C3 cyclopolymerization. IV.1 Cationic polymerization of 1,3-bis(4-vinylnaphthyl) propane and the polymer structure yielded

The compound 1,3-bis(4-vinylnaphthyl)propane was prepared by a convenient dehydration of 1,3-bis[4-(1-hydroxyethyl)naphthyl]propane. The structure was confirmed by nuclear magnetic resonance (NMR) spectroscopy. The monomer was polymerized by antimony pentachloride, tin tetrachloride, titanium tetrachloride, or boron trifluoride etherate at 0°C in toluene, 1,2-dichloroethane, or a mixed solvent of 1,2-dichloroethane and nitromethane. Most of runs except for antimony pentachloride–catalyzed ones gave mainly benzene-soluble polymers. The structures of the polymers were studied by several spectroscopic methods. Comparison of NMR and fluorescence spectroscopic data of the polymers with those of syn-and anti-[3.3](1,4)napthalenophane was especially valuable in leading to the conclusion that they were cyclopolymers containing predominantly syn-[3.3]-(1,4)naphthalenophane units in the main chain.     

Non-ideal kinetics in vinyl polymerization: Note on primary radical termination in benzoyl peroxide initiated polymerization of vinyl chloride in dichloroethane

The kinetics of vinyl chloride polymerization initiated by benzoyl peroxide doubly labelled with ¹⁴C and 'H were studied in 1,2-dichloroethane solution at 60°. The importance of primary radical termination in the polymerization is examined by kinetic analysis and by analysis of polymers for combined initiator fragments.     

The effect of solvents on asymmetric induction cationic copolymerization of l-menthyl vinyl ether with indene

Cationic copolymerization of l-menthyl vinyl ether (l-MVE) with indene (IN) was carried out in several solvents with BF₃OEt₂ as catalyst at 0°C. The solvents used in this study were selected toluene (Tol), chloroform (CHCl₃), chlorobenzene (BzCl), 1,2-dichloroethane (EtCl₂), and nitrobenzene; (BzNO₂)/Tol = 65/35 mixture solvent. l-Methyl residue, which is an optically active side chain of copolymer produced by cationic copolymerization, was removed with dry hydrogen bromide gas by ether cleavage reaction. The copolymer [vinyl alcohol(VA)–lN], produced by the ether cleavage reaction, also showed optical rotation. From this result, therefore, it was concluded that asymmetric induction takes place in the copolymer main chain. The efficiency of asymmetric induction was determined by the measurement of optical rotation of VA–IN copolymer after the ether cleavage reaction. The efficiency of asymmetric induction in the copolymer main chain developed from the variation on polymerization solvents; the order was Tol > EtCl₂ > BzCl > CHCl₃ > BzNO₂/Tol (65/35) mixture solvent.     

Synthesis and Characterization of Cardo Polysulfonates of 1,1′-Bis(4-Hydroxy Phenyl)Cyclohexane with 1,3-Benzene and 2,4-Toluene Disulfonyl Chlorides

Abstract

Cardo polysulfonates (PSBCB and PSBCT) of 1,1′-bis(4-hydroxy phenyl)cyclohexane with benzene-1,3 and toluene-2,4-disulfonyl chlorides have been synthesized by interfacial polycondensation of 1,1′-bis(4-hydroxy phenyl)cyclohexane (0.005 mol) with benzene-1,3/toluene-2,4-disulfonyl chlorides (0.005 mol) using water-chloroform (4:1, v/v) as interphase, alkali (0.015 mol) as acid acceptor, and cetyl trimethyl ammonium bromide (0.125 g) as emulsifier at 0°C for 3 hours. The structures of the polymers were supported by IR and NMR spectral data. The PSBCT was fractionated into several fractions by using 1,2-dichloroethane as solvent and n-butanol as precipitant. The fractions were characterized by GPC and viscometry in different solvents at four different temperatures. Viscosity studies showed that the PSBCT is flexible in solutions and has a specific solvent effect. PSBCB and PSBCT have good biological activity against E. coli and S. citrus organisms, and they possess excellent hydrolytic stability toward acids and alkalis.     

