Polymerization of methyl vinyl ketone

This procedure illustrates a general method for preparing a wide range of spirocyclohexenones and hence spirocyclohexadienones. A number of intramolecular and intermolecular reactions are known to give spirodi-enones however, these methods have limited synthetic application.2 This procedure is superior3 to that developed by Bordwell and Wellman,4 for side reactions such as aldol condensation of the aldehyde and polymerization of methyl vinyl ketone are avoided. These spirodienones are useful intermediates in the synthesis of paracyclophanes.5 6... 

To repress polymerization of methyl vinyl ketone (MVK) under basic conditions, the following procedures may be followed ... 

Several detailed kinetic studies of the polymerization of alkyl vinyl ketones have been reported. Smets and Oosterbosch conducted a study of both bulk and solution polymerization. They observed that the rate law was one-half order to the initiator in bulk and first order in monomer [354]. The energy of activation was calculated to be about 5 kcal/mol in the temperature range —78 to 20 °C and is comparable with a value of 4.8kcal/mol for the CO-initiated polymerization of methyl vinyl ketone [355]. 

The polymer obtained by the base-catalyzed polymerization of methyl vinyl ketone was shown to contain the cyclic units [19] and [20] as well as the 1,2-polymer [18]. Infrared analysis was used to determine this fact (36). Increasing the polymerization temperature resulted in an increase of structures [19] and [20] in the polymer chain. 

Linders et al. [73] studied the Diels-Alder reaction of 6-demethoxy-/J-dihydrothe-baine with an excess of methyl vinyl ketone (used both as reactant and solvent), which gives a mixture of two isomeric adducts. When the reaction was performed using classical heating extensive polymerization occurred, whereas much less poly-... 

In an attempt to prepare new diprenorphine analogs, Linders, in one of the first examples of microwave-induced organic reactions, reported the reaction between methyl vinyl ketone and 6-demethoxy-/J-dihydrothebaine (48) [53], The Diels-Alder reaction, when performed under classical conditions, led to extensive polymerization of the dienophile. A dramatic improvement was achieved when the cycloaddition was conducted in a modified microwave oven at the reflux temperature of methyl vinyl ketone. By use of these conditions adducts 49 and 50 were obtained in a 3 2 ratio, according to HPLC (Scheme 9.12). 

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. 

The most important aspect is the a-C-H activation of simple ketones with a catalyst under neutral conditions. Typically, the C-H activation of cydopentanone in the presence of methyl vinyl ketone and RuCp H(PPh3)2 catalyst in THF at 60 °C gave 2-(3-oxobutyl)cydopentanone (33) in 52% yield [2, 21], Michael addition of simple ketones is quite difficult because of undesirable side reactions such as polycondensation of ketones and polymerization of olefins. Therefore, synthons... 

X-ray diffraction. The bis(enolato) complex Cp2Ti(OCMe=CFl2)2 in the presence of B(C6F5)3 serves as an initiator for the polymerization reaction of methyl vinyl ketone.1549... 

In recent years, methyl vinyl ketone has received considerable attention as a possible component of various polymer products. Almost all the information regarding uses, preparation, methods of polymerization, stabilization, etc., of methyl vinyl ketone is contained in the patent literature. ... 

Conjugate addition reactions, including the Robinson annulation, which make use of reactive Michael acceptors such as methyl vinyl ketone, can suffer from low yields of the desired adduct. The basic conditions required for enolate formation can cause polymerization of the vinyl ketone. Further difficulties arise from the fact that the Michael adduct 42 and the original cyclohexanone have similar acidities and reactivities, such that competitive reaction of the product with the vinyl ketone can ensue. These problems can be minimized by the use of acidic conditions. Sulfuric acid is known to promote the conjugate addition and intramolecular aldol reaction of 2-methylcyclohexanone and methyl vinyl ketone in 55% yield. Alternatively, a silyl enol ether can be prepared from the ketone and treated with methyl vinyl ketone in the presence of a Lewis acid such as a lanthanide triflate" or boron tri fluoride etherate (BF3 OEt2) and a proton source to effect the conjugate addition (followed by base-promoted aldol closure). 

The Wichterle reaction has found widespread utility in the field of organic chemistry. It has found particular utility in annulation reactions where the use of methyl vinyl ketone is incompatible. Methyl vinyl ketone is susceptible to polymerization and is a relatively reactive Michael acceptor that can participate in undesired side reactions. 

