Propene elimination reaction product

That the sequence shown in Scheme 3 is not the only pathway available for H—NiY formation is indicated by the isolation of 1,3-cyclooctadiene from the reaction products of the dimerization of propene with the n-cyclooctenylnickel system (25) (80) it seems reasonable that the H—NiY species 22 in this case is at least in part formed through direct elimination from 25 without prior monomer insertion into the Ni—C—bond [Eq. (6)] ... 

Further information on the mechanisms of these addition reactions is found in a study of the reaction of "phenylpalladium acetate with trans- and cfs-propenylbenzene 24>. The trans-isomer reacted in nearly quantitative yield at 30 °C in methanol solution to produce trans-1,2-diphenyl-l-propene. About a half of a percent yield of l,2-diphenyl-2-propene was also found. Only a trace of the Markovnikov product 1,1-diphenyl-l-propene was seen (See Chart 1). The reaction of cfs-propenyl-benzene under the same conditions produced an 85% yield of olefins containing 65% of cis- 1,2-diphenyl- 1-propene, 22% trans-1,2-diphenyl-1 -propene, 10% 2,3-diphenyl-l-propene and about 3% of 1,1-diphenyl-1-propene. The major products in both reactions are the one expected from a cis-anti-Markovnikov addition of the phenylpalladium acetate followed by a cis-elimination of "hydrodopalladium acetate . There is practically no Markovnikov addition. 

Dibromo-l-(phenylsulfonyl)-l-propene (15) undergoes a similar addition/elimination reaction with anions of 1,3-dicarbonyl compounds (14) (Scheme 3). The addition/elimination product after decarboxylation (16) under-... 

An alkyl halide such as 2-bromopropane has two j8-carbons from which a proton can be removed in an E2 reaction. Because the two j8-carbons are identical, the proton can be removed with equal ease from either one. The product of this elimination reaction is propene. 

Mechanisms for decarbonylation of ( )-2-butenal and ( )-2-methyl-3-phenyl-2-propenal have been studied with different levels of ab initio and DFT methods. Reactants, products, and transition structures were optimized for two kinds of reaction channels a one-step reaction involving a three-membered cyclic TS, and a two-step reaction involving an initial four-membered cyclic TS. The elimination of ( )-2-methyl-3-phenyl-2-propenal yields different products depending on the channel followed. Only one of the three possible one-step mechanisms leads directly to (E)-P-methylstyrene, the corresponding TS rising to the lowest activation Gibbs free energy. 

The first reaction is a nucleophilic substitution at a secondary center by a nucleophile that is also a strong base. A competing elimination reaction to yield propene will also occur, thus decreasing the yield of the ether product. The second reaction occurs by an Sj 2 reaction at a primary center, which tends to occur with htde competition from an elimination reaction. Therefore, the second reaction is the better way to make the desired product. 

The primary and secondary products of photolysis of common diazirines are collected in Table 4. According to the table secondary reactions include not only isomerization of alkenes and hydrogen elimination to alkynes, but also a retro-Diels-Alder reaction of vibrationally excited cyclohexene, as well as obvious radical reactions in the case of excited propene. 

Note that the total product intensity for H2 elimination was similar for the Y + propene and Y + butene reactions. 

Acetylenic acrylates have been used to reduce side reactions in the preparation of acrylic sil(ox)anes by hydrosilylation [13,14], Allylic acrylates are known to result in addition products with both types of double bonds. Elimination of propene under loss of the allylic group is a major concern, because this path yields acryloxy silicone compounds with SiOC linkages of low hydrolytic stability. 

In contrast to the examples of selectivity control discussed in the previous sections, the problem here is control of the regioselectivity of the individual reaction steps. This is evident from the Scheme 5. In the first reaction step the nickel-hydride species adds to propene forming a propyl- or isopropyl-nickel intermediate this step is reversible, and the ratio of the two species can be controlled both thermodynamically and kinetically. In the second step, a second molecule of propene reacts to give four alkylnickel intermediates from which, after j8-H elimination, 8 primary products are produced (Scheme 5). 2-Hexene and 4-methyl-2-pentene could be the products of either isomerization or the primary reaction. Isomerization leads to 3-hexene, 2-methyl-2-pentene (the common isomerization product of 2-methyl-1-pentene and 4-methyl-2-pen-tene), and 2.3-dimethyl-2-butene. It can be seen from the Scheme 5 that, if the isomerization to 2-methyl-2-pentene can be neglected, the distribution of the products enables an estimate to be made of the direction of... 

The most fundamental reaction is the alkylation of benzene with ethene.38,38a-38c Arylation of inactivated alkenes with inactivated arenes proceeds with the aid of a binuclear Ir(m) catalyst, [Ir(/x-acac-0,0,C3)(acac-0,0)(acac-C3)]2, to afford anti-Markovnikov hydroarylation products (Equation (33)). The iridium-catalyzed reaction of benzene with ethene at 180 °G for 3 h gives ethylbenzene (TN = 455, TOF = 0.0421 s 1). The reaction of benzene with propene leads to the formation of /z-propylbenzene and isopropylbenzene in 61% and 39% selectivities (TN = 13, TOF = 0.0110s-1). The catalytic reaction of the dinuclear Ir complex is shown to proceed via the formation of a mononuclear bis-acac-0,0 phenyl-Ir(m) species.388 The interesting aspect is the lack of /3-hydride elimination from the aryliridium intermediates giving the olefinic products. The reaction of substituted arenes with olefins provides a mixture of regioisomers. For example, the reaction of toluene with ethene affords m- and />-isomers in 63% and 37% selectivity, respectively. 

Industrially this diene is made the same way as ethylidenenorbomene from butadiene and ethene, but now isomerisation to 2,4-hexadiene should be prevented as the polymerisation should concern the terminal alkene only. In both systems nickel or titanium hydride species react with the more reactive diene first, then undergo ethene insertion followed by (3-hydride elimination. Both diene products are useful as the diene component in EPDM rubbers (ethene, propene, diene). The nickel hydride chemistry with butadiene represents one of the early examples of organometallic reactions studied in great detail [22] (Figure 9.14). 

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