二甲基二茂锆化合物(1,2-Ph2-4-MeCp)2 ZrMe2的合成及催化乙烯聚合反应研究

在惰性气氛下, 用2 mol甲基锂处理二(1,2-二苯基-4-甲基环戊二烯基)二氯化锆, 合成了大立体位阻的二甲基二茂锆化合物[(1,2-Ph2-4-MeCp)2ZrMe2]. 经元素分析、 核磁共振氢谱、 碳谱和X射线晶体衍射分析, 确定了该化合物的结构. 经Al( i Bu)3/Ph3C+B(C6F5)-4活化, 该化合物催化乙烯聚合反应显示出较高的催化活性, 生成高分子量及高熔点聚乙烯. 该体系的特点是在较低的n(Al)/n(Zr)比下即可有效地催化乙烯聚合.     

新型二茂锆化合物(1,2-Ph2-4-PrCp)2ZrCl2的合成及催化烯烃聚合反应研究

3,4-二苯基环戊-2-烯-1-酮与丙基锂反应,经酸化脱水得新环戊二烯衍生物1,2-二苯基-4-丙基-1,3-环戊二烯(1).用丁基锂处理1得到相应的环戊二烯基锂,再与ZrCl₄在甲苯中反应,生成大立体阻碍二氯二茂锆化合物(1,2-Ph₂-4-PrCp)₂ZrCl₂(2).化合物1和2均经元素分析和核磁共振谱学表征.经甲基铝氧烷(MAO)活化,化合物2在较低Al/Zr比条件下既可有效地催化乙烯聚合,生成高分子量、高熔化温度聚乙烯.2/MAO体系对丙烯聚合表现出高活性,生成低分子量齐聚物,其分子量随聚合温度的降低而升高.     

用Co(naph)2-Al2(C2H5)3Cl3-P(OPh)3催化体系合成中乙烯基液体聚丁二烯

为获得适中乙烯基含量的液体聚丁二烯为目的, 对Co(naph)2-Al2(C2H5)3Cl3-P(OPh)3催化体系进行了较为系统的研究, 考察了该体系的催化剂配比、浓度及供电子试剂对分子量、微观结构和转化率的影响. 实验结果表明, 该体系在一定的条件下可以制备出分子量在700~3500、1,2结构含量在35%~40%且转化率高于55%的液体聚丁二烯.     

MoO_2Br_2体系催化丁二烯聚合中烯丙基卤素的作用

ＭｏＯ２Ｂｒ２－Ａｌ（ｉ－Ｂｕ）２ＯＰｈＣＨ３（－ｍ）体系催化丁二烯１，２－聚合过程中添加Ｃ３Ｈ５Ｘ（Ｘ＝Ｃｌ、Ｂｒ和Ｉ）对聚合物分子量有较好的调节作用，其中以Ｃ３Ｈ５Ｂｒ的调节作用最强，Ｍｎ从１７．５×１０５降至３．５×１０５，但对催化活性有一定的影响．在测定催化体系的ＵＶ光谱、（１３）Ｃ－ＮＭＲ谱、聚合活性和聚合动力学参数的基础上，讨论了Ｃ３Ｈ５Ｘ在催化体系中的行为．     

Regioselective conversion of 3-cyano-6-hydroxy-2-pyridones into 3-cyano-6-amino-2-pyridones

The reaction of a tautomeric mixture of 1-butyl-1,2-dihydro-6-hydroxy-4-methyl-2-oxopyridine-3-carbonitrile and its 2-hydroxy-6-oxo analog with phosphorus oxychloride gave 1-butyl-6-chloro-1,2-dihydro-4-methyl-2-oxopyridine-3-carbonitrile (68%) and 1-butyl-2-chloro-1,6-dihydro-4-methyl-6-pyridine-3-car-bonitrile (3%). Both chloropyridones were converted to their corresponding aminopyridones by reaction with liquid ammonia. Strong support for the molecular structure of 6-amino-1-butyl-1,2-dihydro-4-methyl-2-oxopyridine-3-carbonitrile was obtained on the basis of nmr techniques.     

