Methyl acrylate structure

As already mentioned in previous sections ethylene may also be copolymerised with several non-hydrocarbon polymers. Some of these copolymers are elastomeric and they also have a measure of oil resistance. Two monomers used commercially are vinyl acetate and, the structurally very similar, methyl acrylate ... 

Both experimental [7] and theoretical [8] investigations have shown that the anti complexes of acrolein and boranes are the most stable and the transition states were located only for these four anti complexes. The most stable transition-state structure was calculated (RHF/3-21G) to be NC, while XT is the least stable of the four located. The activation energy has been calculated to be 21.6 kcal mol for the catalyzed reaction, which is substantially above the experimental value of 10.4 1.9 kcal mol for the AlCl3-catalyzed addition of methyl acrylate to butadiene [4a]. The transition-state structure NC is shown in Fig. 8.5. 

The reaction of methyl acrylate and acrylonitrile with pentacarbonyl[(iV,iV -di-methylamino)methylene] chromium generates trisubstituted cyclopentanes through a formal [2S+2S+1C] cycloaddition reaction, where two molecules of the olefin and one molecule of the carbene complex have been incorporated into the structure of the cyclopentane [17b] (Scheme 73). The mechanism of this reaction implies a double insertion of two molecules of the olefin into the carbene complex followed by a reductive elimination. 

If chain transfer of the radical center to a previously formed polymer molecule is followed ultimately by termination through coupling with another similarly transferred center, the net result of these two processes is the combination of a pair of previously independent polymer molecules. T. G. Fox (private communication of results as yet unpublished) has suggested this mechanism as one which may give rise to network structures in the polymerization of monovinyl compounds. His preliminary analysis of kinetic data indicates that proliferous polymerization of methyl acrylate may be triggered by networks thus generated. 

Fig. 6.7. Transition structures for the reaction between 1,3-butadiene and the methyl acrylate—BF3 complex calculated at die ab initio HF/6-31G level. Relative energies are in kcal/mol. Adapted from Tetrahedron, 53, 6057 (1997), by permission of Elsevier.

Fig. 3 Molecular structures of [Cu pyKjc-methyl acrylate)] [PFJ and [CuI(bpy)(7i-styrene)] [CF3SCy [101,102]...

We were recently able to isolate and structurally characterize a series of [CuI(PMDETA)(7i-M][BPh4] complexes (M = styrene, methyl acrylate, methyl methacrylate, and 1-octene) [110,111]. Molecular structures of [Cu PMDETA) (71-methyl acrylate)] [BPhJ and [CuI(PMDETA)(7i-styrene)][BPh4] are shown in Fig. 5. In all complexes, PMDETA acted as a tridentate ligand, while the... 

Fig. 5 Molecular structures of [CuI(PMDETA)(7i-styrene)][BPh4] and [Cu PMDETAXTi-methyl acrylate] [BPhJ. The [BPhJ counterion has been removed for clarity [110]...

Fig. 10.23 X-ray structure of [Rh((R,R)-Et-DuPHOS)((Z)-3-N-acetylamino-3-(phenyl)-methyl propenoate)]+ and of[Rh((S,S)-DIPAMP)((Z)-2-benzoylamino-3-(3,4-dimethoxyphenyl)-methyl acrylate)]+ [62],...

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... 

Strictly speaking, the term polyester ought to refer to a chemical compound containing many ester groups in each molecule. In practice, however, it usually refers to polymeric materials containing ester groups as major structural components of the main chains of the macromolecules of which the polymer is composed, and this is the sense in which it is used here. The term is not now usually applied to polymers that contain ester groups attached to the main chain either directly, as in cellulose triacetate, poly(vinyl acetate) or poly(methyl acrylate), or within short side-chains. 

Hawkins and Loren225 reported simple chiral arylalkyldichloroborane catalysts 352 which were effectively used in the cycloadditions of acrylates lib and 350 to cyclopen-tadiene, affording adducts 351a and 351b, respectively (equation 99). A crystal structure of the molecular complex between methyl crotonate and the catalyst allowed the authors to rationalize the outcome of the reaction. One face of methyl crotonate is blocked by tt-tt donor-acceptor interactions, as becomes clear from the structure of complex 353. The cycloadduct of methyl acrylate and cyclopentadiene (5 equivalents) was obtained with 97% ee, using the same catalyst. Three years later, the authors reported that the cycloadduct was obtained with 99.5% ee in the presence of 10 equivalents of cyclopentadiene226. 

