Methyl isopropenyl ketone, polymerization

Other vinyl monomers, such as acrylonitrile, methacrylonitrile, tert.-butyl vinyl ketone and methyl isopropenyl ketone, polymerize at 203 K, i. e. most probably by non-radical mechanisms. Even here, conversion of monomer to polymer is not complete, and utilization of the initiator is low. Only the polymerization of acrylate momomers proceeds to full monomer consumption at low temperatures. Additional monomer, even when introduced after some delay, is also polymerized. This indicates that a part of the active centres remains living for some time. However, the number of high-molecular-weight chains is lower than the number of added initiator molecules. At the same time, initiation is very rapid [163]. 

Methyl Isopropenyl Ketone. Methyl isopropenyl ketone [814-78-8] (3-methyl-3-buten-2-one) is a colorless, lachrymatory Hquid, which like methyl vinyl ketone readily polymerizes on exposure to heat and light. Methyl isopropenyl ketone is produced by the condensation of methyl ethyl ketone and formaldehyde over an acid cation-exchange resin at 130°C and 1.5 MPa (218 psi) (274). Other methods are possible (275—280). Methyl isopropenyl ketone can be used as a comonomer which promotes photochemical degradation in polymeric materials. It is commercially available in North America (281). 

A similar variation in the quantum yield of the Norrish type I process is illustrated in Figure 3 for solid copolymers of ethylene containing three different ketone structures. The ketone groups in the backbone of the polymer chain in ethylene- copolymers show much lower quantum yields than those from the secondary or tertiary structures induced by copolymerization of methyl vinyl ketone and methyl isopropenyl ketone with ethylene. (See Table I, structures I, II and III.) In the latter two cases, the Norrish type I cleavage produces a small radical and a polymer radical, and it seems likely that the small radical has a much greater probability of escaping the cage than when the radicals produced are both polymeric, as in the case of structure I. 

Polymerizing Tendency of Different Monomers. Among the monomers studied by us the acrylates polymerized most rapidly by far. In sequence follow MMA, styrene, and far behind methyl isopropenyl ketone. Some monomers (methacrylonitrile and vinylidene chloride) showed no polymerization, even at rather high doses. As to methacrylonitrile, this may be due to the technical grade monomer. During the irradiation of the vinylidene chloride emulsion, the pH value of the water phase was not controlled this is probably the reason for the complications. 

METHYL ISOPROPENYL KETONE (814-78-8) Forms explosive mixture with air (flash point 68°F/20°C). Violent reaction with aldehydes, nitric acid, perchloric acid, strong oxidizers. Contact with hydrogen peroxide can form unstable peroxides heat and/or inappropriate level of inhibitor may cause polymerization. 

Another group of positive UV resists operating on the principle of radiation-induced main chain scission utilizes the efficient photochemistry of polymeric ketones, exemplified hy poly(methyl isopropenyl ketone) PMIPK, to effect image discrimination. Scheme 7.21 shows the photolysis of this resist. ... 

Chaudhuri [347] reported a thermally initiated polymerization of methyl isopropenyl ketone in bulk and solution. The reaction order with respect to monomer was less than 2 in homogeneous and greater than 2 in heterogeneous systems. Chain transfer [348] increased in the order benzene < toluene < ethylbenzene as solvents. 

Both UV- and y-irradiation have been applied successfully for the initiation of methyl isopropenyl ketone [349-351] and phenyl vinyl ketone polymerization [341]. Since polymerization initiated by y-irradiation was inhibited by chinone, a radical mechanism was proposed. 

Lyons and Catterall reported on the mechanism of n-butyl lithium-initiated polymerization of methyl isopropenyl ketone in benzene at 0°C [352,358]. Relatively rapid initial consumption of monomer gave rise to a bimodal molecular weight distribution of low which was maintained throughout the entire reaction. 

