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Most nontraditional intrinsic luminescent (NTIL) polymers currently show blue fluorescence. Tuning the emission color of NTIL polymers is of fundamental importance for their applications, but it still remains a scientific challenge. Herein, we initially develop an efficient strategy for bathochromic shifting of NTIL polymers by through-space acceptor-donor charge transfer between the in chain and the side chain. A variety of functionalized polyketones (FPK-R; where R = H, Ph, Me, tBu, F, and Cl) with furan rings built into the polymer chain were prepared by the Paal-Knorr reaction. FPK-R polymers showed bright and bathochromic-shifted fluorescence compared with their counterparts. The emission color could be tuned by changing the postfunctionalization conversion and varying the styrenic monomer substituent. Experimental and theoretical investigations revealed that the color tunability originated from enhanced through-space charge transfer between the side chain phenyl and the in chain furan rings.

Nanocomposite materials with carbon nanotubes and graphene additives have long been considered to be exciting prospective nanomaterials for nanotechnology applications. Some issues of these nanomat...

It is still a significant challenge to rationally design and delicately process or fabricate anion exchange membranes (AEMs) with high ionic conductivity, good mechanical properties, and sufficient...

Acetic anhydride (AA) is usually considered a stable molecule but is shown here to be able to polymerize in closed reactors to a cross-linked polyketone condensate. By using this chemistry, it was ...

The world’s most important plastic, polyethylene, consists of inert hydrocarbon chains. An introduction of reactive polar groups in these chains is much sought-after, to overcome the problematic environmental persistency and enhance compatibility with other materials. However, with state of the art catalytic polymerization processes this has not been possible. Here, we show how a low density of individual in-chain keto groups can be generated in the high molecular weight polyethylene chains by catalytic copolymerization with carbon monoxide. Most importantly, the desirable materials’ properties of high density polyethylene (HDPE) are retained. Processing can be performed by common injection molding and mechanical characteristics are on a par.

Membranes used for pressure-retarded osmosis (PRO) are required to be mechanically strong due to high external hydraulic pressures on the draw solution (DS) side. In this study, a series of nonwoven fabrics of varying thickness, density, and hydrophilicity were used to fabricate reinforced aliphatic polyketone (PK) membranes with excellent mechanical strength and pressure resistance. Three suitable nonwoven fabrics are selected based on the integrities of the PK layers formed on their surfaces. As a result, guidance for choosing suitable reinforcing materials for PK membranes is provided. We show that a PK-based thin-film-composite (TFC) membrane reinforced by an 11-μm-thick polyester (PET) nonwoven fabric provides a flux of 24.7 L m–2 h–1 (in “active layer facing feed solution”, AL-FS mode, 0.6 mol L–1 NaCl as the DS), while maintaining a pressure resistance of 28 bar. This membrane is shown to be capable of producing a power density of at least 6.1 W m–2 in PRO evaluation (with 0.6 mol L–1 NaCl).

We report herein a new methodology for the rapid and selective reduction of carbonyls in the solid phase. By exploiting mechanical energy and using a cheap and air-stable silane, polymethylhydrosiloxane (PMHS), we can reduce a variety of carbonyl compounds, with catalytic amounts of fluorides. A scope of 19 substrates was explored to probe the generality of the method. In addition, an important biomass-based platform chemical, 5-hydroxymethylfurfural (5-HMF), and an insoluble polymer, polyketone, could be reduced with this methodology. A mechanistic study is also presented, suggesting the active role of volatile silane species. This method is particularly appealing to overcome substrate solubility issues and reduce solvent reliance in organic synthesis.

