RING-OPENING POLYMERIZATION OF TRIMETHYLENE CARBONATE CATALYZED BY NOVEL SINGLE COMPONENT RARE EARTH CALIXARENE COMPLEXES

In this paper, ring-opening polymerization of trimethylene carbonate (TMC) with rare earth (Nd, Y, La) p-tert-butylcalix[n]arene (n=4, 6, and 8) complexes as catalysts has been studied. Poly(trimethylene carbonate) (PTMC) with Mv of 21,400 was produced by bulk polymerization under the conditions as follows: [TMC]0/[Nd] (molar ratio)=1000,80℃,8h. Mechanism study reveals that the polymerization proceeds via a coordination mechanism.     

超高分子量聚苯乙烯的合成和聚合反应动力学

杯芳烃钕与Mg(n Bu) 2 、HMPA所组成的三元络合催化剂用于苯乙烯配位聚合能以高收率制得超高分子量聚苯乙烯 .以甲苯为溶剂 ,在一定条件下制成三元配位催化剂 ,当 [Nd]=8× 10 - 4mol L ,[St]=4 .0mol L ,Mg Nd =2 0 .0 (摩尔比 ) ,HMPA Mg =1.0 (摩尔比 ) ,5 0℃聚合 4 5min ,聚合转化率可达到 80 %左右 .所得聚苯乙烯的重均分子量高达 2 10× 10 4 ,分子量分布指数为 1.6 1.间规聚苯乙烯含量为 81% .动力学研究表明 ,聚合反应速率与单体和主催化剂 杯 [6 ]芳烃钕的浓度分别呈 1次方关系 ,聚合反应的表观活化能为 4 1.7kJ mol     

杯芳烃钕/二正丁基镁/六甲基磷酰胺催化4-乙烯基吡啶的均聚及其与苯乙烯的共聚

聚4-乙烯基吡啶[P（4-VP）]是一种功能高分子,由于在吡啶环上有一个碱性的氮原子,它能进一步与酸反应生成各种盐,与卤代烃生成季铵盐以及与金属离子生成配合物,可用作高分子电解质,高分子试剂,高分子功能材料等,因此有不少文献对它的合成进行了报道,合成聚4-乙烯基吡啶及其与苯乙烯（St）的共聚物,除了用丁基锂作引发剂外,过渡金属的Ziegler-Natta催化剂,以及烷基铝和烷基锌等也常被用作催化剂,但用这些催化剂催化所得的聚4-乙烯基吡啶及其与苯乙烯的共聚物产率低,分子量小。     

Synthesis,structures, and conformational characteristics of calixarene monoanions and dianions

The synthesis, complete characterization, and solid state structural and solution conformation determination of calix[n]arenes (n = 4, 6, 8) is reported. A complete series of X-ray structures of the alkali metal salts of calix[4]arene (HC4) illustrate the great influence of the alkali metal ion on the solid state structure of calixanions (e.g., the Li salt of monoanionic HC4 is a monomer; the Na salt of monoanionic HC4 forms a dimer; and the K, Rb, and Cs salts exist in polymeric forms). Solution NMR spectra of alkali metal salts of monoanionic calix[4]arenes indicate that they have the cone conformation in solution. Variable-temperature NMR spectra of salts HC4.M (M = Li, Na, K, Rb, Cs) show that they possess similar coalescence temperatures, all higher than that of HC4. Due to steric hindrance from tert-butyl groups in the para position of p-tert-butylcalix[4]arene (Bu(t)C4), the alkali metal salts of monoanionic Bu(t)C4 exist in monomeric or dimeric form in the solid state. Calix[6]arene (HC6) and p-tert-butylcalix[6]arene (Bu(t)C6) were treated with a 2:1 molar ratio of M(2)CO(3) (M = K, Rb, Cs) or a 1:1 molar ratio of MOC(CH(3))(3) (M = Li, Na) to give calix[6]arene monoanions, but calix[6]arenes react in a 1:1 molar ratio with M(2)CO(3) (M = K, Rb, Cs) to afford calix[6]arene dianions. Calix[8]arene (HC8) and p-tert-butylcalix[8]arene (Bu(t)()C8) have similar reactivity. The alkali metal salts of monoanionic calix[6]arenes are more conformationally flexible than the alkali metal salts of dianionic calix[6]arenes, which has been shown by their solution NMR spectra. X-ray crystal structures of HC6.Li and HC6.Cs indicate that the size of the alkali metal has some influence on the conformation of calixanions; for example, HC6.Li has a cone-like conformation, and HC6.Cs has a 1,2,3-alternate conformation. The calix[6]arene dianions show roughly the same structural architecture, and the salts tend to form polymeric chains. For most calixarene salts cation-pi arene interactions were observed.     

