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Molecular Characterization
Published in Rudolf Puffr, Vladimír Kubánek, Lactam-Based Polyamides, 2019
Two methods, column elution and preparative GPC, were applied to the nylon 12 fractionation.123 In column elution, called also solution fractionation, polymer was deposited onto the support material, placed in a column filled with a nonsolvent, decahydronaphthalene. An eluent mixture was decahydronaphthalene/benzylalcohol (171°C), the composition of which was continuously varied in favor of a better solvent, benzylalcohol. In the preparative GPC, columns were packed with cross-linked polystyrene. Two solvent mixtures were used, 1,1,1,3,3,3-hexafluoro-2-propanol/toluene (1/4 by vol) and 1,1,1,3,3,3-hexafluoro-2-pro-panol/0.04 M CF3COONa. Comparison of the two methods showed advantages of column elution: (1) a larger amount of polymer could be fractionated and (2) narrower fractions were obtained.
Transition-metal-free electrochemical-induced active C(sp3)-H functionalization
Published in Green Chemistry Letters and Reviews, 2023
Xiaolong Ma, Jinfeng Wei, Xu Yang, Huajin Xu, Yi Hu
Later, Xu’s group further described the development of method for electrochemical-induced benzylic C–H amination (Scheme 15) (71). In this reaction, a broad variety of benzylic substrates (45) can proceed with different benzenesulfonamides (46) to afford corresponding products (47) with excellent yield (88%). Intriguingly, the use of solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is the key to the success of product formation whether as co-solvent or sole solvent. It is worth mentioning that this method not only could be used for the efficient synthesis of benzylic amines but also efficiently reacted with O-center nucleophiles such as acetate and alcohol to synthesize corresponding products. It further reflects that this method has nice universality.