Carboxylation of o-dichlorobenzene under pressure

When o-dichlorobenzene was carboxylated with carbon monoxide in presence of water at high pressure the conversions to phthalic acid and benzoic acid at the optimum reaction conditions were 6.20% and 35.80% respectively without any catalyst, while with a catalyst (nickel iodide on silica gel; Ni : SiO₂ = 50 : 50) these conversions were 8.90% and 39.85% respectively. Use of catalyst reduced the optimum temperature and pressure for the conversion to phthalic acid, while it reduced the optimum pressure and residence period for the conversion to benzoic acid.     

Dynamic quenching of 5-(2′-ethyl-hexyloxy)-p-phenylene vinylene (MEH-PPV) by charge transfer to a C60 derivative in solution

The fluorescence of 5-(2′-ethyl-hexyloxy)-p-phenylene vinylene (MEH-PPV) quenched in solution in 1,2-dichlorobenzene by a soluble derivative of C₆₀ [1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C₆₁; [6,6]PCBM] is studied by changing the concentration of the quencher and by varying the temperature. For MEH-PPV and PCBM dissolved in 1,2-dichlorobenzene, the Stern–Volmer constant (K_SV) is 2 × 10³M⁻¹. At high temperature, K_SV is enhanced because thermal energy facilitates the diffusion of PCBM. The results show that dynamic quenching (rather than static quenching) is the basic mechanism. Comparison with data obtained from quenching studies of trans-stilbene indicates that a single acceptor in contact with an MEH-PPV macromolecule quenches the luminescence from hundreds of repeat units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2553–2557, 2001     

Synthesis of p-substituted tetraphenylporphyrins and corresponding ferric complexes with mixed-solvents method

By using mixed-solvents method, five kinds of p-substituted tetraphenylporphyrin compounds [T(p-R)PPH₂, R=NO₂, Cl, CH₃, OCH₃, OH] were synthesized by the condensation of p-substituted benzaldehyde with pyrrole in mixed solvents (propionic acid, acetic acid and nitrobenzene), and corresponding ferric complexes [T(p-R)PPFe^IIICl] were synthesized in dimethylformamide. The above free base porphyrins were obtained in 30%–50% yields, metalation yields were up to 90% and total yields of ferric complexes were 27%–50%. Effects of reactive conditions, solvents and oxidants on yields of free base porphyrins were investigated and the relevant mechanism was discussed. Structures of the above porphyrin complexes were characterized by ultravioletvisible (UV-Vis), infrared (IR) and far infrared (FIR) spectroscopy.     

Synthesis, characterization, and oxygen permeability of homo- and copolymers from p-[tris(trimethylsilyl)silyl]-phenylacetylene

Summary Homopolymerization of p-[tris(trimethylsilyl)silyl]phenylacetylene [p(Me₃Si)₃SiPA] by Rh catalyst provided insoluble polymer. On the other hand, copolymerization of p(Me₃Si)₃SiPA with p-(trimethylsilyl)phenylacetylene (pMe₃SiPA) at 80:20, 50:50, and 20:80 feed ratios afforded high molecular weight copolymers (M _w > 1×10⁶), all of which were soluble in common solvents such as toluene and chloroform. The mole ratios of p(Me₃Si)₃SiPA to pMe₃SiPA unit in copolymers were close to those in the feeds. The oxygen permeability increased monotonously with increasing p(Me₃Si)₃SiPA content of copolymer in correspondence with fractional free volume; the value of the copolymer for the 80:20 feed ratio reached 770 barrers. Received: 30 August 2000/ Accepted: 6 September 2000     

Preparation of composite‐imprinted alumina membrane for effective separation of p‐hydroxybenzonic acid from its isomer using Box–Behnken design–based statistical modeling

Highly selective composite imprinted membrane for p‐hydroxybenzonic acid (p‐HB) was prepared by using semicovalent imprinting technique. A thermally reversible covalent bond was used to link p‐HB molecule to a functional alkoxysilane monomer to generate covalently bound imprint precursor. This precursor was incorporated into a cross‐linked functional silica sol with the tetraethoxysilane as cross‐linker via a typical acid‐catalyzed, sol‐gel synthesis. Then, the SCIM was prepared through dipping and grafting on the upper side and inner pores of the Al₂O₃ microporous membrane and then removing of the template molecule after thermal treatment. Compared with composite imprinted membrane via noncovalent imprinting approach as well as the black Al₂O₃ microporous membrane, the SCIM exhibited higher membrane flux and selective rebinding of p‐HB as well as showing excellent permeability for p‐HB. Response surface methodology was used to investigate the best combination of separation conditions in the dynamic separation process. The optimal conditions for the separation of p‐HB from salicylic acid were as follows: the p‐HB concentration of 5 mg L^?1, the temperature of 10°C, and the flow rate of 1 mL min^?1. Under these conditions, the experimental selective separation factor was 32.75 ± 0.91%, which was close to the predicted selectivity coefficient value. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40621.     