Although there are many variations on how carbon fibers are made, the typical process starts with the formation of PAN fibers from a conventional suspension or solution polymerization process between a mixture of acrylonitrile plastic powder with another plastic, such as methyl acrylate or methyl methacrylate, and a catalyst. The product is then spun into fibers, with the use of different methods, in order to be able to achieve the internal atomic structure of the fiber. After this, the fibers are washed and stretched to the desired fiber diameter. This step is sometimes called "spinning" and is also vital in order to align the molecules inside the fiber and thus provide a good basis for the formation of firmly bonded carbon crystals after carbonization [7]. 

The condensation of biguanide with acrylate esters [e.g. methyl acrylate in presence of sodium methoxide 484)1 was expected to afford a vinyl-triazine (LXXXIV, R = R = H), but gave in fact 2-( 3-methoxy-ethyl)guanamine (LXXXVI) (51%). The desired vinyl-triazine was finally synthesised 486) from phenylbiguanide and acrylyl chloride in aqueous acetonitrile and its structure proved by its hydrogenation to 2-ethyl-6-phenylguanamine. 

Bell, 1989 Rhee and Bell, 1991), random copolymers of methyl acrylate and acrylonitrile were directly polymerized onto the carbon fiber surface. Dimethyl formamide, dimethyl sulfoxide and distilled water proved to be useful as solvents for this process. Polymerization can take place on the carbon fiber electrode, with initial wetting of the fiber surface leading to better adhesion of the polymer formed. The structure and properties of the polymer can be varied by employing different vinyl and cyclic monomers in homopolymerization. Chemical bond can also be formed, such as polymer grafting to the carbon fiber surface. 

For the following idealized structural representations, the semisystematic or trivial source-based names given are approved for use in scientific work the corresponding structure-based names are given as alternative names. Equivalent names for close analogues of these polymers [e.g. other alkyl ester analogues of poly(methyl acrylate)] are also acceptable. 

Because of the repulsion of the cyanide groups the polymer backbone assumes a rod-like conformation. The fibers derive their basic properties from this stiff structure of PAN where the nitrile groups are randomly distributed about the backbone rod. Because of strong bonding between the chains, they tend to form bundles. Most acrylic fibers actually contain small amounts of other monomers, such as methyl acrylate and methyl methacrylate. As they are difficult to dye, small amounts of ionic monomers, such as sodium styrene sulfonate, are often added to improve their dyeability. Other monomers are also employed to improve dyeability. These include small amounts (about 4%) of more hydrophilic monomers, such as -vinyl-2-pyrrolidone (Equation 6.69), methacrylic add, or 2-vinylpyridine (Equation 6.70). 

Fig. 6.4. Transition structures of the reaction between 1,3-butadiene and methyl acrylate, calculated at the ab initio RHF/6-31G level. Total energies are in hartrees and relative energies in kcal/mol. (Reprinted from Ref. 14b, Copyright 1997, with permission from Elsevier Science.)...

The polymerization cir-l-rf-propene by traditional Ziegler-Natta initiators in hydrocarbon solvents yields the erythrodiisotactic structure, while under similar solvent conditions anionic polymerization of cis- -d-methyl acrylate yields the threodiisotactic polymer. Explain the factor(s) responsible for this difference. 

Cyclization is a key reaction in the production of carbon fibers from polyacrylonitrile (PAN) (acrylic fiber see Sec. 3-14d-2). The acrylic fiber used for this purpose usually contains no more than 0.5-5% comonomer (usually methyl acrylate or methacrylate or methacrylic acid). Highly drawn (oriented) fibers are subjected to successive thermal treatments—initially 200-300°C in air followed by 1200-2000°C in nitrogen [Riggs, 1985]. PAN undergoes cyclization via polymerization through the nitrile groups to form a ladder structure (XXVII). Further reaction results in aromatization to the polyquinizarine structure (XXVIII)... 

This becomes even more complicated in the structure of a copolymer derived from more than one species of monomer, such as styrene and methyl acrylate, both of which contribute constitutional units. 

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