A series of polyketone (PK) nanocomposite films with varying content of noncovalently functionalized graphene nanoplatelet with 1-aminopyrene (GNP/APy) is prepared by solution blending with a solvent of hexafluoro-2-propanol. GNP/APy, prepared by a facile method, can effectively induce specific interaction such as hydrogen bonding between the amine functional group of GNP/APy and the carbonyl functional group of the PK matrix. With comparison of GNP and GNP/Py as reference materials, intensive investigation on filler-matrix interaction is achieved. In addition, the dispersion state of the functionalized GNP (f-GNPs; GNP/Py and GNP/APy) in the PK matrix is analyzed by three-dimensional nondestructive X-ray microcomputed tomography, and the increased dispersion state of those fillers results in significant improvement in the water vapor transmission rate (WVTR). The enhancement in WVTR of the PK/GNP/APy nanocomposite film at 1 wt % loading of filler leads to a barrier performance approximately 2 times larger compared to that of PK/GNP nanocomposite film and an approximately 92% reduction in WVTR compared to the case of pristine PK film. We expect that this facile method of graphene functionalization to enhance graphene dispersibility as well as interfacial interaction with the polymer matrix will be widely utilized to expand the potential of graphene materials to barrier film applications.

A new zwitterionic nickel(II) catalyst that comprises a partially fluorinated tetrakis(aryl)borate center in a bidentate phosphine ligand and a cationic Ni center has been developed and studied for CO–ethylene copolymerization in the context of comparison with a previously reported zwitterionic catalyst that carries a nonfluorinated borate anion. The crystal structures of several zwitterionic and related nickel compounds are characterized. Partial fluorination of the tetrakis(aryl)borate only brings a modest increase in productivity (2700 vs 1600 g of polyketone per gram of Ni, g (g of Ni)−1). Like the nonfluorinated catalyst, the fluorinated zwitterionic catalyst is extremely active at the beginning of the polymerization but deactivates rapidly. Deactivation of the two catalysts apparently follows different mechanisms. Stoichometric decomposition studies show that the partially fluorinated tetrakis(aryl)borate in the Ni compounds is stable under acidic conditions either directly introduced by addition of...

The synthesis and characterization of regioregular aliphatic polyketones is reported. Poly(1-oxoheptamethylene), a semicrystalline polyketone, was prepared via ruthenium-catalyzed ring-opening metathesis polymerization (ROMP) of a ketal-protected 7-membered cyclic ketone followed by subsequent hydrogenation and deprotection. Temperature and catalyst studies of the ROMP reaction guided the preparation of polyketones with high monomer conversions, molecular weights as high as 30 kDa, and dispersities as low as 1.4. Because of the symmetric nature of the monomer, the polymer has ketones spaced every six methylene units apart. The thermal properties of this polyketone were investigated by differential scanning calorimetry, revealing a peak melting range of 160–165 °C. A related polymer, poly(1-oxooctamethylene), was also prepared in a similar fashion, and a peak melting range of only 130–133 °C was observed. This difference in melting range is attributed to the lack of the regioregularity in poly(1-oxooctamet...

This paper describes the synthesis and characterization of a high molecular weight cross-conjugated polyketone synthesized via scalable Friedel Crafts chemistry. Cross-conjugated polyketones are precursors to conjugated polyions; they become orders of magnitude more conductive after a two-electron reduction and demonstrate reversible spinless doping upon protonation with acids. Cross-conjugated polyketones are a new polymer platform that possess the same optoelectronic tunability as conventional polymers but with excellent thermal and oxidative stability. We constructed a proof-of-concept organic light-emitting diode device and demonstrate that a cross-conjugated polyketone can be successfully used as an n-dopable semiconducting material.

Although we can efficiently convert bioderived furans into linear alkanes, the most energy-intensive step in this approach is the hydrodeoxygenation of the intermediate polyketone. To fully understand this process, we have examined the hydrodeoxygenation of a model compound, 3-pentanone, which allows us to follow this process stepwise using Pd/C, H2 (200 psi), and La(OTf)3 in acetic acid to remove the oxygen atom at temperatures between 25 and 200 °C. We have found that ketone reduction to an alcohol is followed by acetoxylation, which provides a more facile route to C–O bond cleavage relative to the parent alcohol.

