Dicyanobenzene compounds

Using the same methodology, from ortho, meta, and para dicyanobenzenes compounds 82, 83, and 84 were synthesized in yields of 75%, 85%, and 92% <1991CC369>. As expected, para derivative 84 gave the most stable crystal lattice, presumably due to its linear nature. Further work in the same laboratory involved the synthesis of the 5,5, 5"-(l,3,5-phenylene)tris(l,3,2,4-dithiadiazolium)tri(hexafluoroarsenate) salt 85 in 80% yield. 

PET reactions [2] can be considered as versatile methods for generating radical cations from electron-rich olefins and aromatic compounds [3], which then can undergo an intramolecular cationic cyclization. Niwa and coworkers [4] reported on a photochemical reaction of l,l-diphenyl-l, -alkadienes in the presence of phenanthrene (Phen) and 1,4-dicyanobenzene (DCNB) as sensitizer and electron acceptor to construct 5/6/6- and 6/6/6-fused ring systems with high stereoselectivity. 

The unsymmetrical thiacrown porphyrazines Mg[pz(A3B)], where A = Bn, B = S3 (92a) and Mg[pz(A3B)], where A = Bn, B = S4 crown (93a) were formed by a cross-condensation of excess 3,6-dibutyl-1,2-dicyanobenzene and the corresponding thiaether crown dithiomaleonitrile derivative (91). The porphyrazines were demetalated with TFA and remetalated with either copper or nickel acetate to form Compounds 92c, 93c and 93d (16-18%). 

An asymmetric isoindoline pigment preparation has been claimed, starting from 1,2-dicyanobenzene which is reacted in alcohol and a base, followed by addition of a cyanomethylene compound and subsequently a barbituric acid derivative, whereby all reactions are accomplished without isolation of the corresponding intermediates [22],... 

Abstract Starting with tetracyanodibenzo(l,4,7,10-tetrathia-(12-crown-4)) (1) and 4-nitro-l,2-dicyanobenzene (2), nitro-substituted dimeric phthalocyanine (3) was synthesized. In the second step, using hydrazine hydrate as a reductant, amine-substituted dimeric phthalocyanine (4) was synthesized from nitro-substituted dimeric phthalocyanine. Stractmres of all synthesized compounds were determined by elemental analyses, UV/vis, H-NMR and IR spectroscopy. 

Initial compounds tetracyanodibenzo(l,4,7,10-tetiathia-(12-crown-4)) 1, 4-nitro-1,2-dicyano benzene and 4,5-bis(hexylthio)phthalonitrile were available from earlier study. Nitro-substituted dimeric Co(II) phthalocyanine 3 was prepared by reaction of tetracyanodibenzol-(l,4,7,10-tetiathia-(12-crown-4)) 1, 4-nitro-l,2-dicyanobenzene 2 and zinc(ll) acetate in amyl alcohol. 

This relationship also conveys one of the reasons why the sensing of explosives can be so effective with this method. Most explosives, especially TNT and other nitroaromatic compounds, are highly electron deficient and have favorable reduction potentials. For instance, the reduction potential of TNT and DNT are only —0.7 and—1.0 V (versus SCE) respectively, quite favorable when compared with other electron acceptors, such as 1,4-dicyanobenzene (—1.7 V versus SCE). This means that if the sensory material emits hght, for example, at 460 nm, the oxidation... 

The metallophthalocyanines which have found application as elecfiochromes are mainly the rare earth derivatives, especially lutetium, and second row fiansition metals such as zirconium and molybdenum. Synthesis of these molecules follows the fiaditional routes, e.g. condensation of 1,2-dicyanobenzene with a metal acetate in a high boiling solvent (see Chapter 2). These compounds have structures in which the rare earth element is sandwiched between two phthalocyanine rings, e.g. zirconium bisphthalocyanine (1.92 M = Zr) and lutetium bisphthalocyanine (192 M = Lu), the latter protonated on one of the meso N atoms to balance the charge. 

Synthetic applications of both intermolecular5-6 and intramolecular7 PET initiated cyclodimerizations have been reported. Common electron acceptors (A) arc neutral compounds such as 1,4-dicyanobenzene, 1,4-dicyanonaphthalene or 9,10-dicyanoanthracene usually dissolved in polar solvents like acetonitrile, or arc cationic compounds such as methylacridinium hexafluorophosphate which is soluble in dichloromcthane. 

Yasuda, Pac, and Shima reported the photoamination of aromatic compounds by use of ammonia and primary amines as nucleophiles in the presence of m-di-cyanobenzene as an electron acceptor [30,32], Irradiation of an acetonitrile-water (9 1) solution containing phenanthrene and m-dicyanobenzene in the presence of ammonia or primary amines gives 9-amino-9,10-dihydrophenanthrene deriva-... 

Photoaddition and substitution of electron-deficient aromatic compounds such as o-dicyanobenzene (o-DCNB), p-DCNB, and TCNB by use of group 14 organometallic compounds are classified to the reaction of the radical anions of electron-deficient aromatic compounds with carbon radical species generated... 

Organic constituents that may be found in ppb levels in WP/F smoke include methane, ethylene, carbonyl sulfide, acetylene, 1,4-dicyanobenzene, 1,3-dicyanobenzene, 1,2-dicyanobenzene, acetonitrile, and acrylonitrile (Tolle et al. 1988). Since white phosphorus contains boron, silicon, calcium, aluminum, iron, and arsenic in excess of 10 ppm as impurities (Berkowitz et al. 1981), WP/F smoke also contains these elements and possibly their oxidation products. The physical properties of a few major compounds that may be important for determining the fate of WP/F smoke in the environment are given in Table 3-3. 