NaBH4/I2催化加氢还原碱木质素的研究

从麦草碱法制浆黑液中提取木质素,精制后,以苯乙酮为木质素的模型化合物,对催化剂组成及溶剂进行了考察.在此基础上,以NaBH4/I2为催化剂,无水乙醇为溶剂,对木质素进行加氢还原裂解反应研究.考察了温度和时间对木质素催化加氢效果的影响,采用红外光谱(FTIR)、元素分析及凝胶渗透色谱分析(GPC),表征木质素反应前后结构的变化.凝胶渗透色谱分析表明,加氢还原后木质素的分子量明显降低.采用自动电位滴定法测定反应前后木质素中总羟基含量,反应后木质素中总羟基含量为10.19%.得到了NaBH4/I2催化木质素加氢还原反应的最优条件:以1,2-二氯乙烷和乙醇(2∶1,v/v)作溶剂,m(NaBH4)∶m(I2)=1∶1,温度175℃,反应时间15 h.     

Halofluorination of 1,2-difluoro-1,2-di(p-tolyl)ethene, 1,2,3,4-tetrafluoro-1,4-di(p-tolyl) butadiene and its nonfluorinated parent compounds

The reactions of (E)-1,2-difluoro-1,2-di (p-tolyl) ethene (1) with N-bromo- or N-chlorosuccinimide gave mainly the expected halofluorination products 1-bromo-1,2-di(p-tolyl)-1,2,2-trifluoroethane (2) or 1-chloro-1,2-di(p-tolyl)-1,2,2-trifluoroethane (4), respectively. As a side reaction halogenation of the double bond has been obtained. With (E,E)-1,4-di(p-tolyl)-1,2,3,4-tetrafluorobuta-1,3-diene (6) under the same conditions the products of 1,2- and 1,4-addition or its consecutive hydrolysis products were isolated. (E)-Stilbene (19) on bromofluorination gave solely erythro-1-bromo-2-fluoro-1,2-diphenylethane (20), while with 1,4-diphenylbuta-1,3-diene (17) mainly higher molecular weight products were formed.     

Polymerisations of -caprolactone and β-butyrolactone with Zn-, Al- and Mg-based organometallic complexes

The reaction of EtAlCl₂ with 1,2-{LiN(PMes₂)}₂C₆H₄ (Mes = 2,4,6-Me₃C₆H₂) and of butyloctylmagnesium with 1,2-{NH(PPh₂)}₂C₆H₄ gave [AlEt(1,2-{N(PMes₂)}₂C₆H₄-κ²N,N′)(THF)] (1) and [Mg(1,2-{N(PPh₂)}₂C₆H₄-κ²N,N′)(THF)₂] (2), respectively. Complexes 1 and 2 were fully characterised by NMR (¹H, ¹³C, ³¹P) and IR spectroscopy and mass spectrometry. Complexes 1 and 2 were employed as catalysts in the polymerisation of -caprolactone, which produced polymers with a narrow molecular weight distribution. For comparison the polymerisations of -caprolactone and β-butyrolactone were carried out with the Zn complex [ZnPr{1-N(PMes₂)-2-N(PHMes₂)C₆H₄-κ²N,N′}] (3) as catalyst, which produced polymers with narrow molecular weight distributions and high molecular weights.     

rac-[CH2(3-tert-butyl-1-indenyl)2]ZrCl2/MAO in the Copolymerization of Olefins and Dienes

Olefin-diene copolymerizations in the presence of C₂ symmetric zirconocene rac-[CH₂(3-tert-butyl-1-indenyl)₂]ZrCl₂/MAO catalytic system have been reported and rationalized by experimental and molecular modeling studies. Ethene gives 1,2-cyclopropane and 1,2-cyclopentane, 1,3-cyclobutane, and 1,3-cyclopentane units in copolymerization with 1,3-butadiene, 1,4-pentadiene, and 1,5-hexadiene, respectively. Propene-1,3-butadiene copolymerizations lead to 1,2 and 1,4 butadiene units and to a low amount of 1,2-cyclopropane units.     

