2,2′,3,3′,5,5′-Hexaphenyl-[1,1′-biphenyl]-4,4′-diols as Monomer Units for Redox Polymers: Synthesis and Polymerization Strategies

Abstract

2,2′,3,3′,5,5′-Hexaphenyl-[1,1′,-biphenyl]-4,4′-diol (Ib), which is prepared by the oxidative coupling of 2,3,6-triphenylphenol, and its oxidized form (IIIb) constitute a powerful oxidation-reduction system. The oxidative coupling reaction is carried out in the presence of molecular oxygen with copper(I) chloride as a catalyst and butyronitrile as ligand and solvent. An approach to the incorporation of such biphenols into an oxidation-reduction polymer is presented.     

Stereospecific polymerization of 9-fluorenyl methacrylate: Tacticity effects on the thermal and photophysical properties of the polymers

Poly(9-fluoreneyl methacrylate) was obtained through anionic polymerization with t-BuLi and t-BuMgBr and through radical polymerization with α,α′-azobisisobutyronitrile. Anionic polymerization with t-BuLi in tetrahydrofuran and radical polymerization afforded syndiotactic polymers (rr ∼ 90%), whereas anionic polymerization with Li and Mg initiators in toluene and CH₂Cl₂ led to isotactic polymers. The thermal and photophysical properties of the polymers were examined. A syndiotactic polymer tended to show higher glass transition and decomposition temperatures than an isotactic polymer. However, polymers with different tacticities were not likely to assume specific, distinctive conformations such as a helix or a π-stacked conformation in solution. An isotactic polymer showed stronger interactions in a CH₂Cl₂ solution with 2,4,7-trinitro-9-fluorenylidenemalononitrile, an electron-acceptor molecule, than a syndiotactic polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4656–4665, 2004     

Polymerization of N,N-Dialkylacrylamides with Anionic Initiators Modified by Diethylzinc

Abstract

N,N-Dimethyl-, diethyl-, and dipropylacrylamides were polymerized with 1,1-bis(4′-trimethylsilylphenyl)-3-methylpentyllithium (I) in the presence and absence of diethylzinc in THF. Although the polymers produced with I in the absence of diethylzinc have rather broad molecular weight distributions, the addition of diethylzinc to the polymerization systems causes narrow molecular weight distributions of the polymers. The addition of diethylzinc also affect the stereospecificities of the polymers obtained. The poly(N,N-diethylacrylamide) produced with I/diethylzinc (molar ratio of 1/3-15) is highly syndiotactic, while the one obtained with I is isotactic. The configuration of the poly(N,N-dimethylacrylamide) is changed from isotactic to syndio and heterotactic rich by the addition of diethylzinc to the polymerization mixture. Little effect of diethylzinc is observed on the stereospecificity of the polymerization of N,N-dipropylacrylamide. The stoichiometric additive effect of Et₂Zn toward the initiator in the polymerization of DEAA suggests that the coordination of Et₂Zn aggregates with the propagating carbanionic species narrows the molecular weight distribution and controls the tacticity of the polymer.     

One-pot Synthesis of Pd/Azo-polymer as an Efficient Catalyst for 4-Nitrophenol Reduction and Suzuki-Miyaura Coupling Reaction

The porous polymer matrix with good stability and confined microenvironment is considered as ideal support to stabilize isolated metal centers for catalysis. Herein, we report a “one-pot” method to prepare a kind of palladium complexed with azo porous organic polymer nanospheres (Pd-azo-POPs). The method combines the synthesis of azo-POPs with the reduction of the Pd ion, where azo serves as an anchoring group to limit the growth of Pd. The unique structure is conductive to the formation of a uniform active center and provides improved electron transfer. Pd-azo-POPs-80 exhibits a high catalytic activity and cycling stability both in 4-nitrophenol reduction and Suzuki-Miyaura coupling. The k_nor for the 4-nitrophenol reduction was 174.7 min⁻¹ mM⁻¹ and the conversion remains above 90% after 6 cycles. Meanwhile, the yield was still up to 94.5% after 5 cycles for the Suzuki-Miyaura coupling reaction of benzene derivatives with I/Br under mild conditions.     

