<i>N,N′</i>‐ethylenediyl‐<i>bis</i>‐alkanamides: Differential scanning calorimetry studies

Pryce‐Jones, R.H.; Eccleston, Gillian M.; Abu-Bakar, B.B.; Grant, K. M.

doi:10.1007/bf02523424

Cited by 4 publications

(3 citation statements)

References 15 publications

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“…Based on analyses of more than 250 paints, Pryce-Jones concluded that thixotropy is more pronounced in systems containing nonspherical than spherical particles, and the thixotropy of molecular organogels has been related to SAFINs of interwined and fused fibers 2a,43b,f or ultrathin, extended, and stable fibers with low crystallinity. 43e, Here, the organogels with SAFINs consisting of entangled, long fibers are not thixotropic, while the gels with spherulitic aggregates are. Some form of interactions among the spherulites is necessary for gelation to occur.…”

Section: Resultsmentioning

confidence: 99%

Distinct Kinetic Pathways Generate Organogel Networks with Contrasting Fractality and Thixotropic Properties

et al. 2006

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The kinetics of the isothermal transformation of sols, comprised of a low molecular-mass organogelator (LMOG) and an organic liquid, to their organogel phases have been followed by circular dichroism (CD), fluorescence, small angle neutron scattering (SANS), and rheological methods. The thixotropic properties (in the sense that severe shearing followed by rest lead to reestablishment of viscoelasticity) of the gels have been examined as well by rheological measurements. The compositions of the samples were either 5alpha-cholestan-3beta-yl N-(2-naphthyl) carbamate (CNC) in an n-alkane (n-octane or n-dodecane) or 3beta-cholesteryl N-(2-naphthyl) carbamate (CeNC) in ethyl acetate. Values of Df, the mass fractal dimension of the microcrystalline self-assembled fibrillar networks (SAFINs) in the gels, have been extracted from the kinetic data using a model developed by Dickinson (J. Chem. Soc., Faraday Trans. 1997, 93, 111). The Df values, 1.1-1.3 for the CeNC gels and 1.3-1.4 or 1.6-1.8 (depending on the temperature of incubation of the sol phase) for CNC gels, are consistent with the gel network structures observed by optical microscopy. In addition, comparison of the temperature dependence of both n (the Avrami component) and K (the Avrami "rate constant") for CeNC/ethyl acetate gelation with those reported previously for gelation of CNC/n-alkane sols demonstrate that the very small change of a single bond in CNC to a double bond in CeNC causes significant differences in their gelation abilities and gel properties. The rheological measurements on CNC/n-alkane gels with spherulitic SAFIN units, formed by incubation of their sols at < or =28 degrees C, indicate that they are thixotropic. Gels with the same chemical composition but formed by incubation of their sols at > or =30 degrees C, leading to fiberlike SAFIN units, remain liquidlike after shearing regardless of the periods they are at rest. The time-dependent viscoelastic properties of the gel networks are treated according to a stretched exponential model. The observations from these studies provide detailed insights into the mechanisms of formation of molecular organogel phases and demonstrate the extreme sensitivity of the SAFINs and viscoelastic properties of such organogels to slight modifications in LMOG structure or sample history.

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Section: Resultsmentioning

confidence: 99%

Distinct Kinetic Pathways Generate Organogel Networks with Contrasting Fractality and Thixotropic Properties

et al. 2006

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“…From a synthetic point of view, it is noteworthy that preparation of symmetrical bisamides is widely known and most common via condensation reactions between aldehydes and primary amides, utilizing different homogeneous and heterogeneous catalysts; [44] from diamines, utilizing the corresponding carboxylic acids (or their chlorides), [45] from nitriles, [46] and from DMSO as a methylene source and oxidant [47] . However, in contrast, preparation of unsymmetrical bisamides is rare, and only a dearth of examples is available.…”

Section: Bisamidesmentioning

confidence: 99%

Anodic Oxidation of Aliphatic and Aromatic Amides, Bisamides and Related Derivatives

Becker

2024

ChemElectroChem

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The current comprehensive review covers four main parts, of which some are presented in the form of a personal account. 1. Anodic oxidation of a) N‐alkyl and N,N‐diallyl carbonyl moieties, b) Azacycloalkyl amides and the effect of ring‐size on the outcome, c) Lactams, d) Sulfonamides, and e) The effect of a substituent R attached to carbonyl (N−CO−R) or sulfonamides (N−SO2R) on their oxidation potentials. 2. Anodic oxidation of aromatic amides, in particular of type Ph2CHCONHAr, lacking hydrogen(s) at the α‐position to nitrogen. They undergo three types of bond‐cleavage, yielding a variety of fragmentation products. 3. a) Anodic oxidation of symmetrical bisamides of type ZCONH(CH2)nNHCOZ (Z=Me, Ph, Ar; n=2–4) under constant current electrolysis, in methanol. For n=3, 4 they afford mostly mono‐ and dimethoxylation products. For n=2 they undergo ′CH2−CH2′ bond cleavage to yield fragmentation products. b) Anodic oxidation of symmetrical bisamides of type ArCONH(CH2)2NHCOAr under controlled potential electrolysis, in acetonitrile, leads to gem‐unsymmetrical bisamides of type ArCONHCH2NHCOMe as the major product, in fair yields. 4. Utilization of the anodic process in organic synthesis to form C−C bonds by both intra‐ and inetrmolecular processes; as well as C−O and C−N bonds for generating heterocycles.

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“…Preparation of symmetrical bisamides is widely known and most common via condensation reactions between aldehydes and primary amides, utilizing different homogeneous and heterogeneous catalysts, from diamines, utilizing the corresponding carboxylic acids (or their chlorides), and from nitriles . Recently, it was shown that symmetrical methylenebisamides could be prepared quite efficiently from aromatic nitriles (or amides) by use of DMSO both as methylene source and as oxidant in the presence of NiCl 2 as the catalyst: …”

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confidence: 99%

One-Pot Anodic Conversion of Symmetrical Bisamides of Ethylene Diamine to Unsymmetrical gem-Bisamides of Methylene Diamine

et al. 2019

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Symmetrical bisamides of ethylene diamine of type ArCONHCH2CH2NHCOAr undergo anodic C–C bond cleavage in acetonitrile–LiClO4 under controlled-potential electrolysis. The electrogenerated carbocation intermediates react with the solvent acetonitrile to afford unsymmetrical gem-bisamides of type ArCONHCH2NHCOMe in a one-pot reaction. The yields of the latter products are moderate (up to 60%). Other minor products involve two symmetrical gem-bisamides of type ArCONHCH2NHCOAr and MeCONHCH2NHCOMe and fragmentation products (e.g., ArCONHCHO, ArCONH2, and ArCN).

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N,N′‐ethylenediyl‐bis‐alkanamides: Differential scanning calorimetry studies

Cited by 4 publications

References 15 publications

Distinct Kinetic Pathways Generate Organogel Networks with Contrasting Fractality and Thixotropic Properties

Distinct Kinetic Pathways Generate Organogel Networks with Contrasting Fractality and Thixotropic Properties

Anodic Oxidation of Aliphatic and Aromatic Amides, Bisamides and Related Derivatives

One-Pot Anodic Conversion of Symmetrical Bisamides of Ethylene Diamine to Unsymmetrical gem-Bisamides of Methylene Diamine

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