Synthesis of graft polyesters by ring-opening copolymerization of epoxy-terminated poly(ethylene glycol) with acid anhydrides

The copolymerization of epoxy-terminated poly(ethylene glycol methyl ether) (CH₃PEG–epoxide) with phthalic anhydride catalyzed by tertiary amines was performed in o-dichlorobenzene at 100°C to prepare the PEG graft polyester. 4-Dimethylaminopyridine was the most favorable catalyst to give the graft polyester with relatively high molecular weight. The acidity of the reaction solution decreased and M _n of the graft polyesters increased with reaction time. The CH₃PEG/phthalic acid ratio of the products was little affected by the kind of solvent and the reaction temperature above 100°C, but M _n increased with lowering the polarity of solvents and with raising the temperature. Other acid anhydrides, including maleic, succinic, tetrahydrophthalic, and pyromellitic anhydride, could be copolymerized with CH₃PEG–epoxide. The number of branched CH₃PEG chains was controlled by the mixing of low molecular weight epoxide such as n-butyl glycidyl ether. CH₃PEG component of the graft copolymers melted and crystallized at lower temperature than the raw CH₃PEG because of the restriction on the trunk polyester chain.     

Dissociation constants of long chain fatty acids in methanol-water and ethanol-water mixtures

The pK_a values of lauric acid, myristic acid, palmitic acid and stearic acid in methanol-water and ethanol-water mixtures of different compositions at 303 K and ionic strength, I=0.1M(KNO₃) have been determined. The pK_a values of the fatty acids have been found to increase with the alcohol content of the solvent. It has also been found that, in general, the pK_a values in the ethanolic solvent are greater than those in the methanolic solvent. In a given solvent mixture the observed pK_a value decreases in the order of stearic acid > palmitic acid > myristic acid > lauric acid. Departure from the predicted linearity of the plots of pK_a against the inverse of the dielectric constant, 1/D indicates that the electrostatic effects taken into account by the Born theory are not adequate enough to represent the total medium effects on pK_a.     

Superacid and H-Zeolite Mediated Reactions of Benzaldehyde with Aromatic Compounds and Cyclohexane. The Role of Mono- and Dicationic Intermediates

Reactions of benzaldehyde (1) and related compounds–3-pyridinecarboxaldehyde (9) and acetophenone with benzene, chlorobenzene, o-dichlorobenzene and cyclohexane in the presence of superacids or H-form zeolite, HUSY were (re)investigated. In accordance with previous data, 1 condenses with benzene in triflic acid (CF₃SO₃H) as well as on HUSY to give triphenylmethane. At elevated temperature 1 also reacts with chlorobenzene but is inert towards o-dichlorobenzene. While 1 does not react with cyclohexane in CF₃SO₃H–SbF₅, 9 undergoes readily selective ionic hydrogenation to give 3-pyridilcarbinol (14). In the presence of excess of AlCl₃, however, as well as on HUSY, 1 reacts with cyclohexane to produce toluene. The mechanistic aspects of these reactions are discussed. Opposed to earlier, repeatedly cited suggestions that the reactivity of 1 involves, as in case of 9, superelectrophilic diprotonated species, we show that a monocationic intermediate is the best rationale for these results     

Effect of acrylic acid neutralization on ‘livingness’ of poly[styrene‐ran‐(acrylic acid)] macro‐initiators for nitroxide‐mediated polymerization of styrene

