Acrylonitrile In Dimethylformamide Research Articles

The uranium recovery from aqueous solutions using amidoxime modified cellulose derivatives. III. Modification of hydroxypropylmethylcellulose with amidoxime groups

Grafting of acrylonitrile on hydroxypropyl methylcellulose films has been carried out by means of 60Co-γ radiation, using a constant amount of hydroxypropyl methylcellulose films, at different concentrations of acrylonitrile in dimethylformamide. Grafting percentage—dose curves were obtained. 63 % of grafting yield were reached at around 3 kGy dose. Conversion of nitrile groups to amidoxime groups were achieved by aqueous solutions of NH2OH·HCl–NaOH at 50 °C. The amidoxime conversion was followed by using FTIR spectrophotometer and determined as percentage. 98 % amidoxime conversion was achieved within 50 h. The structural, morphological and thermal evaluations of acrylonitrile grafted hydroxypropyl methylcellulose films, before and after amidoxime conversion, were performed using FTIR, AFM, Contact Angle, SEM and TGA analyses.

Enzyme‐catalyzed transesterification of vinyl esters on cellulose solids

AbstractEnzyme‐catalyzed transesterification of several cellulose solids in organic media have been investigated. Several protease enzymes were made soluble in organic media through ion‐paired enzyme–surfactant complexes. Subtilisin Carsberg was found to be catalytically active in the transesterification of cellulose with vinyl propionate and vinyl acrylate in anhydrous pyridine. The ester carbonyl groups in acylated cellulose derivatives were confirmed by Fourier transform infrared spectroscopy. The surfaces of these cellulose derivatives became hydrophobic as demonstrated by increased water‐contact angles. The enzyme‐catalyzed transesterification was confirmed to regioselectively target the primary hydroxyl group of cellulose by reactions on specifically substituted cellulose. The cellulose esters from enzyme‐catalyzed transesterification could be hydrolyzed partially by the same enzyme in aqueous media, and were thus biodegradable. Surface grafting of cellulose acrylate was demonstrated using azobisisobutyronitrile‐initiated polymerization of acrylonitrile in dimethylformamide. Polyacrylonitrile (PAN)‐g‐cellulose shows a different thermal behavior from cellulose, homopolymer PAN, and PAN/cellulose blends. The grafted PAN on PAN‐g‐cellulose at a 16% grafting add‐on is incapable of cyclization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1931–1939, 2001

The inhibited polymerization of lithium methacrylate and copolymerization with acrylonitrile

Results for the determination of initiation rate of the polymerization reaction of lithium methacrylate and its copolymerization with acrylonitrile in dimethylformamide at various temperatures are reported. The inhibition method involving the stable radical N, N-diphenyl- N′-picrylhydrazyl has been used. The initiation rate constant 2k df and the activation energy of initiation E 2k df have been determined. An influence of the initial monomer mixture concentration on the measured quantities has been revealed.

Vinyl monomers bearing chromophore moieties and their polymers. VI. Synthesis and photochemical behavior of acrylic monomer bearing phenoxazine moiety and its polymer

An acrylic monomer having phenoxazine moiety, i.e., N-acryloylphenoxazine (APO), has been synthesized by dehydrochlorination of N-(3-chloropropionyl)phenoxazine with 1,5-diazabicyclo[5.4.0]undec-5-ene in dimethyl sulfoxide. The monomer can be polymerized with AIBN as an initiator. The photochemical behavior, including the fluorescence and photosensitizing properties of this monomer and its polymer, has been studied. It has been recorded that the absorption spectrum of polymer P(APO) displays a few blue shifts compared with its monomer APO. It has also been observed that the fluorescence emission intensity of the monomer is dramatically lower than that of its polymer at the same chromophore concentration. This may be ascribed to the charge transfer interacting between the coexisting electron-accepting acrylic carbon-carbon double bond and the electron-donation phenoxazine moiety in APO, intramolecularly or intermolecularly on excitation. The fluorescence of the APO polymer, which does not have carbon-carbon double bond, can be quenched by electron-deficient unsaturated nitriles and esters, clarifying that the electron-deficient carbon-carbon double bond does play an important role for the fluorescence quenching of the monomer. Thus, we term such phenomena as structural self-quenching effect, differing from the concentrational self-quenching effect, which is caused mainly by concentrational factors. The fluorescence quenching of P(APO) by C60 has also been demonstrated. The formation of the charge transfer complex of P(APO) with C60 in the ground state is revealed by the upward deviation from the linearity of the Stern-Volmer plot. APO can act as a photoinitiator to sensitize the photopolymerization of vinyl monomers such as acrylonitrile in dimethyl formamide and pursued kinetically. From the ultraviolet analysis of the PAN sensitized by APO, it is proved that APO not only sensitizes the photopolymerization of AN, but also incorporates in the PAN chain. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:481–489, 1997

