Crosslinking of polystyrene under friedel–crafts conditions in dichloroethane and carbon tetrachloride solvents through the formation of strongly colored polymer–AlCl3–solvent complexes

Polystyrene was crosslinked in either 1,2-dichloroethane or carbon tetrachloride in the presence of aluminum chloride. Apparently, the reactions involve Friedel–Crafts substitution of phenyl ring with CH₂CH₂Cl or CCl₃ groups, which than participate in crosslinking, giving CH₂CH₂ or CCl₂, CCl, and C bridges. In the first stage a charge-transfer complex is formed between AlCl₃, polystyrene and the solvent. After heating this complex above 35–40°C a rapid formation of HCl occurs and a crosslinked polymer is formed. This final product is insoluble, infusible, and inflammable. It decomposes at 400°C without melting.     

Organometallic polymers. III. Organometallic modifications of diene polymers

A process for the chemical modification of polybutadienes and natural rubber by various metallocene compounds is described. Soluble products of up to 43% ferrocene content were obtained. The effect of substrate, metallocene, and reaction conditions on the course and extent of substitution was investigated. The glass transition temperature T_g was found to increase considerably with the degree of substitution, e.g., cis-polybutadiene substituted with ferrocene (18 mole-%) has a T_g of 30°C, as compared with ?91°C for the unsubstituted polymer.     

Polymerization of coordinated monomers. V. Polymerization of methyl methacrylate–Lewis acid complexes

The polymerization of the complex of methyl methacrylate with stannic chloride, aluminum trichloride, or boron trifluoride was carried out in toluene solution at several temperatures in the range of 60° to ?78°C by initiation of α,α′-azobisisobutyronicrile or by irradiation with ultraviolet rays. The tacticities of the resulting polymers were determined by NMR spectroscopy. Both the 1:1 and the 2:1 methyl methacrylate–SnCl₄ complexes gave polymers with similar tacticities at the polymerization temperatures above ?60°C. With decreasing temperature below ?60°C, the isotacticity was more favored for the 2:1 complex, whereas the tacticities did not change for the 1:1 complex. On the ESR spectroscopy of the polymerization solution under the irradiation of ultraviolet rays at ?120°C, the 1:1 SnCl₄ complex gave a quintet, while the 2:1 SnCl₄ complex gave both a quintet and a sextet. The sextet became weaker with increasing temperature and disappeared at ?60°C. This behavior of the sextet corresponds to the change of the tacticities of polymer for the 2:1 SnCl₄ complex. An intra–intercomplex addition was suggested for the polymerization of the 2:1 complex, which took a cis-configuration on the basis of its infrared spectra. The sextet can be ascribed to the radical formed by the intracomplex addition reaction, while the quintet can correspond to that formed by the intercomplex addition reaction. The proportion of the intracomplex reaction was estimated to be about 0.25 at ?75°C, and the calculated value of the probability of isotactic diad addition of the intracomplex reaction was found to be almost unity.     

Chelatkomplexe von Rheniumtetrachlorid. Die Kristallstrukturen von ReCl4(DME) und ReCl4(DPPE) · Tolan

