Reactions of nitrophenide and halonitrophenide ions with acrylonitrile and alkyl acrylates in the gas phase: addition to the carbonyl group versus Michael addition

Gas‐phase reactions of isomeric nitrophenide ions and p‐halonitrophenide ions with acrylonitrile, methyl acrylate, and ethyl acrylate have been studied using mass spectrometry and computational methods. Depending on the structure of the α,β‐unsaturated compound, formation of adducts to the carbonyl group of the acrylate (for methyl acrylate and ethyl acrylate) and β‐adducts (adducts of p‐halonitrophenide ions to α,β‐unsaturated compounds in β position) was observed. Further transformations of these adducts lead to the products of elimination of an alcohol molecule and the anionic products of intramolecular substitution of a halogen atom, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Acrylonitrile‐Butadiene Rubber (NBR) Prepared via Living/Controlled Radical Polymerization (RAFT)

In the current work we present results on the controlled/living radical copolymerization of acrylonitrile (AN) and 1,3‐butadiene (BD) via reversible addition fragmentation chain transfer (RAFT) polymerization techniques. For the first time, a solution polymerization process for the synthesis of nitrile butadiene rubber (NBR) via the use of dithioacetate and trithiocarbonate RAFT agents is described. It is demonstrated that the number average molar mass, , of the NBR can be varied between a few thousand and 60 000 g · mol⁻¹ with polydispersities between 1.2 and 2.0 (depending on the monomer to polymer conversion). Excellent agreement between the experimentally observed and the theoretically expected molar masses is found. Detailed information on the structure of the synthesized polymers is obtained by variable analytical techniques such as infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and electrospray ionization‐mass spectrometry (ESI‐MS).

     

Redox polymerization process: An efficient tool for the synthesis of block copolymers

The synthesis of poly(acrylonitrile)-block-poly-(ethylene glycol)-block-poly(acrylonitrile) copolymers has been carried out using a redox system consisting of ceric ion and poly(ethylene glycol)s of various molecular weights in aqueous medium. The generation of intermediate radicals in the redox process has been confirmed by ESR spectroscopy and the polymerization progressing through ‘blocking from’ mechanism has been postulated. The formation of the block copolymers has been confirmed by chemical tests and fractional precipitation technique as well as by FT-IR and FT-NMR [¹H and ¹³C–(¹H)] spectroscopic techniques. The triblock nature of the block copolymers has been ascertained through the cleavage of ether linkage of the PEG segment. TG/DTA studies of the block copolymers with PEG molecular weights of 1000 and above revealed two-stage decomposition, while their DSC traces exhibited a shift in the melting peak of PEG. GPC investigations of the block copolymers manifested a high homogeneity with unimodal distribution of molecular weights. SEM studies indicated significant changes in the morphological characteristics of the block copolymers. © 1995 John Wiley & Sons, Inc.     

Synthesis and Structure of 1—Cyclopentylindenyl Lanthanide（Ⅱ）Complexes and Their Catalytic Behavior for Polymerization of Acrylonitrile

The reaction between K(1‐C₅H₉C₉H₆) and anhydrous LnCl₃ (Ln=Sm, Yb) in the molar ratio of 2:1 in THF with subsequent treatment by Na‐K alloy afforded (1‐C₅H₉C₉H₆)₂Ln‐(THF)_n(Ln=Sm, n=1; Ln=Yb, n=2), while the reaction of Sml₂ with K(1‐C₅H₉C₉H₆) in the molar ratio of 1:2 in THF gave the anionic complex K(1‐C₅H₉C₉H₆)₃Sm(THF)₃. The X‐ray structure of (1‐C₅H₉C₉H₆)₂Yb(THF)₂ showed that central metal Yb is coordinated by two cyclopentadienyl rings of 1‐cyclopentylindenyls and two oxygen atoms from two tetrahydrofuran molecules to form pseudo‐tetrahedral coordinate geometry. All these complexes are active for the polymerization of acrylonitrile.     