Solvation of Calix[4]arene-bis-crown-6 Molecules

Single crystal X-ray diffraction analyses of calix[4]arene-bis-crown-6 (1) and calix[4]arene-bis-benzocrown-61,2-dichloroethane (2) are reported. Thesestructures offer an opportunity to study the conformation of calix[4]arene-bis-crown-6 molecules in the absence of solvent, and when very weakly solvated. These structures exhibit different conformations of the crown ring, and limited flexibility of the calix[4]arene,but do not show solvent or crown inclusion in the calix[4]arene cavity. Comparisons to similar structures are made, and the implications for cesium binding are discussed.     

Kinetics of swollen surface layer formation in poly(vinyl chloride)–solvent system

The kinetics of formation of a swollen surface layer by diffusion of liquid solvent into solid poly(vinyl chloride) in the glassy state has been studied. The apparent Fickian diffusion coefficients of cyclohexanone, cyclopentanone, tetrahydropyrane, 1,2-dichloroethane, N,N-dimethyl-formamide, and monohalogen derivatives of benzene in PVC is calculated with the use of Crank's model for discontinuous change of diffusion coefficient with concentration. It is found that the apparent activation energy for diffusion is in the range 6–17 kcal/mole and is dependent on the polarity of the solvent molecule.     

Effect of solvent upon competitive liquid-liquid extraction of alkali metal cations by isomeric dibenzo-16-crown-5-oxyacetic acids

The selectivity and efficiency of competitive liquid-liquid extraction of alkali metal cations into organic solvents containingsym-(octyl)dibenzo-16-crown-5-oxyacetic acid (2) andsym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxyacetic acid (3) have been determined. Solvents examined include: dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, benzene, toluene,p-xylene, chlorobenzene, 1,2-dichlorobenzene, and 1,2,3,4-tetrahydronaphthalene. The Na⁺/K⁺ and Na⁺/Li⁺ extraction ratios are highest in chloroform. The extraction selectivity is found to correlate with the diluent parameter (DP) of the organic solvent.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Structural irregularities in poly(vinyl alcohol)

Poly(vinyl alcohols) derived from the product of polymerization of vinyl acetate in methanol have been characterized by various physical and chemical methods before and after NaIO₄ cleavage. The 220-MHz ¹H-NMR spectra confirm the reliability of NaIO₄ titrimetry for estimating 1,2-glycol content and help explain the tendency for viscometry to grossly underestimate the 1,2-glycol content for low molecular weight polymers. The spectra and related chemical evidence indicate that the major endgroups are HOCH₂CH₂? and CH₃CH(OH)CH(OH)CH₂? . ß-Hydroxyethyl groups also occur as short chain branches, mainly attached to α carbon atoms in the normal head-to-tail polymer chain sequence. The concentrations of the branch and endgroups depend on polymerization conditions and help explain polymerization “solvent” effects on physical properties.     

Ultrasonic Modification of Polymers. II. Degradation of Polystyrene,Substituted Polystyrene,and Poly(n-vinyl Carbazole) in the Presence of Flexible Chain Polymers

Abstract

Ultrasonic (20 kHz, 70 W) solution degradations of polystyrene, substituted polystyrenes, and poly(n-vinyl carbazole) have been carried in toluene and tetrahydrofuran at 27 and -20°C in the presence of flexible chain polymers. Polystyrene formed block copolymers at 27°C with stiff-chain polymer PVCz; however, in the presence of flexible chain polymers, e.g., poly(vinyl methyl ketone) or poly(vinyl methyl ether), there were no block copolymers formed. Poly(n-vinyl carbazole) does not seem to form any block copolymers at 27°C with flexible chain polymers, e.g., poly(octadecyl methacrylate) and poly(ethyl methacrylate). Poly(p-chlorostyrene) and poly(p-methoxystyrene) also do not form block copolymers at 27°C with poly(octadecyl methacrylate) but do so with poly(hexadecyl methacrylate). It is quite possible that these may only be blends of two homopolymers. Poly(octa-decyl methacrylate) does yield a block copolymer when sonicated at -15°C with poly(p-isopropyl α-methylstyrene).     