Chelate Complexes of Rhenium Tetrachloride. The Crystal Structures of ReCl₄(DME) and ReCl₄(DPPE) · Tolan Bright green crystals of ReCl₄(DME) have been prepared by the reaction of rhenium pentachloride with dimethoxyethane (DME) in dichloromethane. ReCl₄(DPPE) · tolan was obtained in form of red crystals by the reaction of the alkyne complex [ReCl₄(Ph? C?C? Ph)(POCl₃)] with bis(diphenylphosphino)ethane (DPPE) in dichloromethane. The complexes were characterized by X-ray structure determinations. ReCl₄(DME): Space group I4 2d, Z = 8, 829 observed unique reflexions, R = 0.022. Lattice dimensions at 19.5°C: a = b = 960.60(6), c = 2337.2(6) pm. The complex forms monomeric molecules with DME as chelating ligand; the Re? O bond lengths are 213.1 pm. The chlorine atoms, arranged in trans position to the chelating ligand, have slightly shorter Re? Cl bonds than the chlorine atoms in cis position (232,1 pm). ReCl₄(DPPE) · tolan: Space group P2₁/n, Z = 4,4313 observed unique reflexions, R = 0.040. Lattice dimensions at ?80°C: a = 1095.7(1), b = 1764.2(2), c = 1898.0(2) pm, β = 99.229(8)°. The compound consists in form of monomeric molecules [ReCl₄(DPPE)] and diphenylacetylene molecules, which are incorporated in the lattice. The two phenyl rings of the tolan molecules are twisted towards each other along the C? C axis with a dihedral angle of 21°. The DPPE molecules are bonded to the rhenium atom in a chelating fashion with medium Re? P lengths of 250.4 pm. The chlorine atoms, arranged in trans position to this ligand, with Re? Cl bond lengths of 234.5 pm are slightly longer than the Re? Cl bonds in cis position with 232.3 pm.     

CRYSTAL STRUCTURE OF (Ph_2Ppy)_2 (μ-Cl)_2Cu_2Cl_2

<正> (Ph2Ppy)2(μ-Cl)2Cu2Cl2 (C34H28Cl4Cu2N2P2): Mr=795.5, triclinic, Pl, a=13.891(2), b= 13.196(3), c= 20.158(4) A, d= 90.28(1)°, β=110.05(2)°, r= 90.13(1)°, Z=4, V= 3471.04A3, Dx=1.53 gcm-3, R=0.066, Rw= 0.076 for 5486 observed unique reflections. The complex was prepared by the reaction of (Ph2Ppy)2NiCl2 with CuC≡CPh in CH2Cl2 solution.     

Hydriding of intermetallic compound Ti2Ni

Conditions of formation of the Ti₂NiH_3.3 hydride phase in the reaction of the Ti₂Ni intermetallic compound with ammonia and hydrogen have been determined. The products of the reaction of the intermetallide with ammonia in the presence of the NH₄Cl activator in the temperature range 100–500°C have been identified. It has been shown that the use of ammonia at temperatures >400°C leads to the formation of titanium nitride and nickel.     

Structure and stability of halogenated polymers: Part 2—Chain-chlorinated polystyrene

Chain-chlorinated polystyrene samples have been prepared and characterised, containing from 2·5 to 34·3% chlorine by weight (from 0·1 to 1·3 chlorine atoms per styrene unit). Chlorination has been found to involve mainly substitution of the tertiary hydrogen atoms, followed by methylene substitution at reactant concentrations of more than 1 mole Cl₂ per styrene unit. Reaction with chlorine is quantitative in CCl₄ in the absence of air and the amount of ring-chlorination as a side reaction is very small.Chlorination in the backbone destabilises the polymer, which first loses hydrogen chloride on heating. The double bonds formed provide points of weakness for chain scission, which occurs at lower temperatures than for PS. Under programmed heating, the dehydrochlorination and chain scission reactions overlap to some extent in temperature range, but highly conjugated partially degraded polymer can be made from extensively chain-chlorinated PS. At more than 1 Cl per styrene unit, HCl is almost the sole volatile product, although the conjugated polymer breaks up to chain fragments above 300°C.     

Die ersten Fluorotrithiatetraphosphaheptane

The First Fluoro-trithiatetraphospha-heptanes Fluorinated α- and β-tetraphosphorus-trisulfur molecules were prepared by the reaction of α- or β-P₄S₃X₂ (X = Cl, Br, I) with (n-butyl)₃SnF. The substitution reaction of the α-isomers yields under retention of the configuration at the phosphorus atoms α-P₄S₃XF and α-P₄S₃F₂. In the reaction of the β-isomers more products were observed, because the configuration of the phosphorus atom can be retained or inversed in the first step of the substitution which yields β-P₄S₃X_exoF_exo or β-P₄S₃X_exoF_endo. The mass relation of the products depends on the halogen ligand. In the second substitution β-P₄S₃(F_exo)₂ or β-P₄S₃F_exoF_endo are formed. β-P₄S₃(F_endo)₂ was not observed. By the reaction of β-P₄S₃I₂ with BiX₃ (X = Cl, Br, I) we also were able to prepare small amounts of β-P₄S₃X_endoX_exo-molecules (X = I, Cl, Br) with an inversed configuration at one phosphorus atom. The ³¹P- and ¹⁹F-NMR parameter of all compounds are discussed.     