Solid-Phase Functionauzation of Isotactic Polypropylene with Maleic Anhydride. Influence of Solvents and Additives on the Level of the Reaction

Abstract

Radical reaction between isotactic polypropylene and maleic anhydride initiated by peroxide at temperatures lower than the melting point of the polymer in the absence of liquid medium in the solid phase was studied. It was found that conversion of the reaction in the case of mixing of reagents into a pulverized polymer by the impregnation method is satisfactory in comparison with reaction conversion in the melt. It was found that reaction conversion in the solid phase can be increased up to 30% in the presence of a small amount of an organic solution, such as xylene (5 to 10%).     

Nucleosides and nucleotides. Part 8. Synthesis of dinucleotides with thymidine and 1-(deoxy-beta-D-ribofuranosyl)-2(1H)-pyridone as building blocks]

In order to investigate the stability of 1-(2′-deoxy-β-D-ribofuranosyl)-2(1H)-pyridone (Π_d, 3 ) under the conditions of oligonucleotide synthesis, the dinucleoside monophosphates (MeOTr)Π_d-T_d ( 9 ) and Π_d-T_d ( 11 ), and the dinucleotides Π_d-T_dp ( 15 ) and pII_d-T_d ( 19 ) were prepared, using various procedures. The N-glycosidic bond between the deoxyribose and the 2(1H)-pyridone proved to be much more labile than the one in the naturally occuring nucleosides. It was partially cleaved in condensation reactions with TPS or MS, but no cleavage was observed when DCC was used. Similarly, the glycosidic linkage was attacked by hot 80% acetic acid, the usual reagent for the removal of a p-methoxytrityl group in thymidine oligonucleotides. Milder treatment with acetic acid/pyridine 7:3 at 100° removed this protecting group and left the N-glycoside intact. The compounds prepared were characterized by paper and thin layer chromatography as well as by enzymatic degradation.     

Asymmetric oxidative coupling polymerization affording polynaphthylene with 1,1′-bi-2-naphthol units

The oxidative coupling polymerizations of racemic-, (R)-, and (S)-2,2′-dimethoxymethoxy-1,1′-binaphthalene-3,3′-diols were carried out with a copper catalyst with various ligands, such as N,N,N′,N′-tetramethylethylenediamine (TMEDA), (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine, (−)-sparteine, and (S)-(−)-2,2′-isopropylidenebis(4-phenyl-2-oxazoline) [(−)-Phbox], under an O₂ atmosphere. For example, a 10/1 (v/v) MeOH · H₂O-insoluble polymer with a number-average molecular weight of 3.8 × 10³, from a polymerization with CuCl–TMEDA followed by acetylation of the hydroxyl groups, was obtained in a 71% yield. Polymerization with (−)-Phbox proceeded in an S-selective manner to give a polymer with the highest negative specific rotation from the (S)-monomer. The obtained polymer was successfully converted into a polymer with the optically pure 1,1′-bi-2-naphthol unit based on the original monomer structure, which could be used as a polymeric chiral auxiliary and showed catalytic activity for the asymmetric diethylzinc addition reaction to aldehydes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4528–4534, 2004     

Syndiotactic and isotactic poly(tert-butylethylene oxide)

The rate of polymerization of t-BuEO by t-BuOK in DMSO is about one-tenth that of propylene oxide. The slow rate of propagation was accompanied by considerable chain transfer. In the absence of solvent, the polymer obtained was crystalline, different from the isotactic form and therefore must be syndiotactic. The NMR spectra indicate the isotactic polymer exists in solution preferentially in the skew₁ form, while syndiotactic is about 60% skew₁, 40% skew₂. Amorphous polymer accompanying isotactic exists about 50% in the trans conformer, by NMR data.     

Characterization of Nitro-Substituted Polybenzimidazole Synthesized by the Reaction with Nitric Acid

Abstract

Nitro-substituted poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole]s (PBIs) were synthesized by the reaction of PBI with nitric acid in sulfuric acid under various conditions. The number of nitro groups substituted on the aromatic ring of PBI per polymeric unit varied from 1.44 to 3.55 according to the reaction conditions. An increase in reaction temperature and concentration of the nitric acid increased the degree of substitution. The inherent viscosity of the substituted polymer increased as the reaction temperature decreased. When the reaction temperature was 30°C, the inherent viscosity of the polymer increased as the concentration of nitric acid increased. The nitro-substituted PBI exhibited polyelectrolyte behavior in formic acid. The nitro groups substituted on PBI were dissociated when the polymer was heated to 450°C, displaying exothermic behavior, and the decomposition of polymer was proportional to its nitro group content. All nitro-substituted PBIs showed better solubilities in polar aprotic and acidic solvents, such as dimethylacetamide, dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, formic acid, sulfuric acid, and trifluoromethanesulfonic acid.     