Controlling Aromatic Inclusion Within Nonaqueous Copper Iodide Coordination Polymers

Abstract

The formation and characterization of two novel coordination polymers based upon copper iodide and pyrazine have been observed that demonstrate varying aromatic inclusion. By changing the solvent from 1,2-dichlorobenzene to nitrobenzene, the ability to include the solvent as a guest molecule within the two-dimensional coordination polymer has been realized. In the nitrobenzene example, unlike the 1,2-dichlorobenzene example, honeycomb shaped cavities form along the polymeric chain that allows aromatic inclusion.     

Complexation study of dibenzo-18-crown-6 with UO2 2+ cation in binary mixed non-aqueous solutions

The complexation reaction of macrocyclic ligand, dibenzo-18-crown-6 (DB18C6) with UO₂ ²⁺ cation was studied in ethylacetate-1,2-dichloroethane (EtOAc/DCE), acetonitrile-1,2-dichloroethane (AN/DCE), methanol-1,2-dichloroethane (MeOH/DCE) and ethanol-1,2-dichloroethane (EtOH/DCE) binary solutions at different temperatures using the conductometric method. The conductance data show that the stoichiometry of the complex formed between DB18C6 and UO₂ ²⁺ cation is affected by the nature of the solvent systems. A non-linear behaviour was observed for changes of log K _f of (DB18C6.UO₂)⁺² complex versus the composition of the binary mixed solvents. The values of thermodynamic quantities (?S°_c, ?H°_c) for formation of (DB18C6.UO₂)⁺² complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots. The results show that in most cases, the complex is enthalpy stabilized and in all cases entropy stabilized and both parameters are affected by the nature and composition of the mixed solvents. In addition, the complex formation between dicyclohexyl-18-crown-6 (DCH18C6) and UO₂ ²⁺ cation was studied in pure AN and the results were compared with those of the (DB18C6.UO₂)⁺² complex.     

Sorption phenomena of organic solvents in polymers: Part II

In this work we use the vapor-sorption equilibrium data to show the degree of solvent upturn in each solvent-polymer system. For this purpose, sixty-one isothermal data sets for forty copolymer + solvent binaries and for fourteen of their parent homopolymer + solvent binaries have been used in the temperature range of 23.5-80 °C. Solvents studied are acetone, acetonitrile, 1-butanol, 1,2-dichloroethane, chloroform, cyclohexane, hexane, methanol, octane, pentane, and toluene. Copolymers studied are poly(acrylonitrile-co-butadiene), poly(styrene-co-acrylonitrile), poly(styrene-co-butadiene), poly(vinyl acetate-co-ethylene), and poly(vinyl acetate-co-vinyl chloride). All copolymers are random copolymers. Some homopolymers are also studied: polyacrylonitrile, poly(cis-1,4-butadiene), poly(ethylene oxide), polystyrene and poly(vinyl acetate).According to these data sets, solvent weight fraction in the polymer is plotted against solvent vapor activity that is calculated assuming an ideal gas phase of pure solvent vapor neglecting the vapor pressure of the polymer. We use the Flory-Huggins theory to obtain dimensionless interaction parameter, χ. Also the Zimm-Lundberg clustering theory and non-ideality thermodynamic factor, Γ are used to interpret the equilibrium data.     

