4-nitro- benzene trans

Nitro substituted stilbenes have been used as models in stUbene cis trans-isomerization studies. It had been reported previously, that cis -v benzene solution, and a photostationary state of 99.5% trans isomer had been reached 132) ... 

Ziegler catalysts prepared from nickel or cobalt 2-ethylhexanoate and triethylaluminum (3 or 4 1 ratio) are very efficient for the hydrogenation of aromatic compounds.o-Xylene (51) gives a mixture of cis- (52) and trans-1,2-dimethylcyclohexane (53) in 65 35 ratio. Phenol (54), dimethyl phthalate and dimethyl terephthalate are also reduced in high yield, while nitro-substituted benzene and phenols cannot be reduced. Catalytic activity toward benzene hydrogenation decreases in the order Ni > Co > Fe > Cr > Cu. ... 

C14H11N02 trans-1-nitro-2-(2-phenylvinyl)benzene 4264-29-3 25.00 1.2172 2 26986 C14H1204 piceatannol 10083-24-6 25.00 1.2428 2... 

C13H2804 4,4 -(2-ethyt-2-nitro-1,3-propanediyl)bismor 1854-23-5 497.35 43.630 2 26806 C14H11CI 1-chloro-3-(trans-2-phenylvinyl)benzene 14064-43-8 595.15 53.097 2... 

A solution of nitrosyl chloride (3.2 g, 49 mmol) in THF (10 mL) was added dropwise with stirring to a solution of methyl 2,3-dipropylcycloprop-2-ene-l-carboxylate (6.2 g, 34 mmol) in THF (10 mL) at — 30CC. The reaction was stirred at — 10°C for 1.5 h and then cooled to — 50CC, and the precipitate that formed was rapidly filtered off and washed with cooled THF to give the dimer (4.8 g, 57%). A second washing with cooled cyclohexane gave an analytically pure product mp 71,5 72°C IR (paraffin oil) vmal = 1295 cm 1 (trans-dimer of tertiary nitro compound). The substance was readily soluble in benzene and cyclohexane, and less readily in EtzO and CC14 the solutions were blue in color. 

In most cases studied, the cis isomer predominates in the photoequilibrium. There exist, however, some cases in the series of sterically hindered stilbenes where the cis isomers are thermodynamically the more stable isomers. For example, oc,/ -dichloro- and a-carboxystilbene contain larger amounts of cis than of trans isomers [12, 53, 55, 56] and only the cis isomer is known for a-nitrostilbene [58], Maciaszek and co-workers [58] were also interested in the photochemical preparation of the less stable isomer of several stilbenes bearing bulky substituents in the a-position Photochemical isomerization was found impracticable for cis-a-nitro- and ot-CONH2-4,4 -dimethylstilbene. With a-carboxy- and a-methoxycarbonyl-4,4 -dimethylstil-bene in benzene, however, a considerable amount of less stable trans isomer has been observed under steady state conditions. 

Dilute solutions ( 10" moldm" ) of Wilkinson s complex in organic solvents such as ethanol/benzene actively catalyse the hydrogenation of alkynes and alkenes at ambient temperature and pressure (1 atm, H2). Traces of oxygen must be excluded. Hydrogenation rates are dependent on steric effects. The following general order has been established 1-alkenes > cis-2-alkenes > trans-2-alkenes > trans-3-alkenes. An exception is ethene itself, which forms a rather stable complex (Fig. 5.19) so that higher temperatures are required. Arenes, esters, ketones, carboxylic acids, amides and nitro compounds are unaffected, but aldehydes are slowly decarbonylated. 

B, products giving positive Tollen s Reagent tests were obtained. No attempts were made to isolate either 9A or 9B since previous work had indicated that such compounds were subject to decomposition, and bromine oxidation was attempted on the crude reaction mixture. For both systems, as bromine addition was carried out, a transient blue color was noticed and white precipitates appeared in the reaction mixtures. In order to obtain 11A and IIB in purer form, the precipitated crude polymer was subjected to Soxhlet extraction with ethanol. This was followed by azeotropic distillation of benzene over the insoluble products. These two purification steps removed most of the non-polymeric by-products including unreacted or partially reacted nitro compounds as well as water and ethanol. Both llA and IIB showed strong IR absorption at 1200 cm" characteristic of the trans nitroso dimer bond, and a medium sharp absorption... 

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