Hexahydroxy-triphenylene

The hexasubstituted derivatives of triphenylene were among the first discotic meso-gens to be discovered. The most commonly studied derivatives are the hexaethers and hexaesters of 2,3,6,7,10,11-hexahydroxy-triphenylene, and their basic synthesis is illustrated in Scheme 15.1,2-Dimethoxyben-zene (veratrole) is oxidatively trimerized using chloranil in concentrated sulfuric acid to give hexamethoxytriphenylene [40], The reaction takes about a week. Demethyl ation with boron tribromide [41] or hydro-bromic acid [42] yields the hexaphenol. 

Vauchier et al. [67] investigated the effect of surface treatment on the anchoring of the director of the mesophases of certain triphenylene compounds. Glass surfaces coated with flat molecules (e.g., hexahy-droxybenzene, mellitic acid, hexahydroxy-triphenylene and rufigallol) orient the phase, and in some cases the D phases as well, with the director perpendicular to the wall (i.e. with the disks parallel to the... 

Scheme 8.17 PIDA-Induced facile oxidative trimerization to hexahydroxy-triphenylene.

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