Conformational and electronic interaction studies of α-substituted carbonyl compounds. Part 9. ω-Hetero-substituted acetophenones

CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. XI. ω-(p-PHENYLTHIO)-p-SUBSTITUTED ACETOPHENONES

“…On the other hand Table I1 shows that when the para substituent at the phenylthio group is constant (Y = OMe or H) and the para substituent at the phenacyl group varies from electron-donating to electron-attracting substituents, there is a progressive increase in absolute value of the negative carbonyl frequency shifts of the gauche rotamers for compounds X-+-C(O)CH,S+-OMe (7), (4), (1) and X-4-C(O)CH,S+H (8), (9, (2) in relation to the corresponding parent acetophenones X-+-C(O)CH, (12), (ll), (10) except for the case of the p-nitrophenylthio derivatives X-+C(O)CH,S+-NO, (9), (6), (3) where the gauche shifts vary from slightly positive to negative ( + 1 to -2 cm-l) value.…”

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

“…A series of papers have investigated the rotation isomerism of α-haloketones using Raman [ 11 ], IR [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ] and NMR [ 24 , 25 ] spectroscopy. Although α-haloketones can exist as two stereoisomers [ 11 ], it has been established, however, that the steric repulsion between the Cl-atom and O-atom, in the liquid state, is much less than that between Cl-atom and an alkyl group.…”

“…An intensive conformational and electronic interaction studies of α-substituted carbonyl compounds made by Olivato and co-workers [ 25 ]. These studies strongly indicate that α-haloacetophen-ones display a cis (I)/ gauche (II) rotational isomerism.…”

Dipole Moments of Compounds Containing Double Bonds

“…Usually this conformation is not very interesting: when the functional groups are separated by a longer chain, it is then approaching the statistical model of a free rotation of all parts (random coil) 2 . Also, in halogen ketones, the mutual position of CDO and C Hal dipoles has a great impact on the overall dipole moments and their electrostatic interaction is considered an important factor controlling the conformational equilibrium 8,13 . In steroidal ketones with an additional substituent, the values of were used to determine conformation of the six-membered ring 10 .…”