This work reports the use of X-ray spectrometry (XRS) allied to chemometric techniques to easily distinguish types of Portland cements, as well as to quantify some of their constituent elements. The samples were irradiated as powders for 200 s using two distinct irradiation conditions, one more adequate for heavier elements (condition 1) and the other (condition 2) for lighter elements, using a conventional bench top energy dispersive X-ray fluorescence (EDXRF) equipment. The spectra were processed via the software The Unscrambler, version 9.2. The PLS 1 LV1 T LV2 scores graph shows a classification into five groups, in accordance with the calcium concentration, using condition 2. The classification of the cements by producer was feasible using the PLS1 LV1 T LV3 scores graph, with condition 1. The elements Ca, Si, Al and Mg were successfully quantified using multivariate calibration of the whole spectra. However, for Fe, S and K, better results were obtained by correlating their corresponding Ka peaks with concentrations in a univariate procedure, using irradiation condition 2.Chemometric tools allied to XRS are powerful techniques to classify Portland cements, regarding to their origins and their calcium concentration, which is related to the cement type. The PLS chemometric tool was very useful to easily quantify light elements, such as Al, Si and Mg, a challenge in most X-ray analytical methods, since their Ka emission peaks are very close to each other.
Complexos de paládio foram obtidos pela reação de ciclofosfazenos substituídos com fosfinas, (P 3 N 3)(O-C 6 H 4-PR 2) 6 , em que R = fenil, iso-propil ou cicloexil, com Pd 2 (dba) 3 empregando uma razão molar Pd/ligante de 3/1. Os complexos (P 3 N 3)(O-C 6 H 4-PR 2) 6 Pd 3 (dba) x foram caracterizados por análise elementar, espectrometria de massas, RMN de 31 P e espectroscopia no infravermelho onde foi sempre observada uma banda característica de n C=C de dba coordenado ao paládio. Todos os complexos foram testados em reações de acoplamento de Suzuki entre ácido fenilborônico e haletos de arila. Para complexos em que R = cicloexil, foram obtidos números de turnover de até 17.500 para o acoplamento entre 2-bromotolueno e ácido clorofenilborônico. O complexo em que R = fenil foi também imobilizado em matriz de sílica através do processo sol-gel. Experimentos preliminares mostraram que o catalisador imobilizado pode ser usado em pelo menos três reações consecutivas com a mesma atividade catalítica. Palladium complexes were obtained by reaction of phosphine-linked cyclophosphazenes, (P 3 N 3)(O-C 6 H 4-PR 2) 6 , where R = phenyl, i-propyl or cyclohexyl, with using a Pd/ligand molar ratio of 3/1. The (P 3 N 3)(O-C 6 H 4-PR 2) 6 Pd 3 (dba) x complexes were characterized by elemental analyses, mass spectrometry, 31 P NMR and FT-IR where a characteristic n C=C band of dba coordinated to palladium was always observed. All complexes were tested in Suzuki coupling reactions between phenylboronic acid and aryl halides. Turnover numbers as high as ca. 17,500 for the coupling of 2-bromotoluene with chlorophenylboronic acid could be obtained for R = cyclohexyl. The complex based on-PPh 2 was also immobilized in silica matrixes by the sol-gel method. Preliminary experiments showed that the immobilized catalyst could be used in at least three consecutive Suzuki reactions with the same catalytic activity.
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