The mechanistic details of many polyketide synthases (PKSs) remain elusive due to the instability of transient intermediates that are not accessible via conventional methods. Here we report an atom replacement strategy that enables the rapid preparation of polyketone surrogates by selective atom replacement, thereby providing key substrate mimetics for detailed mechanistic evaluations. Polyketone mimetics are positioned on the actinorhodin acyl carrier protein (actACP) to probe the underpinnings of substrate association upon nascent chain elongation and processivity. Protein NMR is used to visualize substrate interaction with the actACP, where a tetraketide substrate is shown not to bind within the protein, while heptaketide and octaketide substrates show strong association between helix II and IV. To examine the later cyclization stages, we extended this strategy to prepare stabilized cyclic intermediates and evaluate their binding by the actACP. Elongated monocyclic mimics show much longer residence time within actACP than shortened analogs. Taken together, these observations suggest ACP-substrate association occurs both before and after ketoreductase action upon the fully elongated polyketone, indicating a key role played by the ACP within PKS timing and processivity. These atom replacement mimetics offer new tools to study protein and substrate interactions and are applicable to a wide variety of PKSs.

Structure-property-performance relationships of disulfonated poly(arylene ether sulfone) multiblock copolymer membranes were investigated for their use in direct methanol fuel cell (DMFC) applications. Multiple series of reactive polysulfone, polyketone, and polynitrile hydrophobic block segments having different block lengths and molecular composition were synthesized and reacted with a disulfonated poly(arylene ether sulfone) hydrophilic block segment by a coupling reaction. Large-scale morphological order of the multiblock copolymers evolved with the increase of block size that gave notable influence on mechanical toughness, water uptake, and proton/methanol transport. Chemical structural changes of the hydrophobic blocks through polar group, fluorination, and bisphenol type allowed further control of the specific properties. DMFC performance was analyzed to elicit the impact of structural variations of the multiblock copolymers. Finally, DMFC performances of selected multiblock copolymers were compared against that of the industrial standard Nafion in the DMFC system.

Nagata et al. recently developed high-impact polyketone/polyamide-6 (PK/PA) alloys and investigated their mechanical properties (Nagata et al. Polym. Prep. Jpn. 2006, 55, 4286−4287). This paper presents the results of investigations of their morphology, such as the domain size of PA and PK, features of crystalline phase of PK (the long period and thickness of lamellae are deduced), and the change in crystalline form of PA in the PK/PA alloys, using solid-state nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Solid-state 13C and 15N NMR results revealed that the γ crystalline phase of PA changes into a thermodynamically stable α crystalline phase after alloying with PK. The difference in the long period of lamellae of PK/PA alloys between dry and wet conditions is discussed. We conclude that the characteristic morphology of PK and humidity of the amorphous phase of PA in the wet condition are very important factors enabling the PK/PA alloys ...

Two pairs of enantiomerically pure chiral bidentate nitrogen-donor ligands (N*-N) featuring one sp(3) and one sp(2) nitrogen atom have been applied to the CO/vinyl arene copolymerization reaction catalyzed by the corresponding monocationic palladium(11) complexes [Pd(CH3)(CH3CN)-(N*-N)][PF6]. The ligand frame containing the sp(2) nitrogen atom is a 2-pyridinyl or an 8-quinolinyl building block, while the chiral framework of the ligand derives from (S)-(+)-2.2'-(2-azapropane-1,3-diyl)-1,1'-binaphthalene or from trans-2.5-dimethylpyrrolidinyl. Ligands with the binaphthyl moiety generate catalysts showing a moderate activity, while ligands having the pyrrolidinyl fragment results in very low activity species. The stereochemistry of the synthesized polyketones depends of the sp(2) nitrogen-containing fragment: ligands with the 2-pyridinyl group lead to atactic copolymers, whereas those with the quinolinyl moiety give an isotactic polyketone. The effect of the nature of the quinone, added to the reaction mixture as oxidant, has been investigated MALDI-TOF analysis reveals the formation of several polymeric chains, differing in the presence of various end-groups.