Figure 5.3 Synthetic conditions for the mixed-ligand Pc complexes, containing one Pc ligand. Route 1 interaction of o-dicyanobenzene(s) and their analogues with lanthanide salts. Route 2 metallation reaction of the macrocyclic ligand or its dianione by lanthanide compounds. Route 3 reactions of axial substitution in the environment of the central atom in lanthanide complexes ([96] and references cited therein). (From Ref. 96, with permission.)...

Metal phthalocyanines are easily synthesized by vapor-phase condensation of four molecules of dicyanobenzene in the presence of molecular sieves such as faujasites or A1PO-5 (123-126). This results in direct entrapment of the macrocycle inside the molecular sieve s channels and cages. There are also reports of ship-in-a-bottle synthesis of porphyrins in zeolites, but since porphyrin synthesis requires a mixture of pyrrole and an aldehyde instead of a single compound, porphyrin synthesis is a much less clean process than phthalocyanine preparation (127). Alternatively, soluble porphyrins or phthalocyanines can be added to the synthesis gel of, for example, zeolite X. This also results in entrapped complexes (128). 

Differences between the reactivities of meta- and para-isomers also seem to reflect the electron densities on the cyano group [14]. For instance, a lower electron density may be expected on the cyano group of 1,4-dicyanobenzene in comparison with 1,3-dicyanobenzene and the much greater reactivity of the former compound is in accordance with this expectation. 

There are many reports of the photoreactions of aromatic compounds with alkenes and dienes and many of these have been previously reviewed (Davidson, 1975) and are also discussed later in this chapter (Section 8). Some interesting newer developments include the reaction of 1,4-dicyanobenzene with tetramethylethylene to give [79] and [80] (Arnold et al., 1980). The course of this reaction is somewhat similar to that of cyanopyridines with alkenes (Bemardi et al., 1981) referred to on p. 63. When 1,4-dicyanonaphthalene is used in place of 1,4-dicyanobenzene [81], [82] and [83] are formed and these can be readily accounted for in terms of intermediate radical ions. Clear... 

The reaction of phenanthrene and unsaturated compounds, such as furan, 1,1-diphenylethylene and indene, in the presence of electron acceptors and a nucleophile leads to products incorporating the nucleophile (Majima et ai, 1981). Thus furan gives [96], Excitation generates the radical cation of phenanthrene (Phent) and the radical anion of 1,4-dicyanobenzene. Phent oxidises furan to its radical cation which reacts in the manner as shown in Scheme 16. 

Lewis and his coworkers reported the intramolecular photoaddition of aliphatic secondary amines to arylalkenes to give 5- and 6- membered cyclic amines (Scheme 17) [66-67]. Ohashi reported that the other type of photoaddition reaction takes place when 1,4-dicyanobenzene and triethylamine are used as substrates. This photoreaction can be explained in terms of the deamination of the initially produced diethylaminoethylated compound (Scheme 18) [68]. 

Photochemical electron transfer reactions of electron donor-acceptor pairs in polar solvents provide a convenient and effective method for the generation of radical cations which can be trapped by complex metal hydrides. One of the most effective systems is based on irradiation of a solution of substrate, sodium borohydride and 1,4- or 1,3-dicyanobenzene. A range of bi- and poly-cyclic aromatic hydrocarbons has been converted into the dihydro derivatives in this way. An especially important aspect of this route to dihydroaromatic compounds is that it may give access to products which are regioisomeric with the standard Birch reduction products. Thus, o-xylene is converted into the 1,4-dihydro product (229) rather than the normal 3,6-dihydro isomer (228). The m- and p-xylenes are similarly reduced to (230) and (231), respectively. ... 

A dye molecule that has found widespread attention in the synthetic metals community is phthalocyanine 186, which can be readily made from ortho-dicyanobenzene 187 in a metal-assisted cyclotetramerization that directly provides metal complex derivatives 188 (see scheme 44) [251]. A tuning of the electronic properties is possible via the central atom and, for example, by proceeding to the related tetranaphthalene compound 189 [252]. The importance of phthalocyanines 188 in both fundamental and industrial research comes from the great number of possible applications [253]. Also, 188 can be stacked into columnar arrays by using axial ligands at the metals or by linking silicon centers as central atoms by suitable spacers [254]. The introduction of long chain alkoxy... 

The photochemical reactions of the bicyclic compounds (201 a, c) in acetonitrile-methanol solution in the presence of 1,4-dicyanobenzene have been studied. The irradiation of (201a) affords the mixture of trans cis methoxy derivatives (201b) which are also photochemically reactive under the same conditions. The products from (201a) are formed by the photochemical addition of methanol to the furan (202). This furan is formed by production of the radical cation of (201a) followed by deprotonation affording a doubly benzylic radical. The study was extended to the monocyclic system (203) which on electron-transfer-induced irradiation afforded the acetal... 

The iodine-doped, paramagnetic compound [Pc2ln](13)2/3 can be synthesized directly from In T1 alloy and 1,2-dicyanobenzene under a stream of iodine. " The solid-state structure features onedimensional stacks of [Pc2ln] columns and I3 chains. A triple-decker indium(III) phthalocyanine complex [Pc3ln2], which is diamagnetic, has been obtained by reacting In-Sn alloy with 1,2-dicyanobenzene at 210 Indium atoms are six-coordinate, and are located between the... 

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