Photo-oxidation of poly(vinyl chloride)

The photo-oxidation of PVC has been studied over the temperature range 30–150°C. Initiation with ultraviolet (2537A) radiation has been correlated with the presence of minute amounts of ozone. The contribution of atomic oxygen and singlet oxygen (¹Δ_g) molecules to the initiation mechanism is discussed. The β-chloroketones probably formed in the photo-oxidation of PVC, decomposed according to a Norrish type I reaction without loss of chlorine atoms. The gaseous products of the photo-oxidation of PVC at 30°C were carbon dioxide, carbon monoxide, hydrogen, and methane. Hydrogen chloride was obtained only when PVC was heated at high temperatures. When PVC was photo-oxidized and then heated at high temperature, benzene was obtained in addition to hydrogen chloride. The gaseous products from the photo-oxidations of model compounds, such as 4-chloro-2-butanone and 2,4-dichloropentane, were also compared with those from PVC. Hydrogen chloride was detected only after photo-oxidation at temperatures of 25°C or higher. Therefore, it was concluded that hydrogen chloride is mainly a product of thermal decomposition. Since unsaturation was not observed in photo-oxidized PVC films, the cause of discoloration is unclear. When PVC was modified by stabilizers or additives, the oxidative degradation was further complicated by side reactions with the additives.     

Living cationic polymerization of vinyl ethers with a naphthyl group: Decisive effect of the substituted position on naphthalene ring

Living cationic polymerization of a vinyl ether with a naphthyl group [2‐(2‐naphthoxy)ethyl vinyl ether, βNpOVE] was achieved using base‐assisting initiating systems with a Lewis acid. The Et_1.5AlCl_1.5/1,4‐dioxane or ethyl acetate system induced the living cationic polymerization of βNpOVE in toluene at 0 °C. The living nature of this reaction was confirmed by a monomer addition experiment, followed by ¹H NMR and matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) analyses. In contrast, the polymerization of αNpOVE was not fully controlled; under similar conditions, it produced polymers with broad molecular weight distributions. The ¹H NMR and MALDI‐TOF‐MS spectra of the resultant poly(αNpOVE) revealed that the products had undesirable structures derived from Friedel–Crafts alkylation. The higher reactivity of αNpOVE in electrophilic substitution reactions, such as the Friedel–Crafts reaction, was attributable to the greater electron density of the naphthyl ring, which was calculated based on frontier orbital theory. The naphthyl groups significantly affected the properties of the resultant polymer. For example, the glass transition temperatures (T_g) of poly(NpOVE)s are higher by approximately 40 °C than that of poly(2‐phenoxyethyl vinyl ether). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Friedel-crafts copolymerization of thiophene and p-di(chloromethyl)benzene. I. Products,kinetics, and mechanism of the early stages of the reaction