Synthesis of （p—Substituted phenyl）azo Calix[4] arenes

A novel method for the preparation of chromogenic calixarenes with azo groups was reported.p-Substituted(-NO2,-CH3,-Cl)amilines were diazotized with isoamyl nitrite in EtONa/EtOH under refluxing condition.Fifteen mono-,bis-,tris-and tetrakis(p-substituted phenyl)azo calix[4]arenes (including proximal and distal isomers) were obtainged respectively by diazo-coupling in different molar ratio to calix[4]arenes(1) under pH=7.5-9.0 in non-aqueous solution at 0-5℃.^1H NMR and ^13C NMR spectra of (p-substtituted phenyl)azo calix[4]-arenes indicated that they existed in cone conformation in solution.     

HETEROCYCLIC SCHIFF BASE NEODYMIUM COMPLEX AS CATALYST FOR RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

An aromatic heterocyclic Schiff base neodymium complex bearing thiazole was synthesized and its activity in the ring-opening polymerization ofε-caprolactone(CL)was examined.The conditions of the CL/Nd molar ratio,monomer concentration,polymerization time and temperature were investigated.Activities of ca.171 kg/Nd·h were obtained under the optimum condition(CL/Nd=1600(molar ratio),[CL]=2.26 mol L~(-1),1 h at 50℃),giving a poly(ε-caprolactone)(PCL)of number-average molecular weight M_n=5.4×10~4 and molecular weight distribution MWD=1.96.The conversion of CL monomer as high as 94% was observed after polymerized for one hour.The mechanism of coordination polymerization has also been illustrated.     

Hydrophilic–hydrophobic AB diblock copolymers containing poly(trimethylene carbonate) and poly(ethylene oxide) blocks

AB‐type block copolymers with poly(trimethylene carbonate) [poly(TMC); A] and poly(ethylene oxide) [PEO; B; number‐average molecular weight (M_n) = 5000] blocks [poly(TMC)‐b‐PEO] were synthesized via the ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of monohydroxy PEO with stannous octoate as a catalyst. M_n of the resulting copolymers increased with increasing TMC content in the feed at a constant molar ratio of the monomer to the catalyst (monomer/catalyst = 125). The thermal properties of the AB diblock copolymers were investigated with differential scanning calorimetry. The melting temperature of the PEO blocks was lower than that of the homopolymer, and the crystallinity of the PEO block decreased as the length of the poly(TMC) blocks increased. The glass‐transition temperature of the poly(TMC) blocks was dependent on the diblock copolymer composition upon first heating. The static contact angle decreased sharply with increasing PEO content in the diblock copolymers. Compared with poly(TMC), poly(TMC)‐b‐PEO had a higher Young's modulus and lower elongation at break. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4819–4827, 2005     

Synthesis of （p-Formylphenyl）azo Calix[4]arenes

Five novel azo calix[4]arenes were reported. The p-aminobenzaldehyde was diazotized with sodium nitrite in aqueous hydrochloride solution. Mono-, bis-, tris- and tetrakis(p-formylphenyl)azo calix[4]arenes (including proximal and distal isomers) were obtained respectively by diazo-coupling in different molar ratio to calix[4]arene(1) under pH=7.5--8.5 at 0-5℃. All (p-formylphenyl)azo calix[4]arenes were characterized by ^1H NMR, ^13C NMR, IR, MS (ESIMS) spectroscopies and elemental analysis.     

