US EPA

8703781 

Journal Article 

Estimation of the conformation of 2-hydroxy-4,6-dimethylbenzophenone and 2,4,6-trimethoxybenzophenone from electronic absorption spectra and PPP LCI ca 

Miertuš, S; Kysel, O 

1975 

Yes 

Journal of Molecular Structure
ISSN: 0022-2860
EISSN: 1872-8014 

26 

2 

163-173 

English 

10.1016/0022-2860(75)80002-0 

The twisting effect of benzene rings on the electronic spectra of derivatives of benzophenone (BPh), 2-hydroxy-4,6-dimethylbenzophenone (2-OH-4,6-diCH3BPh) and 2,4,6-trimethoxybenzophenone (2,4,6-triOCH3BPh) has been interpreted by the PPP method. The effect of structure, protonation, ionization and interaction with proton-acceptor solvent on the twisting of aromatic rings is discussed. The following twist angles of substituted ring (θI) and unsubstituted ring (θII) in 2-OH-4,6-diCH3BPh were found: neutral form in cyclohexane θI = 39°-48°, θII = -30°-(-45°); neutral form in ethanol θI = 66°-72°, θII = -30°-0°; protonized form θI = 64°-6°, θII = -30°-0°; ionized form θI = 66°-74°, θII = -30°-0°. In the neutral form of 2,4,6-triOCH3PBh the substituted ring is twisted by angle θI ~ 70° while in the protonated form the unsubstituted ring is twisted by angle θII ~ 60° and the substituted one is coplanar with the CO group. 1975.