Vinyl monomers bearing chromophore moieties and their polymers. VI. Synthesis and photochemical behavior of acrylic monomer bearing phenoxazine moiety and its polymer

An acrylic monomer having phenoxazine moiety, i.e., N-acryloylphenoxazine (APO), has been synthesized by dehydrochlorination of N-(3-chloropropionyl)phenoxazine with 1,5-diazabicyclo[5.4.0]undec-5-ene in dimethyl sulfoxide. The monomer can be polymerized with AIBN as an initiator. The photochemical behavior, including the fluorescence and photosensitizing properties of this monomer and its polymer, has been studied. It has been recorded that the absorption spectrum of polymer P(APO) displays a few blue shifts compared with its monomer APO. It has also been observed that the fluorescence emission intensity of the monomer is dramatically lower than that of its polymer at the same chromophore concentration. This may be ascribed to the charge transfer interacting between the coexisting electron-accepting acrylic carbon-carbon double bond and the electron-donation phenoxazine moiety in APO, intramolecularly or intermolecularly on excitation. The fluorescence of the APO polymer, which does not have carbon-carbon double bond, can be quenched by electron-deficient unsaturated nitriles and esters, clarifying that the electron-deficient carbon-carbon double bond does play an important role for the fluorescence quenching of the monomer. Thus, we term such phenomena as structural self-quenching effect, differing from the concentrational self-quenching effect, which is caused mainly by concentrational factors. The fluorescence quenching of P(APO) by C60 has also been demonstrated. The formation of the charge transfer complex of P(APO) with C60 in the ground state is revealed by the upward deviation from the linearity of the Stern-Volmer plot. APO can act as a photoinitiator to sensitize the photopolymerization of vinyl monomers such as acrylonitrile in dimethyl formamide and pursued kinetically. From the ultraviolet analysis of the PAN sensitized by APO, it is proved that APO not only sensitizes the photopolymerization of AN, but also incorporates in the PAN chain. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:481–489, 1997

Thermal characteristics of N-antipyryl-acrylamide—acrylonitrile copolymers using different spectroscopic techniques

N-antipyryl-acrylamide monomer (NAA) (2,3-dimethyl-1-phenyl-5-oxo-3-pyrazolin-4-yl acryloylamine) was copolymerized with acrylonitrile in dimethyl formamide using azobisisobutyronitrile (AIBN) as initiator. The homopolymer and also the copolymers were characterized by a variety of spectral and thermal methods. Thermogravimetry (TG) and differential thermal analysis (DTA) data showed a remarkable improvement in the thermal behaviour of the investigated copolymers. A mechanism for the participation of the acryloyloxy units in the nitrile oligomerization is proposed and confirmed by interpretation of the fragmentation patterns of the mass spectrum of the N-antipyryl-acrylamide (NAA) monomer and also the IR spectra of the copolymers after heating.

Tris-(π-allyl)-chromium-2,2′-dipyridyl system as catalyst for the polymerization of acrylonitrile

It has been established that the complex catalyst tris-(π-allyl) chromium-2,2′-dipyridyl initiates the effective polymerization of acrylonitrile in dimethylformamide in a wide temperature range.

The Mechanism of Initiation of the Anionic Polymerization of Acrylonitrile with 14C-Labeled Lithium Alkoxides in Dimethylformamide

Abstract Investigations of the anionic polymerization of acrylonitrile in dimethylformamide initiated with 14C-labeled lithium tertiary butoxide have shown that the tertiary butoxide group is not incorporated into the polymer chain, Comparison with the initiation behavior of other lithium alkoxides has indicated that the amount of incorporation of the alkoxyl groups from the anionic lithium alkoxide initiators depended on the basicity of the alkoxide group. A new initiation mechanism is proposed which involves as initiator an active center which consists of an electron donor-acceptor complex of the lithium alkoxide with the solvent dimethylformamide and the acrylonitrile monomer.

