Topic
Substituent
About: Substituent is a research topic. Over the lifetime, 42877 publications have been published within this topic receiving 516716 citations. The topic is also known as: side chain & side group.
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TL;DR: According to the electronic effect, azo dyes with stronger electron-withdrawing group at specific positions could be more easily biodecolored than those with a carboxyl group.
83 citations
TL;DR: In this paper, a method for the introduction of Lewis acidic boron centers into the side chains of organic polymers is presented. But the method is not suitable for the case of poly(4-trimethylsilylstyrene) (S−Si).
Abstract: We have developed a highly efficient new method for the introduction of Lewis acidic boron centers into the side chains of organic polymers. Our methodology involves three steps: (i) the controlled polymerization of the functional monomer 4-trimethylsilylstyrene (S−Si), (ii) the exchange of the silyl groups in poly(4-trimethylsilylstyrene) (PS−Si) with BBr3 to give the reactive polymer poly(4-dibromoborylstyrene) (PS−BBr), and (iii) the fine-tuning of the Lewis acidity of the individual boron centers through substituent exchange reactions with nucleophiles. Treatment of PS−BBr with ethoxytrimethylsilane and THF respectively yields the moderately Lewis acidic poly(arylboronate)s PS−BOR (R = Et, 4-bromobutyl). The alkoxy groups in PS−BOR have been exchanged with pinacol to form the air-stable polymer PS−BPin (Pin = pinacolato). Treatment of PS−BBr with 2-thienyltrimethyltin and pentafluorophenylcopper respectively gives the well-defined highly Lewis acidic triarylborane polymers PS−BTh and PS−BPf (Th = 2-t...
83 citations
TL;DR: In this article, a series of monohydroxamic acids toward copper (II) and iron (III) ions were studied by pH-metric, spectrophotometric and EPR methods.
83 citations
83 citations
TL;DR: Statistical analysis suggested that the introduction of substituents at the ortho-position relative to the sulfonate group favors enantiomorphic site control over chain end control in the chain propagation step.
Abstract: Moderately isospecific homopolymerization of propylene and the copolymerization of propylene and polar monomers have been achieved with palladium complexes bearing a phosphine-sulfonate ligand. Optimization of substituents on the phosphorus atom of the ligand revealed that the presence of bulky alkyl groups (e.g. menthyl) is crucial for the generation of high-molecular-weight polypropylenes (Mw ≈10(4) ), and the substituent at the ortho-position relative to the sulfonate group influences the molecular weight and isotactic regularity of the obtained polypropylenes. Statistical analysis suggested that the introduction of substituents at the ortho-position relative to the sulfonate group favors enantiomorphic site control over chain end control in the chain propagation step. The triad isotacticity could be increased to mm=0.55-0.59, with formation of crystalline polar polypropylenes, as supported by the presence of melting points and sharp peaks in the corresponding X-ray diffraction patterns.
83 citations