Methyl acrylate, formation

Scheme 5.6 Proposed mechanism for methyl acrylate formation from [(L-L)Pd(COOMe)] O3SCF3 (L-L=bpy, dppe, 2-(2-diphenylphosphino)ethylpyridine) and ethane (adapted from [38])...

Reaction conditions depend on the reactants and usually involve acid or base catalysis. Examples of X include sulfate, acid sulfate, alkane- or arenesulfonate, chloride, bromide, hydroxyl, alkoxide, perchlorate, etc. RX can also be an alkyl orthoformate or alkyl carboxylate. The reaction of cycHc alkylating agents, eg, epoxides and a2iridines, with sodium or potassium salts of alkyl hydroperoxides also promotes formation of dialkyl peroxides (44,66). Olefinic alkylating agents include acycHc and cycHc olefinic hydrocarbons, vinyl and isopropenyl ethers, enamines, A[-vinylamides, vinyl sulfonates, divinyl sulfone, and a, P-unsaturated compounds, eg, methyl acrylate, mesityl oxide, acrylamide, and acrylonitrile (44,66). 

The Michael-type addition of maleic hydrazide and other pyridazinones to activated alkenes, such as methyl acrylate, acrylonitrile, methyl vinyl ketone and other a,/3-unsatu-rated carbonyl compounds, results in the formation of mono-lV-substituted products. 

The formation of an enamine from an a,a-disubstituted cyclopentanone and its reaction with methyl acrylate was used in a synthesis of clovene (JOS). In a synthetic route to aspidospermine, a cyclic enamine reacted with methyl acrylate to form an imonium salt, which regenerated a new cyclic enamine and allowed a subsequent internal enamine acylation reaction (309,310). The required cyclic enamine could not be obtained in this instance by base isomerization of the allylic amine precursor, but was obtained by mercuric acetate oxidation of its reduction product. Condensation of a dihydronaphthalene carboxylic ester with an enamine has also been reported (311). 

By using this technique acrylamide, acrylonitrile, and methyl acrylate were grafted onto cellulose [20]. In this case, oxidative depolymerization of cellulose also occurs and could yield short-lived intermediates [21]. They [21] reported an electron spin resonance spectroscopy study of the affects of different parameters on the rates of formation and decay of free radicals in microcrystalline cellulose and in purified fibrous cotton cellulose. From the results they obtained, they suggested that ceric ions form a chelate with the cellulose molecule, possibly, through the C2 and C3 hydroxyls of the anhy-droglucose unit. Transfer of electrons from the cellulose molecule to Ce(IV) would follow, leading to its reduction... 

Butadiene with an electron donating group at the 2-position has the largest HOMO amplitude on C, (Scheme 15). A bond forms between Cj of the dienes and Cp of the dienophiles (Scheme 17b). This is in agreement with the exclusive formation of 1,4-disubstituted cyclohexene in the reaction of 2-ethoxybutadiene with methyl acrylate (Scheme 13b) [13, 14]. 

Similar behavior has been observed in the formation of methyl cinnamate from iodobenzene and methyl acrylate... 

A 41 bottle of of methyl acrylate that had been stored for a long time detonated a few hours after being transported from the storage place to the laboratory. This explosion was explained by the formation of peroxides, which thanks to the stirring of the medium caused by the transport, gave rise to violent... 

Treatment of 71a with phosphorus oxychloride readily afforded the dichloro derivative 79 in 95% yield. Michael addition with methyl acrylate in the presence of Triton B led to the regioselective formation of 80 (Scheme 3)... 

The low yields obtained with extremely strong bases, LDA and NaH, suggested the formation of another reactive intermediate. Therefore, the reaction was carried out in the presence of methyl acrylate as a Michael acceptor and afforded a new adduct 35 in addition to the expected vinylcyclopropane derivative 33 (see Equation 8). 

A mechanistic interpretation for the formation of 35 is depicted in Scheme 5. Deprotonation of an allylic proton yields ylide intermediate 36. This then adds to methyl acrylate to give intermediate 37, which cyclizes to construct a cyclopropane ring together with the fission of the S-C bond to afford the final adduct 35. 