Use of samarium (III) acetate as initiator in ring-opening polymerization of trimethylene carbonate

Abstract

In this work was evaluated the activity of samarium acetate (III) (Sm(OAc)₃) as a possible initiator in the polymerization by ring opening of trimethylene carbonate (TMC). All polymerizations were carried out under solvent-free melt conditions in ampoules-like flasks, equipped with a magnetic stirrer. The effects of different parameters of reaction, such as molar ratio monomer to initiator, temperature and reaction time, on typical variables of polymers, e.g., conversion of TMC to poly(trimethylene carbonate) (PTMC), dispersity and molar mass, were analyzed. The molar ratio of monomer to initiator was varied between 0 and 1000?mol/mol and the temperature among 70 and 150?°C. Nuclear Magnetic Resonance (¹H-NMR and HMBC) and Size Exclusion Chromatography (SEC) were used to characterize the polymers. The results indicate that the Sm(OAc)₃ induces the polymerization of TMC to high conversion with number-average molecular weights of 3.11?×?10³ to 38.40?×?10³?Da. Based on the ¹H-NMR end-group analysis of low-molecular-weight PTMC, it was proposed a coordination–insertion mechanism for the polymerization, with a breakdown of the acyl-oxygen bond of the TMC. In according to the kinetic study carried out, the polymerization rate is first-order with respect to monomer concentration with apparent rate constants of k_ap?=?7.02?×?10^?4?mol?×?L^?1?×?h^?1.     

HETEROCYCLIC SCHIFF BASE NEODYMIUM COMPLEX AS CATALYST FOR RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

An aromatic heterocyclic Schiff base neodymium complex bearing thizole was synthesized and its activity in the ring-opening polymerization of ε-caprolactone (CL) was examined. The conditions of the CL/Nd molar ratio, monomer concentration, polymerization time and temperature were investigated. Activities of ca.171 kg/Nd·h were obtained under the optimum condition (CL/Nd = 1600 (molar ratio), |CL] = 2.26 mol L-1, 1 h at 50℃), giving a poly(ε-caprolactone) (PCL) of number-average molecular weight Mn = 5.4 × 104 and molecular weight distribution MWD = 1.96. The conversion of CL monomer as high as 94% was observed after polymerized for one hour. The mechanism of coordination polymerization has also been illustrated.     

Styrene polymerization with rare earth catalysts using a magnesium alkyl cocatalyst

A new highly active rare earth coordination catalyst composed of rare earth phosphonate, di-n-butylmagnesium (MgBu), and hexamethyl phosphoramide (HMPA) for the polymerization of styrene has been developed for the first time. High molecular weight polystyrene (M̄_ν = 50–70 × 10⁴) in 100% conversion could be prepared at following conditions: [Nd] = 6–8 × 10⁻⁴ mol/L, [St] = 3.0 mol/L, Mg/Nd = 11, and HMPA/Mg = 1–1.5 (molar ratio). The catalytic activity of this new catalyst is 3530 g PSt/g Nd. Kinetics study shows that the polymerization rate is of first order with respect to both monomer concentration and catalyst concentration, and activation energy of the polymerization is 40.1 kJ/mol. © 1996 John Wiley & Sons, Inc.     

A novel catalytic system—NdCl3 · HMPA/AI(i‐6u)3 for copolymerization of isoprene and styrene

Co polymerization of styrene (St) and isoprene (IP) was carried out with a catalyst system composed of anhydrous lanthanide chloride hexamethyl phosphor amide complex (LnC1₃‐HMPA) and aluminum organic compound (AOC). Among the catalysts examined, catalyst NdC1₃*HMPA/Al(i‐Bu)₃ showed a high activity in the copolymerization under certain conditions giving copolymers (5%‐158 St content) with high cis‐1, 4 microstructure in IP Units (>95%). The effects of HMPA/Nd molar ratio, Al/Nd molar ratio, monomer/Nd molar ratio, St feed ratio, and the reaction time on copolymerization were examined with this catalytic system. The obtained copolymers were characterized by ¹H and ¹³C NMR spectroscopies and gel‐permeation chromatography (GPC).     