The rate of polymerization of thiophene, at concentrations of catalyst (SnCl₄), and thiophene of the same order as was subsequently used in studying the reaction between thiophene and di(chloromethyl)benzene, is of the order of 10^-2%/hr at 30°C. There is no significant self-condensation of DCMB under the same conditions. Since the reaction between thiophene and DCMB is complete at 30°C in minutes rather than hours, it is assumed that self-condensation of thiophene or DCMB during the reaction between them will be negligible and should not influence the course of the reaction or the structure of the resulting polymer. Reaction at 30°C is much too fast for convenient study. A temperature of 0°C is more appropriate and was used in subsequent kinetic work. The first two products of the condensation of p-di(chloromethyl)benzene (DCMB) with thiophene have been identified by a combination of mass, infrared, and nuclear magnetic resonance spectroscopy as thenylchloromethylbenzene (TCMB) and dithenylbenzene (DTB). DCMB, TCMB, and DTB have been estimated quantitatively during the course of the reaction by gas-liquid chromatography (GLC), and it has been established that the rates of each of the two reaction steps is first-order with respect to the chloro compound (DCMB and TCMB respectively), thiophene, and SnCl₄. Rate constants for these two consecutive reactions were calculated to be k₁ = 2.79 × 10^-4l.²/mole²-sec, k₂ = 6.37 × 10^-3l.²/mole²-sec; the corresponding energies of activation are E₁ = 7.93 kcal/mole, E₂ = 7°67 kcal/mole. These rate constants are appreciably higher than values previously obtained for the corresponding DCMB–benzene reactions.     

DSC study of the deposition reactions of zinc pack coatings up to 550°C

Zn pack coating formation takes place in three steps as differential scanning calorimetry shows. The initial step (at 193.9°C) is endothermic and involves the transformation of α-NH₄Cl to β-NH₄Cl and the NH₄Cl decomposition to NH₃ and HCl. During the second step (at 248.6°C), which is exothermic, Zn²⁺ salts are formed and most probably ZnCl₂. Finally at 264.1°C (endothermic reaction) it seems that ZnCl2 is decomposed to form Zn that is deposited on the ferrous substrate. The as-cast Zn diffuses in the iron substrate forming the gamma and delta phase of the Fe–Zn phase diagram. Al₂O₃ is not involved in the above-mentioned mechanism and acts only as filler.     

Thermal analysis of β-Co2(OH)3Cl and Zn5(OH)5Cl2 · H2O

Samples of β-Co₂(OH)₃Cl and Zn₅(OH)₈Cl₂ · H₂O have been prepared and their thermal decomposition studied in air and N₂ by DTA and TG up to 1000°C. X-Ray diffraction analysis of the thermal treatment products in air at various temperatures from 100 to 100°C was also carried out. The results obtained made it possible to establish the steps through which the pyrolysis of both compounds proceeds.     

Stereoselective nucleophilic substitution of poly(vinyl chloride) with sodium thiophenate in cyclohexanone solution: Influence of the reaction temperature on the mechanism

Nucleophilic substitution of PVC with sodium thiophenate was carried out in cyclohexanone solution at 5, 25, 40, 60, and 70°C. The initial rate obeys an Arrhenius law from 25 to 60°C, with an activation energy of 70 kJ/mol. Conversion limits are observed which strongly depend on the temperature. The stereoselectivity of the reaction with respect to the configurational triads does not depend on the temperature: the distribution of configurations is only dependent on the conversion. Assuming an S_N2 substitution mechanism governed by steric factors, the Monte Carlo simulation procedure described in a prior study is shown to give a good account for all temperatures above 40°C assuming for the mm, mr or rm, and rr triads a reactivity such as R_mm = 2 R_mr and R_rr nil at low temperature and very low at temperatures ≥ 40°C. The low conversion limits observed at 5 and 25°C cannot be explained by a limited accessibility of a part of the polymer. Finally, it is shown that the elimination reaction, which remains limited, does not interfere with the substitution process.     

Long branching in poly(vinyl acetate) and poly(vinyl alcohol). III. Kinetic study of the branching reaction in the radical polymerization of vinyl acetate

