Effective Conversion of Amide to Carboxylic Acid on Polymers of Intrinsic Microporosity (PIM-1) with Nitrous Acid
1
School of Chemical Sciences, The University of Auckland, Auckland 1142, New Zealand
2
School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, Broadway NSW 2007, Australia
*
Authors to whom correspondence should be addressed.
Membranes 2018, 8(2), 20; https://doi.org/10.3390/membranes8020020
Received: 27 March 2018 / Revised: 12 April 2018 / Accepted: 12 April 2018 / Published: 18 April 2018
(This article belongs to the Special Issue Polymeric Membranes for Gas Separation)
Carboxylate-functionalised polymers of intrinsic microporosity (C-PIMs) are highly desirable materials for membrane separation applications. The recently reported method to afford C-PIMs was via an extensive base hydrolysis process requiring 360 h. Herein, a novel and effective method to convert PIM-CONH2 to C-PIM using nitrous acid was studied. The chemical structure of C-PIM was characterised by 1H NMR, 13C NMR, FTIR, elemental analysis, UV-Vis, TGA and TGA-MS. Complete conversion from amide to carboxylic acid groups was confirmed. Decarboxylation of C-PIM was also successfully studied by TGA-MS for the first time, with a loss of m/z 44 amu (CO2) observed at the first degradation stage. TGA also revealed decreased thermal stability of C-PIM relative to PIM-CONH2 under both N2 and air atmosphere. Gel permeation chromatography (GPC) analysis showed continuous molecular weight degradation of C-PIM with extended reaction time. Aromatic nitration was also observed as a side reaction in some cases.
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MDPI and ACS Style
Wu, W.-H.; Thomas, P.; Hume, P.; Jin, J. Effective Conversion of Amide to Carboxylic Acid on Polymers of Intrinsic Microporosity (PIM-1) with Nitrous Acid. Membranes 2018, 8, 20.
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