Extraction of copper with p-tert-butyl-calixarenes

The extraction of copper with calixarenes was researched by comparing the results from calix[4]-,calix[6]-and calix[8]-arenes.Hie extraction ability increased as the order:calix [4]-> calix[8]-> calix[6]-arenes,with the binding ratio being 1:1.The extraction mechanism was also discussed,and itsequation Cu(NH3)42 H2L(0)Cu(NH3)4L(0) 2H and the extraction equilibrium constants(Ker)for calix[6]-and calix[8]-arenes were obtained respectively.     

N-硫脲基套索杯[4]冠醚与四硫脲基杯[4]芳烃的合成

控制反应物的物质的量比, 杯式对叔丁基杯[4]-1,3-二乙酸乙酯衍生物1与5或50倍二乙烯三胺反应, 分别得到杯[4]氮杂冠醚2和开链的氮杂杯[4]芳烃衍生物3. 化合物2和3进一步与异硫氰酸苯酯反应得到首例侧链含硫脲基的套索杯[4]氮杂冠醚4和含4个硫脲基的杯[4]芳烃衍生物5, 产率为92%和87%. 新化合物的结构与构象经元素分析、红外、质谱、核磁共振谱等表征证实.     

Potassium Sensing Calix[4]arene Crown Ethers

1,3-Alternate calix[4]arene crown-5 (1) and corresponding biscrown-5 (2) were synthesized and the complexation behavior with alkali metal ions examined. For both 1 and 2, potassium ion was selectively extracted from aqueous phase into organic phase over other alkali metal ions based on two phase extraction experiment. The complexation ratio between calix[4]arene biscrown-5 (2), in which two crown cavities connect to the calix[4]arene framework by 1,3-alternate fashion and potassium metal ion is found to 1:1 by proton NMR spectroscopy and extraction equilibria. Association constants (logK_a) for 1 and 2 were determined to give 2.51 and 3.49, respectively.     

Oxidative polymerization of 2,6‐dimethylphenol to form poly(2,6‐dimethyl‐1,4‐phenylene oxide) in water through one water‐soluble copper(II) complex of a zwitterionic calix[4]arene

In the presence of excess NaOH, reaction of Cu(OAc)₂·H₂O with equimolar ammonium calix[4]arene [H₄L]I₄ ( 1 , H₄L = [5,11,17,23‐tetrakis(trimethylammonium)‐25,26,27,28‐tetrahydroxycalix[4]arene]) resulted in the formation of a mononuclear cationic Cu(II) complex [Cu(II)L(H₂O)]I₂ ( 2 ) in 43% yield. Complex 2 was characterized by elemental analysis, infrared (IR), and single crystal X‐ray diffraction. The Cu(II) atom in 2 is coordinated by four oxygen atoms of one L^4? ligand and one O atom from one water molecule, forming a square pyramidal geometry. Complex 2 exhibited high catalytic activity in the oxidative polymerization of 2,6‐dimethylphenol using O₂ as oxidizing agent in water under mild conditions. The selective polymerization produced poly(2,6‐dimethyl‐1,4‐phenylene oxide) in high yields with almost no diphenoquinone. The influence of the polymerization temperature, the time interval, the molar ratio of 2,6‐dimethylphenol/ 2 , the concentrations of sodium hydroxide, and sodium n‐dodecyl sulfate were examined. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Controlled trans-stereospecific polymerization of isoprene with lanthanide(III) borohydride/dialkylmagnesium systems: The improvement of the activity and selectivity,kinetic studies,and mechanistic aspects

