement had a positive and significant influence on the participant's measured characteristics; (b) causal attribution was not causally related to self-concept or academic achievement when the task involved finding causes for success, but, self-concept and causal attributions were found to be significantly and reciprocally related when the task involved finding causes accounting for failure; (c) self-concept was statistically and predominantly causally related to academic achievement, but not vice versa; and (d) aptitude and self-concept accounted for academic achievement, although the effect of self-concept was predominant. These results suggest that in adolescence, cognitive-affective variables become crucial in accounting for academic behavior.