BF_3·OEt_2对钼体系催化合成1,2-聚丁二烯的影响

在以加氢汽油为溶剂,MoCl_3(C_7H_(15)COO)_2(Mo)为主催化剂,(i-Bu)_2AlO〈O〉(Al)为助催化剂合成1,2-聚丁二烯的二元催化体系中,添加BF_3CH3·OEt_2等,对体系的催化活性影响显著。以的混合物为第三组份加入催化体系,较大幅度提高了钼系催化体系的活性。在Mo/Bd=8.0×10~(-5)(摩尔比),聚合5小时,丁二烯转化率可达到70％。初步搞清了钼催化体系合成的1,2-聚丁二烯中产生凝胶的条件,推测了凝胶的生成原因,考察了聚合条件对催化活性、分子量及微观结构含量的影响。     

Synthesis and characterization of poly(ethylene oxide-co-ethylene sulfone)s and their precursors: Poly(ethylene oxide-co-ethylene sulfide)s

Three poly(ethylene oxide-co-ethylene sulfide)s with oxygen to sulfur ratios of 2/1, 2/2, and 1/2 were prepared by phase-transfer catalyzed polycondensations of (1) sodium sulfide and 1,2-bis (2-chloroethoxy)ethane, (2) 1,2-ethanedithiol and 1,2-bis(2-chloroethoxy)ethane, and (3) 1,2-ethanedithiol and 2-chloroethyl ether, respectively. A buffered solution with pH between the pK_a of the monothiol (RSH) and the pK_a2 of the dithiol (HS–R–SH), or H₂S, was needed to obtain high molecular weight polymers, which suggests that nucleophiles transfer and react as monoanions rather than dianions. These poly(ethylene oxide-co-ethylene sulfide)s were oxidized completely to poly(ethylene oxide-co-ethylene sulfone)s using 3-chloroperoxybenzoic acid as oxidant. Both the final polymers and the precursors have regular sequenced structures and are semicrystalline. As expected, their glass transition temperatures and melting points increase and solubilities decrease with the decrease of ether oxygen to sulfur ratio. © 1994 John Wiley & Sons, Inc.     

Die Reaktion von 1,2-Epoxy-octan mit 2-Dimethylamino-äthanol

2-Dimethylaminoethanol reacts with 1,2-epoxyoctane presumably via a hydrogen-bonded complex to form a quaternary ammonium compound which exhibits a fair stability at lower temperatures. At higher temperatures the quaternary structure decomposes with the resulting formation of a wide variety of products. Most of the products have been identified and a reasonable mechanistic picture for their formation is presented. The main products of the reaction are 1-(ß-dimethylaminoethoxy)-2-octanol (IIIa) and 1-dimethylamino-2-octanol (IV), the latter being formed according to several pathways concurrently with ethylene oxide, 2-methyl-4-hexyl-1, 3-dioxolane (VI), and 2-hexyl-1, 4-dioxane (VII). Some of the higher molecular weight products are secondary products resulting from the action of epoxide on the primary reaction products IIIa and IV. The relative amount of each product formed depends on the ratio of starting materials and reaction temperature. In the presence of an additional hydroxylic solvent such as ethanol, the solvent enters also into the reaction.     

Surface chemistry of monochlorinated and dichlorinated benzenes on Si(100)2x1: comparison study of chlorine content and isomeric effects