We report here the synthesis and characterization of stepladder and ladder poly(p-phenylene-alt-anthrylene)s (SLPPPA and LPPPA respectively) containing 9,10-anthrylene building groups within the main chain. The polyketone ladder polymer precursors are prepared by palladium-catalyzed Suzuki-type cross-coupling. The solution optical spectra of SLPPPA and LPPPA exhibit broad absorption bands with large Stokes shift unusual for rigid, ladder-type polymers. SLPPPA shows an intense yellow emission with a maximum at 584 nm while LPPPA is more red-shifted in emission with a maximum at 693 nm due to the planarization of the aromatic repeat units. Cyclic voltammetry studies reveal that both SLPPPA and LPPPA undergo fully reversible p- and n-doping processes. The methylene-bridged 1,4-di(10-phenylanthracen-9-yl)benzene LMC and the bis(methylene)bridged 9,10-diphenylanthracene SLMC are also synthesized, they serve as ladder and stepladder model compounds respectively and their optical properties are discussed in comp...

A [P-O]Pd catalyst based on o-alkoxy derivatives of diphenylphosphinobenzene sulfonic acid (I) has recently been shown by Drent et al. to perform nonalternating CO/C(2)H(4) copolymerization with subsequent incorporation of ethylene units into the polyketone chain. The origin of the nonalternation is investigated in a theoretical study of I, where calculated activation barriers and reaction heats of all involved elementary steps are used to generate a complete kinetic model. The kinetic model is able to account for the observed productivity and degree of nonalternation as a function of temperature. Consistent with the energy changes obtained for the real catalyst model, the selectivity toward a nonalternating distribution of both comonomers appears to be mainly a result of a strong destabilization of the Pd-acyl complex.

The synthesis and first examples of structurally characterized, single-site palladium complexes containing a phosphine sulfonate chelate (PSO) for the nonalternating copolymerization of ethylene and carbon monoxide are reported. Extra incorporation of ethylene up to 30% has been achieved relative to the alternating polyketone structure with modest activities. As exemplarily shown, high molecular weight random copolymers have been produced with Mw ≈ 370 000, polydispersity (Mw/Mn) = 2, and melting points of 220−230 °C.

Illumination of air-free aqueous solutions containing sulfonated poly(ether ether ketone) and poly(vinyl alcohol) with 350 nm light results in benzophenone ketyl radicals of the polyketone. The polymer radicals form with a quantum yield 0.02 and decay with a second-order rate constant 6 orders of magnitude lower than that of typical alpha-hydroxy radicals. Evidence is presented that the polymeric benzophenone ketyl radicals reduce Ag+, Cu2+, and AuCl4- to metal particles of nanometer dimensions. Decreases in the reduction rates with increasing Ag(I), Cu(II), and Au(III) concentrations are explained using a kinetic model in which the metal ions quench the excited state of the polymeric benzophenone groups, which forms the macromolecular radicals. Quenching is fastest for Ag+, whereas Cu2+ and AuCl4- exhibit similar rate constants. Particle formation becomes more complex as the number of equivalents needed to reduce the metal ions increases; the Au(III) system is an extreme case where the radical reactions operate in parallel with secondary light-initiated and thermal reduction channels. For each metal ion, the polymer-initiated photoreactions produce crystallites possessing distinct properties, such as a very strong plasmon in the Ag case or the narrow size distribution exhibited by Au particles.

Palladium(II) complexes with the formula [Pd(H2O)(OTs)(P-P)]OTs, where P-P is 1,1‘-bis(dimethylphosphino)ferrocene (dmpf), 1,1‘-bis(diethylphosphino)ferrocene (depf), or 1,1‘-bis(diisopropylphosphino)ferrocene (dippf), have been synthesized and used to catalyze the carbonylation of ethylene in MeOH, water, or a 1/1 water/1,4-dioxane mixture. In MeOH, the reactions catalyzed by the dmpf and depf complexes gave alternating polyketone (alt-E-CO), while methyl propanoate and 3-pentanone were selectively produced with the dippf catalyst. The last catalyst was inactive in aqueous solvent. In contrast, the dmpf and depf catalysts were active in either water or water/1,4-dioxane for the copolymerization of CO with ethylene. These two catalysts were efficient also for the terpolymerization of CO with ethylene and propene in MeOH or water/1,4-dioxane. Operando high-pressure NMR experiments and in situ reactions with model compounds have provided useful information to rationalize the activity and selectivity of the ...

