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A correlation Analysis Study Reinvestigation of a 13 C SCS for Some Substituted Poly Aromatic Fused Rings | ||
| Journal of Misan Researches | ||
| Article 1, Volume 5, Issue 9, 2009, Pages 23-36 | ||
| Author | ||
| Nezar . L . Shihab Aldain | ||
| Abstract | ||
| Abstract : -The substituent effect on the 13C substituent chemical shift ( SCS ) and the additively for series namely . ( 1 – X – naphthalene ( I ) , 2 – X – naphthalene ( II ) , 9 – X – anthracene ( III ) , have been investigated by using MSP , DSP . Tafts model was the best on the DSP model due to the wide scale of resonance parameters ( O+ R , O- R , O R BA , OR O ) . 13C chemical shift of distant carbons could be predicted reason ably well on the basis of calculated change of electron densities . The influences of electronic , steric and the conformational analysis of the fused system were discussed . The fused aromatic system have a behavior differ than the simple aromatic system due to its regularity . In this work 13 C ( SCS ) proved to be used as a monitor in many physical calculation like qualitative and quantative studies . This may be lead to the field effect the difference in planarity like in COMe . while OMe and OEt = 26 and CO2H ( 1.1 ) , Cl (2) , Br ( -2.2 ) . C10 have a small effect on the substituent change and in this fused system the change in chemical shift for most of the carbon atoms was small . So that it can not be evaluated or to estimate a reasonable feature about this difference . The dielectric field (12) effect have been studied intensively in this type of poly cyclic aromatic rings and a separation between л – Polarization and DEF effects a not straight – forward , DEF effects were suggested to be the reason for the high field shift of the carbon atoms . Like the high field of C – 2 in 1 – nitro – naphthalene , the electric field effect will polarize the C – H bond decrease the electron density at the proton and consequently interact at the carbon nucleus . As 13 C chemical shifts are much more sensitive to changes in electron density than at 1H shifts , one expects the high field of the carbon resonance to be much stronger than the corresponding low field shift of the proton . | ||
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