Using X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD), the room temperature (RT) adsorption and thermal evolution of monochlorobenzene (MCB) and 1,3-dichlorobenzene (1,3-DCB) on Si(100)2x1 have been investigated and compared with that of 1,2-dichlorobenzene (1,2-DCB) reported previously. Like 1,2-DCB, the C 1s features observed at 284.6 (C(1)) and 286.0 eV (C(2)) for both MCB and 1,3-DCB could be attributed to the C-H and C-Cl bonds, respectively. The C(1)/C(2) intensity ratios for MCB (5.0) and 1,3-DCB (2.0) are found to follow the stoichiometric ratios of the C-H to C-Cl bonds for MCB and 1,3-DCB, respectively, indicating that both MCB and 1,3-DCB adsorb on Si(100)2x1 molecularly with negligible C-Cl dissociation at RT, in marked contrast to the partial C-Cl dissociation found for 1,2-DCB. Unlike 1,2-DCB with two discernible Cl 2s features at 270.3 and 271.2 eV, a single Cl 2s feature at 271.2 eV is observed for MCB and 1,3-DCB, in accord with the single local chemical environment for Cl. The TPD results show that MCB undergoes molecular desorption exclusively, similar to that found for benzene. Both molecular desorption and recombinative HCl desorption are found for 1,3-DCB, similar to that for 1,2-DCB. Despite the different Cl contents and relative Cl locations on the benzene ring, both MCB and 1,3-DCB exhibit RT adsorption behavior remarkably similar to that of benzene. To explain the C-Cl dissociation observed for 1,2-DCB, we propose a possible transition state involving the Cl atoms located at more physically compatible positions with the surface Si dimers in order to facilitate the conversion of 1,2-DCB (preferentially over 1,3-DCB) to dissociated products at RT. However, the thermal evolution of 1,3-DCB is closer to that of 1,2-DCB than that of MCB and benzene. The breakage of C-Cl bonds is found to occur at a relatively low temperature of 425 K, which suggests a relatively low activation barrier for the dechlorination of 1,3-DCB adspecies. Calculated energetics for 1,4-DCB on Si(100)2x1 shows that double dechlorination is not as favorable a process as those for 1,2-DCB and 1,3-DCB.     

Reversible addition‐fragmentation chain transfer polymerization of diisopropyl fumarate using various dithiobenzoates as chain transfer agents

Dialkyl fumarates as 1,2‐disubstituted ethylenes exhibit unique features of radical polymerization kinetics due to their significant steric hindrance in propagation and termination processes and provide polymers with a rigid chain structure different from conventional vinyl polymers. In this study, we carried out reversible addition‐fragmentation chain transfer polymerization of diisopropyl fumarate (DiPF) in bulk at 80 °C using various dithiobenzoates with different leaving R groups as chain transfer agents to reveal their performance for control of molecular weight, molecular weight distribution, and chain end functionality of the resulting poly(DiPF) (PDiPF). 2‐(Ethoxycarbonyl)‐2‐propyl dithiobenzoate ( DB1 ) and 2,4,4‐trimethyl‐2‐pentyl dithiobenzoate ( DB2 ) underwent fragmentation and reinitiation at a moderate rate and consequently led to the formation of PDiPF with well‐controlled chain structures. It was confirmed that molecular weight of PDiPF produced by controlled polymerization with DB1 and DB2 agreed with theoretical one and molecular weight distribution was narrow. Dithiobenzoate and R fragments were introduced into the polymer chain ends with high functionality as 95% by the use of DB1 . In contrast, polymerizations using 1‐(ethoxycarbonyl)benzyl dithiobenzoate ( DB3 ), 1‐phenylethyl dithiobenzoate ( DB4 ), and 2‐phenyl‐2‐propyl dithiobenzoate ( DB5 ) resulted in poor control of molecular weight, molecular weight distribution, and chain end structures of PDiPF. Fragmentation and reinitiation rates of the used benzoates as chain transfer agents significantly varied depending on the R structures in an opposite fashion; that is, introduction of bulky and conjugating substituents accelerated fragmentation, but it retarded initiation of DiPF polymerization. It was revealed that balance of fragmentation and reinitiation was important for controlled polymerization of DiPF. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3266–3275     

Kinetic and mechanistic study of the quasiliving cationic polymerization of styrene with the 2-phenyl-2-propanol/AlCl3 · OBu2 initiating system

The cationic polymerization of styrene with the 2-phenyl-2-propanol (CumOH)/AlCl₃ · OBu₂ initiating system at various dibutyl ether concentrations in a mixture of 1,2-dichloroethane and n-hexane (55:45 v/v) at −15 °C was investigated. The experimental results showed that an increase in dibutyl ether concentration leads to a noticeable decrease in the polymerization rate as well as to the more controlled polymerization in terms of molecular weight (M_n) and molecular weight distribution (MWD) evolutions. The kinetic investigation revealed that the polymerization proceeds in two stages. The first stage is characterized by high polymerization rate and slow initiation relative to propagation. During this stage molecular weight decreases or does not change and MWD increases with conversion. In the second stage considerably slower quasiliving polymerization of styrene occurs. The quasiliving nature of the styrene polymerization by the CumOH/AlCl₃ · OBu₂ system is proved and mechanistic scheme of the polymerization is proposed.     