Cationic Grafting of Vinyl Polymers onto a Carbon Whisker,Initiated by Acylium Perchlorate Groups Introduced onto the Surface

Abstract

The cationic graft polymerization of vinyl monomers onto a carbon whisker, vapor-grown carbon fiber, initiated by acylium perchlorate groups introduced onto the surface, was investigated. The introduction of acylium perchlorate groups onto a carbon whisker was achieved by the treatment of a carbon whisker having acyl chloride groups, which were introduced by the reaction of surface carboxyl groups with thionyl chloride, with silver perchlorate in nitrobenzene. It was found that the cationic polymerization of vinyl monomers, such as styrene, indene, N-vinyl-2-pyrrolidone, and n-butyl vinyl ether, is initiated by acylium perchlorate groups on a carbon whisker. In the polymerization, the corresponding vinyl polymers were grafted onto a carbon-whisker surface based on the propagation of polymer from the surface: the percentage of grafting of polystyrene and polyindene reached 42.5 and 100.3%, respectively. The percentage of polystyrene grafting decreased with increasing polymerization temperature because of preferential chain transfer reactions at higher temperatures. Polymer-grafted carbon whisker gave a stable colloidal dispersion in a good solvent for grafted polymer.     

Application of Crown Ether to Chemical Analysis. III. Extraction of Amines with Crown Ether

Abstract

The protonated amines were extracted with crown ether as the picrate into organic solvent. The overall extraction constants(Kex) for the 1 : 1 : 1 complexes, AHLP, of 18-crown-6 with protonated amines and picrate between 1,2-dichloroethane and water have been determined at 25°C. The extractability of complexes decreased in the sequence: primary amines > secondary amines, which indicated that the type of amine was a most important factor. The log Kex values were determined to be 6.6, 7.6, 7.9, 8.3, 9.6, 2.5 and 3.8 for tert-butylamine, ethylamine, n-butylamine, sec-butylamine, n-hexylamine, diethylamine and di-n-propylamine respectively.     

Poly(vinyl chloride-g-butyl rubber)

The synthesis of poly(vinyl chloride-g-butyl rubber) and some of its physical properties are described. The key to the synthesis involves copolymerization initiation of an isobutylene–isoprene charge by a PVC/Et₂AlCl initiator system with 1,2-dichloroethane as solvent. The graft is a thermoplastic; cast films are flexible and optically clear. Proof of grafting is the crosslinking with S₂Cl₂ of the pentane-extracted product in THF solution. Crosslinking the butyl rubber moiety in the graft reduces overall stress properties.     

Study of complex formation between dicyclohexyl-18-crown-6 and UO2 2+ cation in some binary mixed non-aqueous solvents using conductometric method

In the present work, the complexation process between UO₂ ²⁺ cation and the macrocyclic ligand, dicyclohexyl-18-crown-6 (DCH18C6) was studied in ethyl acetate/1,2-dichloroethane (EtOAc/DCE), acetonitrile/1,2-dichloroethane (AN/DCE), methanol/1,2-dichloroethane (MeOH/DCE) and ethanol/1,2-dichloroethane (EtOH/DCE) binary solutions at different temperatures using the conductometric method. The conductance data show that in most cases, the stoichiometry of the complex formed between DCH18C6 and UO₂ ²⁺ cation is 1:1 [M:L], but in some solvent systems also a 1:2 [M:L₂] complex is formed in solutions. The values of stability constant of (DCH18C6·UO₂)²⁺ complex which were obtained from conductometric data, show that the stability of the complex is affected by the nature and also the composition of the solvent system and in all cases, a non-linear behavior is observed for the variation of (log?K _f) of the (DCH18C6·UO₂)²⁺ complex versus the composition of the binary mixed solvents. The values of thermodynamic quantities $ \Updelta H_{c}^{\circ} $ and $ \Updelta S_{c}^{\circ} $ for formation of (DCH18C6·UO₂)²⁺ complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots. The experimental results show that depending on the nature and composition of the solvent systems, the complex is enthalpy stabilized or destabilized, but in most cases, it is stabilized from entropy view point and both thermodynamic parameters are affected by the nature and composition of the binary mixed solutions.     