However, the structural survey of the low molecular weight products by Kawabata and Tsuruta58 seems to indicate that carbonyl addition was not a predominant side-reaction since the amount of butyl isopropenyl ketone (BIPK) formed was very small, particularly in the polymerization in toluene. The problem was solved almost completely by totally deuterated monomer technique.59-63 The poly(MMA-rf8) prepared with n-C4H9Li in toluene showed in lH NMR signals due to the methyl (0.79 ppm) and methylene... 

Some abnormalities were reported in the initiations of methyl methacrylate polymerizations in toluene by butyllithium. Their nature is such that they suggest the possibility of more than one reaction taking place simultaneously. One, which must be the major one, is that of the oiganomet-allic compound reacting with the carbon-to-carbon double bond as shown above. The other, minor one, may be with the carbon-to-oxygen double bond. The major reaction produces methyl methacrylate anions. The minor reaction, however, yields butyl isopropenyl ketone with an accompanying formation of lithium methoxide ... 

Several different nucleophilic substitution reactions have been observed in the polymerization of methyl methacrylate. Attack of initiator on monomer converts the active alkyl-lithium to the less active alkoxide initiator (Eq. 5-75). Further, methyl methacrylate (MMA) is converted to isopropenyl alkyl ketone to the extent that this reaction occurs. 

Recently, we reported (ii) the synthesis and preliminary characteristics of the first poly (acylsilane), poly(l-trimethylsilyl-2-propen-l-one) (PVTMSK), which was obtained by a free-radical polymerization of 1-tri-methylsilyl-2-propen-l-one (12) (vinyl trimethylsilyl ketone [VTMSK], III). In this chapter, we report the lithographic evaluation of PVTMSK and our attempts to synthesize an a-methyl derivative of PVTMSK, poly(l-trimeth-ylsilyl-2-methyl-2-propen- 1-one) (poly[isopropenyl trimethylsilyl ketone] [PIPTMSK], IV). 

Two simple a, P-unsaturated acylsilanes, l-trimethylsilyl-2-propen-l-one (III) and l-trimethylsilyl-2-methyl-2-propen-l-one (IV) were chosen for polymerization studies. The polymerization of the carbon analogues of these a,p-unsaturated acylsilanes, that is, 4,4-dimethyl-2-propen-3-one (vinyl tert-butyl ketone, V) and 2,4,4-trimethyl-2-propen-3-one (isopropenyl tert-hutyl ketone, VI) has been studied by Willson et al. 16, IT), These authors reported that whereas V readily polymerizes under free-radical-polymerization conditions, VI undergoes polymerization only under anionic-initiation conditions in the presence of a crown ether as a complexing reagent. On the basis of UV and NMR spectroscopic data, Willson et al. (i6, 17) ascribed the difference in polymerization behavior to the nonplanar, unconjugated structure of ketone VI brought about by steric hindrance caused by the methyl group at C-2. 

Differently from poly(7-benzyl S-glutamate) (PBLG), poly( -benzyl S-aspartate) (PBLA) is known to amme a left-handed a-helical conformation which is less stable than the a-helical conformation of PBLG (20). In this respect, it is of interest to examine the asymmetric addition of dodecanethiol to isopropenyl methyl ketone [Eq. (9)] catalyzed by the terminal amino group of PBLA. By using PBLA, prepared by the polymerization of the corresponding NCA in a mixture of 1,2-dichloroethane and tetrahydrofuran with butylamine as initiator, Fukushima and Inoue (21) observed the occurrence of asymmetric nthesis as own in Table 4. 

The principal drawback to using alkaloids as catalysts in asymmetric synthesis is the separation of the product from the catalyst. This has been overcome by radical copolymerization of cinchona alkaloids with vinyl monomers in a way that retains the stereoselectivity of the alkaloid. The reaction of dodecanethiol with isopropenyl methyl ketone in toluene in the presence of quinidine acrylonitrile copolymer (21) gives the (+) enantiomer, in excess, 57 % ee, which is claimed to be the highest value ever achieved in the asymmetric reactions catalysed by synthetic organic copolymers. Previous studies with this type of polymeric catalyst had shown poor asymmetric efficiencies. ... 

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