SciELO - Scientific Electronic Library Online

 
vol.28 issue3Biochemistry and cytotoxicity of alpha-aminoketonesHomogeneity testing of a lot of silicon metal prepared as a reference material author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

Related links

Share


Química Nova

Print version ISSN 0100-4042On-line version ISSN 1678-7064

Abstract

SILVA, João Bosco P. da et al. Principal component analysis for verifying 1H NMR spectral assignments: the case of 3-aryl (1,2,4)-oxadiazol-5-carbohydrazide benzylidenes. Quím. Nova [online]. 2005, vol.28, n.3, pp.492-496. ISSN 1678-7064.  http://dx.doi.org/10.1590/S0100-40422005000300022.

The 1H NMR data set of a series of 3-aryl (1,2,4)-oxadiazol-5-carbohydrazide benzylidene derivatives synthesized in our group was analyzed using the chemometric technique of principal component analysis (PCA). Using the original 1H NMR data PCA allowed identifying some misassignments of the proton aromatic chemical shifts. As a consequence of this multivariate analysis, nuclear Overhauser difference experiments were performed to investigate the ambiguity of other assignments of the ortho and meta aromatic hydrogens for the compound with the bromine substituent. The effect of the 1,2,4-oxadiazol group as an electron acceptor, mainly for the hydrogens 12,13, has been highlighted.

Keywords : PCA; 1H NMR assignment; 1,2,4-oxadiazol.

        · text in Portuguese     · Portuguese ( pdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License