A novel group transfer polymerization of 1-trimethylsiloxy-benzocyclobutene via hetero Diels-Alder reaction

A novel group transfer polymerization via hetero-Diels-Alder reaction is described. When 1-trimethylsiloxybenzocyclobutene ( 1 ) was treated with a catalytic amount of p-anisaldehyde (4-methoxybenzaldehyde) and TASF (tris(dimethylamino)sulfonium difluorotrimethylsilanide) at room temperature for 0.5 h, poly[1,2-phenylene-1-(trimethylsiloxy)ethylene] was obtained quantitatively. The number-average molecular weight of the polymer was M̄_n = 2000 and the molecular weight distribution was narrow (ratio of weight-to number-average molecular weights M̄_w/M̄_n = 1.18). Structural characteristics suggested a polymerization mechanism involving isomerization of 1 to o-quinodimethane and successive hetero-Diels-Alder reaction leading to poly[1,2-phenylene-1-trimethylsiloxy ethylene]. The living-like nature of the polymerization was supported by a monomer addition experiment in which the molecular weight increased according to the increase of the added monomer.     

Pd(0)‐catalyzed polyaddition of bifunctional vinyloxiranes with 1,3‐dicarbonyl compounds: The synthesis of polymers containing hydroxy and carbonyl groups

The palladium(0)‐catalyzed polyaddition of bifunctional vinyloxiranes [1,4‐bis(2‐vinylepoxyethyl)benzene ( 1a ) and 1,4‐bis(1‐methyl‐2‐vinylepoxyethyl)benzene ( 1b )] with 1,3‐dicarbonyl compounds [methyl acetoacetate ( 4 ), dimethyl malonate ( 6 ), and Meldrum's acid ( 8 )] was investigated under various conditions. The polyaddition of 1 with 4 was carried out in tetrahydrofuran with phosphine ligands such as PPh₃ and 1,2‐bis(diphenylphosphino)ethane (dppe). Polymers having hydroxy, ketone, and ester groups in the side groups ( 5 ) were obtained in good yields despite the kinds of ligands employed. The number‐average molecular weight value of 5b was higher than that of 5a . The polyaddition of 1b and 6 was affected by the kinds of ligands employed. The corresponding polymer 7b was not obtained when PPh₃ and 1,2‐bis(diphenylphosphino)ferrocene were used. The polyaddition was carried out with dppe as the ligand and gave polymer 7b in a good yield. The molecular weight of the polymer obtained from 1b and 8 was much higher than those of polymers 5b and 7b . The polyaddition with Pd₂(dba)₃ · CHCl₃/dppe as a catalyst (where dba is dibenzylideneacetone) produced polymer 9b in a 92% yield (number‐average molecular weight = 45,600). The stereochemistries of all the obtained polymers were confirmed as an E configuration by the coupling constant of the vinyl proton. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2487–2494, 2002     

Vanadium complexes possessing N2O2S2-based ligands: highly active procatalysts for the homopolymerization of ethylene and copolymerization of ethylene/1-hexene

