Acrylonitrile reaction rate data

Simple alkyl radicals such as methyl are considered to be nonnucleophilic. Methyl radicals are somewhat more reactive toward alkenes bearing electron-withdrawing substituents than towards those with electron-releasing substituents. However, much of this effect can be attributed to the stabilizing effect that these substiments have on the product radical. There is a strong correlation of reaction rate with the overall exothermicity of the reaction. Hydroxymethyl and 2-hydroxy-2-propyl radicals show nucleophilic character. The hydroxymethyl radical shows a slightly enhanced reactivity toward acrylonitrile and acrolein, but a sharply decreased reactivity toward ethyl vinyl ether. Table 12.9 gives some of the reactivity data. 

Rideout and Breslow first reported [2a] the kinetic data for the accelerating effect of water, for the Diels Alder reactions of cyclopentadiene with methyl vinyl ketone and acrylonitrile and the cycloaddition of anthracene-9-carbinol with N-ethylmaleimide, giving impetus to research in this area (Table 6.1). The reaction in water is 28 to 740 times faster than in the apolar hydrocarbon isooctane. By adding lithium chloride (salting-out agent) the reaction rate increases 2.5 times further, while the presence of guanidinium chloride decreases it. The authors suggested that this exceptional effect of water is the result of a combination of two factors the polarity of the medium and the... 

Because of the speed of data acquisition of NIR instrumentation with nonmoving parts, opportunities arise to study reaction rates and mechanisms. One example includes the crosslinking reaction of liquid carboxylated poly(acrylonitrile-Co-butadiene) or nitrile rubber (NBR) with dicumyl peroxide (DCPO). This reaction was studied by electron spin resonance (ESR) spectroscopy and the crosslinking reaction was followed in situ in dioxane by monitoring of the disappearance of the pendant vinyl double bond with Fourier transform NIR (FT-NIR). The overall activation energy and rate equation of the reaction were able to be determined and provided insight into the reaction mechanism [42]. 

Although TiCl3- based Z.N. catalysts are in this case inactive, A. Yamamoto has shown [/. Am. Chem. Soc., 5989 (1967)] that it is possible to tailor the ligand field around the transition metaJ so that it could tolerate strongly coordinating substrates. More precisely, the reaction of Fe(AcAc)3 with AIR2OR in the presence of bipyridyl has produced a soluble iron alkyl bis(bipyridyl) complex, able to polymerize (meth-)acry-lates, vinyl acetate, vinyl ethers and even (meth-)acrylonitrile. From kinetic data (rates and competitions) and structural determinations, it can be concluded that a typical coordinative cw-insertion mechanism is operative, wherein chelation of the chain (and maybe of the monomer) ensures stereoselection (i.e. production of isotactic PMMA). 

Absolute rate constants for addition reactions of cyanoalkyl radicals are significantly lower than for unsubstituted alkyl radicals falling in the range 103-104 M V1.341 The relative reactivity data demonstrate that they possess some electrophilic character. The more electron-rich VAc is very much less reactive than the electron-deficient AN or MA. The relative reactivity of styrene and acrylonitrile towards cyanoisopropyl radicals would seem to show a remarkable temperature dependence that must, from the data shown (Table 3.6), be attributed to a variation in the reactivity of acrylonitrile with temperature and/or other conditions. 

Kochi (1956a, 1956b) and Dickerman et al. (1958, 1959) studied the kinetics of the Meerwein reaction of arenediazonium salts with acrylonitrile, styrene, and other alkenes, based on initial studies on the Sandmeyer reaction. The reactions were found to be first-order in diazonium ion and in cuprous ion. The relative rates of the addition to four alkenes (acrylonitrile, styrene, methyl acrylate, and methyl methacrylate) vary by a factor of only 1.55 (Dickerman et al., 1959). This result indicates that the aryl radical has a low selectivity. The kinetic data are consistent with the mechanism of Schemes 10-52 to 10-56, 10-58 and 10-59. This mechanism was strongly corroborated by Galli s work on the Sandmeyer reaction more than twenty years later (1981-89). 

