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Cyclopolymerization Leading to Ladder Polymers
Published in George B. Butler, Cyclopolymerization and Cyclocopolymerization, 2020
A vinylcyclopentane structure was discovered by use of NMR spectroscopy in anionically polymerized polybutadiene70 with lithium counterions in presence of N, N, N’,N’-tetramethylethylenediamine. The structure apparently was formed from intramolecular cyclization during propagation.
Radial Tire Compound Polymer Blends
Published in Brendan Rodgers, Tire Engineering, 2020
Rather than blending an SBR with a BR or polyisoprene, for example, copolymers or terpolymers based on styrene and butadiene, butadiene and isoprene, styrene and isoprene, or styrene, butadiene and isoprene, can be prepared having a dual Tg. Using n-butyllithium catalyst and a polar modifier such as N,N,N′,N′-tetramethylethylenediamine (TMEDA), a range of polymer dual-glass transition temperatures can be obtained (Table 7.3).
Direct (Hetero)Arylation Polymerization for the Preparation of Conjugated Polymers
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
J. Terence Blaskovits, Mario Leclerc
The most widely-used catalysts in this regard are PCy3 and P(t-Bu)2Me.HBF4. Substantial steric hindrance is therefore necessary, and yet there are examples in which phosphines that are too sterically demanding inhibited the reaction. For example, the copolymerization of tetrafluorobenzene or octafluorobiphenyl with other phenyl derivatives required the presence of a sterically demanding phosphine (P(t-Bu)2Me.HBF4), whereas in the presence of other, even more bulky phosphines (P(t-Bu)3.HBF4 or SPhos), the reaction did not occur (Figure 5.19).91,125 The significance of the ligand in suppressing β-defects in polar conditions was also shown in a study which promoted various degrees of branching in P3HT through the choice of ligand used. Of the reaction conditions tested, the ligand-free system led to the highest degree of branching, while the bidentate ligands 2,2ʹ-bipyridine and tetramethylethylenediamine (TMEDA) suppressed β-branching entirely.
Mesophase behaviour of 1,2,3-triazole-based nematic liquid crystals influenced by varying alkyl chains and halogen atom substitution
Published in Liquid Crystals, 2022
Dan Xiong, Xiaoping Xiong, Ziran Chen, Wenhao Yu, Chun Feng, Hongmei Chen, Hailiang Ni, Biqin Wang, Keqing Zhao, Ping Hu
The intermediate alkyl azide compounds were synthesised by a nucleophilic substitution reaction between the corresponding alkyl bromides and sodium azide [39]. As depicted in Figure 1, the Steglich esterification reaction of 4-ethynylbenzoic acid with 4-(4'-propyl)-cyclohexylphenol afforded the key intermediate 2. The 4-(4-propylcyclohexyl)phenyl 4-(1-alkyl-5-hydro/halo-1,2,3 -triazol-4-yl)benzoate series 1 was synthesised by the classical copper(I)-catalysed azide alkyne cycloaddition (CuAAC) reaction between 2 and alkyl azide with different alkyl chain lengths in a CuI catalytic system (0.3 eq) under nitrogen atmosphere [33]. The 1,4-substituted-5-halo-1,2,3-triazole products 1c-X (× = Cl, Br, and I) were successfully prepared by the one-step in situ tandem reaction of CuAAC, aerobic oxidation, and halogenation reaction in a CuX catalytic system (1.3 eq) under air atmosphere [40]. Note that the reaction medium with products 1c-Cl and 1c-I must be added to NCS and TBDMsCl as additives, respectively, to effectively obtain the product in high yield. The 1,4-substituted-5-fluoro-1,2,3-triazole compound 1c-F was prepared by halogen exchange between 1,4-substituted 5-iodo-1,2,3-triazole compounds 1c-I and 5 eq of AgF using tetramethylethylenediamine (TMEDA) as a ligand, in a heated system [41]. Furthermore, the 1,4-substituted-5-thiophene-1,2,3-triazole-based compound 1c-Th was synthesised by the Suzuki coupling reaction of 1c-I with 2-thiopheneboronic acid.
Synthesis and structural features of copper(II) complexes of N,N,N′,N′-tetramethylethylenediamine with 2-chlorobenzoate1− and 2-hydroxybenzoate1−
Published in Journal of Coordination Chemistry, 2018
Syeda Shahzadi Batool, Syeda Rubina Gilani, Muhammad Nawaz Tahir, William T. A. Harrison, Liviu Mitu, Sania Mazharr
A perspective view together with the atom labeling scheme for [Cu(tmen)(salH)2(H2O)] (2) is given in Figure 3 and its unit cell with hydrogen bonding details is given in Figure 4. Selected bond parameters are given in Table 2 and hydrogen bonding parameters are presented in Table 3. The neutral complex is monomeric in which the CuN2O3 chromophore has a distorted square pyramidal geometry (Figure 3). The central copper(II) ion is five-coordinated by two N-atoms of a chelating tmen and two O-atoms of carboxylate groups of two monodentate salicylate ions, forming a basal square plane and by an apical O atom of water, forming a distorted square pyramidal structure. N,N,N’,N’-tetramethylethylenediamine ligand adopts its usual gauche conformation [36].
Synthesis, crystal structure, thermal studies, and antimicrobial activity of benzene-1,4-dicarboxylate-copper(II) based coordination polymer incorporating N,N,N′,N′-tetramethylethylenediamine
Published in Journal of Coordination Chemistry, 2022
Syeda Shahzadi Batool, Syeda Rubina Gilani, Syeda Sakina Zainab, William T. A. Harrison, Muhammad Nawaz Tahir, Muhammad Salman Haider, Quratulain Syed, Sania Mazhar, Muhammad Shoaib
CuCl2·2H2O (Merck), N,N,N′,N′-tetramethylethylenediamine, benzene-1,4-dicarboxylic acid, and NaOH (Sigma-Aldrich) were of analytical grade. Elemental combustion analysis was performed using a Perkin-Elmer 2400 II elemental analyzer. Infrared absorption spectra of KBr pellets were obtained with a FT/IR-4100typeA spectrometer from 4000 to 400 cm−1. Thermal analysis was performed on a TGA Q50 V6.5 Build 196 under an atmosphere of nitrogen at a heating rate of 10 °C min−1. The UV-visible spectrum of 1 was recorded from 200 to 1000 nm in DMSO using a Mega-2100 Double Beam UV-Visible spectrophotometer.