BACKGROUND: The effect of acrylic acid neutralization on the degradation of alkoxyamine initiators for nitroxide‐mediated polymerization (NMP) was studied using styrene/acrylic acid and styrene/sodium acrylate random copolymers (20 mol% initial acrylate feed concentration) as macro‐initiators. The random copolymers were re‐initiated with fresh styrene in 1,4‐dioxane at 110 °C at SG1 mediator/BlocBuilder^® unimolecular initiator ratios of 5 and 10 mol%. RESULTS: The value of k_pK (k_p = propagation rate constant, K = equilibrium constant) was not significantly different for styrene/acrylic acid and styrene/sodium acrylate compositions at 110 °C (k_pK = 2.4 × 10^?6–4.6 × 10^?6 s^?1) and agreed closely with that for styrene homopolymerization at the same conditions (k_pK = 2.7 × 10^?6–3.0 × 10^?6 s^?1). All random copolymers had monomodal, narrow molecular weight distributions (polydispersity index M?_w/M?_n = 1.10–1.22) with similar number‐average molecular weights M?_n = 19.3–22.1 kg mol^?1. Re‐initiation of styrene/acrylic acid random copolymers with styrene resulted in block copolymers with broader molecular weight distributions (M?_w/M?_n = 1.37–2.04) compared to chains re‐initiated by styrene/sodium acrylate random copolymers (M?_w/M?_n = 1.33). CONCLUSIONS: Acrylic acid degradation of the alkoxyamines was prevented by neutralization of acrylic acid and allowed more SG1‐terminated chains to re‐initiate the polymerization of a second styrenic block by NMP. Copyright © 2008 Society of Chemical Industry     

Topochemistry Part XXXV. The Formation of Mixed Dimers from Solid Solutions of Trans-Cinnamic Acids and Trans-Cinnamides

Irradiation (λ >300 nm) of eight two-component solid solutions of β-arylacrylamides, prepared by melting and crystallising equimolar quantities of the amides tr-ArCH:CHCONE where Ar=C₆H₅, p-MeOC₆H₄, p-ClC₆H₄, p-MeC₆H₄, and 2-thienyl, which appeared in the α crystal form, gave three photoproducts for each system studied: two α-truxillic homodimers, derived from the respective monomers, and an α-truxillic heterodimer. No other isomers were found. Similarly, two-component solid solutions were prepared by melting and crystallising ring-substituted cinnamic acids (tr-ArCH:CHCO₂H, where Ar=C₆H₅ (α-form), p—ClC₆H₄(β), p-MeC₆H₄(α), p-MeOC₆H₄(γ), o-ClC₆H₄(β) and o-CH₃C₆H₄(γ)) and irradiated. A solid solution of two α-type acids (each photodimerising in the solid to α-truxillic acid) behaved like the amides, affording two α-truxillic homodimers and an α-truxillic heterodimer. A solid solution of an α-type acid with a β-type acid (photodimerising to β-truxinic acids) gave six photoproducts: three α-truxillic acid dimers and three β-truxinic acid dimers (i.e., four homodimers and two heterodimers). Irradiation of a solution of a γ-type acid (non-photodimerising in the solid state) with an α-type acid afforded α-truxillic dimers (two homodimers and one heterodimer). The above results are consistent with mutual miscibility of the two components which gives rise to mixed crystal formation and subsequent photo-behaviour within each crystal which is characteristic of the particular lattice type. However, irradiation of the mixed crystals from p-methoxycinnamic acid (γ-type) and p-chlorocinnamic acid (β-type), which afford two α-truxillic dimers (methoxy-homodimer and methoxy, chloro-heterodimer) and two β-truxinic dimers (chloro-homodimer and methoxy, chloro-heterodimer) indicates that new phases, unobserved for the pure compounds, can also be generated. The new dimers were all characterised by the NMR and mass spectra of their dimethyl ester derivatives and, when possible, by conversion to known compounds.     

Synthesis and properties of photosensitive rubbers. IV. Photosensitive rubbers from hydroxyethyl cinnamate and polyisoprene modified with maleic anhydride

Polyisoprene in o-dichlorobenzene solution were reacted with maleic anhydride at 180°C under nitrogen atmosphere to form modified polyisoprene with α-substituted succinic anhydride groups. These groups were converted by reaction with hydroxyethyl cinnamate in pyridine at 25°C to cinnamate groups. Various amounts of cinnamate groups as photosensitive groups could be easily introduced into polyisoprene up to 75 mol % toward polyisoprene repeating units. Polymer glass transition temperatures of the products rose linearly from ?70°C for polyisoprene to 60°C with increasing amounts of the side groups. The solution viscosity of the products in chloroform decreased from 9.34 for polyisoprene to 0.77 with increasing amounts of the side groups. The photosensitivity of the polyisoprene, which is based on the photodimerization of the cinnamate groups, was higher than that of polypentenamer having cinnamate groups due to the interaction by the free carboxylic acids neighboring with the cinnamate groups. The photosensitivity of the cinnamate group was kinetically evaluated in terms of the dependence on the polymer glass transition temperature. The interaction by the free carboxylic acid groups in the polyisoprene reduced the dependence of the photosensitivity on the mobility of the polymer segments. Linear relationship between observed rate constants of the photodimerization and (T_UV ? T_g + 50)^?1 was obtained and the slope of the line changed and became very small at higher glass transition temperatures.     