Catalytic Activity of Polymer Anchored Cu-tren Complex in the Oxidation of 2,6-Di-t-butyl Phenol

Poly(styrene-co-dimethylaminoethyl methacrylate) and poly(methyl methacrylate-co- dimethylaminoethyl methacrylate) were prepared by solution polymerization. These polymers were quaternized by methyl iodide and n-hexyl bromide. The produced polymers were used as support in the aqueous oxidation of 2,6-di-tert-butylphenol (DBP) using hydrogen peroxide catalyzed by tris(2-aminoethyl)amine copper(II) complex “Cu(II)-tren complex” anchored on the prepared polymers. The products obtained from the reactions were 3,3′-5,5′-tetra-tert-butyldiphenoquinine (DPQ) and 2,6-di-tert-butyl-p-benzoquinone (BQ). No reaction products were obtained when the reaction was carried out in the absence of polymeric catalyst. The polymer composition and reaction medium greatly affect product distribution of the reaction. Polar organic solvent like DMF and methanol favor the formation of DPQ, while nonploar organic solvent like benzene and methylene chloride favor the formation of BQ. Hydrophobic branches of polymers 6 (PS-HexBr-Cu-TREN) and 8 (PMMA-HexBr-Cu-TREN) favor BQ formation as the weight of support increased. On the other hand, DPQ is favored in the presence of hydrophilic branches as observed for both polymeric catalysts 5 (PS-MeI-Cu-TREN) and 7 (PMMA-MeI-Cu-TREN).     

Highly selective oxidative cross‐coupling polymerization with copper(I)‐bisoxazoline catalysts

The asymmetric oxidative coupling polymerization of methyl 6,6′‐dihydroxy‐2,2′‐binaphthalene‐7‐carboxylate with the copper‐diamine catalysts under an O₂ atmosphere was carried out. As is the case with the CuCl‐2,2′‐(S)‐isopropylidenbis(4‐phenyl‐2‐oxazoline) [(S)IPhO] catalyst, a polymer with a high cross‐coupling selectivity of 96% was obtained in 71% yield, whose THF‐soluble part had a number‐average molecular weight of 4.5 × 10³. To estimate the enantioselectivity with respect to the cross‐coupling linkage in the obtained polymer, the model asymmetric oxidative cross‐coupling reaction with CuCl‐(S)IPhO was also conducted, and the products showed a 94% cross‐coupling selectivity and enantioselectivity of 31% ee (S). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6287–6294, 2005     

Synthesis,Characterization, and Photocrosslinking Properties of Poly(4‐Methacrylamidophenyl‐2′,3′‐benzostyryl Ketone)

Abstract

A new methacrylamide monomer, 4‐methacrylamidophenyl‐2′,3′‐benzostyryl ketone (MPBSK) having a free‐radical polymerizable group and a photocrosslinkable functional group, was synthesized by reacting 4‐(2′,3′‐benzocinnamoyl)aniline with methacryloyl chloride in the presence of triethyl amine. The monomer, MPBSK was polymerized in methyl ethyl ketone (MEK) at 70°C using benzoyl peroxide (BPO) as the initiator. The polymer was characterized by UV, IR, ¹H‐NMR, and ¹³C‐NMR spectroscopy. The polymer was found to be soluble in several polar aprotic solvents and in chlorinated solvents but insoluble in aliphatic and aromatic hydrocarbons and in alcohols. The molecular weight data of the polymer as obtained from gel permeation chromatography suggests a higher tendency for chain termination by disproportionation than dimerization. The glass transition temperature of the polymer was determined by differential scanning calorimetry. Thermogravimetric analysis of the polymer carried out in air reveals that it possesses good thermal stability required of a negative photoresist. The photocrosslinking property of the polymer was investigated by irradiating the polymer solution with UV light in the presence and absence of triplet photosensitizers. The effect of the solvent on the rate of photocrosslinking of the polymer was also studied.     

