Triphenylene, deuteration

Using small-angle neutron scattering (SANS), it was shown that alkoxy-substituted triphenylenes associate in deuterated hexadecane.70 At low concentrations small aggregates are formed and at higher concentrations (10 3 M)... 

Fig. 27. Semilogarithmic plot of the nonradiative triplet rate constant against (E— o)/> for the normal and deuterated hydrocarbons listed in Ref. t)). The broken line, derived from phosphorescence spectra, is taken from Ref. t). The slopes of the two solid lines differ by a factor 1.35. (O.Ci-jjH, E = 4000 cm l 0 Ci fl Z>u, =5500 cm t). The following totally deuterated hydrocarbons are included benzene, triphenylene, acenaphtene, naphthalene, phenanthrene, chrysene, biphenyl, p-terphenyl, pyrene, 1,2-benzanthracene, anthracene (in the order of increasing /S). (From Siebrand and Williams, Ref. l)...

An organocopper intermediate was detected by Lewin and Cohen in the reaction of / -iodotoluene with copper in a good complexing solvent (184). Analysis of protonated aliquots from a reaction performed in quinoline indicated an accumulation of />-tolylcopper to a maximum of 43% after 95 hours, at which point the iodide was consumed, and then a slow decrease to by dimerization. Other experiments also indicate the formation of an arylcopper compound in Ullmann reactions (127,141, 210). The isolation of deuterated products, presumably from the decomposition of an intermediate organocopper species in deuterated benzene and cyclohexane, suggested decomposition to free radicals (127). Decompositions of certain o-haloarylcopper intermediates by a benzyne mechanism cannot be totally excluded. The formation of a dichlorobenzene and by-products such as dibenzofuran and triphenylene from only the ortho isomer of the chloroiodobenzenes in Ullmann coupling reactions (210)... 

Deuterium NMR spectroscopy of the discotic phase of hexa-n-hexyloxy triphenylene has led to similar conclusions. Spectra of two selectively deuterated isotopic species, one in which all aromatic positions are substituted and the other in which only the a-carbon side chains are substituted, bring out the difference between the order parameters of the cores and the tails. Fig. 6.1.3 gives the quadrupole splittings of the aromatic and the a-aliphatic deuterons versus temperature in the meso-phase region. It is seen that the rigid core is highly ordered, the orientational order parameter s ranging from 0.95 to 0.90, whereas the a-aliphatic chains are in a disordered state. 

A report describes a novel method for the deuteration of aromatic hydrocarbons, without the need for forcing conditions or oxidizing mineral acids (Scheme 19)." The chemistry utilizes catalytic amounts of arenium ion salts, such as the mesitylene derivative (82a), and deuterated solvents. The solvent acts as the deuterium source, while cyclohexadienyl cation is the deuteron carrier. Thus, an equilibrium is established between (82a) and the deuterated isotopomers (82b) and the deuterium exchange then occurs at the hydrocarbon. Deuteration was demonstrated for several polycyclic aromatic hydrocarbons, including triphenylene (83) (98% yield, 94% D incorporation). Corranulene was deuterated in 78% yield and 96% D incorporation using this chemistry. 

FIGURE 9.6. Experimental 2D spectra of the core deuterated (3S, 2S)-2-chl-oro-3-methyl-pentanoyloxi-pentakis (pentyloxi) - triphenylene taken at 270 K and tm = 10 ms. Note that for the powder sample (a) the ridges perpendicular to the frequency axis are not totally linear. This effect is due to an asymmetry parameter rj = 0.06, (b) for an oriented sample (after Ref. [9.7]). 

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