Synthesis and Biological Evaluation of Nipecotic Acid and Guvacine Derived 1,3-Disubstituted Allenes as Inhibitors of Murine GABA Transporter mGAT1

A new class of nipecotic acid and guvacine derivatives has been synthesized and characterized for their inhibitory potency at mGAT1–4 and binding affinity for mGAT1. Compounds of the described class are defined by a four-carbon-atom allenyl spacer connecting the nitrogen atom of the nipecotic acid or guvacine head with an aromatic residue. Among the compounds investigated, the mixture of nipecotic acid derivatives rac-{(R_a)-1-[4-([1,1′:2′,1′′-terphenyl]-2-yl)buta-2,3-dien-1-yl](3R)-piperidine-3-carboxylic acid} and rac-{(S_a)-1-[4-([1,1′:2′,1′′-terphenyl]-2-yl)buta-2,3-dien-1-yl](3R)-piperidine-3-carboxylic acid} ( 21 p ), possessing an o-terphenyl residue, was identified as highly selective and the most potent mGAT1 inhibitor in this study. For the (R)-nipecotic acid derived form of 21 p , the inhibitory potency in [³H]GABA uptake assays was determined as pIC₅₀=6.78±0.08, and the binding affinity in MS Binding Assays as pK_i=7.10±0.12. The synthesis of the designed compounds was carried out by a two-step procedure, generating the allene moiety via allenylation of terminal alkynes which allows broad variation of the terminal phenyl and biphenyl subunit.     

Chemical synthesis of cross-linked polyaniline by a novel solvothermal metathesis reaction of p-dichlorobenzene with sodium amide

We reported the chemical synthesis of cross-linked polyaniline (PANI) by a novel solvothermal metathesis reaction of p-dichlorobenzene (C₆H₄Cl₂) with sodium amide (NaNH₂) in benzene at 220 °C. In this method, the aniline monomer and complicated treatment were needless and the yield of final products was over 50%. The as-synthesized brown samples were NMP-soluble but water-insoluble; and they were characterized by XRD, FT-IR, UV-vis absorption, XPS, elemental analysis, TGA, and TEM. It was found that solvents have significant influence on the final product. The predominant mechanism of chain growth in PANI polymerizations was proposed as the ionic S_NAr process; however, further theoretical and experimental investigations are needed to obtain the undoubted evidences. We believe that this novel solvothermal metathesis reaction will give us a new guideline for the synthesis of some polymers.     

Effects of Microbial Utilization of Phenolic Acids and their Phenolic Acid Breakdown Products on Allelopathic Interactions

Reversible sorption of phenolic acids by soils may provide some protection to phenolic acids from microbial degradation. In the absence of microbes, reversible sorption 35 days after addition of 0.5–3 mol/g of ferulic acid or p-coumaric acid was 8–14% in Cecil A_p horizon and 31–38% in Cecil B_t, horizon soil materials. The reversibly sorbed/solution ratios (r/s) for ferulic acid or p-coumaric acid ranged from 0.12 to 0.25 in A_p and 0.65 to 0.85 in B_t horizon soil materials. When microbes were introduced, the r/s ratio for both the A_p and B_t horizon soil materials increased over time up to 5 and 2, respectively, thereby indicating a more rapid utilization of solution phenolic acids over reversibly sorbed phenolic acids. The increase in r/s ratio and the overall microbial utilization of ferulic acid and/or p-coumaric acid were much more rapid in A_p than in B_t horizon soil materials. Reversible sorption, however, provided protection of phenolic acids from microbial utilization for only very short periods of time. Differential soil fixation, microbial production of benzoic acids (e.g., vanillic acid and p-hydroxybenzoic acid) from cinnamic acids (e.g., ferulic acid and p-coumaric acid, respectively), and the subsequent differential utilization of cinnamic and benzoic acids by soil microbes indicated that these processes can substantially influence the magnitude and duration of the phytoxicity of individual phenolic acids.     