Aspects of the kinetics of the radiation-induced polymerization of acrylonitrile in dimethylformamide

The radiation-induced homopolymerization of acrylonitrile (AN) in dimethylformamide (DMF) has been followed in detail over a range of monomer concentrations. In all cases a short induction period was observed which was equivalent to 1.6 × 104 rad. The initial rates of polymerization for solutions of AN in DMF of mole fraction (×) of 0.33, 0.20, and 0.10 are 1.44 × 10−5, 7.23 × 10−6, and 2.79 × 10−6 mole/dm3rad, respectively. Deviations of the polymerization pathway from the standard unity in monomer dependence are examined in terms of radical production ratios to the monomer and the solvent (ΦM/ΦS) and the polymer together with the solvent (Φp/Φs), for various mole fractions of AN in DMF. Thus, an indirect route to Gradical(events) is provided together with the corresponding k/kt values.

Kinetics of copolymerization—I. Kinetic investigation of the polymerization of acrylonitrile in homogeneous phase

A detailed study was made of the kinetics of initiated homopolymerization of acrylonitrile in dimethylformamide and dimethylsulphoxide at 40–60°. The rate of polymerization was found to be proportional to the (initiator concentration) 1/2. The rate of initiation of polymerization was determined by the inhibition method, using three stable free radicals. Trends in the average rate of polymerization were also studied for various initial monomer and solvent concentrations. The overall rate constant ( K) was strongly dependent on monomer concentration decreasing with decrease of monomer concentration. It has been shown that the hot radical theory describes accurately, without physical contradiction, the solvent dependence of rate constants of polymerization systems.

Copolymerisation radiochimique du styrene avec l'acrylonitrile en solution

The radiation-initiated copolymerization of styrene and acrylonitrile was investigated at 20° in dimethylformamide (DMF) and in benzylalcohol solutions. The compositions of the copolymers were only slightly affected by these polar solvents. The influence of temperature on the copolymerization in DMF solutions was studied in greater detail. It was found that the acrylonitrile content in the copolymer obtained at -78° drastically increased as a result of an anionic polymerization of acrylonitrile. Fractional precipitation of the products obtained at -78° showed that they were not mixtures of polymers but were block copolymers containing long sequences of acrylonitrile units. This copolymer is assumed to arise as a result of the simultaneous growing of the two ends of a primary radical-ion, acrylonitrile adding to one end by an anionic mechanism while the free radical end initiates a random copolymerization of styrene and acrylonitrile. The anionic contribution to the over-all process was established. The anionic homopolymerization of acrylonitrile was studied in DMF, toluene and their mixtures. The rate was found to exhibit a maximum for 20% acrylonitrile in DMF. It was further noticed that significant amounts of DMF could be replaced by toluene or styrene without affecting the rate. The reduction in rate in more concentrated monomer solutions was attributed to an autoinhibition of acrylonitrile in its anionic polymerization.

Vinyl polymerization. 294. Decomposition of tetramethyltetrazene in the presence of p‐substituted benzyl chlorides

AbstractA study was made of the polymerization of acrylonitrile in dimethylformamide (DMF) initiated by the binary systems of tetramethyltetrazene (TMT) and p‐substituted benzyl chlorides. The polymerization rate increased linearly with the σ‐constants of substituents as electron‐releasing groups were introduced to the phenyl ring of benzyl chloride. In order to elucidate the initiation mechanism of the polymerization, a kinetic investigation was also undertaken of the decomposition of TMT in the presence of p‐substituted benzyl chlorides in DMF. The decomposition rate was first‐order in TMT and first‐order in p‐substituents benzyl chloride. The decomposition rate also increased with the σ constants of substituents as electron‐releasing groups were introduced. On the basis of the results, the initiation mechanism for the polymerization was discussed.