Baeyer−Villiger oxidation of poly[(S)-2-methyl-1-oxopropane-1,3-diyl] (1) with m-chloroperbenzoic acid provided poly(ketone/ester) (2) in a ratio of ketone/ester = 82/18 in 73% isolated yield. Methanolysis of 2 (Mn = 8600) gave only a trace amount of methyl 3-hydroxybutyrate (5) which resulted from neighboring two ester units, −[OCH(CH3)CH2C(O)]2−. The major product was oligoketone (Mn = 650). A low yield of 5 indicates that an ester unit likely exists to distribute randomly in 2 rather than to form a block copolymer of a polyketone and a polyester.

Photoresponsive γ-polyketones substituted by azobenzene side chains were synthesized via asymmetric alternating copolymerization of the corresponding α-olefins in the presence of the Pd-(R,S)-BINAPHOS complex. 13C NMR of the polyketone having a tetramethylene spacer between the backbone and the azobenzene moiety disclosed that both ketone and spiroketal units existed in chloroform and that the spiroketal unit was transformed back to a ketone unit upon dissolution in 1,1,1,3,3,3-hexafluoro-2-propanol. Conformation of the polymer containing only ketone units was not affected by trans−cis photoisomerization of the side-chain azo chromophore, whereas the corresponding ketone/spiroketal polymer drastically changed its main-chain conformation upon trans-to-cis photoisomerization, as evidenced by increase of CD intensity by 70% at a carbonyl region.

Five new nonsymmetric 1-diphenylphosphino-3-{bis[aryl]phosphino}propane ligands 1b−f [aryl: b = 3,5-bis(trifluoromethyl)phenyl, c = 3,5-dimethylphenyl, d = 3,5-difluorophenyl, e = 2-(trifluoromethyl)phenyl, f = 2,4,6-trifluorophenyl] and their corresponding neutral dichloro palladium(II) 2b−f, diiodo palladium(II) 3d,e, and dicationic diacetonitrile palladium(II) ditetrafluoroborate complexes 4b−f were synthesized. The symmetric ligand 1,3-bis{bis[3,5-bis(trifluoromethyl)phenyl]phosphino}propane (1a) and the related palladium(II) complexes 2a and 4a were prepared for comparison. Solid state structures of new ligands were determined by X-ray structure analysis in the form of the dichloro (2a−c,f) and diiodo (3d,e) compounds. The properties of the symmetric (4a) and nonsymmetric catalysts (4b−f) were tested in propene/CO copolymerization experiments. A clear correlation between primarily steric effects of these ligands and the catalyst activity as well as the molecular weight of the resulting polyketone ma...

Conformation of a chiral γ-polyketone, poly((S)-1-oxo-2-methyltrimethylene) (1), in solution was investigated by CD and ORD spectropolarimetry and static light scattering refractometry. Variable-temperature CD and ORD spectra of 1 as compared with that of a chiral diketone (S)-3-methyl-2,5-hexanedione (3), a model compound of 1, afforded no evidence of polyketone 1 forming stable helical conformation. Static light scattering refractometry showed Mw value of 1 was 18 800, smaller than Mw 27 600 measured by GPC, indicating the existence of an extended conformation. The number-average root-mean-square radius of gyration Rg,n is evaluated to be 9.94 nm by static light scattering.

Novel aromatic polyketones (8a, 8b) without ether linkage in the main chain were successfully synthesized via nickel-mediated aromatic coupling polymerization of bis(chlorobenzoyl)dimethoxybiphenyls (3a, 3b). The polymers affording flexible films were obtained in the reaction where an excess amount of bipyridyl and a stoichiometric amount of the nickel(II) bromide were present. The resulting polyketones (8a, 8b) have sufficiently high molecular weight (inherent viscosity: 0.59 dL/g for polyketone 8a; 0.35 dL/g for polyketone 8b) and a highly amorphous nature with a rather high glass transition temperature: 218 °C for polyketone 8a; 192 °C for polyketone 8b.

