Styrenes nitrostyrenes

Styrene-nitrostyrene copolymer Thermal decomposition studies [72]... 

A combination of TGA and/or DSC and FT-IR spectroscopy has been used to study the thermal behaviour of some polymethacrylates [53] and polyamides [54], chlorinated elastomers [55], polyamides and polyimides [56], poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [57], polypropylene carbonate [58], polyacrylonitrile [59], polyimides [54], polyurethanes [60], styrene-nitrostyrene copolymers [61], bisphenol A-based polycarbonates [62], and polymethacrylates [53]. 

DTA used in conjunction with mass spectrometry has been used to measure energy changes caused by phase transformations in polymers [16-19]. Fernandez [19] used DTA to determine the activation energy of the degradation of styrene-nitrostyrene copolymers. This technique in conjunction with TGA has also been used to examine the influence of allyl glycidylester in its copolymer with dimethylaminoethyl methacrylate on the thermo-oxidative degradation of the copolymer [20]. 

Excellent yields of the oximes of phenylacetaldehydes are obtained by reduction of 6-nitrostyrenes over Pd-on-C in a pyridine solvent (74,75). The technique gives yields of only about 60% when applied to aliphatic unsaturated nitrocompounds better yields are obtained in acidic media(6 5). Over 5% Rh-on-Al203 in ethanol-acetic acid-ethyl acetate, 2- 6-dinitro-styrenes are converted to 2-nitrophenylacetaldehyde oximes (13). 

Bromo-j3-nitrostyrene and triphenylphosphine in dry benzene gave the phosphonium bromide (47). Using methanol as the solvent, the rearranged product (48) was formed, possibly via an azirine intermediate. Substituted -bromo-/3-nitrostyrenes yield the phosphoranes (49) and a phosphonium salt. When the aryl group is electron-donating, the reaction follows a different course to form the styrene (50) by initial attack of the phosphine on halogen. 

B. m-Nitrostyrene. In a 250-ml. two-necked flask equipped with a 250° thermometer and an air condenser are placed 30 g. (0.155 mole) of m-nitrocinnamic acid, 2 g. of copper powder, and 60 ml. of dry quinoline (Note 3). The flask is heated with a Bunsen burner to 185-195°, during which time a steady stream of carbon dioxide is evolved. After 2-3 hours (Note 4), the reaction mixture is cooled and poured into a mixture of 75 ml. of concentrated hydrochloric acid and 175 g. of ice. The m-nitro-styrene is isolated by steam distillation, approximately 1 1. of... 

This procedure has been used in the preparation of other nitrostyrenes in the following yields o-nitrostyrene (40%),2 / -nitrostyrene (41%),2 and 3-nitro-4-hydroxystyrene (60%).2 A better procedure for more volatile styrenes involves simultaneous decarboxylation and codistillation with quinoline from the reaction flask. This method has been used to prepare the following styrenes o-chlorostyrene (50%),3 4 m-chlorostyrene (65%),4 -chlorostyrene (51%),4 m-bromostyrene (47%),4 o-methoxystyrene (40%),4 -methoxystyrene (76%),4 m-cyano-styrene (51%),3 and j -formylstyrene (52%).9... 

The direct conversion of styrene to P-nitrostyrene using clay doped with nitrate salts has been reported. Styrene and clayfen (iron nitrate on clay) or clayan (ammonium nitrate on clay) are mixed well and then heated at 100-110 °C in solid state to give P-nitrostyrene in 68% yield.551 A more simple one-pot synthesis of P-nitrostyrene from styrene has been reported P-nitrostyrene is prepared in 47% yield on treatment of styrene with CuO HBF4,12, andNaN02 in MeCN at room temperature.55b... 

Corey et al. investigated the kinetic isotopic effect (KIE) in asymmetric dihydroxylation. 12C/13C KIE was measured for the dihydroxylation of styrene, p-nitrostyrene, and 4-methoxy-benzoate (Figure 7).197 The observed similar 12C/13C isotopic effect of two olefinic carbons... 

Solid-state synthesis of /J-nitrostyrenes has been reported by Varma et al. in a process that uses readily available styrene and its substituted derivatives and inexpensive clay-supported nitrate salts, clayfen and clayan (Scheme 6.50) [170], In a simple experiment, admixed styrene with clayfen or clayan is irradiated in a MW oven (-100-110 °C, 3 min) or heated in an oil bath (-100-110 °C, 15 min). For clayan intermittent heating is recommended with 30-s intervals to maintain the temperature below 60-70 °C. Remarkably, the reaction proceeds only in solid state and leads to the formation of polymeric products in organic solvent. 

P-nitrostyrenes, preparation by nitration of styrenes, 16 581 P-n-methylionone, 24 565 P-octaalkylporphyrins, 14 552 Betapace... 

Al-Nitrosodiethanolamine, 2 449, 450 Nitroso dyes, 9 263-264 Nitro soluble dyes, 7 373t Nitroso soluble dyes, 7 373t Nitrosomonas, use in recirculating aquaculture biofiltration, 3 196 P-Nitrostyrenes, preparation by nitration of styrenes, 16 581 Nitrosyl chloride, 20 634 Nitrosyl complexes, osmium, 19 642 Nitrosyl perchlorate, 18 279 Nitrosyl tetrafluoroborate, 4 144t n-Nitrotoluene, 17 263... 

