Anthracene, cyanation

Anthracene, cyanation, 50, 55 Arndt-Eistert reaction, modified, 50, 77... 

ANDROSTAN-nU-OL, 52,122 Anthracene, cyanation, 50, 55 Amdt-Eistert reaction, modified, 50, 77 7-Aryl-0-diketones, general synthesis, 51, 131... 

Cyanation of aromatic hydrocarbons, also a carbon-carbon coupling reaction, is achieved in the case of anthracene in MeCN-Et4NCN to yield 54% 9,10-dicyanoanthracene [165]. The cyanation is simplified when it is carried out in an emulsion system (aqueous sodium cyanide, dichloromethane, and TBAHSO4). Its synthetic utility in this mode has been demonstrated for the preparation of 4-alkoxy-4-cyanobiphenyls, a class of liquid crystals [166]. 

Figure 8. The azide anion, when enclosed in the dizinc(II) cryptate [Zn2(44)]causes the quenching of the facing anthracene fragment an electron is transferred from the electron rich anion to the photoexcited spacer. Inclusion of cyanate anion does not alter fluorescence emission, due to lack of the suitable redox potential allowing electron transfer.

The direct nature of attack of CN on radical cations of aromatic compounds has been demonstrated by CV [221]. The reversible one-electron oxidation of anthracene becomes irreversible in the presence of CN, and 2 F electrolysis gives a mixture of cyano and isocyano addition across the 9,10-position. Interestingly, it appears that cyanation of 9,10-diphenylanthracene gives the 9,10-diphenyl-9,10-dicyano-9,10-dihydroanthra-cene only [233]. 

Residual isocyanate monomeric extracts from 19 commercial polyurethanes were analyzed as their 9-(methylaminomethyl)anthracene derivatives on a 45°C C,g column (2 = 254 nm, ex 412 nm, em). An 80/20 ac onitrile/water (3% TEA to pH 3 with H3PO4) mobile phase was used [1024]. Analytes included 2,4- and 2,6-toluenediisocyanate, 2,4-toluene diisocyanate dimer, diphenylmethane-4,4 -diiso-cyanate, hexamethylene diisocyanate, cyclohexyl-, phenyl-, and octadecylisocyanate and, isopherone diisocyanate. The effect of varying the level of acetonitrile (70-85%) on retention (as Id) was presented as a plot for six different C,g matoiafs. Detection limits were reported as 0.03 mg/kg. 

Photochemical cyanation of aromatic hydrocarbons in acetonitrile solution is a higher yield process when the potassium cyanide complex of 18-crown-6 is the cyanide ion source [31] compared to similar reactions in mixed organic aqueous solvent systems [32] (see Eq. 7.16). A ten-fold excess of 18-crown-6/KCN over the aromatic hydrocarbon (present in 10 " M) was used. The yield improvements were attributed to increased activity of cyanide due to diminished hydration of the ion. Biphenyl, naphthalene, phenanthrene, and anthracene were photocyanated in 50%, 15%, 25% and 20% yields respectively the latter being an equimolar mixture of mono and dicyanation products [31]. 

---