Diastereoselective reduction of enantiomerically pure polymer is described. Reduction of poly((S)-1-oxo-2-methylpropylene) [(S)-1] with tetrabutylammonium borohydride (Bu4N·BH4) provided the corresponding polyol, poly(1-hydroxy-2-methylpropylene) (2), in a quantitative yield. The absolute configuration of the local structure was determined by the unambiguous synthesis of four diastereomers of 3-methyl-2,5-hexanediol. The newly formed asymmetric carbon was controlled to S-configuration with S/R ratio of 70/30. The S-selectivity contradicts to the conventional Cram-selectivity with which R-configuration is predicted from (S)-1. The origin of the selectivity is discussed by comparing the results with the reduction of a model molecule, 3-methyl-2,5-hexanedione.

Very efficient syntheses of “long” bisphenol and activated dihalide monomers containing keto groups were developed on the basis of α-aminonitrile chemistry. Known and novel activated dihalide monom...

To address the insolubility problem of polyketones, we used an approach to high molecular weight wholly aromatic polyketones without ether linkages via soluble precursors derived from isophthaldehyde-based bis(aminonitrile)s. Polymerization of bis(α-aminonitrile)s with activated dihalides using NaH as base in DMF yielded soluble, high molecular weight poly(aminonitrile)s, which were hydrolyzed in acidic conditions to produce the corresponding aromatic polyketones without ether linkages or alkyl substituents in the polymeric backbones. These polyketones displayed excellent thermal properties and solvent resistance. For the synthesis of poly(aminonitrile)s and polyketones containing ether linkages in the polymeric backbone, only low to medium molecular weight polymers were obtained. Model studies proved that the carbanions of the aminonitriles reacted with ether linkages to form more stable phenoxide anions and cause the termination of the polymerization.

To address the insolubility problem of polyketones, we used a new approach to high molecular weight wholly aromatic polyketones without ether linkages via soluble precursors derived from isophthaldehyde-based amino nitriles.1 High molecular weight, soluble poly(amino nitrile)s 2 were synthesized from the anions of these bis(amino nitrile)s 1 and 4,4‘-difluorobenzophenone using sodium hydride as base under mild reaction conditions. Hydrolysis of the poly(amino nitrile)s under acidic conditions yielded the corresponding polyketone, poly(p-phenylenecarbonyl-p-phenylenecarbonyl-m-phenylenecarbonyl) (3). This all aromatic polyketone, with an absence of ether linkages in the polymer backbone, displays excellent thermal properties and solvent resistivity. It is infusible and insoluble in most common organic solvents.

The palladium-catalyzed copolymerization of carbon monoxide and ethylene to give polyketone polymers, [−CH2CH2C(O)−]n, has been accomplished by the use of either (dppp)Pd(OAc)2 or (dppp)Pd[C(O)tBu]...

6 pags., 8 figs., 5 tabs., In the second part of this series the influence of monomer concentration on the chemical structure and the shape and size of poly(aryl ether ketone ether ketone ketone) (PEKEKK) particles was reported. The present study of the thermal behavior and microstructure of aromatic polyketone samples in the form of particles has been carried out by means of differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). Samples before and after reprecipitation and annealing were investigated. Similar to other polyketones, PEKEKK shows two polymorphic forms: form II, less stable, is currently observed in the samples, while the reprecipitated polymer preferentially shows form I. Form II is partially converted into form I upon short annealing treatment of the material. The semicrystalline materials show melting points and glass transition temperatures which are higher for the samples with higher molecular weight and more regular chain structure. A comparison of thermal properties of “as obtained” and “reprecipitated” samples reveals the influence of the particle architecture on the chain mobility. The latter determines the ability of polyketone chains to crystallize. Infrared dichroism was also used to characterize the arrangement of polymer chains inside the polyketone particles showing crystal habits., Grateful acknowledgment is due to DGICYT, Spain, for the support of this investigation (grant PB94-0049). M.G.Z. also thanks DGICYT for the tenure of a sabbatical grant during his research work in Madrid

