ZnCl2 Complexes Research Articles

Grafting of Acrylonitrile onto Gelatin in Zinc Chloride Medium

Abstract Grafting of gelatin with acrylonitrile in zinc chloride medium has been studied using potassium persulfate as the initiator. The rate of grafting, grafting efficiency, and percentage of grafting are calculated. The grafting results are discussed in the light of the rate of grafting. The enhanced activity of the monomer is due to the formation of AN … ZnCl2 complexes.

Thermal and radiation‐induced polymerizations of N‐tert‐butylacrylamide and (N‐tert‐butylacrylamide)2–ZnCl2 complex

AbstractThe thermal and radiation‐induced in‐source and postirradiation polymerizations of N‐tert‐butylacrylamide and (N‐tert‐butylacrylamide)2–ZnCl2 complex of this monomer were studied at various temperatures. In in‐source, solid‐state polymerizations of monomer and complex the conversion was about 95% at 21°C in about eight days. Their postirradiation polymerizations were also studied in solid state. The conversion‐time curves of these two systems show an autoacceleration as in‐source polymerization. In both types of polymerization the overall rate of polymerization of complex was higher than that of pure monomer at the same polymerization temperature. In investigations of the thermal polymerization of N‐tert‐butylacrylamide and ZnCl2‐complex it was observed that the ZnCl2‐complex system can be polymerized in air in the molten and solid state. The conversion of monomer to polymer reaches limiting values in solid state in about 1 hr. The thermal polymerization of ZnCl2‐complex in the molten state was also studied and 100% conversion was obtained in 30 min. The thermal polymerization of pure monomer was studied in vacuum and an appreciable amount of polymer was obtained in the molten state; however, the thermal polymerization of this monomer is negligible in solid state. In this work rates of polymerization for N‐tert‐butylacrylamide and (N‐tert‐butylacrylamide)2–ZnCl2 are compared under various experimental conditions and overall activation energies are calculated.

Solvation Effect on the Complex Formation between o-Quinones and Metal Chlorides in Nonaqueous Media

Abstract The complex formation of o-quinones with metal chlorides was studied by means of spectrophotometry in CH3NO2 and CH3CN, where the metal chloride behaved as a nonelectrolyte. The results obtained in both solutions showed that the complex formation was obviously affected by the solvation of CH3CN to the metal chloride. The participation of CH3CN in the o-quinone–ZnCl2 complex was assumed as a result of comparing the Δνmax values, and the results obtained by NMR and spectrophotometry proved the coordination of two molecules of CH3CN to the complex. The values of Kc in CH3NO2 increased in the order of BiCl3<ZnCl2, whereas those in CH3CN were in the reverse order; this fact was ascribed to the number of the solvent molecules liberated in the complex formation. The conventional elimination of the solvation effect from the observed Kc was proposed in order to obtain a parameter of solvation-free Kc.

Radical polymerization in the presence of complexing agents. III. Effect of low concentrations of ZnCl2 on the radical polymerization of methyl methacrylate

AbstractThe formation of complexes between ZnCl2 and methyl methacrylate (MMA) or between ZnCl2 and AIBN was tested at two different polymerization temperatures, taking into account the Haeringer and Riess treatment. For any concentration of ZnCl2 between 0.01 and 0.1 mole/liter the formation of ZnCl2−MMA complexes is favored, whereas AIBN−ZnCl2 complexes are hardly showed. The effect of zinc chloride on the stereostructure of poly(methyl methacrylate) was also investigated at both temperatures.

On the copolymerization of acrylonitrile with styrene in the presence of Lewis acid, 3. Photoinitiated copolymerization

AbstractThe rate of the acrylonitrile (AN)‐styrene (St) copolymerization (Rp) photoinitiated (λ=365 nm) by the StANZnCl2 complex at 30°C is proportional to the square root of the intensity of radiation. The limiting viscosity number [η] of alternating copolymers increases with the intensity of radiation. The 1/[η] vs. Rp relationship for the StAN copolymers is similar as has been found for the initiation of copolymerization by thermal decomposition of 2,2‐azoisobutyronitrile. Provided benzophenone combined with 2‐propanol is used as a photosensitizer, the rate of the StAN copolymerization in acetone—at constant concentrations of both comonomers, zinc chloride, and benzophenone—decreases with 2‐propanol concentration in the reaction mixture. If benzophenone alone (e.g. without 2‐propanol) is used as a photosensitizer under equal conditions, the observed values of the rate of copolymerization are lower in comparison with the system where the ternary molecular complex is empolyed as a photosensitizer. Moreover, Rp decreases with increasing concentration of benzophenone in the system. These findings are interpreted as a result of the termination reactions of ketyl radicals (hydroxydiphenylmethyl radicals) with macroradicals of copolymer.

Alternating copolymerizations of styrene and acrylic monomers initiated with carbanions in the presence of ZnCl2

AbstractOn electrochemical initiation of alternating copolymerizations of styrene–acrylonitrile (AN) and styrene–diethyl fumarate (DEF) in the presence of ZnCl2, radical anions of AN–ZnCl2 and DEF–ZnCl2 complexes produced at the cathode were assumed to initiate copolymerization. In analogy with the cathode‐initiated copolymerization, the radical anions of AN–ZnCl2 and DEF–ZnCl2, generated with the carbanions such as sodium naphthalene, disodium α‐methylstyrene tetramer dianion, and butyllithium, were also found to produce alternating copolymers of styrene–AN and styrene–DEF. On the contrary, no polymers were obtained from methyl methacrylate (MMA)–styrene and methacrylonitrile (MAN)–styrene in the presence of ZnCl2 either with carbanions or by electrochemical reduction. Styrene–MAN–ZnCl2 yielded an alternating copolymer with carbanions upon introduction of oxygen.

Studies in Cyclocopolymerization. XII. Cyclocopolymerization of the Donor:Acceptor Pair 1,4-Diene:Monoolefin Lewis Acid Complex

Abstract Acrylonitrile (AN) is known to form a cyclocopolymer with 1,4-dienes such as divinyl ether (DVE) and 3,3-dimethyl-1,4-pentadiene with radical initiators. Since AN has a high tendency toward homopolymerization, the copolymers are not of regular structure. Lewis acids such as ZnCl2 and Al(Et)3 were used in this paper to increase the e-values of AN and methacrylonitrile (MAN) through complexation. AN, MAN, and 2- and 4-vinylpyridine were copolymerized with DVE and 1,4-pentadiene with Lewis acids. In all cases the rate of copolymerization was much enhanced and the alter-nating tendency of the cyclocopolymer increased with the amount of added Lewis acids. A 1:2 DVE:AN alternating cyclocopolymer was obtained spontaneously or with AIBN with Al(Et)3 in hexane. Also 1:2 alternating cyclocopolymer was successfully obtained in acetone by using a large amount of ZnCl2. The identification of charge-transfer (CT) complex-ation between the DVE and (AN,1 2, ZnCl2 complex, and between the 1-hexene and (AN)2ZnCl2 complex may supoort the par-ticipation of a CT complex formed between all 1,4-dienes studied and the monoolefin-Lewis acid complexes in the

The Infrared Spectra of Metallooctaethylporphyrins

Abstract The infrared spectra of the Mg(II), Co(II), Cu(II), Zn(II), Pd(II), Ni(II), and Ge(IV)Cl2 complexes of octaethylporphyrins have been studied over the range 4000–100 cm−1. Metal sensitive bands have been observed at about 980, 920, 340, 230, and 130 cm−1.