China
Africa
Explore chapters and articles related to this topic
Nonconjugated Symmetrical Dienes
Published in George B. Butler, Cyclopolymerization and Cyclocopolymerization, 2020
Polymers containing 4-N-pyrrolidinopyridine were prepared by cyclopolymerization of N-4-pyridylobis-methacrylamide in aqueous solution followed by lithium aluminum hydride reduction.217 Cyclopolymerization of 4-(diallylamine)pyridine hydrochloride via free radical initiation gave water-soluble polymers.218 The palladium-catalyzed oxidation of poly(N-phenyl-3,4-dimethylenepyrrolidine) which was prepared by AIBN-initiated polymerization of N-phenyl-3,4-dimethylene-pyrrolidine yielded thermally stable poly(N-phenyl-3,4-dimethylenepyrrole).219 Hydrogenation and reduction of the latter polymer by hydrogen-platinum oxide and diimide, respectively, failed to yield poly(N-phenyl-3,4-dimethylenepyrrolidine).
Polymeric Second-Order Nonlinear Optical Materials and Devices
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
In general, two different processes are used for the synthesis of PEIs, nitrogen-displacement of anhydride and imidization of polyamicacid. However, such synthetic method is not applicable for a side-chain NLO PEI because of harsh reaction conditions. The alternative synthetic approach for making the NLO polyetherimides is the use of the single-step reaction of NLO chromophores with terminal diol and diimide by the Mitsunobu reaction using diethyl azodicarboxylate (DEAD) and triphenylphosphine in tetrahydrofuran. In this method, the polyimide structure is directly formed during mild condensation polymerization without a thermal imidization step [26].
N-Polyheterocycles
Published in Navjeet Kaur, Metals and Non-Metals, 2020
Lv and Bao [63], while exploring new copper-catalyzed domino reactions, reported that diimine moiety was a versatile building block in designing Cu-catalyzed cascade reactions. 1,2-Disubstiuted benzimidazoles were synthesized by a nucleophilic attack on the electron-deficient carbon of diimide, with subsequent intramolecular carbon-nitrogen coupling of the imidamide intermediate. A significant benefit of this reaction was that imidazoles, amines and phenols could all be used as nucleophilic partners and enabled great structural diversity in the products (Scheme 22) [48].
Mechanochemical in situ generated gas reactant for the solvent-free hydrogenation of porphyrins
Published in Green Chemistry Letters and Reviews, 2021
Marta Pineiro, Carla Gomes, Mariana Peixoto
From the sustainability point of view, hydrazine hydrate oxidation, a known source of diimide either by catalytic or thermal decomposition, is more interesting than sulfonylhydrazines because it only generates N2 and H2 after complete decomposition avoiding the formation of p-toluenesulfinic acid reducing to the minimum the generation of waste. Hydrazine hydrate was successfully used, in fairly sustainable conditions, for the catalyst-free reduction of alkenes in the presence of oxygen at 35 °C in ethanol (34). Under those reaction conditions, only traces of the desired chlorin were obtained, 26% after 7 days at 35 °C. Therefore, we performed the reduction of 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)porphyrin using hydrazine hydrate (20 μL, 5.5 equiv) under ball milling at 30 Hz frequency. After 2 h a conversion of 63% was obtained with 90% selectivity for the desired chlorin (entry 1, Table 1). Increasing the reaction time to 3 h, increases conversion to 85% of chlorin (entry 2, Table 1) while selectivity remained unchanged. The increase of the reaction time to 4 h (entry 3, Table 1) or increase of hydrazine hydrate equivalents and reaction time (entry 4, Table 1) do not significantly change conversion or selectivity to chlorin. Considering the mechanism for the catalytic decomposition of hydrazine hydrate to form diimide jointly with the mechanism of the macrocycle reduction, in which it is established that only the syn diimide is capable of transferring the hydrogen atoms (31) at least two equivalents of hydrazine hydrate will be necessary to reduce one porphyrin. Using 2.5 equiv of hydrazine hydrate (entry 5, Table 1) a significative decrease of conversion was observed. Therefore, the best results were obtained milling the porphyrin with 5.5 equivalents of hydrazine hydrate at 30 Hz during 3 h.