摘要:

A sensitive analytical technique for the determination of soluble selenium species [Se(IV), Se(VI), Se(0,-II), dimethyl selenide (DMSe), and oxidized methylated organo-Se compounds], using hydride generation atomic absorption spectrophotometry is described. Dimethyl selenide is purged out of a solution and trapped on a U-tube immersed in liquid N2. After controlled heating of the sample trap, DMSe is quantified in a quartz flame-in-tube atomizer aligned in the optical path of an atomic absorption spectrophotometer. Selenite [Se(IV)] and oxidized methylated Se-compounds are reduced by NaBH4in 4 M HCl to H2Se and DMSe, repectively. Entrained by a He carrier gas the H2Se and DMSe are trapped in a liquid N2cooled U-tube. Their separation is accomplished by controlled heating of the sample trap.

ISSN:0038-7010    

DOI:10.1080/00387019108020658

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The1H and13C NMR spectra of three aromatic ketimines with varying degrees of fluoro substitution have been extensively studied using one and two dimensional techniques. COSY experiments were conducted to identify the protons on each of the aromatic groups, HETCORR experiments were then utilized to identify the corresponding carbon atoms, and then the order of the carbon atoms was established by long-range HETCORR (HRTCORRLR) results. These studies have allowed rigorous assignments to be made for most of the carbon and hydrogen atoms present in these compounds. Fluorine splittings were very helpful in the analyses. In the course of this study, the NMR absorbances (1H and13C) of related aldimines have also been assigned. This constitutes the first report on the assignments of1H and13C absorbances for ketimines. The observed spectral properties suggest that the structure of aromatic ketimines is one in which the aromatic rings are in three different planes. Two of the aromatic rings, the N-substituted ring and the C-substituted ring in the cis configuration, are twisted substantially out of the plane with respect to the -C=N- bond. The remaining C-substituted aromatic ring, trans to the N-substituted ring, lies in the deshielding zone of the imine bond.

ISSN:0038-7010    

DOI:10.1080/00387019108020659

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The use of commercially produced spreadsheets is demonstrated to be an efficient and rapid method for the determination of the spectral parameters of a vibration-rotational band with resolved fine structure.

ISSN:0038-7010    

DOI:10.1080/00387019108020660

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0038-7010    

DOI:10.1080/00387019108020647

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor