Vinyl ketone polymers

Photochemistry of Ketone Polymers in the Solid Phase Thin Film Studies of Vinyl Ketone Polymers... 

Methyl Vinyl Ketone 3-Buten-2-one A3-2 -but-enone methylene acetone acetyl ethylene 3-oxo -a -butyl-ene. C4H(0 mol wt 70.09. C 68.55%, H 8.63%, O 22.83%. CHJCOCH=CHi. Prepn by condensation of acetone and formaldehyde to 3 -keto butanol and dehydration to methyl vinyl ketone Merling Kohler, J. Soc. Chem. Ind 29> 1037 (1910) White, Haward, X Chem. Soc. 1943, 25. Prepn from vinylaoetylene Conaway, U S. pat. 1,967,225 (1934 to du Pont). For review and polymerization characteristics see 4Polymer Science and Technology vol. 14 (Interscience, New York, 197]) pp 617-636. 

A macromolecular chain presents a unique reaction situation in which, in certain cases, groups which are potential reactants at elevated temperature are located in close proximity. Thus intramolecular cyclization may occur, which may or may not involve elimination of small molecules. For example, vinyl ketone polymers such as poly(methyl vinyl ketone) (PMVK), poly(methyl isopropenyl ketone) (PMIK) and poly(phenyl vinyl ketone) undergo random cyclization of adjacent monomer units with release of water. The reaction for PMVK is illustrated in Scheme 4. 

Poly(vinyl methyl ketone) Methyl vinyl ketone polymer 25038-87-3 3-Biiten-2-one, homopoiymer R (C4Hf,0).,... 

Vinylidene chloride-vinyl chloride polymers are also self-extinguishing and possess very good resistance to a wide range of chemicals, including acids and alkalis. They are dissolved by some cyclic ethers and ketones. 

If the head-to-tail structure is assumed for the polymer of methyl vinyl ketone... 

Frequently B will also undergo a back hydrogen transfer which regenerates the parent ketone, as well as cyclization (in most cases a minor reaction) as a result of this competition the quantum yields of fragmentation are typically in the 0.1-0.5 range in non-polar media. When the Norrish Type II process takes place in a polymer it can result in the cleavage of the polymer backbone. Poly(phenyl vinyl ketone) has frequently been used as a model polymer in which this reaction is resonsible for its photodegradation, reaction 2. 

This paper reports a study of the photochemistry of polymers and copolymers containing o-tolyl vinyl ketone units. 

Several carbonyl-containing peroxide additives have been shown to increase the initial rate of the nonoxidative photo-dehydrochlorination of PVC (54). In studies with polymeric ketones unrelated structurally to PVC, the excited singlet and triplet states of the carbonyl groups in these polymers were found to sensitize 0-0 homolysis at rates approaching diffusion control (55). Similar reactions may well occur in oxidized vinyl chloride polymers. 

The same hyperbranched polyglycerol modified with hydrophobic palmitoyl groups was used for a noncovalent encapsulation of hydrophilic platinum Pincer [77]. In a double Michael addition of ethyl cyanoacetate with methyl vinyl ketone, these polymer supports indicated high conversion (81 to 59%) at room temperature in dichloromethane as a solvent. The activity was stiU lower compared with the noncomplexed Pt catalyst. Product catalyst separation was performed by dialysis allowing the recovery of 97% of catalytic material. This is therefore an illustrative example for the possible apphcation of such a polymer/catalyst system in continuous membrane reactors. 

The ORD and CD curves of optically active polymers containing chromo-phoric groups show that the chromophores can be asymmetrically perturbed by the chirality of the substituents and of the main chain conformation. This is the case with poly( ec-butyl vinyl ketone) (377), which presents a Cotton effect at 292 nm, its intensity being greater in the prevalently isotactic polymer than in the atactic polymer. 

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. 

Other polymers undergo cyclization, but there are no commercial applications. Poly (methacrylic acid) cyclizes by anhydride formation and poly(methyl vinyl ketone) by condensation (with dehydration) between methyl and carbonyl groups. 

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. 

Evidently, many simple chiral organic compounds that act as catalysts can be covalently bound to polymer backbones. Polymer-anchored quinine catalyzes the asymmetric Michael addition of a jS-keto ester to methyl vinyl ketone, which proceeds in 22-42% optical yield (Scheme 13) (29). 

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 catalysts containing cinchona alkaloids were re-examined by d Angelo for the reaction of l-indanone-2-carboxylate and methyl vinyl ketone, in which the structure of the spacer connecting the base moiety to the Merri-field resin dramatically influenced the enantioselectivity (Scheme 5) [12]. Catalyst 4 (n=7) with a 7-atom-length spacer to quinine exhibits 87% ee, while 4 (n=3) with a 5-atom spacer and 4 ( =9) with an 11-atom spacer gave only 13% and 31% ee, respectively. 

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