Catalytic Conversions of Polychlorinated Benzenes and Dioxins with Low-chlorine Using V2O5/TiO2

Chlorinated benzene, especially 1,2-dichlorobenzene (1,2-DCB), has been widely used as one of surrogate compounds of dioxin to find the noble methods to control dioxin. However, the relationship between the catalytic activity of dioxin surrogate compound and dioxin has not been understood quite well. In this work, we used a vanadium based catalyst (V₂O₅/TiO₂) to compare catalytic activity of chlorinated benzenes and dibenzo-p-dioxins with low-chlorine content using the lab-scale system. We investigated the catalytic conversions of low-chlorinated dioxins, [2-monochlorodibenzo-p-dioxin (2-MCDD), 2,3-dichlorodibenzo-p-dioxin (2,3-DCDD)] and polychlorinated benzenes [1,2-DCB, 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB), pentachlorobenzene (PeCB), hexachlorobenzene (HCB)] using a V₂O₅/TiO₂ catalyst to understand quantitative relationship between dioxin and benzene with the chlorination level. The catalytic decomposition of chlorinated aromatic compounds was following 1,2-DCB > 1,2,3,4-TeCB > 2-MCDD > PeCB ≥ 2,3-DCDD > HCB. It might be more reasonable that PeCB or HCB should be used as the dioxin surrogate compound rather than 1,2-DCB. Also, we investigated the effect of both O₂ content and space velocity (SV) on the catalytic decomposition of 1,2-DCB in the presence of V₂O₅/TiO₂ catalyst because these factors should be considered significantly in combustion facilities to control various pollutants. The decomposition of 1,2-DCB shows dependency on the SV while the effect of oxygen content on the catalytic decomposition is negligible in the range of 5–20%.     

Electro-oxidation of rutin in the presence of <Emphasis Type="Italic">p</Emphasis>-toluenesulfinic acid

We report the electrochemical oxidation of rutin in acetonitrile-sodium phosphate (4:1 (v/v); pH 2.0) in the presence of p-toluenesulfinic acid. Cyclic voltammetry and controlled potential electrolysis were used to study rutin electro-oxidation and to prepare the sulfone derivatives. Chromatographic methods were employed to separate the products and IR, ¹H NMR, ¹³C NMR, MS and microanalysis to their characterization. Data from cyclic voltammetry allow the identification of three rutin oxidation processes in the presence of p-toluenesulfinic acid (E _p^I = 0.56 V, E _p^II = 0.81 V and E _p^III = 1.32 V). Only the electrode process around peak I was exhaustively studied. The first oxidation step leads to the formation of the corresponding o-quinone, which participates in a Michael addition reaction with the p-toluenesulfinic acid, forming the 6′(4-methylphenylsulfonyl)rutin and 6′(4-methylphenylsulfonyl)quercetin as majority products.     

Methacrylic acid and dodecyl methacrylate (MAc‐DMA) hydrogel for enhanced catalytic activity of lipase of Bacillus coagulans MTCC‐6375

An alkaline thermotolerant bacterial lipase of Bacillus coagulans MTCC‐6375 was purified and immobilized on a methacrylic acid and dodecyl methacrylate (MAc‐DMA) hydrogel. The lipase was optimally bound to the matrix after 20 min of incubation at 55°C and pH 9 under shaking conditions. The matrix‐bound lipase retained approximately 50% of its initial activity at 70–80°C after 3 h of incubation. The immobilized lipase was highly active on medium chain length p‐nitrophenyl acyl ester (C: 8, p‐nitrophenyl caprylate) than other p‐nitrophenyl acyl esters. The presence of Fe³⁺, NH₄⁺, K⁺, and Zn²⁺ ions at 1 mM concentration in the reaction mixture resulted in a profound increase in the activity of immobilized lipase. Most of the detergents partially reduced the activity of the immobilized lipase. The immobilized lipase performed ～62% conversion in 12 h at temperature 55°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1420–1426, 2006     

Adhesion of conventional and self-adhesive resin cements to indirect resin composite using different surface conditioning methods