Polymer Intermediates and Polymers Derived from 5-t-Butyl-m-Xylene

Abstract

A series of condensation polymer intermediates, which included several new compositions, was prepared from 5-t-butyl-m-xylene (I) so that the effect of the bulky t-butyl group on polymer properties could be determined. Compound (I) was oxidized with nitric acid to obtain 5-t-butyl-isophthalic acid (II), which was converted successively to the diacid chloride, the diamide, the dinitrile, and finally to 5-t-butyl-m-xylene-α,α′-diamine (VI); the overall yield was 80%. The dimethyl ester of (II) was prepared and converted to 5-t-butyl-m-xylene-α,α′-diol (VIII), a new composition, in 79.5% overall yield; the diphenyl ester was also prepared. The sodium salt of (II) was catalytically reduced to obtain 5-t-butyl-1,3-cyclohexanedicarboxylic acid (IIa) in 95% yield. (IIa) was converted successively to the diacid chloride, the diamide, the dinitrile, and finally to 5-t-butyl-1,3-cyclohexanebis(methylamine) (VIa), a new composition; the overall yield was 37%. (IIa) was also converted to the dimethyl ester and finally to 5-t-butyl-1,3-cyclohexanedimethanol (VIIIa), a new composition; the overall yield was 64%. Condensation polymers were prepared from the intermediates (II), (IIa), (VI), (VIa), (VIII), and (VIIIa). These polymers had higher glass transition temperatures (T_g) than corresponding polymers containing no t-butyl groups. This general effect of the t-butyl group to increase the T_g value of the polymer was noted in all polymers prepared, regardless of whether the intermediate carrying the t-butyl group was a diacid, a diol, or a diamine, or whether the polymer was a polyamide, a polyester, or a polyurethane.     

Structure and optical activity of a crystalline modification of isotactic poly-(S)-4-methyl-1-hexene

The results of an x-ray and polarimetric study of a crystalline modification (form I) of isotactic poly-(S)-4-methyl-1-hexene are reported and discussed. The x-ray fiber spectra of this polymer are practically indistinguishable from those of isotactic poly-(R)-(S)-4-methyl-1-hexene. Although the crystal structure of the latter can be described on the basis of helices of different screw sense packed in a P4 space group, the crystal structure of poly-(S)-4-methyl-1-hexene is better described on the basis of a P1 space group. The conclusion of the x-ray investigation, that in the crystals of the optically active polymer an equal number of right-handed and left-handed helices must be present, is supported by the polarimetric measurements, which have shown that the polymer in the crystalline form I possesses a rather low rotatory power.     

Efficient Synthesis of 2′-Deoxy-β-D-furanosyl C-Glycosides. Palladium-Mediated Glycal-Aglycone Coupling and Stereocontrolled β- and α-Face Reductions of 3-Keto-furanosyl Moieties

ABSTRACT

Efficient routes for selective syntheses of 2′-deoxy-β-D-furanosyl C-glycosides have been developed and demonstrated by preparation of the isomers 5-[2′-deoxy-β-D-ribo- (=arabino)furanosyl]-1,3-dimethyl-2,4(1H,3H)-pyrimidinedione and 5-[2′-deoxy-β-D-xylo-(=lyxo)furanosyl]-1,3-dimethyl-2,4(1H,3H)-pyrimidinedione. The syntheses involved regio-and stereospecific palladium-mediated coupling of a new glycal, 1,4-anhydro-2-deoxy-3-O-[(1,1-dimethylethyl)diphenylsilyl]-D-erythro-pent-1-enitol with an appropriate aglycone derivative to form a single 2′-deoxy-3′-keto-β-D-furanosyl C-glycoside (as the corresponding silyl enol ether). Following desilylation, the ketone group of the furanosyl ring was reduced stereo-selectively in either of two ways: by delivery of hydride from (a) the most hindered face of the carbonyl carbon using sodium (triacetoxy)borohydride or (b) the least hindered face using potassium tri-(sec-butyl)borohydride.     

Effect of sub-Tg relaxations on chromophore reorientation in corona-poled polymers

Activation volumes for chromophore reorientation were measured for a series of guest–host polymeric materials, indicating a significant coupling between chromophore motion and the glassy α and β relaxation dynamics of the polymer host. The specific systems studied were formed by individually dissolving N,N-dimethyl-p-nitroaniline (DpNA), 4-(dimethylamino)-4′-nitrotolane (DMANT), 4-(diethylamino)-4′-nitrotolane (DEANT), and 1-((4-(dimethylamino)phenyl)ethynyl)-4-((4-nitrophenyl)ethynyl)benzene (DMAPEANT) in poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(isobutyl methacrylate) (PiBMA). In each of these systems, the isothermal, sub-T_g decay of the second-order optical susceptibility χ⁽²⁾ was monitored as a function of pressure using second harmonic generation. In each system, the observed decay of χ⁽²⁾ was represented by a stretched exponential equation from which the decay time τ₀ and decay distribution width β_KWW were determined. For each dopant molecule, the decrease in activation volume with the increasing size of the polymer host's alkyl side group and the pressure dependence of β_KWW were indicative of partial coupling between chromophore rotation and the glassy β relaxation dynamics of the polymer host. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1013–1024, 1998     