The dependence of relative rates in radical addition reactions on the nucleophilicity of the attacking radical has also been demonstrated by Minisci and coworkers (Table 7)17. The evaluation of relative rate constants was in this case based on the product analysis in reactions, in which substituted alkyl radicals were first generated by oxidative decomposition of diacyl peroxides, then added to a mixture of two alkenes, one of them the diene. The final products were obtained by oxidation of the intermediate allyl radicals to cations which were trapped with methanol. The data for the acrylonitrile-butadiene... 

Effect of Molecular Configuration of Elastomer. The extent of the impact and strength improvements of ERL-4221 depends on the chemical structure and composition of the elastomer modifier. The data shown in Table I indicate that the carboxyl terminated 80-20 butadiene-acrylonitrile copolymer (CTBN) is the most effective toughening and reinforcing agent. The mercaptan terminated copolymer (MTBN) is considerably less effective as far as tensile strength and heat distortion temperature are concerned. The mercaptan groups are considerably less reactive with epoxides than carboxyls (4), and this difference in the rate of reaction may influence the extent of the epoxy-elastomer copolymerization and therefore the precipitation of the rubber as distinct particles. 

These findings suggest strongly that the composition of the elastomeric molecule and the nature of the functional groups affect its compatibility and rate of reaction with the epoxy resin, which in turn affect the molecular and morphological structure of the heterophase system. These data indicate the importance of the acrylonitrile comonomer and the carboxyl groups in controlling the polarity of the rubber, and subsequently its compatibility characteristics with the epoxy. We could also... 

A cyclopentadienylcopper-fcr/-butyl isocyanide complex catalyzes the Michael addition of dimethyl methylmalonate to acrylonitrile at room temperature to give an S6% yield of the adduct 249). As the CU2O—BNC complex can also catalyze the addition of indene to methyl acrylate, the intermediate is most likely an organocopper complex. The reactions and kinetic data support the mechanism given by Eq. (118) to (120), involving metalation and nucleophilic attack by the carbanion on the olefin within the complex. Displacement of a solvent ligand by the olefin and coordination of the latter to the copper species are essential features of the mechanism. The rate of reaction is decreased if the compound with the... 

The rate of loss of epoxides increases with the percent acrylonitrile in the CTBN elastomer. Figure 9 plots the rate of loss of epoxides versus percent acrylonitrile. These data, however, do not discriminate the two possible mechanisms for the loss of epoxides 1. Enhancement of the rate of loss of epoxides via a "solvent" effect, and 2. A second side reaction involving reaction of epoxides and the rubber itself. 

The comparison of entry 1 and the stoichiometric steps described before for the phosphine PH(Is)Ph shows that the catalytic reaction is very slow and the ee is much lower. Reactions with less bulky and more nucleophilic phosphines (entries 2-6) were faster but less selective. This data shows that complex 16 is rather inert towards P-H oxidative addition probably because acrylonitrile is more strongly bound to Pt than traw -stilbene and therefore more difficult to be displaced by the phosphine. To promote oxidative addition a bulky alkene, tert-butyl acrylate, was used in entries 7-9, which resulted in enhanced rates and slightly improved enantioselectivities, though still very modest. 

In an effort to probe the nature of the initial interaction between propane and the surface of the gallium antimonate-based catalyst, the rates of propane and isobutane ammoxidation were compared (134). In all instances, the propane conversion was greater than the conversion of isobutane vmder the same reaction conditions. Likewise, the rate of acrylonitrile formation from propane was greater than the rate of methaciylonitrile formation from isobutane. Assuming that the rate-determining step is abstraction of hydrogen from the hydrocarbon, the data suggest that abstraction does not occur at a secondary or tertiary carbon, but rather at a primary carbon site and that the first... 

---