Olefin with butadiene, thermal reactions

Thermal Reactions of Olefins with Butadiene. The rate constant of the reaction of ethylene with butadiene was reported by Rowley and Steiner (18), whereas that of propylene or butenes with butadiene has not been reported. Tarasenkova (22) reported that the thermal reaction of propylene with butadiene at 600°C gave toluene, the yield of which was twice as large as the yield of benzene plus xylenes. Moreover, the thermal reactions of 1-butene with butadiene and 2-butene with butadiene at 500° — 550°C gave as main products ethylbenzene and o-xylene, respectively. The ratio of ethylbenzene to total xylenes was close to the ratio of 1-butene to 2-butene in the feed. 

Thermal reactions of olefins with butadiene were examined in this study at temperatures from 510° to 670°C and with short residence times. Thermal reaction of the mixture ethylene-propylene-butadiene gave cyclohexene (CH), 4-methylcyclohexene (MCH), and 4-vinylcyclohex-... 

For the pyrolysis of paraffinic hydrocarbons at 700- 800 C, yields of olefins such as ethylene, propylene, butenes, butadiene and cycloolefins increase during the initial stage of the reaction, pass through their maxima, and later decrease yields of aromatics, hydrogen and methane however increase monotonically throughout the reaction course. Sakai et al. (1 ) reported previously the result of a kinetic study on thermal reactions of ethylene, propylene, butenes, butadiene and these respective olefins with butadiene at the conditions similar to those of paraffin pyrolysis, directing their attention on the rates of formation of cyclic compounds. Kinetic features of the thermal reactions of these olefins are sunnnarized in Table I combined with the results obtained in later investigations for thermal reactions of cycloolefins ( 2) and benzene O). 

A summary of rate data is given for the systematic study of the formation of cyclic compounds during thermal reactions of olefins or of olefins with butadiene. As a next step in order to investigate cyclization at pyrolysis conditions, the reactions of allyl radicals with olefins were studied kinetically. 1,5-Hexa-diene (diallyl) and diallyl oxalate (DAO) were employed as source... 

Summary New silacyclopropanes were synthesized quantitatively under mild thermal conditions by reaction of olefins with cyclotrisilane (cyclo-(Ar2Si)3, Ar = Me2NCH2QH4) 1, which transfers all of its three silylene subunits to terminal and strained internal olefins. Thermolysis of silacyclopropanes 3a und 3b indicated these compounds to be in a thermal equilibrium with cyclotrisilane 1 and die corresponding olefin. Silaindane 13 was synthesized by reaction of 1 with styrene via initially formed 2-phenyl-1-silacyclopropane 3d. Reaction of 1 with conjugated dienes such as 2,3-dimethyl-l,3-butadiene, 1,3-cyclohexadiene or anthracene resulted in the formation of the expected 1,4-cycloaddition products in high yield. 

Formation of Cyclic Compounds When we noted that the addition of small amounts of butadiene increased the yield of cyclics formed in the thermal reaction of ethylene and propylene, an effort was made to relate directly the formation of cyclics in thermal reaction of ethylene and propylene, respectively, to the Diels-Alder reaction between feed olefins and product butadiene. Reactions between product olefins and product butadiene were neglected owing to their small concentrations. Cyclics were deferred as the sum of C rings with and without alkyl or vinyl groups. 

The reversibility of the Diels-Alder reaction has been put to good use in the protection of olefins. Ardis [69] used the butadiene adduct to protect the olefin in his synthesis of vinylidene cyanide. Alder [70] was able to monoepoxidise various benzoquinones as their cyclopentadiene adducts, and Chapman [71] used the same method to obtain half-reduction of benzoquinone. Regeneration of the olefin is achieved thermally and Alder [70] noted that this was easier with the fulvene adduct than with the cyclopentadiene adduct. Sauer [72] observed that the retro-Diels-Alder reaction was easier with adducts involving furan, fulvene, and anthracene as the diene component, and he made the anhydride (8) using this method. 

On orbital symmetry grounds, the addition of ethylene to ethylene with ring closure (cycloaddition) should be thermally forbidden. If one compares this reaction with the reaction of trimethylene with approaching ethylene and butadiene (Fig.4), it is readily seen that, the A level being below the S level in trimethylene, the behaviour with respect to cycloaddition to olefins is reversed, that is, trimethylene is essentially an anti-ethylene structure. This principle can be generalized for instance (16) ... 

The reaction of carbenes with olefins to form cyclopropyl derivatives has been used to modify elastomers. Pinazzi and Levesque and Berentsvich et al. found that carbene addition had a significant influence on the properties of polydienes. Thermogravimetric analysis (TGA), flammability and oil resistance in NR and dichlorocarbene modified styrene butadiene rubber (DCSBR) blends were investigated by thermogravimetrie analysis as a funetion of different composition. The TGA plots confirmed the better thermal stability and flame resistance of DCSBR as well as its blends with NR. The amount of DCSBR in the blend significantly affected the properties of blends. 

Maleic anhydride grafting (cont.) poly(styrene-co-divinylbenzene), 694 poly(styrene-co-isobutylene), 675, 689 poly(styrene-co-nfialeic anhydride), 676, 679 poly(vinyl acetate), 676, 694 poly(vinyl acetate-co-vinyl fluoride), 678 poly(vinyl alkyl ethers), 675, 679, 692, 701 poly(vinyl chloride), 683, 692, 693, 695, 702 poly(vinylidene chloride), 691 poly(vinyl toluene-co-butadiene), 689 radical—initiated, 459-462, 464-466, 471, 475, 476 radiation—initiated, 459, 461, 466, 471, 474 redox-initiated, 476 rubber, 678, 686, 687, 691, 694 to saturated polymers, 459-466, 475, 476 solvents used 460-463, 465, 466, 469, 474-476 styrene block copolymers, 679 tall oil pitch, 678, 697 terpene polymers, 679, 700 thermally-initiated, 462, 464-467, 469, 476 to unsaturated polymers, 459, 466-474 vapor-phase techniques, 464, 474, 475 to wool fibers, 476 Maleic anhydride monomer acceptor for complex formation, 207-210 acetal copolymerization, 316 acetone CTC thermodynamic constants, 211 acetone photo-adduct pyrolysis, 195, 196 acetylacetone reaction, 235 acetylenic photochemical reactions, 193-196 acrylamide eutectic mixtures, 285 acylation of aromatic acids, 97 acylation of aromatics, 91, 92 acylation of fused aromatics, 92, 95, 97, 98 acylation of olefins, 99 acylation of phenols, 94-96 acylic diene Diels-Alder reactions, 104-111, 139 addition polymer condensations, 503-505 adduct with 2-cyclohexylimino-cyclopentanedi-thiocarboxylic acid, 51 adducts for epoxy resins curing, 507-510 adduct with 2-iminocyclopentanedithiocarboxylic acid, 51... 

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