The family of ligands containing an N2O2S2 core, namely, 1,2-di(3-Me-5-t-Bu-salicylaldimino-o-phenylthio)ethane (H2L1), 1,3-di(3-Me-5-t-Bu-salicylaldimino-o-phenylthio)propane (H2L2), 1,4-di(3-Me-5-t-Bu-salicylaldimino-o-phenylthio)butane (H2L3), and 1,2-di(3-Me-5-t-Bu-salicylaldamino-o-phenylthio)ethane (H2L4), have been prepared and complexed with a variety of vanadium chlorides and alkoxides to afford complexes of the form [V(X)L1] (X = O (1), Np-tol (2), Cl (3)), [V(O)(L2,3)] (L2 (4), L3 (5)), and [V(L4)] (6). Crystal structure determinations of H2L1 and H2L4 show the molecule to be centrosymmetric about the bridging ethane moiety, with structural determination of 1 and 3 revealing isostructural monomeric complexes in which the ligand chelates in such a way as to afford pseudo-octahedral coordination at the vanadium center. Prolonged reaction of H2L1 with [V(Np-tol)(OEt)3] led, via oxidative cleavage of the C-S bond, to the bimetallic complex [V2L1(3-Me,5-t-Bu-salicylaldimino-o-phenylthiolate)2] [VL'] (7), as characterized by single-crystal X-ray crystallography. 7 was also isolated from the reaction of H2L4 and [VO(On-Pr)3]. The ability of 1-7 to catalyze the homopolymerization of ethylene and the copolymerization of ethylene/1-hexene in the presence of dimethylaluminum chloride (DMAC) has been assessed: screening reveals that for ethylene homopolymerization 1-7 are all highly active (>1000 g/mmol.h.bar), with the highest activity (ca. 11 000 g/mmol.h.bar) observed using catalyst 3; the use of trimethyl aluminum (TMA) or methylaluminoxane (MAO) as the cocatalyst led only to poorly active systems producing negligible polymer. Analysis of the polyethylene produced showed high molecular weight linear polymers with narrow polydispersities. For ethylene/1-hexene copolymerization, activities as high as 1,190 g/mmol.h.bar were achieved (4); analysis of the copolymer indicated an incorporation of 1-hexene in the range of 5-13%.     

Cationic cyclopolymerization of new divinyl ethers: The effect of ether and ester neighboring functional groups on their cyclopolymerization tendency

The cationic polymerization of two new divinyl ethers, 1‐(2‐vinyloxyethoxy)‐2‐[(2‐vinyloxyethoxy)carbonyl]benzene ( 2 ) and 1,2‐bis[(2‐vinyloxyethoxy)carbonyl]benzene ( 3 ), as well as 1,2‐bis(2‐vinyloxyethoxy)benzene ( 1 ), with BF₃OEt₂ in CH₂Cl₂ at 0 °C at low initial monomer concentrations ([M]₀ = 0.15 and 0.075 M) gave soluble polymers with relatively high molecular weights and broad molecular weight distributions (MWDs), whereas reactions with the HCl/ZnCl₂ initiating system yielded soluble polymers with relatively narrow MWDs (weight‐average molecular weight/number‐average molecular weight ? 1.6) under similar reaction conditions. An NMR structural analysis of the HCl/ZnCl₂‐mediated polymers from the divinyl ethers showed that poly( 1 ) had virtually no unreacted vinyl ether groups throughout the polymerization (monomer conversion = 28–98%), whereas poly( 2 ) and poly( 3 ) possessed some amount of unreacted vinyl ether groups in the initial stage of the polymerization; the content of the vinyl groups of poly( 2 ) was 18 mol % at a 15% monomer conversion, and the content of the vinyl groups of poly( 3 ) was 31 mol % at an 18% monomer conversion. Therefore, divinyl ether 1 underwent cyclopolymerization exclusively to give almost completely cyclized polymers [degree of cyclization (DC) ～ 100%], whereas divinyl ethers 2 and 3 exhibited a lower cyclopolymerization tendency [DC for poly( 2 ) = 82%; DC for poly( 3 ) = 69%]. The differences in the cyclopolymerization tendencies among the divinyl ethers can be explained by the differences in the solvation powers of the neighboring functional groups adjacent to the vinyl ether moiety with the active center: the ether oxygen of the ether neighboring group solvates intramolecularly with the active center to accelerate the intramolecular propagation, but such an interaction is less effective with the more electron‐deficient oxygen attached to the carbonyl group of the ester neighboring group. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 281–292, 2003     

Oligomerization of phenylacetylene on fe-catalysts

Using a low activity system as a catalyst gives additional opportunities for study of polymerization mechanism. We made an attempt using phenylacetylene as a monomer to synthesize, separate, and identify oligomers of this alkyne on melting iron catalyst—“naked” metal. Four components with the lowest molecular weight were identified as: (compound 1) isomers of 1,2-diphenylcyclobutadiene, (compound 2) 1,3-diphenylcyclobutadiene, (compound 3) 1,4-diphenylbuten-1-yne-3, and (compound 4) triphenyl substituted Dewar benzene. It was shown, that in the presence of iron catalysts the phenylacetylene oligomerization proceeds as a linear polymerization through a 2 + 2 cycloaddition.