Neodymium trisborohydride, associated with MgR₂ alkylating agents, affords an efficient initiator for the stereospecific polymerization of isoprene. This system presents good activity (150 kg of polyisoprene/mol of Nd/h; 95% yield in 2 h) and is trans-stereospecific (up to 97.7%), and its polymerization shows a quasi-living character. The molecular weights are controlled by the [Isoprene]/[Nd] ratio, with a polydispersity index lower than 1.6. A full study is presented here, including the influence of the nature of the alkylating reagent (MgR₂), the solvent, the reaction temperature, the [MgR₂]/[Nd] ratio, and the replacement of neodymium by other lanthanides. This work also includes a kinetic study of the system and a detailed NMR study of the microstructure of the trans-polyisoprene obtained, providing mechanistic insights about the polymerization reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2400–2409, 2007     

Thermodynamics of sublimation of calix[4]arene complexes with solvent molecules

The inclusion of small neutral organic guests (C₆H₁₄, CH₂Cl₂, CH₃OH) by calix[4]arene receptors was found by ¹H NMR spectroscopy and microanalysis. The studied calix[4]arenes can form stable intramolecular complexes with solvent molecules which keep the stoichiometric composition without changing under conditions of the sublimation experiment. The saturated vapour pressures of calix[4]arenes and complexes of calix[4]arenes with solvent molecules were determinated for the first time by the Knudsen’s effusion method in the wide temperature range. The changing of standard thermodynamic parameters of complexation by transfer process from condensed state to vapour phase was estimated. It was shown that the large flexibility of the calixarene ligand structure corresponds to a strongly negative entropic contribution as well as negative enthalpy term to the Gibbs energy of formation of host–guest complexes in the gas phase.     

Solvent-Impregnated Resins Based on the Mixture of (2-Diphenylphosphoryl)-4-ethylphenoxy)methyl) diphenylphosphine Oxide and Ionic Liquid for Nd(III) Recovery from Nitric Acid Media

Novel solvent-impregnated resins (SIRs) were prepared by treatment of styrene–divinylbenzene copolymer (LPS-500) with mixtures of the promising polydentante extractant (2-diphenylphosphoryl)-4-ethylphenoxy)methyl)diphenylphosphine oxide (L) and an ionic liquid [C₄mim]⁺[Tf₂N]⁻for the extraction chromatography recovery of Nd(III) from nitric acid solutions. It was shown that introduction of the ionic liquid into the SIR composition results in considerable enhancement of the Nd(III) recovery efficiency compared with resin impregnated only by L in slightly acidic media. The influence of the L: ionic liquid molar ratio in the SIRs composition, their percentages, concentration of metal and HNO₃ in the eluent, and acid type on the value of synergistic effect and adsorption efficiency of Nd(III) recovery was studied. The SIR containing 40% of mixture of L and [C₄mim]⁺[Tf₂N]⁻ with molar ratio 2:1 turned out to be the most efficient. The selectivity of Nd(III) separation from light and heavy rare-earth elements was studied and the optimal conditions of Nd(III) adsorption recovery and stripping by this SIR were chosen. It was found that in recovery efficiency of Nd(III) developed SIR exceeded the SIR containing Cyanex 923 (a mixture of monodentate trialkylphosphine oxides) and [C₄mim]⁺[Tf₂N]⁻.     

Synthesis of methyl 12-benzoyldehydroabietate in ionic liquid

In the presence of the ionic liquid [bmim]Br/AlCl₃ as green reaction medium, methyl 12-benzoyldehydroabietate was synthesized through Friedel-Crafts acylation reactions on the aromatic ring of methyl dehydroabietate. The optimum synthetic conditions of the target product were found to be as follows: molar ratio of methyl dehydroabietate to [bmim]Br to AlCl₃ to benzoyl chloride 1:4:8:8, reaction temperature 40°C, reaction time 2 h. The target product was analyzed and characterized by means of IR, MS, NMR and elemental analysis. The results show that this novel method has the advantages of mild condition, short reaction time and environmental benignity. __________ Translated from Chemistry, 2008, 71(2): 138–143