Determination of the Substituent Effect on the O−H Bond Dissociation Enthalpies of Phenolic Antioxidants by the EPR Radical Equilibration Technique

2002 ◽  
Vol 67 (14) ◽  
pp. 4828-4832 ◽  
Author(s):  
Giovanni Brigati ◽  
Marco Lucarini ◽  
Veronica Mugnaini ◽  
Gian Franco Pedulli
Keyword(s):  
Substituent Effect ◽  
Phenolic Antioxidants ◽  
Bond Dissociation

Substituent effect on N–H bond dissociation enthalpies of carbamates: a theoretical study

2015 ◽  
Vol 93 (3) ◽  
pp. 279-288 ◽  
Author(s):  
Rupinder preet Kaur ◽  
Damanjit Kaur ◽  
Ritika Sharma
Keyword(s):  
Substituent Effect ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Stabilization Energy ◽  
Isodesmic Reactions ◽  
Bond Dissociation ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Orbital Analysis

The present investigation deals with the study of the N–H bond dissociation enthalpies (BDEs) of the Y-substituted (NH2-C(=X)Y-R) and N-substituted ((R)(H)NC(=X)YH) carbamates (X, Y = O, S, Se; R = H, CH3, F, Cl, NH2), which have been evaluated using ab initio and density functional methods. The variations in N−H BDEs of these Y-substituted and N-substituted carbamates as the effect of substituent have been understood in terms of molecule stabilization energy (ME) and radical stabilization energy (RE), which have been calculated using the isodesmic reactions. The natural bond orbital analysis indicated that the electrodelocalization of the lone pairs of heteroatoms in the molecules and radicals affect the ME and RE values depending upon the type and site of substitution (whether N- or Y-). The variations in N−H BDEs depend upon the combined effect of molecule stabilization and radical stabilization by the various substituents.

Preconcentration of synthetic phenolic antioxidants by using magnetic zeolites derived with carboxylatocalix[4]arenes combined with high performance liquid chromatography

The Analyst ◽  
2015 ◽  
Vol 140 (17) ◽  
pp. 5944-5952 ◽  
Author(s):  
Shaoyan Zhou ◽  
Zheng Li ◽  
Xueju Lv ◽  
Bin Hu ◽  
Qiong Jia
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Phenolic Antioxidants ◽  
Magnetic Zeolite ◽  
Synthetic Phenolic Antioxidants

A hybrid adsorbent assembling carboxylatocalix[4]arene onto the surface of magnetic zeolite was prepared and used for the preconcentration and determination of synthetic phenolic antioxidants coupled with HPLC.

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