Effects of salts of metals on vinyl polymerization. Part 7.—Spectrophotometric studies of the ferric chloride-photosensitized polymerization of acrylonitrile in dimethylformamide

A study has been made of the ultra-violet and visible spectrum of the reaction mixture during the photolysis of 5 × 10–3 M ferric chloride in a 3.02 M solution of acrylonitrile in N,N-dimethyl formamide at 25°. Under these conditions, the spectrum is attributable entirely to the presence of the metal salt, which acts as both initiator and terminator for the polymerization. A marked change in the type of spectrum is noted as the reaction proceeds, as a result of which optical density cannot always be used as a measure of ferric iron concentration during reaction. The species present after reaction has commenced do not correspond to ferric chloride; the change of spectrum is interpreted as being due to interaction between chlorides produced in the reaction and the cation Fe(DMF)nCl+2, to increase the relative concentration of the FeCl–4 species, the two complexes formed when ferric chloride is dissolved in N,N-dimethyl formamide. Possible reaction products are capable of bringing about the change of spectrum. Both cationic and anionic species must be considered as possible initiators, but changes in their relative concentration do not seem to have a significant effect on either initiation or termination steps.

Polymerization of acrylonitrile in dimethylformamide induced by anionic catalysts

TH~ fact that there are comparatively few papers on homogeneous polymerization of acrylonitrile (AN) induced by anionic catalysts can be explained by the very limited choice of suitable solvents, inert to the catalysts used. In a study of the polymerization of AN in dimethylformamide (DMF) catalysed by sodiumdiphenyl, Tsukamote [1] states that sodiumdiphenyl does not react with the solvent at temperatures below --40 °. Zilkha and his collaborators [2-4] in studying the polymerization of AN under the influence of lithium butyl, C4H~Li, using DMF as the medium or as an electronating additive, did not take account of the possibility of reaction occurring between C4H~Li and DMF. Dimethylformamide reacts vigorously with alkali metal alkyls or aryls however. The products of the reaction after decomposition with water are aldehydes and amines [5]. We have been able to demonstrate that even at --70 ° D1KF reacts instantaneously with C4H~Li, and under carefully controlled reaction conditions the primary product is lithium butyl(dimethylamino)carbinolate [6]

The [formula omitted] equilibrium and its influence on the ferric chloride photosensitized, cupric chloride inhibited polymerization of acrylonitrile in N,N-dimethylformamide

The Cu(I),Fe(III)Cu(II),Fe(II) equilibrium in dimethylformamide solution has been found to favour the ferric/cuprous states. Cupric chloride has been used to inhibit the ferric chloride-photosensitized polymerization of acrylonitrile in dimethylformamide. The kinetics of the reaction are discussed in terms of termination by both ferric and cupric chlorides, and the reduction of cupric chloride by ferrous chloride. The value 1.75 × 105 M−1 sec−1 has been obtained for the rate constant for the scavenging of polyacrylonitrile radicals by cupric chloride.

Effect of Some Inorganic Salts on Methyl Methacrylate and Acrylonitrile in Dimethylformamide

Abstract A polarometric titration was utilized to determine the extent to which the monomers methyl methacrylate and acrylonitrile complex with inorganic salts in dimethylformamide solution. No complexes were obtained with the nitrates of sodium, potassium, cesium, and lead. Evidence for 1: 1 complexes between acrylonitrile and LiCl, LiNO3, Mg(NO3)2 · 6H2O, FeCl2 · 4H2O, FeCl3 · 6H2O, MnCl2 · 4H2O, Co(NO3)2 · 6H2O, Ni(NO3)2 · 6H2O, and ZnCl2 and between methyl methacrylate and LiNO3, La(NO3)3 · 6H2O, MnCl2 · 4H2O, FeCl3 · 6H2O, Co(NO3)2 · 6H2O, and ZnCl2 was obtained. A 1: 2 (salt/monomer) complex was also indicated between acrylonitrile and MnCl2 · 4H2O, FeCl3 · 6H2O, Co(NO3)2 · 6H2O, and Ni(NO3)2 · 6H2O and between methyl methacrylate and MnCl2 · 4H2O. Although the presence of certain salts influenced the co-polymerization of methyl methacrylate and acrylonitrile, particularly at high temperatures, the existence of a complex was not an a priori indication of unusual copolymerization behavior. Tacticitie...

