Trans-4,4 -Dinitrostilbene

Thus it takes less than a minute for traits stilbene to react with the oxidizer at 0 °C producing trans stilbene oxide in higher than 90% yield. The physical constants of the oxide show a full retention of the starting material configuration. Similar results were observed with cis stilbene, which was converted to cis stilbene oxide without any trace of the trans isomer. Substituted stilbenes react as well, as evidenced by the transformation of trans 4-chlorostilbene and trans 4,4 -dinitrostilbene to the corresponding epoxides in 90% and 70% yield respectively (figure 9). 

It has recently been shown 90> that the olefin tetracyanoethylene, (CN)2C= C(CN)2, can displace phenylacetylene from the bis-triphenylacetylene from the bis-triphenylphosphine platinum(O) complex, the first time such a reaction has been achieved. Preparative work on olefin complexes of platinum(0) of the same type has also shown that electron-withdrawing substituents on the olefin increase the stability of the complex, e.g. trans-4,4-dinitrostilbene forms a more stable complex than trans-stilbene itself 86L... 

Being involved in a charge-transfer complex with A/,A-dimethylaniline, d5 -a,p-dinitrostilbene undergoes a conversion into its trans form with no changes in the nitro group (Todres et al. 1986 Scheme 2.11). 

Dinitrostilbene, trans, yel ndls (from glac acet ac), mp 240—42°, bp — sublimes at 175° under 0.001mm press (Ref 4)... 

Radical anions of frans-stilbene and stiff stilbenes, generated by y-radi-ation in MTHF at — 196°C, exhibit maxima at 500-560nm, e = (1 — 2) x 104M 1cm 1 [509], A similar spectrum and e50o = 6.1 x 104M 1 cm 1 was recorded by pulse radiolysis at room temperature [510]. The anion and cation radicals of cis-stilbene lead efficiently to the trans isomer, while an analogous conversion to the cis isomer from the radical anion and radical cation of frans-stilbene was not found [491]. The cis-stilbene radical cation isomerizes to the more stable frans-stilbene radical cation [511]. The radical anion of cis-4-nitrostilbene has been observed by EPR [512], In the cases of 4-nitro-,4,4-dinitrostilbene and 4,4 -NMS the electron transfer occurs in the triplet state, for example, from DABCO toward the 3t state [513]. 

The analysis with this kinetic model was extended to the photoisomerization of trans-l,T-azonaphthalene in polycarbonate film Victor and Torkelson compared the photoisomerizations of azobenzene, l,r-azonaphthalene, stilbene, 4,4 -dinitrostilbene, 4,4 -diphenylstilbene, and thioindigo in polystyrene with those in toluene solution. The final extents of these reactions in polystyrene were related to... 

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