The branching reaction in the radical polymerization of vinyl acetate was studied kinetically. Branching occurs by polymer transfer as well as terminal double-bond copolymerization. The chain-transfer constants to the main chain (C_p,2) and to the acetoxy methyl group (C_p,1) on the polymer were calculated on the basis of the experimental data described in the preceding paper giving C_p,2 = 3.03 × 10^?4, C_p,1 = 1.27 × 10^?4 at 60°C, and C_p,2 = 2.48 × 10^?4, C_p,1 = 0.52 × 10^?4 at 0°C. Chain transfer to monomer is important with respect to the formation of the terminal double bond. The total values of transfer constants to the α- or β-position in the vinyl group and the acetoxymethyl group in vinyl acetate was determined to be 2.15 × 10^?4 at 60°C. The transfer constant to the acetyl group in the monomer (C_m,1) was also evaluated to be 2.26 × 10^?4 at 60°C from the quantitative determination of the carboxyl terminals in PVA. These facts suggest that the chain-transfer constant to the α- or β-position in the monomer (C_m,2) is nearly equal to zero within experimental error. Copolymerization reactivity parameters of the terminal double bond were also estimated. In conclusion, it has become clear that the formation of nonhydrolyzable branching by the terminal double-bond reaction can be almost neglected, and hence that the long branching in PVA is formed only by the polymer transfer mechanism. On the other hand, a large number of hydrolyzable branches in PVAc are prepared by the terminal double-bond reaction rather than by polymer transfer.     

The Whitlockite Phase in the system CaO?P2O5?MgO at 1000°C

Mixtures of reagent grade CaHPO₄, MgO, and CaCO₃ were sintered at 1000°C both in air and in dry carbon dioxide to investigate the stability field of β-Ca₃(PO₄)₂ in the ternary CaO? P₂O₅? MgO system along the CaO? P₂O₅ and the β-Ca₃(PO₄)₂? Mg₃(PO₄)₂ join. The extent of substitution of Mg for Ca in β-Ca₃(PO₄)₂ was determined to be near 14.7% Mg of the cat-ions, both in air and in dry carbon dioxide. Lattice parameters of products with various degrees of substitution are presented. There is a decrease of the c-axis up to 10% substitution after which an increase of the c-axis occurs on further substitution of Ca by Mg. This is probably related to substitution in two different sublattices. At 1000°C the carbonate ion could not be incorporated in the β-Ca₃(PO₄)₂ structure, and along the CaO? P₂O₅ join the Ca/P range of solid solution for β-Ca₃(PO₄)₂ was found to be immeasurably small both in air and in dry carbon-dioxide.     

Synthesis,Characterization and Crystal Structures of 1,2,4‐Triazole based Schiff‐Bases and their Copper(I) Complexes

The reaction of of 4‐amino‐5‐ethyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AETT, L ) with furfural in methanol led to the corresponding Schiff‐Base ( L1 ). The reaction of L1 with [Cu(PPh₃)₂]Cl in methanol gave to the neutral compound [( L1 )Cu(PPh₃)₂Cl] ( 1 ). By recrystallization of 1 from CH₃CN the complex [( L1 )Cu(PPh₃)₂Cl]·CH₃CN ( 1a ) was obtained. All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for L1 at ?80 °C: space group with a = 788.4(1), b = 830.3(2), c = 928.8(2) pm, α = 84.53(1)°, β = 65.93(1)°, γ = 72.02(1)°, Z = 2, R₁ = 0.0323; for 1 at ?100 °C: space group with a = 1166.3(1), b = 1423.8(2), c = 1489.1(2) pm, α = 62.15(1)°, β = 72.04(1)°, γ = 88.82(1)°, Z = 2, R₁ = 0.0338 and for 1a at ?100 °C: space group P2₁/c with a = 1294.1(1), b = 1019.8(2), c = 3316.9(4) pm, β = 94.73(1)°, Z = 4, R₁ = 0.0435.     

COPPER(I) COMPLEXES WITH N-(P-NITROPHENYL)-N′-ALKOXYCARBONYLTHIOUREA: SYNTHESES AND CRYSTAL STRUCTURES OF [Cu(H2net)2CI] · CH2CI2 AND [Cu(H2nmt)2CI]2·(CHCI3)2

