Ring strain and polymerizability of cyclic esters

Saiyasombat, W; Molloy, Robert; Nicholson, Timothy M.; Johnson, A. F.; Ward, I. M.; Poshyachinda, S.

doi:10.1016/s0032-3861(97)10370-6

Cited by 83 publications

(80 citation statements)

References 5 publications

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“…The infrared and Raman spectra of (6) were found to be coincident with those already reported for this molecule, relative to freshly distilled samples. 29 The spectra of (7) are identical to those reported in the well-known infrared/Raman Atlas of Organic Compounds. 30…”

Section: Introductionsupporting

confidence: 58%

“…Since all wavenumber values are real, the geometries correspond to energy minima and, as a consequence, to stable configurations of the ground state. Harmonic wavenumbers of (6) and (7) have been compared with experimental values 26,29,30 to correct for the mode anharmonicity. Average scaling factors 0.9920 and 0.9826 are found for (6) and (7), respectively, when, for the sake of convenience, C-H and C=O stretching modes are excluded from the analysis.…”

Section: Vibrational Calculationsmentioning

confidence: 99%

See 1 more Smart Citation

Raman and infrared characterization of the vibrational properties of the antimalarial drug artemisinin

Moroni

Gellini

Miranda

et al. 2008

J Raman Spectroscopy

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Artemisinin is one of the most powerful new generation antimalarial drugs. The active center is the peroxide group of the caged trioxane heterocycle, which either blocks the free heme released by the Plasmodium falciparum parasite or acts on key proteins causing the parasite death. Both processes involve the activation of the 1,2,4-trioxanic ring through interaction with the Fe(II)-heme complex. Since considerable effort was made to synthesize antimalarial drugs containing the endoperoxide group, it becomes fundamental to know the structural and dynamical properties of artemisinin. For this reason, Raman and Fourier transform (FT) infrared studies have been undertaken here on the vibrational properties of artemisinin, its derivative artemether and d-valerolactone, the latter being the molecule mimicking the lactonic ring of artemisinin. The vibrational data of the three molecules have been analyzed through the comparison with ab initio calculations based on DFT/B3-LYP/cc-pVDZ procedures. Modes of artemisinin have been correlated with those of component units.

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Section: Introductionsupporting

confidence: 58%

Section: Vibrational Calculationsmentioning

confidence: 99%

Raman and infrared characterization of the vibrational properties of the antimalarial drug artemisinin

Moroni

Gellini

Miranda

et al. 2008

J Raman Spectroscopy

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“…By increasing the amount of lactone, the experimental reaction enthalpy Dh exp decreases because of the lower ring strain of g-lactones in comparison to epoxy rings. [8,9] From the Dh exp of the pure DGEBA a heat of 93 kJ Á eq À1 was estimated. This value is similar to the reported for other epoxy groups, [22] and it was used, along with a theoretical heat of 7 kJ Á eq À1 , [8,9] for the opening of a lactone ring, to determine a theoretical reaction heat Dh theo associated with the complete conversion of all the reaction species.…”

Section: Resultsmentioning

confidence: 99%

“…[4][5][6] We used this kind of lactone because its homopolymerization is thermodynamically unfavourable. [7][8][9] During the cationic copolymerization of epoxy/ lactone systems, an intermediate spiroorthoester (SOE) is formed. SOEs can subsequently react with epoxides or homopolymerize by ring-opening with some degree of expansion.…”

Section: Introductionmentioning

confidence: 99%

New Thermosets Obtained by Thermal and UV‐Induced Cationic Copolymerization of DGEBA with 4‐Phenyl‐γ‐butyrolactone

Fernández‐Francos

Salla

Pérez

et al. 2009

Macro Chemistry & Physics

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Mixtures of DGEBA with 4‐phenyl‐γ‐butyrolactone (PhBL) were cationically copolymerized in the presence of ytterbium triflate or triarylsulfonium hexafluoroantimoniate as thermal or photo initiator respectively. Changes during curing and final properties of the cured materials were studied by means of DSC, FT‐IR/ATR, TMA, DMTA, TGA and densitometric measurements. The formation of a network containing polyether and poly(ether‐ester) moieties was demonstrated to take place through the ring‐opening polymerization of a spiroorthoester intermediate (SOE) formed during the copolymerization. An increase in the proportion of lactone resulted in an increase in the curing rate, a decrease in the shrinkage after gelation and in the thermal stability and glass transition temperature (Tg). A strong influence of the initiator on the curing mechanism was observed. As a consequence, the photocured materials exhibited superior thermal stability and Tg than those obtained thermally.magnified image

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“…Furthermore, the band of g-BL is newly formed, which seems to indicate that some degree of depolymerization by back biting takes place at the last steps of the curing, giving g-BL which now cannot reacts with epoxy groups because they are not present, and g-BL does not homopolymerize by thermodynamical reasons. [16,17] The evolution of these three species, SOE, lactone and epoxy, was followed by recording the FTIR spectrum of the samples after different curing times. The conversion of SOE groups was calculated from the variation of the carbonyl linear ester band at 1 734 cm À1 , the conversion of g-BL from the variation of the carbonyl band at 1 770 cm À1 , and the conversion of epoxides from the decrease in the band at 914 cm À1 .…”

Section: Resultsmentioning

confidence: 99%

Microwave‐Accelerated Polymerization of 2‐Phenoxymethyl‐1,4,6‐trioxaspiro[4,4]nonane with Diglycidyl Ether of Bisphenol A

Canadell¹,

Mantecón²,

Cádiz³

2007

Macro Chemistry & Physics

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The cationic copolymerization of 2‐phenoxymethyl‐1,4,6‐trioxaspiro[4,4]nonane with DGEBA under microwave irradiation using ytterbium and lanthanum triflates as initiators is described. A comparison with thermal heating showed a great enhancement in the reaction rates and a higher SOE incorporation in the network. The double ring opening of SOE reduces the usual shrinkage of epoxy resins on curing, and it was lower under microwave irradiation. Moreover, the ytterbium triflate initiator lead to a higher incorporation of linear ester moieties in the network than lanthanum triflate.

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Ring strain and polymerizability of cyclic esters

Cited by 83 publications

References 5 publications

Raman and infrared characterization of the vibrational properties of the antimalarial drug artemisinin

Raman and infrared characterization of the vibrational properties of the antimalarial drug artemisinin

New Thermosets Obtained by Thermal and UV‐Induced Cationic Copolymerization of DGEBA with 4‐Phenyl‐γ‐butyrolactone

Microwave‐Accelerated Polymerization of 2‐Phenoxymethyl‐1,4,6‐trioxaspiro[4,4]nonane with Diglycidyl Ether of Bisphenol A

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