Diazomethane is also decomposed by N O)40 -43 and Pd(0) complexes43 . Electron-poor alkenes such as methyl acrylate are cyclopropanated efficiently with Ni(0) catalysts, whereas with Pd(0) yields were much lower (Scheme 1)43). Cyclopropanes derived from styrene, cyclohexene or 1-hexene were formed only in trace yields. In the uncatalyzed reaction between diazomethane and methyl acrylate, methyl 2-pyrazoline-3-carboxylate and methyl crotonate are formed competitively, but the yield of the latter can be largely reduced by adding an appropriate amount of catalyst. It has been verified that cyclopropane formation does not result from metal-catalyzed ring contraction of the 2-pyrazoline, Instead, a nickel(0)-carbene complex is assumed to be involved in the direct cyclopropanation of the olefin. The preference of such an intermediate for an electron-poor alkene is in agreement with the view that nickel carbenoids are nucleophilic 44). 

Scheme 10 Activity reduction in ethylene-methyl acrylate copolymerizations due to the formation of stable chelate 1.30...

The formation of the hydrogen bond between hydroperoxide and polar monomer, for example, methyl acrylate or acrylonitrile, does not influence the rate constant of the reaction of hydroperoxide with the double bond of monomer [101]. The values of the rate constants of the reaction of hydroperoxide with olefins are given in Table 4.13. The effect of multidipole interaction was observed for reactions of hydroperoxide with polyfunctional monomers (see Table 4.14, Ais the Gibbs energy of multidipole interaction in the transition state). 

A tandem radical addition/cyclization process has been described for the formation of benzindolizidine systems from l-(2-iodoethyl)indoles and methyl acrylate <00TL10181>. In this process, sun-lamp irradiation of a solution of the l-(2-iodoethyl)ethylindoles 149 in refluxing benzene containing hexamethylditin and methyl acrylate effects intermolecular radical addition to the activated double bond leading to the stabilized radical 150. Intramolecular cyclization to the C-2 position of the indole nucleus then affords the benzindolzidine derivatives 151 after rearomatization of the tricyclic radical. 

The theoretical interpretation of the results was made (334) in terms of the molecular orbital perturbation theory, in particular, of the FMO theory (CNDO-2 method), using the model of the concerted formation of both new bonds through the cyclic transition state. In this study, the authors provided an explanation for the regioselectivity of the process and obtained a series of comparative reactivities of dipolarophiles (methyl acrylate > styrene), which is in agreement with the experimental data. However, in spite of similar tendencies, the experimental series of comparative reactivities of nitronates (249) toward methyl acrylate (250a) and styrene (250b) are not consistent with the calculated series (see Chart 3.17). This is attributed to the fact that calculation methods are insufficiently correct and the... 

Some chemicals are susceptible to peroxide formation in the presence of air [10, 56]. Table 2.15 shows a list of structures that can form peroxides. The peroxide formation is normally a slow process. However, highly unstable peroxide products can be formed which can cause an explosion. Some of the chemicals whose structures are shown form explosive peroxides even without a significant concentration (e.g., isopropyl ether, divinyl acetylene, vinylidene chloride, potassium metal, sodium amide). Other substances form a hazardous peroxide on concentration, such as diethyl ether, tetrahydrofuran, and vinyl ethers, or on initiation of a polymerization (e.g., methyl acrylate and styrene) [66]. 

In reactions in which methyl acrylate is used as the dienophile (Scheme 6.33), cycloadditions occur with lower levels of enantioselection (23% ee, as compared to 53 % observed for acrolein), but with significantly higher degrees of diastereoselectivity (17 1, endo-.exo). Improved levels of endo selectivity are observed in the case of the methyl ester (Scheme 6.33) this is perhaps because, at least in part, the dienophile p-system is oriented towards the t-butoxy ligand, where the steric influence of the bulky substituent is expected to be more pronounced. As before, formation of the endo isomer may occur to a greater extent, since the transition structure that leads to the exo isomer would involve energetically unfavorable interactions between the diene... 

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