AbstractThe fluxional behaviour of 4‐methyl[2] paracyclo[ 2] (2,5)furanophane, [6] paracyclophane, 8‐methyl[6]‐paracyclophane and 8‐hydroxymethyl[ 6] paracyclophane was studied by dynamic NMR spectroscopy to yield kinetic parameters which were compared with available data for related compounds.

3,4-Di-t-butylbenzoic acid (1) was synthesized by a seven-step sequence from 4-t-butylbenzoic acid, and its structure was determined by X-ray diffraction and refined to a residual of 0.065 for 1403 independent observed reflections. The crystals are triclinic, Pī , a 6.080(1), b 8.777(1), c 13.912(3)Ǻ, α 80.76(2), β 80.84(2), γ 75.62(2)°. It is the only example of a simple ortho-di-t-butylbenzene whose structure has been determined. The benzene ring experiences some out-of-plane distortion but, in general, strain is relieved by in-plane bond stretching and angular distortions.

The 4J(Me-CC-H) coupling constant, previously established as a probe of bond order,1-3 was used to examine bond orders in a number of quinones. It was found that the presence of a quinone moiety does not cause bond localization in aromatic rings adjacent to the quinone ring.

AbstractThe magnitude of the 4J proton‐proton coupling constant across the fragment CH3CCH (a probe of the bond order between the central sp2‐sp2 hybridized carbon atoms) has been found to be essentially independent of substitution on a toluene fragment and on the size of the ring containing the ortho‐allylic fragment. The coupling constant is sensitive to direct substitution on the ortho‐allylic fragment, especially where the substituent is placed α to the methyl group.