We propose a hypothetical carbon-sulfur polymer (CS), which conceptually derives from both the experimentally known trithiapentalene molecule (TIT) and the theoretically suggested "polyketone". Using the extended Hiickel method, we examine the electronic structure of this system first in a planar conformation. The polytrithiapentalene formulation, with electron-rich multicenter S-S bonding and six electrons in the x system of each C& repeat unit, fits best the electronic structure calculated. The x band filling suggests both that the carbon sublattice will undergo a Peierls distortion and that the intriguing multicenter sulfur bonding of TTP carries over into the polymer; however, half-filled sulfur lone pair bands imply that a pairing distortion is likely in the sulfur sublattice too. We contrast this with planar polyketone, where there is no electronic reason for pairing but rather a driving force to distort into a helix. Studying the likely pairing distortions of carbon and sulfur sublattices in polythiene, we conclude that pairing of the carbons is marginally energetically favorable, whereas pairing of the sulfurs is strongly favorable. Two possible combinations of carbon and sulfur pairing compete for being the lowest-energy conformation. We examine helical (i.e., nonplanar) conformations and find an energy minimum for a very slightly twisted conformation. Finally we discuss the role, we think small. of 3d basis functions on sulfur.

Using long-path FTIR absorption spectroscopy, the kinetics and products of the reaction of OH radicals with the enediol form of acetylformoin, 3,4-dihydroxy-3-hexene-2,5-dione, an important aromatic photooxidation product, have been investigated in a 1080-L reaction chamber. A rate coefficient of (2.7±0.7)×10 -10 cm 3 molecule -1 s -1 has been obtained for the reaction at 296±2 K in 1000 mbar of synthetic air. Pyruvic acid and CO have been identified as minor reaction products. The experimental evidence supports that the major product is probably a hydrated vicinal polyketone, 3,3-dihydroxyhexane-2,4,5-trione. The results also imply that polyketones will be important products in the photooxidation of alkylated benzenes and that they could account for 25-30% of the missing carbon in aromatic oxidation systems

We now report a novel nucleophilic carbon-carbon bond-forming polymerization route for the synthesis of new poly(arylene ketone sulfone)s, devoid of any ether linkages in the backbone, via soluble precursors. These polymers can be synthesized at moderate temperatures and in high yields

The copolymerization of propylene with carbon monoxide using a catalytic system based on palladium acetate, modified with the atropisomeric chiral ligand (S)-(6,6{prime}-dimethylbiphenyl-2,2{prime}-diyl)bis(dicyclohexylphosphine), gives poly[spiro-2,5-(3-methyltetrahydrofuran)]. This material is transformed into the isomeric poly(1-oxo-2-methyltrimethylene) by dissolution in hexafluoro-2-propanol and precipitation with methanol. A mechanism based on a carbene intermediate is proposed in order to account for the formation of the polyketone material in the spiroketal form. 22 refs., 1 fig.

Thin films of poly(vinyl alcohol) (PVA) were exposed to a 25-kV electron beam under high vacuum conditions and to a 175-kV electron beam at atmospheric pressures of N{sub 2}. The decomposition of PVA by the electron beam sequentially formed materials that had polyketone- and polyethylene-like structures, respectively. Contrary to previous reports we show that the ketone groups formed as a result of the electron beam exposure are not due to an oxidation step by molecular oxygen. Damage cross sections for the electron beam decomposition (at 25 kV) were determined for PVA and the polyketone, and G values were determined for decomposition of {minus}OH groups and formation of ketone functional groups.

Full conversion of polybutadienes to polyketones was easily achieved using low oxygen pressure and catalytic amounts of palladium chloride and copper chloride in 1,2-dimethoxyethane at 80 °C. The conversions and selectivities of this Wacker-type reaction are controlled by the reaction conditions. The polyketone products were characterized by 1H and 13C NMR and infrared spectroscopy and by gel permeation chromatography.

We report a new strategy for synthesis of stereoblock polymers involving ancillary ligand exchange during a living transition-metal-catalyzed polymerization. We have also demonstrated cooperativity between chain-end and site control mechanisms through ligand exchange. On the basis of these results, stereoblock copolymer synthesis was approached by first growing an isotactic segment with I-2, then switching on syndiotactic growth by displacing the bisoxazoline ligand from the Pd(II) catalyst with bipyridine. 18 refs., 1 fig.