To reduce to the active formula, see the zinc reduction as given in the reduction section, CPB, 16, 217 (1968). This reduction is specifically matched to 3-bromo-4,5-methylenedioxy-B-nitrostyrene and other highly substituted ring type styrenes and propenes. Zinc reductions carried out properly are very gentle and do not destroy delicate ring substituents, while some reductions do. Zinc reductions can reduce any nitrostyrene or propenes, but some of these compounds must use the zinc reduction. Which compounds Compounds with lots of ring substituents, like 2,5-dimethoxymethylenedioxy, 3-methoxy-4-0-carbethoxy, etc. This is not to say that some of the other reductions are not capable of gentle reductions. 

Results of Dulog, Kern et ah, and a few others (27, 31) are summarized in Table I. From the ra values, toward the unsubstituted styrene-peroxy radical, the most reactive styrene—p-methoxystyrene—is three times as reactive as the least reactive, m-nitrostyrene. Thus, the best electron donor shows the highest reactivity (lowest enthalpy of activation) toward the electron-accepting styrene-peroxy radical. The deviations from unity of the rarb products measure the effects of substitution on the selectivity of the peroxy radicals. These products depart more from unity with increasing differences in the electron-donating and accepting properties of the nuclear substituents. The same trends appear within the other styrene combinations. 

The characterization and calorimetric results for a series of displacement reactions (equations 231-233) show little difference between CeHg and CH2C12 solvent.644 The relative displacement energies are P(OPh)3 ethylene > cyclooctene > cis-butene > styrene > cyclopentene > nitrostyrene > cyclohexene. These data are used to give a thermodynamic description of the trans effect. 

The eclipsed tetra-BINAP porphyrin 171 was conveniently synthesized by condensation of the meso-tetrakis(2,6-dihydroxyphenyl)porphyrin 173 with the (S)-BINAP derivative 174 in the presence of K2C03. After removal of the staggered isomer iron was inserted by addition of Fe(CO)5/I2, and the resulting Fe(III)-complex 171 was used as a catalyst (0.2%) to epoxidize a series of six styrene derivatives in the presence of an excess of PhIO. In every case the corresponding (R)-epoxides were preferentially formed in yields up to 72%. The best ee-values were obtained for the electron deficient substrates 2-nitrostyrene (80% ee) and pentafluorostyrene (74% ee), [114],... 

To a vigorously stirred suspension of 20 g 3,4-methylenedioxy-B-nitro -styrene in 100 mL anhydrous MeOH there was added a freshly prepared solution of 5.5 gelemental sodium in 100 mLMeOH. The nitrostyrene goes into solution over... 

The synthesis of 2C-T-17 R required starting with the S isomer of secondary butanol. The S 2-butanol in petroleum ether gave the lithium salt with butyllithium which was treated with tosyl chloride (freshly crystallized from naphtha, hexane washed, used in toluene solution) and the solvent was removed. The addition of 2,5-dimethoxythiophenol, anhydrous potassium carbonate, and DMF produced S 2,5-dimethoxyphenyl s-butyl sulfide. The conversion to R 2,5-dimethoxy-4-(s-butyl-thio)benzaldehyde (which melted at 78-79 °C compared to 86-87 °C for the racemic counterpart) and its conversion in turn to the nitro-styrene, S -2,5-dimethoxy-4-(s)-butylthio-B-nitrostyrene which melted at 70-71 °C compared to 68-69 °C for the racemic counterpart, followed the specific recipes above. The preparation of the intermediates to 2C-T-17 S follows the above precisely, but starting with R 2-butanol instead. And it is at these nitrostyrene stages that this project stands at the moment. 

Kureshy et al. have reported that ruthenium-Schiff base complexes 27 serve as a catalyst for enantioselective epoxidation of styrene derivatives (Scheme 6B.26) [71], An electronic effect similar to that described in the Mn-salen-catalyzed epoxidation (vide supra) is observed in this epoxidation, that is, an electron-donating group on the catalyst and electron-withdrawing group on the substrate lead to higher enantioselectivity. For example, the epoxidation of styrene with 27c shows modest enantioselectivity (38% ee), whereas that of m-nitrostyrene with 27a exhibits much higher enantioselectivity (80% ee). 

Keywords styrene,, clayan, nitration, microwave irradiation, / -nitrostyrene... 

Monomers with electron withdrawing groups are polymerized by phosphines (acrylic and methacrylic esters, acrolein, methyl vinyl ketone, /J-nitrostyrene, nitro-ethylene, acrylonitrile), whereas the phosphines have no effect on monomers more susceptible to acid catalysts (isobutylene, styrene). 

Kinetic studies, with both Cu(II) and Ru(II) catalysts, have revealed that this addition is also sensitive to polar effects of substituents on the benzene ring. Thus the order of reactivity, which is 4-methylstyrene> styrene> 4-chlorostyrene> 4-fluorostyrene> 3-nitrostyrene, also supports a coordination mechanism670. 

The Schiff-base complex 17 of ruthenium was developed by Scott et al. [51] and shows substantially high efficiency for ACP. The cyclopropanes derived from 4-nitrostyrene and EDA were obtained in 92% yield with a 99 1 trans-to-cis ratio and 98% ee for the trans form [51]. In most cases, in order to attain high trans-cis stereoselectivity, bulky ester groups of diazoesters were effective. Nevertheless, Nguyen et al. [52] reported in 2002 that the reaction of the smaller and common EDA with styrene assisted by Ru-salen-pyridine complexes 18 (1 mol %) at room temperature produced the cyclopropane products in high yield, 90-96%, and 98-99% ee for the trans form and 95-96% ee for the cis form. Zhang et al. [53] reported that a N,0-mixed polydentate ligand pro-... 

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