Vibrational Stark effect: Theoretical determination through the semiempirical AM1 method

1992 ◽  
Vol 13 (7) ◽  
pp. 821-829 ◽  
Author(s):  
Josep Martí ◽  
Agustí Lledós ◽  
Juan Bertrán ◽  
Miquel Duran
Keyword(s):  
Stark Effect ◽  
Am1 Method ◽  
Theoretical Determination ◽  
Semiempirical Am1 Method

Gas Phase Basicity of Substituted Benzaldehydes and Methylbenzoates.A Semiempirical Molecular Orbital Study

1988 ◽  
Vol 43 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Walter Fabian
Keyword(s):  
Gas Phase ◽  
Population Analysis ◽  
Resonance Effect ◽  
Am1 Method ◽  
Proton Affinities ◽  
Isodesmic Reactions ◽  
Mulliken Population ◽  
Semiempirical Am1 Method ◽  
Substituted Benzaldehydes ◽  
The Difference

AbstractThe semiempirical AM1 method is used to calculate relative proton affinities of a series of meta-and para-substituted benzaldehydes and methylbenzoates. Close agreement between the results of these calculations and experimental relative gas phase basicities could be obtained. The influence of a substituent on the stability of both neutral as well as protonated forms is estimated via isodesmic reactions. In any case the influence of a substituent is most pronounced in the protonated carbonyl compound. The contribution of the inductive/field effect of a substituent is approximated by the results of isolated molecule calculations. The resonance contribution is estimated by the charge transfer to or from the substituent as revealed by a Mulliken population analysis. Alternatively, the difference between isodesmic stabilization energies and isolated molecule results for the protonated compounds is taken as a measure for the resonance effect. Linear regression analyses with these substituent parameters show good correlation with both experimental as well as calculated relative basicities of the compounds studied.

Reaction sites of N,N′-substituted p-phenylenediamine antioxidants

2007 ◽  
Vol 61 (1) ◽  
Author(s):  
I. Kortišová ◽  
M. Breza ◽  
Z. Cibulková
Keyword(s):  
Second Step ◽  
Am1 Method ◽  
Antioxidant Effectiveness ◽  
Semiempirical Am1 Method

AbstractThe geometries of N,N′-diphenylbenzene-1,4-diamine (DPPD), N-phenyl-N′-(1-phenylethyl)benzene-1,4-diamine (SPPD), N-(4-methylpentan-2-yl)-N′-phenylbenzene-1,4-diamine (6PPD), N-propan-2-yl-N′-phenylbenzene-1,4-diamine (IPPD), N-(2-methoxybenzyl)-N′-phenylbenzene-1,4-diamine (MBPPD), and N-phenyl-N′-(2-phenylpropan-2-yl)benzene-1,4-diamine (CPPD) as well as of their dehydrogenation products were optimized by the semiempirical AM1 method. The results support the idea of stable NB=CX structures formation during the consecutive dehydrogenation of SPPD, 6PPD, IPPD, and MBPPD antioxidants. The biradicals formed during the second step of dehydrogenation of substituted phenylenediamines might be important for their antioxidant effectiveness.

scholarly journals Analysis Of The Enantiomers Ratio Of Citronellal From Indonesian Citronella Oil Using Enantioselective Gas Chromatography

2014 ◽  
Vol 9 (2) ◽  
Author(s):  
Edy Cahyono ◽  
Harno Dwi Pranowo ◽  
Muchalal Muchalal ◽  
Triyono Triyono
Keyword(s):  
Capillary Column ◽  
Theoretical Study ◽  
Structure Identification ◽  
Am1 Method ◽  
Capillary Gc ◽  
Reduced Pressure ◽  
Citronella Oil ◽  
Cymbopogon Winterianus ◽  
Semiempirical Am1 Method ◽  
Enantioselective Gas Chromatography

Citronellal 97,3% has been isolated from Java citronella oil (Cymbopogon winterianus) from Yogyakarta Indonesia by fractional distillation under reduced pressure (5 cmHg, 110-120 oC). Citronellal has two optical isomerics that can be separated by capillary column of chiral GC phase. Enantioselective capillary GC with heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin (β-DEX-225) as stationary phase has been used for analysis of the enantiomers ratio of citronellal. The analysis of enantiomer ratio showed that citronellal contain of 88.21% ee of (R)-(+)-citronellal. Physical properties of isolated citronellal showed that the compound was (+) enantiomer. Structure identification of citronellal was carried out by GC-MS, IR, and 1H NMR, resulted identical fragment and spectra with standard citronellal. Theoretical study with semiempirical-AM1 method showed that energy of (R)-(+)-citronellal on the β-DEX 225 was lower than its (S)-(-)-citronellal.

A study of photoelectron spectra in the framework of the semiempirical AM1 method

1993 ◽  
Vol 42 (5) ◽  
pp. 822-826
Author(s):  
V. K. Turchaninov ◽  
A. I. Vokin ◽  
D. -S. D. Toryashinova ◽  
S. E. Korostova
Keyword(s):  
Photoelectron Spectra ◽  
Am1 Method ◽  
Semiempirical Am1 Method
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