Studies of the chemical modifications of wool and their effects on the wool‐water relationship. Part I. Chemical modification of wool

AbstractWool has been modified to render it more hydrophobic by two methods. The first method involved treating the wool with benzoyl, lauroyl, stearoyl, and dodecenyl chlorides and with trifluoroacetic anhydride. Substantial degrees of reaction with the wool were achieved when the correct solvent media and reaction conditions were used. These varied with the particular reagent employed. Pyridine was particularly effective with the acid chlorides, whereas dimethyl sulfoxide was best with trifluoroacetic anhydride. Pyridine is believed to function both as a swelling agent and as an acid acceptor in these treatments. The second method of treatment was the grafting of vinyl and allyl monomers to wool by the use of high energy radiation. Both 60Co γ‐rays at 0.3 Mrad/hr. and Van de Graaff γ‐radiation at 3 Mrad/min. were found to be highly effective. The presence of a swelling agent in the monomer solution was found to be essential even in the case of acrylonitrile in dimethyl formamide. Water and methanol in small amounts were found to be highly efficient swelling agents. Substantial quantities of monomer could be grafted in most cases without difficulty when the correct conditions were used.

Influence of pressure on the radical polymerization of acrylonitrile in dimethylformamide solution

1. The rate of homogeneous radical polymerization of acrylonitrile in dimethylformamide at 50°, in contrast to the heterogeneous radical polymerization of acrylonitrile, quadruples when the pressure is raised from atmospheric to 2000 kg/cm2, while the average molecular weight of the polymer increases by 50%. 2. The comparatively small increase in the molecular weight of the polymer at 2000 kg/cm2 is evidently due to the fact that a substantial role in the system studied is played by the reaction of chain transfer through dimethylformamide, and this reaction is accelerated by pressure almost to the same degree as the reaction of chain growth.

Effects of salts of metals on vinyl polymerization. Part 2.—Ferric chloride as photo-initiator and terminator in the polymerization of acrylonitrile in dimethylformamide

A study has been made of the kinetics of the polymerization of acrylonitrile in dimethylformamide between 25 and 50°C. At ferric chloride concentrations below 5 × 10–4 M, the rate of polymerization is proportional to the square root of the ferric chloride concentration, whereas at concentrations above 2 × 10–3 M, the rate varies inversely with the ferric chloride concentration. The rate varies directly with the monomer concentration over the range 1.5–4.5 M. At higher monomer concentrations the system becomes heterogeneous thus complicating the kinetics of the reaction. The overall activation energy is about 5.5 kcal/mole at low ferric chloride concentrations and in the region of 2 kcal/mole when the ferric chloride concentration is above 2 × 10–3 M. These results indicate that, at low ferric chloride concentrations, the termination involves the mutual interaction of growing polymer radicals, while, at higher concentrations, termination proceeds by reaction between the growing polymer radicals and ferric chloride. Again, at low ferric chloride concentrations, where a relatively small fraction of the initiating light is absorbed by the ferric chloride, the rate of initiation is directly proportional to the ferric chloride concentration, whilst at higher concentrations all the initiating irradiation is absorbed, and the rate of initiation becomes independent of the ferric chloride concentration. The intensity exponent at high ferric chloride concentrations is 0.6–0.7 and not unity as expected. This difference is attributed to solvent participation in the initiation reaction. This view is supported by the results of preliminary work using radioactive ferric chloride, which also show that chlorine is incorporated in the polymer in the termination reaction but not in the initiation step. The value of the velocity coefficient for the reaction between a growing polymer radical and ferric chloride agrees well with the results in the literature, if the efficiency of initiation is about 0.23, a value supported by kinetic and tracer measurements.

Termination of the anionic polymerization of acrylonitrile at low catalyst concentrations

AbstractThe homogeneous anionic polymerization of acrylonitrile in dimethylformamide with n‐butyllithium was studied. Two different termination reactions were found to exist depending on catalyst concentration. At high catalyst concentrations termination was bimolecular by chain transfer to monomer, while at relatively low catalyst concentrations termination was monomolecular, by an inner cyclization reaction of the growing chain end. The existence of chain transfer only at high catalyst concentrations suggests the possibility of free catalyst molecules participating in the transfer reaction. At intermediate catalyst concentrations, both monomolecular and bimolecular terminations were found to occur side by side, and DP = Kp[M]/(Ktr[C][M] + Kt). Study of the dependence of molecular weight on per cent conversion at low catalyst concentrations showed that, up to about 30% conversion, there is a linear relationship between molecular weight and concentration of monomer consumed which is independent of temperature and monomer. After this degree of conversion, molecular weight stopped to increase and remained constant due to monomolecular termination. All over the wide range of catalyst concentrations investigated, the catalyst efficiency in initiating polymerization was found to be low. In the lowest range where there is a linear dependence of molecular weight on per cent conversion it was also found that the molecular weights are proportional to [M]/[C], which is a property of “living” systems.