Acrylonitrile‐containing polymers via a combination of metal‐catalyzed living radical and nitroxide‐mediated free‐radical polymerization routes

2‐Phenyl‐2‐[(2,2,6,6‐tetramethylpiperidino)oxy] ethyl 2‐bromopropanoate was successfully used as an initiator in consecutive living radical polymerization routes, such as metal‐catalyzed living radical polymerization and nitroxide‐mediated free‐radical polymerization, to produce various types of acrylonitrile‐containing polymers, such as styrene–acrylonitrile, polystyrene‐b‐styrene–acrylonitrile, polystyrene‐b‐poly(n‐butyl acrylate)‐b‐polyacrylonitrile, and polystyrene‐b‐polyacrylonitrile. The kinetic data were obtained for the metal‐catalyzed living radical polymerization of styrene–acrylonitrile. All the obtained polymers were characterized with ¹H NMR, gel permeation chromatography, and differential scanning calorimetry. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3374–3381, 2006     

Controlled radical copolymerization of β‐pinene and acrylonitrile

The feasibility of the radical copolymerization of β‐pinene and acrylonitrile was clarified for the first time. The monomer reactivity ratios evaluated by the Fineman–Ross method were r_β‐pinene = 0 and r_{acrylonitrile} = 0.66 in dichloroethane at 60 °C with AIBN, which indicated that the copolymerization was a simple alternating copolymerization. The addition of the Lewis acid Et₂AlCl increased the copolymerization rate and enhanced the incorporation of β‐pinene. The first example for the synthesis of an almost perfectly alternating copolymer of β‐pinene and acrylonitrile was achieved in the presence of Et₂AlCl. Furthermore, the possible controlled copolymerization of β‐pinene and acrylonitrile was then attempted via the reversible addition–fragmentation transfer (RAFT) technique. At a low β‐pinene/acrylonitrile feed ratio of 10/90 or 25/75, the copolymerization with 2‐cyanopropyl‐2‐yl dithiobenzoate as the transfer agent displayed the typical features of living polymerization. However, the living character could be observed only within certain monomer conversions. At higher monomer conversions, the copolymerizations deviated from the living behavior, probably because of the competitive degradative chain transfer of β‐pinene. The β‐pinene/acrylonitrile copolymers with a high alternation degree and controlled molecular weight were also obtained by the combination of the RAFT agent cumyl dithiobenzoate and Lewis acid Et₂AlCl. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2376–2387, 2006     

端羟基丁二烯/丙烯腈共低聚物的合成及其力学性能I.控制组成的计算方法

通过分批聚合，制备具有均匀组成的共聚物。提出了为控制共聚物组成在反应过程中补加单体的计算方法。它不仅适用于丁二烯与丙烯腈的共低聚反应，也适用于其它二元共低聚反应     

Solid-Phase Synthesis of (E)-3-Substituted Acrylonitriles from Polystyrene-Supported α-Selenoacetonitrile

A facile method for solid-phase organic synthesis of (E)-3-substituted acrylonitriles in good yields using polystyrene-supported α-selenoacetonitrile has been developed. The advantages of this method include straightforward operation, lack of odor, good stability, and high purity of the products.     

Transport properties of crosslinked acrylonitrile butadiene rubber/poly(ethylene‐co‐vinyl acetate) blends

The diffusion and transport of organic solvents through crosslinked nitrile rubber/poly(ethylene‐co‐vinyl acetate) (NBR/EVA) blends have been studied. The diffusion of cyclohexanone through these blends was studied with special reference to blend composition, crosslinking systems, fillers, filler loading, and temperature. At room temperature the mechanism of diffusion was found to be Fickian for cyclohexanone–NBR/EVA blend systems. However, a deviation from the Fickian mode of diffusion is observed at higher temperature. The transport coefficients, namely, intrinsic diffusion coefficient (D*), sorption coefficient (S), and permeation coefficient (P) increase with the increase in NBR content. The sorption data have been used to estimate the activation energies for permeation and diffusion. The van't Hoff relationship was used to determine the thermodynamic parameters. The affine and phantom models for chemical crosslinks were used to predict the nature of crosslinks. The experimental results were compared with the theoretical predictions. The influence of penetrants transport was studied using dichloromethane, chloroform, and carbon tetrachloride. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1815–1831, 1999     

二（叔丁基环戊二烯基）钕甲基配合物催化丙烯腈聚合

二（叔丁基环戊二烯基）钕甲基配合物催化丙烯腈聚合任劲松，扈晶余，沈琪（中国科学院长春应用化学研究所稀土化学与物理开放实验室长春１３００２２）（苏州大学化学系苏州）关键词丙烯腈，配位聚合，钕配合物丙烯腈聚合通常采用ＢＦ＿３、ＴｉＣｌ＿４、过氧化苯甲酰￣...