Abstract

Two copper(I) complexes, [Cu(H₂net)₂Cl] · CH₂Cl₂ (1) and [Cu(H₂nmt)₂Cl]₂ · (CHCl₃)₂ (2), were synthesized by the reaction of CuCl₂ · 2H₂O with N-(p-nitrophenyl)-N′-(ethoxycarbonyl)-thiourea (H₂net) and N-(p-nitrophenyl)-N′-(methoxycarbonyl)-thiourea(H₂nmt), respectively. Both complexes crystallize in the monoclinic space group C2/c. For complex 1, a = 29.52(2), b=13.920(6), c = 14.873(3)Å; β= 101.75(2)°, V = 5984(4) ų, Z = 8 and R = 0.053; for complex 2, a = 30.68(1), b = 13.369(4), c = 14.226(7) Å, β = 99.52(4)°. V = 5754(4) ų, Z = 4 and R = 0.063. In complex 1, two H₂net molecules are bonded to Cu(I) atom through two S atoms forming a mononuclear complex with trigonal geometry for the Cu(I) ion [Cl(1)-Cu-S(1)=118.54(7), Cl(1)-Cu-S(2)=119.70(7), S(1)-Cu-S(2)=112.17(8)°, Cu-S(1) = 2.251(2), Cu-S(2) = 2.255(2), Cu-Cl(1) = 2.263(2) Å]. Complex 2 is a dimer formed by long Cu-S interactions [Cu-S* = 2.607(3) Å] from adjacent twc H₂nmt molecules; the Cu(I) ion has distorted tetrahedral coordination [Cl(1)-Cu-S(1) = 119.8(1), Cl(1)-Cu-S(2)=120.0(1), S(1)-Cu-S(2)=108.85(9)°] with unequal Cu-S [2.268(2), 2.247(2)Å] and Cu-Cl(1) [2.255(2)Å] bonds.     

Heteroatomfunktionalisierte Methylgold-Komplexe: Synthese und Struktur von Chlormethyl(triphenylphosphin)- und Phenylthiomethyl(trimethylphosphin)gold

Heteroatom-functionalized Methylgold Complexes: Synthesis and Structure of Chloromethyl(triphenylphosphine)- and Phenylthiomethyl(trimethylphosphine)gold [AuCl(PPh₃)] reacts with Mg(CH₂Cl)Cl, prepared in situ from CH₂ClI and iPrMgCl, in ether at –65 °C to give [Au(CH₂Cl)(PPh₃)] ( 1 a ). 1 a reacts with LiI, NaOMe and PPh₃ to give [Au(CH₂I)(PPh₃)] ( 2 ), [Au(CH₂OMe)(PPh₃)] ( 3 ) and [Au(CH₂PPh₃)(PPh₃)]Cl ( 4 ), respectively. 2 decomposes rapidly at room temperature, yielding ethylene and [AuI(PPh₃)]. The reaction of [AuCl(PMe₃)] with LiCH₂SPh in THF affords [Au(CH₂SPh)(PMe₃)] ( 5 ). The chloromethyl and the phenylthiomethyl complex 1 a and 5 were isolated and characterized by NMR (¹H, ¹³C, ³¹P) spectroscopy as well as by single-crystal X-ray structure analysis. In the solid state discrete molecules of 1 a and 5 are found with linear C–Au–P units [C–Au–P 179,8(4)° ( 1 a ), 179,1(1)° ( 5 )]. The angle Au–C–Cl (115,4(6)°) in 1 a is slightly greater than the tetrahedral angle.     

Polymerization of 1-chloro-2-β-naphthylacetylene by Mo catalysts and polymer properties

1-Chloro-2-β-naphthylacetylene (ClβNA) polymerized in good yields in the presence of MoCl₅-based catalysts. The highest weight-average molecular weight of poly(ClβNA) reached about 3 × 10⁵. The polymer was a yellow solid (absorption cutoff in CHCl₃ 450 nm). It was soluble in toluene, chloroform, etc., and provided a tough film by the solvent casting method. The polymer retained its weight up to 300°C in air; it was thermally less stable than poly(1-chloro-2-phenylacetylene) but more stable than poly(β-naphthylacetylene). The oxygen permeability coefficient (P_O2) of this polymer was 19 barrers (25°C), which is fairly small for a substituted polyacetylene. © 1996 John Wiley & Sons, Inc.