70301-50-7Relevant academic research and scientific papers
Aromatic dialdehyde-based bisbenzoxazines: The influence of relative position of oxazine rings
Tavernier, Romain,Granado, Lérys,Foyer, Gabriel,David, Ghislain,Caillol, Sylvain
, (2021)
Polybenzoxazines are known to have superior thermal stability. Especially, the use of aromatic aldehydes instead of formaldehyde for the synthesis of benzoxazines monomers could improve this stability. However, the increase in aromatic content of the mono
Oxazine Ring-Substituted 4th Generation Benzoxazine Monomers & Polymers: Stereoelectronic Effect of Phenyl Substituents on Thermal Properties
Mukherjee, Sourav,Amarnath, Nagarjuna,Lochab, Bimlesh
, p. 9510 - 9525 (2021/10/25)
Oxazine ring-substituted benzoxazine monomers inherit a smart architecture to cater intriguing properties offered by this upcoming latest generation of polybenzoxazines. It is therefore encouraging to study the regio-effect of oxazine ring substitution on ROP (ring-opening polymerization) temperature, thermal stability of the monomers and polymers to guide future designing of structures. Herein, we report a systematic analysis on the thermal properties with variation in the number and position of substituent (2- and/or 4-) in phenyl-substituted benzoxazines. Successful syntheses of monomers and structural characterization were confirmed using 1D NMR (nuclear magnetic resonance spectroscopy), HRMS (high-resolution mass spectrometry), and XRD (X-ray diffraction). Polymerization behavior and thermal stability was studied by DSC (differential scanning calorimetry), FTIR (Fourier transform infrared) spectroscopy, and TGA (thermogravimetry analysis). In-depth structural analysis by 2D NMR [1H - 1H COSY (correlation spectroscopy), 1H - 13C HSQC (heteronuclear single quantum correlation), and HMBC (heteronuclear multiple bond correlation)] experiments, crystal data, TGA-GC-MS (thermogravimetry analysis-gas chromatography-mass spectrometry), and DFT (density functional theory) calculation provided mechanistic insights of the effect of substitution on thermal behavior of monomers. It is found that besides the molecular mass of monomers and intermediates, the stereo-electronic effect of substituents at the 2- and/or 4-positions governs both the evaporation of monomer/cleaved intermediates and ring-opening reaction. Activation energy (Ea) of polymerization depends upon the position and degree of phenyl substituent(s). Among the studied varieties, the 2,4-substituted benzoxazine monomer showed the lowest ROP temperature with the least mass-loss during polymerization, the lowest Ea value of polymerization. Additionally, the resultant 2,4-substituted polybenzoxazine showed the highest thermal stability and char yield. An astute choice of selective positioning of groups in the oxazine ring can be a guiding principle for the structural designing of monomers to advocate a wide variety of applications.
Screening of simple carbohydrates as a renewable organocatalyst for the efficient construction of 1,3-benzoxazine scaffold
Y?ld?r?m, Ayhan,Kaya, Yunus,G?ker, Mustafa
, (2021/10/12)
A convenient protocol for the two component preparation of 1,3-benzoxazines by using several protected and unprotected carbohydrate molecules as organocatalysts have been developed which is broadly applicable to condensation reaction between variety of Ma
Synthesis and spectral studies on Ni(II) complexes involving N-furfuryl-N-substituted benzyldithiocarbamates and PPh3: Anagostic and C–H…π(chelate) interactions in (N-furfuryl-N-(4-fluorobenzyl)dithiocarbamato-S,S′)(thiocyanato-N)(tr
Sathiyaraj,Thirumaran,Ciattini, Samuele
, p. 1042 - 1050 (2016/07/06)
Twelve new nickel(II) complexes of functionalized dithiocarabamates [Ni(S2CNRR?)2](1-6) and [Ni(S2CNRR?)(NCS)(PPh3)](7-12) [where R=furfuryl; R?=2-hydroxy benzyl (1,7), 3-hydroxy benzyl (2,8), 4-hydroxy benzyl (3,9), 4-methoxy benzyl
Intra-molecular Diels-Alder reactions of citraconamic acids from furfurylamines and citraconic anhydride: Effects of substitution in the furan ring on regioselectivity
Murali, Rajappa,Surya Prakash Rao,Scheeren, Hans W
, p. 3165 - 3174 (2007/10/03)
Regioselectivity in the intra-molecular Diels-Alder (IMDA) reaction of furfurylcitraconamic acids derived from N-benzylfurfurylamines and citraconic anhydride can be controlled by substituents located in the furan ring and by reaction conditions. Reactions conducted under kinetic conditions resulted in cycloaddition products having methyl and aminomethylene substituent in 1,3-relationship whereas under thermodynamic conditions, excepting in the case of the 3-methylsulfanyl group, the products rearranged to more stable cycloadducts in which the substituents are in 1,2-relationship. Product formation can be explained on the basis of frontier orbital interactions and steric considerations.
