Carbonylation methyl methacrylate

Comparison of Table 5.4 and 5.7 allows the prediction that aromatic oils will be plasticisers for natural rubber, that dibutyl phthalate will plasticise poly(methyl methacrylate), that tritolyl phosphate will plasticise nitrile rubbers, that dibenzyl ether will plasticise poly(vinylidene chloride) and that dimethyl phthalate will plasticise cellulose diacetate. These predictions are found to be correct. What is not predictable is that camphor should be an effective plasticiser for cellulose nitrate. It would seem that this crystalline material, which has to be dispersed into the polymer with the aid of liquids such as ethyl alcohol, is only compatible with the polymer because of some specific interaction between the carbonyl group present in the camphor with some group in the cellulose nitrate. 

The chlorinated surface of glass then acted as a coinitiator, and when photochemically treated with metal carbonyl in the presence of MMA monomer, a thin layer of 0.4 /Am thickness of poly(methyl methacrylate) was obtained. 

Although carbonyl compounds, such as formaldehyde (27,28], can couple with Ce(IV) ion to initiate acrylonitrile (AN) or methyl methacrylate (MMA) polymerization, the remarkable activity of aliphatic aldehyde had not been noticed until the paper of Sun et al. [29] was published. They found that aliphatic aldehydes always... 

The initiator efficiency has to be considered jointly with the monomers involved The nucleophilicity of the initiator should be matched to the electron affinity of the monomer, as initiation should be fast and quantitative 7). If it is too small, initiation may be slow (and/or incomplete), which implies broadening of the molecular weight distribution and possibly loss of molecular weight control. If the nucleophilicity of the initiator is too high, side reactions may occur, as in the case of methyl methacrylate, where the ester carbonyl is attacked15). 

Carbonylation of methanol to acetic acid is fully discussed in Chapter 9. Another carbonylation process using a phosphine ligand to control the course of the reaction is a highly atom efficient route to the widely used monomer methyl methacrylate (Scheme 4.19). In this process the catalyst is based on palladium acetate and the phosphine ligand, bisphenyl(6-methyl-2-pyridyl) phosphine. This catalyst is remarkably (>99.5%) selective for the 2-carbonylation of propyne under the relatively mild conditions of <100 °C and 60 bar pressure. 

A considerable viscosity increase in copolymers of tributylstannyl methacrylate with methyl methacrylate, butyl acrylate and styrene upon prolongated storage has been observed and special agents to eliminate this effect have been proposed 108). It is likely that the destruction of intermolecular coordination complexes formed by involvement of tin and carbonyl groups in comonomer units takes place in this case. 

Some transition metal ir-allyl compounds are not catalysts for polymerization. For example, Zr (allyl) 4 will not polymerize methyl methacrylate. Spectroscopic and other studies have shown that this allyl compound, unlike those of chromium, react with the carbonyl group of the monomer giving compounds of the type... 

Palladium(II) acetate was found to be a good catalyst for such cyclopropanations with ethyl diazoacetate (Scheme 19) by analogy with the same transformation using diazomethane (see Sect. 2.1). The best yields were obtained with monosubstituted alkenes such as acrylic esters and methyl vinyl ketone (64-85 %), whereas they dropped to 10-30% for a,p-unsaturated carbonyl compounds bearing alkyl groups in a- or p-position such as ethyl crotonate, isophorone and methyl methacrylate 141). In none of these reactions was formation of carbene dimers observed. 7>ms-benzalaceto-phenone was cyclopropanated stereospecifically in about 50% yield PdCl2 and palladium(II) acetylacetonate were less efficient catalysts 34 >. Diazoketones may be used instead of diazoesters, as the cyclopropanation of acrylonitrile by diazoacenaph-thenone/Pd(OAc)2 (75 % yield) shows142). 

Methyl methacrylate may be prepared by the catalytic oxidative carbonylation of propylene in the presence of methanol. 

Many substituents stabilize the monomer but have no appreciable effect on polymer stability, since resonance is only possible with the former. The net effect is to decrease the exothermicity of the polymerization. Thus hyperconjugation of alkyl groups with the C=C lowers AH for propylene and 1-butene polymerizations. Conjugation of the C=C with substituents such as the benzene ring (styrene and a-methylstyrene), and alkene double bond (butadiene and isoprene), the carbonyl linkage (acrylic acid, methyl acrylate, methyl methacrylate), and the nitrile group (acrylonitrile) similarly leads to stabilization of the monomer and decreases enthalpies of polymerization. When the substituent is poorly conjugating as in vinyl acetate, the AH is close to the value for ethylene. 

Many papers have been published on the polymerization of methyl methacrylate (MMA) with alkylllthlum. It was reported that In the Initiation step an attack of alkylllthlun on monomer occurred In the first few seconds and took place on both olefinlc and carbonyl double bonds and a considerable amount of oligomer was formed in the early stage of the polymerization (1, 3 4 ... 

The reaction of poly (methyl methacrylate) on electron-beam exposure has been thoroughly studied and the elimination of methoxycarbonyl group is considered to be the primary mechanism, by which the main-chain scission is initiated (20,21). However, in this work the formation of acid carbonyl group... 

Acrylates, for example, contain an a, 3-unsaturated carbonyl system and as such undergo Michael addition reactions. This is believed to be the basis of the carcinogenic properties of acrylates [21]. Incorporation of a methyl (-CH3) group on the a-carbon (to provide a methacrylate) decreases the electrophilicity (i.e., reactivity) of the (3-carbon [40], hence methacrylates do not undergo 1,4-Michael addition reactions as readily. Methacrylates often have commercial efficacy similar to that of acrylates in many applications, but are less likely to cause cancer because they are less reactive. This point can be demonstrated by comparing methyl methacrylate (6), which does not cause cancer in experimental animals [41], with ethyl acrylate (7), which causes cancer in experimental animals in assays similar to those used to test 6 [42]. 

Coleman et al. 2471 reported the spectra of different proportions of poly(vinylidene fluoride) PVDF and atactic poly(methyl methacrylate) PMMA. At a level of 75/25 PVDF/PMMA the blend is incompatible and the spectra of the blend can be synthesized by addition of the spectra of the pure components in the appropriate amounts. On the other hand, a blend composition of 39 61 had an infrared spectrum which could not be approximated by absorbance addition of the two pure spectra. A carbonyl band at 1718cm-1 was observed and indicates a distinct interaction involving the carbonyl groups. The spectra of the PVDF shows that a conformational change has been induced in the compatible blend but only a fraction of the PVDF is involved in the conformational change. Allara M9 250 251) cautioned that some of these spectroscopic effects in polymer blends may arise from dispersion effects in the difference spectra rather than chemical effects. Refractive index differences between the pure component and the blend can alter the band shapes and lead to frequency shifts to lower frequencies and in general the frequency shifts are to lower frequencies. 

PCTFE was found to add to methyl methacrylate via the use of a stoichiometric amount of chloro(pyridine)cobaloxime(III). In the IR spectrum of the resulting product, the carbonyl group of a saturated ester was shown as a strong band at 1735 cm-1. However, the loss in the chloride band at 975 cm1 was tremendous, and strong, broad bands due to the... 

Similar to the case of ethyl acrylate, the chemospecificity of the addition of PCTFE to methyl methacrylate was improved by using a catalytic amount of chloro(pyridine)cobaloxime(III). The IR spectrum of the resulting polymer showed the carbonyl band at 1731 cm-i. Although the bands due to the side reaction were also present, the decrease in the absorbance of the chloride band at 974 cm-i became less obvious, inferring that the extent of the side reaction was lowered. 

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