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Evaluation of enthalpies of cyclic alkene–benzene and ether–benzene interactions based on MO calculations
Author(s) -
Iida Takahiro,
Endo Tadashi,
Ito Masato M.
Publication year - 2000
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/1099-1395(200006)13:6<330::aid-poc248>3.0.co;2-g
Subject(s) - chemistry , benzene , alkene , ether , standard enthalpy of formation , computational chemistry , benzene derivatives , organic chemistry , medicinal chemistry , catalysis , chemical synthesis , biochemistry , in vitro
Enthalpies of alkene–benzene and ether–benzene interactions were evaluated by semi‐empirical MO (PM3) calculations of heats of formation for (i) alkenes and ethers (Y) and (ii) Y–benzene (PhH) pairs. In the case of the acyclic alkene–benzene systems, calculated enthalpies of the interactions (ΔΔ H f ) had no close correlation with experimental values (ΔΔ H t ) determined by GLPC. This was also true for the acyclic ether–benzene systems. The ΔΔ H f values for cyclic alkenes and cyclic ethers were both more negative than the corresponding acyclic ones by 0.3–0.9 kcal mol −1 , in essential agreement with the ΔΔ H t for alkenes and ethers. With cyclic ethers and substituted benzenes, a close relationship exists between the theoretical (ΔΔ H f ) and experimental interaction enthalpies (ΔΔ H t ), the correlation coefficient (ρ) for the ΔΔ H f –ΔΔ H t plot being 0.95; using the correlation equation, the experimental enthalpies (ΔΔ H t ) for cyclic ethers can be estimated from the theoretical enthalpies (ΔΔ H f ) with an accuracy of ≤0.1 kcal mol −1 . With all the cyclic systems so far examined (Y = cyclic alkenes, cyclic ethers and substituted benzenes), however, the correlation coefficient (ρ) was reduced to 0.90. Copyright © 2000 John Wiley & Sons, Ltd.