Anionic polymerization. VI. Effect of polar modifiers on alkylsodium and alkylpotassium polymerization of butadiene

It was found that N,N,N′,N′-tetramethylethylene diamine and hexamethyl phosphorus triamide minimize chain transfer reactions in the polymerization of 1,3-butadiene in hydrocarbon solvent with alkylsodium or alkylpotassium initiators. The polymers obtained with alkylsodium initiators had a high molecular weight and high vinyl content at 90–95% conversion. The molecular weight of the polybutadiene made by alkylsodium and alkylpotassium initiators was dependent on the polymerization temperatures and modifier ratios, but the vinyl contents were independent of the modifier ratios. Vinyl contents of alkylpotassium-initiated polymers showed a slight dependency on polymerization temperature; the vinyl contents of alkylsodium-initiated polymers were independent of temperature. Addition of lithium tert-butoxide and potassium tert-amylate to these initiators in the presence of the modifiers affected the molecular weight but not the microstructure.     

INDIRECT DETERMINATION OF MERCURY BY ATOMIC ABSORPTION SPECTROPHOTOMETRY USING ZINC HOLLOW CATHODE LAMP

Abstract

An indirect atomic absorption spectrophotometric method for mercury has been developed on the basis of solvent extraction chemistry. Mercury(II) was converted into a bromo-complex anion and extracted into 1,2-dichloroethane with the 2,2′-bipyridyl-zinc chelate cation. The resulting zinc in the extract, which was equivalent to a specific amount of mercury, was determined by atomic absorption spectrophotometry. The sensitivity for the determination of mercury could be enhanced to the level of zinc by the proposed method.     

Intramolecular Charge Transfer Complexes. 4. Poly(N-(2-hydroxyethyl)carbazolyl Acrylate-co-Picryl Methacrylate)

Abstract

Radical copolymerization of N-(2-hydroxyethyl)carbazolyl acry-late with picryl methacrylate takes place mainly through the inter-monomeric charge transfer complex (CTC) in dioxane solution. When the solvent is 1, 2-dichloroethane, concurrent chain transfer reactions arise. The copolymers obtained are intramolecular CTC. The charge transfer interaction depends on copolymer composition and conformation, and on the copolymerization solvent.     

Lewis acid-promoted Kharasch-Curran additions: a competition kinetics study of bromine atom transfer addition of N-alpha-bromoacetyl-oxazolidinone to 1-hexene

Lewis acids can efficiently promote free radical atom transfer reactions of an oxazolidinone imide substrate, 1, derived from alpha-bromo acetic acid. Thus, 1 undergoes a radical chain addition to 1-hexene giving the atom transfer addition compound, 6, in the presence of scandium or ytterbium triflate in 1,2-dichloroethane or a cosolvent mixture of 1/9 THF/dichloromethane. In 1,2-dichloroethane the solution is heterogeneous, while the cosolvent mixture gives a homogeneous solution, even at temperatures of -78 degrees C. Competition experiments were carried out in both solvent systems with added carbon tetrachloride to study how Lewis acid affected the product distribution. In the presence of carbon tetrachloride, chloride 7 is formed in addition to 6 and the ratio of these two products depends on the amount of Lewis acid present. In the presence of ytterbium triflate, in the cosolvent system, the reaction rate of bromine atom transfer was enhanced up to 400-fold compared to the reaction without added Lewis acid. Significant rate enhancements were also obtained in the solvent 1,2-dichloroethane, although the analysis of the system is complicated by the heterogeneous nature of the medium. Computation of C-Br bond dissociation energies (BDE) of the complexed and uncomplexed oxazolidinone bromide suggest that complexation lowers the BDE due to the effect of the strong electron-withdrawing group on the C-Br bond dipole.