The temperature dependence of nematic liquid crystalline polymer melt diffusion

Abstract

Polymer chain diffusion in the nematic mesophase was studied using a model main chain liquid crystalline (LC) polyether based on 2,2′-dimethyl-4,4′-dihydroxyazoxybenzene and mixed alkane spacers. A side chain LC polymethacrylate containing an azobenzene mesogenic group was also investigated. Tracer diffusion coefficients were determined as a function of temperature by an ion-beam depth profiling technique, forward recoil spectrometry. The results confirm that main chain LC polymer chain dynamics are dramatically affected by phase transitions and sample geometry. This behaviour is in marked contrast to the side chain LC polymer which exhibited no phase dependence on the part of the tracer diffusion coefficient.     

Polymerization of propene with organomagnesium–reduced titanium (IV) chloride-based catalyst

A kinetic study of the polymerization of propene by use of magnesium–reduced titanium (IV) chloride-based catalyst systems has been carried out and the tacticities and molecular weights of the polymers formed have been investigated. The rate constant for the formation of isotactic polymer is estimated to be 69 ± 18 dm³/mole sec and that for the atactic polymer to be 12 ± 5 cm³/mole sec. The number of active sites producing atactic polymer has been determined as 3 ± 1% of the Ti atoms present, whereas sites producing isotactic material amount to 0.36 ± 0.13% of the Ti atoms. The overall tacticity of the polymers corresponds to approximately 40% isotactic material. This figure is barely affected by heat treatment of the catalyst.     

Isolation of a new flavonoid and waste to wealth recovery of 6-O-Ascorbyl Esters from Seeds of Aegle marmelos (family- Rutaceae)

Aegle marmelos is a plant species native to India. Commercially available food products such as jam, jelly, candy, squash etc. are prepared from ripe fruit pulp of A. marmelos. Ripe fruit processing accounts for 60% of whole fruit mass while 40% remains unutilized and generates waste (hard shell, pomace, fiber and seeds) on a massive scale which do not have high value applications. A new flavone 3,5,7-trihydroxy-2-(4′-hydroxy-3′-isopentyloxyphenyl-4H-chromen-4-one (5) in addition to the known compounds 1–4, has been isolated from seeds of A. marmelos. Also, compound 7-(3′-methylbut-2′-enyloxy)-2H-chromen-2-one (2) has been isolated for the first time from A. marmelos. The structure of compounds 1–5 was determined by spectral analysis (UV, IR, NMR, etc.). Additionally, the non-edible oil obtained from seeds was investigated for waste to wealth recovery of 6-O-ascorbyl esters in high regioselectivity via one step semi-synthetic approach in the presence of ascorbic acid and H₂SO₄ at ambient temperature.     

Stereospecific and asymmetric polymerization of 1-phenyldibenzosuberyl methacrylate with radical and anionic initiators

Stereospecific and asymmetric (helix-sense-selective) polymerization of 1-phenyldibenzosuberyl methacrylate (PDBSMA) was performed with radical and anionic initiators. A highly isotactic polymer having triad isotacticity greater than 97% was obtained by radical polymerization with (i-PrOCOO)₂ at 40°C. The radical polymerization of PDBSMA in (+)- and (-)-menthol gave (-)-and (+)-polymers, respectively, whose optical activity is ascribed to the prevailing one-handed helical conformation of a polymer chain. The radical copolymerization of PDBSMA with a small amount of an optically active monomer, (+)-phenyl-2-pyridyl-o-tolylmethyl methacrylate, afforded an optically active copolymer with the prevailing one-handed helical structure of PDBSMA sequences. Asymmetric anionic polymerization of PDBSMA was carried out with the complex of N, N′-diphenylethylenediamine monolithium amide and a chiral ligand, (+)-1-(2-pyrrolidinylmethyl)pyrrolidine in toluene at −78°C. The obtained polymer was highly isotactic and optically active due to nearly 100% one-handed helical structure.