This study evaluated the adhesion of conventional and self-adhesive resin cements to indirect resin composite (IRC) using different surface conditioning methods. Cylindrical IRC specimens (N = 192) were randomly assigned to four surface conditioning methods (n = 8 per group): (a) Control group, (b) Hydrofluoric acid, (c) Tribochemical silica-coating, and (d) 50 μm Al₂O₃ air-abrasion. Specimen surfaces were finished using silicon carbide papers up to 600 grit under water irrigation, rinsed and dried. Direct composite blocks were bonded to IRC specimens using three conventional resin cements (Multilink, Panavia F2.0, and Resicem) and three self-adhesive resin cements (RelyX U100, Gcem, Speed Cem). Specimens were subjected to shear bond strength test in a Universal Testing Machine (0.5 mm/min). Failure types were categorized as mixed, adhesive and cohesive. Data were analyzed using 2-way ANOVA and Tukey’s tests. Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. The bond strength results (MPa) were significantly affected by the surface conditioning method (p < 0.0001) and cement type (p < 0.001). For Panavia F2.0, Resicem, air-abrasion with 50 μm Al₂O₃ significantly increased the results (22.6 ± 6.5, 26.2 ± 6.5, respectively) compared to other conditioning methods (13.6 ± 1.4–21.9 ± 3.1) but for Multilink, hydrofluoric acid etching (20.5 ± 3.5) showed significantly higher results (p < 0.01). For the self-adhesive resin cements, air-abrasion with 50 μm Al₂O₃ significantly increased the results compared to other conditioning methods, except for RelyX U100 (p < 0.05). After air-abrasion with Al₂O₃, Gcem, (11.64), RelyX U100 (9.05), and SpeedCem (8.29) presented higher Weilbul moduli. Exclusively cohesive failure in the IRC was observed with RelyX U100 and Speedcem after Al₂O₃ air-abrasion.     

Acid-catalyzed condensation of oleic acid into estolides and polyestolides

Oleic acid, when treated with 1.0 equivalent of perchloric acid at 50°C, produced a 76% yield of polyestolide. The concentration of mineral acid greatly affected the rate of estolide formation, with increased rates under high acid concentrations. Over a range of temperatures from room temperature to 100°C, reaction rates increased at higher temperatures. However, high acid concentrations and temperatures produced undesirable side products, primarily lactones. Other acids catalyze the condensation of oleic acid to form estolide with the following relative rates: HClO₄ >H₂SO₄>p-toluenesulfonic>BF₃·Et₂O> montmorillonite K-10>HCl>H₃PO₄, HNO₃. Addition of water impedes the formation of estolide.     

Effect of reaction medium on radical copolymerization of acrylonitrile with vinyl acids

Radical polymerization of acrylonitrile (AN) with methacrylic acid (MAA) and itaconic acid (IA) was carried out in a mixture of dimethylformamide (DMF) and water at 70°C using α, α′‐azobisisobutyronitrile (AIBN) as an initiator. Monomer feed in the polymerization vessel was 98:2 (AN:MAA/IA) in the molar ratio, and the DMF:H₂O ratio was varied between 20:80 and 80:20 (w/w). Copolymers were characterized by FTIR, carbon, hydrogen, nitrogen elemental CHN analysis, ¹H‐ and ¹³C‐NMR, and viscometry. The rate of polymerization (R_p) was found to decrease with an increase in DMF concentration in the reaction medium, that is, in 20% DMF for AN–MAA system, the R_p is 1.23% min⁻¹ in 1 h of polymerization, while in 80% DMF, R_p is reduced to 0.37% min⁻¹. The nature of the vinyl acid also affects the R_p. It has been shown that the rate of polymerization is higher for an AN–MAA system as compared to an AN–IA system (R_p = 1.0% min⁻¹) and the methacrylic or itaconic acid content in the copolymer increases with an increase in the DMF concentration. The MAA content in the poly(AN–MAA) polymer produced in 20% DMF is 3.2 mol %, which increases to 6.1 mol % (calculated through FTIR spectra) when DMF is increased to 80% in the reaction medium. The intrinsic viscosity [η] of the poly(AN–IA) and poly(AN–MAA) copolymers in DMF was found to be in the range of 0.67–2.90 dLg⁻¹ depending on the reaction medium. In determining the intrinsic viscosity, a definite deviation from rectilinearity of the concentration dependence in the high‐dilution region is observed, thereby demonstrating the polyelectrolyte behavior of these polymers. Through FTIR and NMR spectral studies, PAN homopolymer and other copolymers have shown the formation of a small quantity of acrylamide units. In addition copolymer P₁₀, which contains 10.1 mol % IA, has shown anhydride formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1640–1652, 2001