Structural analysis of the alternating copolymer poly(chloroacrylonitrile-alt-cyclohexadiene)

Panchalingam, V.; Reynolds, John R.

doi:10.1021/ma00182a020

Cited by 11 publications

(4 citation statements)

References 6 publications

(8 reference statements)

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“…13 As expected the spectra are essentially identical except for three peaks. In our studies of poly(a-CAN/1,3-CHD) we found that the copolymers' thermal stability was limited by a dehydrochlorination that begins below 200'C.…”

Section: Resultssupporting

confidence: 74%

“…The FT-IR spectrum of poly( 1,3-CHD/a-FAN) is given in Figure 1 and is compared to poly ( a-CAN/ 1,3-CHD) . 13 As expected the spectra are essentially identical except for three peaks. A strong C-F stretch of poly( 1,3-CHD/a-FAN) is visible at 1020 cm-' while the poly( a-CAN/1,3-CHD) exhibits 2 strong C -C1 stretching absorbances at 736 and 490 cm-l.…”

Section: Equivalent Only One Resonance Is Observed For Thesesupporting

confidence: 74%

“…This is in contrast to the a-CAN/1,3-CHD copolymer which formed in higher yields 7 over the same amount of time using similar feed ratios. 13 It has been reported that 1,3-CHD does not undergo radical homopolymerization, most likely due to chain transfer processes. 19 The facile copolymerization between 1,3-CHD and a-CAN to form an alternating copolymer, irrespective of the comonomer feed ratios, has been attributed to the formation of a 1: 1 EDA complex between the monomer pair.…”

Section: Resultsmentioning

confidence: 99%

“…Several important features become evident in comparing the 13C-NMR spectrum of poly( 1,3-CHD/a-FAN) to poly( a-CAN/l,S-CHD) . 13 Specifically, a downfield shift ( -30 ppm) is observed for the quarternary carbon, substituted with both CN and F, which is due to the higher electron withdrawing ability of F relative to C1. The 'V-NMR spectrum ofpoly( 1,3-CHD/a-FAN), shown in Figure 4, exhibits one distinct resonance centered at ca.…”

Section: Cand "F-nmr Spectroscopymentioning

confidence: 93%

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Poly(1,3-cyclohexadiene-alt-alpha-fluoroacrylonitrile): Synthesis and Structural Analysis of a New Alternating Copolymer

Panchalingam¹,

Reynolds²

1991

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Section: Resultssupporting

confidence: 74%

Section: Equivalent Only One Resonance Is Observed For Thesesupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Cand "F-nmr Spectroscopymentioning

confidence: 93%

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Poly(1,3-cyclohexadiene-alt-alpha-fluoroacrylonitrile): Synthesis and Structural Analysis of a New Alternating Copolymer

Panchalingam¹,

Reynolds²

1991

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Poly(1,3‐cyclohexadiene‐alt‐α‐fluoroacrylonitrile): Synthesis and structural analysis of a new alternating copolymer

Panchalingam

Reynolds

1992

J. Polym. Sci. A Polym. Chem.

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Poly(1,3‐cyclohexadiene‐alt‐α‐fluoroacrylonitrile) [poly(1,3‐CHD/α‐FAN)], an alternating copolymer of α‐fluoroacrylonitrile and 1,3‐cyclohexadiene has been prepared in bulk using varied monomer feed ratios and AIBN as initiator at 65°C. Elemental and 1H‐NMR analyses indicate that the copolymer contains an equimolar composition of α‐FAN and 1,3‐CHD as observed for alternating copolymers with donor‐acceptor polymerizations. A 2‐D 1H‐COSY NMR experiment indicates that the copolymer contains 1,4‐linkages across the cyclohexene unit while more reliable 13C‐NMR spectra suggests the copolymer to contain both 1,2‐ and 1,4‐linkages. Poly(1,3‐CHD/α‐FAN) exhibits improved thermal stability relative to the alternating copolymer of 1,3‐CHD and α‐chloroacrylonitrile due to a higher resistance to HF elimination relative to HCl elimination.

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Extraction of Pyridines into Fluorous Solvents Based on Hydrogen Bond Complex Formation with Carboxylic Acid Receptors

2007

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A molecular receptor embedded in a 'poor-solvent' receiving phase, such as a fluorous phase, should offer the ideal medium for selective extraction and sensing. The limited solubility of most solutes in fluorous phases enhances selectivity by reducing the extraction of unwanted matrix components. Thus, receptor-doped fluorous phases may be ideal extraction media. Unfortunately, sufficient data do not exist to judge the capability of this approach. The solubilities of very few nonfluorous solutes are known. As far as we are aware, such important quantities as the strength of a hydrogen bond in a fluorous environment are not known. Thus, it is currently impossible to predict whether a particular receptor/solute complex based on a particular set of noncovalent interactions will provide enough thermodynamic stabilization to extract the solute into the fluorous phase. In this work, fluorous carboxylic acids (a carboxylic acid-terminated perfluoropolypropylene oxide called Krytox and perfluorodecanoic acid (PFDA)) were used as receptors and substituted pyridines as solutes to show that the fluorous receptor dramatically enhances the liquid-liquid extraction of the polar substrates from chloroform into perfluorohexanes. The method of continuous variations was used to determine the receptor-pyridine complex stoichiometry of 3:1. The free energies of formation of the 3:1 complexes from one pyridine and 3/2 H-bonded cyclic dimers of the fluorous carboxylic acid are -30.4 (Krytox) and -37.3 kJ mol-1 (PFDA). The free energy required to dissociate the dimer in perfluorohexanes is +16.5 kJ mol-1 (Krytox). The crystal structure of the complex showed a 1:1 stoichiometry with a mixed strong-weak hydrogen-bonded motif. Based on the stoichiometry, crystal structure, and UV and IR spectroscopic shifts, we propose that the 3:1 complex has four hydrogen bonds and the carboxylic acid transfers a proton to pyridine. The resulting pyridinium carboxylate N+H-O- hydrogen bond is accompanied by a weak pyridine ring CH-O bond and is supported by two more carboxylic acid H-bond donors. We estimate that the free energy of formation of this complex from a free acid, pyridine, and a carboxylic acid dimer to be approximately -39 kJ mol-1; this is the first reported hydrogen bond strength in a fluorous environment.

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Structural analysis of the alternating copolymer poly(chloroacrylonitrile-alt-cyclohexadiene)

Cited by 11 publications

References 6 publications

Poly(1,3-cyclohexadiene-alt-alpha-fluoroacrylonitrile): Synthesis and Structural Analysis of a New Alternating Copolymer

Poly(1,3-cyclohexadiene-alt-alpha-fluoroacrylonitrile): Synthesis and Structural Analysis of a New Alternating Copolymer

Poly(1,3‐cyclohexadiene‐alt‐α‐fluoroacrylonitrile): Synthesis and structural analysis of a new alternating copolymer

Extraction of Pyridines into Fluorous Solvents Based on Hydrogen Bond Complex Formation with Carboxylic Acid Receptors

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