Michael addition with -acoxyketones. 2-Ni-tropropane and Na-acetate added at 0-5° to a soln. of NaOH in methanol-water, after salt formation is complete 3-ketobutyl acetate added dr op wise during 15 min., and kept 20 hrs. at 40-45° 5-methyl-5-nitro-2-hexanone. Y 92%.—3-Ketobutyl acetate, the precursor of methyl vinyl ketone, is quite stable toward polymerization and can be stored readily at room temp. F. Michael additions, also with 2-acoxy-nitro compounds, s. J. Org. Ghem. 26, 1348. 

Methyl Vinyl Ketone. Methyl vinyl ketone [78-94-4] (3-buten-2-one) is a colorless Hquid with a pungent odor. It is stable only below 0°C, and readily polymerizes on standing at room temperature. It can be inhibited for storage and transportation by a mixture of acetic or formic acid and hydroquinone or catechol (266). This ketone is completely soluble in water, and forms a binary azeotrope with water (85 MVK 15 H2O vol %) at 75.8°C. 

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). 

Methyl vinyl ketone 2 tends to polymerize, especially in the presence of a strong base the yield of annulation product is therefore often low. A methyl vinyl ketone precursor, e.g. 6, is often employed, from which the Michael acceptor 2 is generated in situ, upon treatment with a base. The quaternary ammonium salt 6 can be obtained by reaction of the tertiary amine 5, which in turn is prepared from acetone, formaldehyde and diethylamine in a Mannich reaction. 

Polar monomers, such as methyl (meth)acrylate, methyl vinyl ketone, and acrylonitrile, are more reactive than styrene and 1,3-dienes because the polar substituent stabilizes the carba-nion propagating center by resonance interaction to form the enolate anion. However, the polymerizations are more complicated than those of the nonpolar monomers because the polar... 

Polymerizations of vinyl ketones such as methyl vinyl ketone are also complicated by nucleophilic attack of the initiator and propagating carbanion at the carbonyl group although few details have been established [Dotcheva and Tsvetanov, 1985 Hrdlovic et al., 1979 Nasrallah and Baylouzian, 1977]. Nucleophilic attack in these polymers results in addition, while that at the ester carbonyl of acrylates and methacrylates yields substitution. The major side reaction is an intramolecular aldol-type condensation. Abstraction of an a-hydrogen from a methyl group of the polymer by either initiator or propagating carbanion yields an a-carbanion that attacks the carbonyl group of the adjacent repeat unit. 

The first application of the ferrous ion-hydrogen peroxide initiation for polymerizing vinyl monomers on and into cellulose fibers has been reported by Landeias and Whewell (41) in three successive papers. They are apparently the first who applied the "anchored catalyst technique, which other people have termed "in situ polymerization to cellulose grafting. The authors internally deposited methyl methacrylate, acrylonitrile, styrene, methyl vinyl ketone and methacrylamide in amounts between 10 and 80%. No attempt had been made to determine if actual grafting had occurred. In 1961 Richards (42) studied this question in great detail. Products obtained by polymerization of acrylonitrile and of styrene in viscose rayon were acetylated. Fractionation of... 

Copolymers of acrylonitrile and methyl acrylate and terpolymers of acrylonitrile, styrene, and methyl methacrylate are used as bamer polymers. Acrylonitrile copolymers and multipolymers containing butyl acrylate, ethyl aciylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methaciylate. vinyl acetate, vinyl ethers, and vinylidene chlonde are also used in bamer films, laminates, and coatings. Environmentally degradable polymers useful in packaging are prepared from polymerization of acrylonitrile with styrene and methyl vinyl ketone. 

Polymer Photochemistry. The occurrence of these reactions in polymeric ketones was first demonstrated by Guillet and Norrish (6, 7), who studied poly (methyl vinyl ketone) in solution and showed that the main features of the photodegradation could be accounted for quantitatively on the basis of Type I and Type II reactions. The conclusion was later confirmed by Wissbrun (13). Recent studies of the ethylene-carbon monoxide polymer (9) confirm that both Type I and Type II reactions occur. The Type I reaction results in the formation of two polymer radicals, one of which is an acyl radical which may subsequently decarbonyl-ate (Reaction 4). 

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