5001-26-3Relevant academic research and scientific papers
Formaldehyde-Free Polybenzoxazines for High Performance Thermosets
Tavernier, Romain,Granado, Lérys,Foyer, Gabriel,David, Ghislain,Caillol, Sylvain
, p. 2557 - 2567 (2020)
We report the synthesis and ring-opening polymerization of new formaldehyde-free benzoxazines. The polybenzoxazines obtained displayed high thermal stability and high char yields. Data from the literature combined with our analyses by differential scanning calorimetry and thermogravimetric analyses gave deeper understanding about the use of aromatic aldehydes instead of formaldehyde for the generation of polybenzoxazines. Using pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) at different temperatures, we provided qualitative data to propose some polymerization and degradation mechanisms associated with these new structures. A dialdehyde was also used for the first time in order to obtain difunctional monomers, instead of using diamines or bisphenols. Interestingly, we demonstrated that formaldehyde, which is a CMR (carcinogenic, mutagenic, and/or reprotoxic) substance, could be avoided for the synthesis of polybenzoxazines without any loss of thermal performance. Finally, some interesting structure-properties relationships are herein discussed. In particular, the use of benzyl amines, rather than aromatic amines, was found to significantly increase the char yields.
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
Br?nsted acid catalysed chemo- andortho-selective aminomethylation of phenol
Li, Dongdong,Liu, Lu,Peng, Dan,Tang, Zhiqiong,Yue, Yidi
, p. 5777 - 5781 (2021/07/12)
We have developed a Br?nsted acid catalysed highlyortho-selective functionalization of free phenols with readily availableN,O-acetals under mild conditions, furnishing various corresponding aminomethylated phenol products in moderate to excellent yields. The salient features of this transformation include mild conditions, good substrate scope, excellentortho-selectivity, high efficiency, and ease of further transformation.
(η5-Pentamethylcyclopentadienyl)iridium Complex Catalyzed Imine Reductions Utilizing the Biomimetic 1,4-NAD(P)H Cofactor and N-Benzyl-1,4-dihydronicotinamide as the Hydride-Transfer Agent
Soetens, Mathieu,Drouet, Fleur,Riant, Olivier
, p. 929 - 933 (2017/03/27)
The interaction between synthetic organometallic complexes and metabolic cofactors has proven to be a newly emerging topic in bioorganometallic chemistry. Thus, the first cationic Cp*Ir-catalyzed (Cp=η5-pentamethylcyclopentadienyl) imine reduction in neutral buffered aqueous medium was examined. The reaction was found to proceed through hydride transfer from NADH as the hydride source at room temperature in air. Cationic Cp*Ir complexes proved to be the most efficient catalysts for this transformation. We also highlighted that the choice of the proton source was essential. The method was subsequently applied to cyclic and noncyclic imines. Eventually, the concept was extended to the reductive alkylation of one amine.
Chemical design and synthesis of unsymmetrical diamino proligands employing a flexible route
Ledesma, Gabriela N.,Signorella, Sandra R.
, p. 5699 - 5702 (2012/10/30)
Three new unsymmetrical diamino proligands with a central alcohol group and four different pendant arms were obtained, employing a five step synthesis. The synthesis of these compounds involves inexpensive and commercially available reagents. The versatility of the synthetic route allows accessing to compartmental diamines with two chemically different adjacent coordination chambers.
Mild and rapid method for the generation of ortho -(naphtho)quinone methide intermediates
Shaikh, Abdul Kadar,Cobb, Alexander J. A.,Varvounis, George
, p. 584 - 587 (2012/03/10)
A new mild method has been devised for generating o-(naphtho)quinone methides via fluoride-induced desilylation of silyl derivatives of o-hydroxybenzyl(or 1-naphthylmethyl) nitrate. The reactive o-(naphtho)quinone methide intermediates were trapped by C,
Functional models for enzyme-substrate adducts of catechol dioxygenase enzymes: The Lewis basicity of facially coordinating tridentate phenolate ligands tunes the rate of dioxygenation and product selectivity
Visvaganesan, Kusalendiran,Ramachitra, Somasundaram,Palaniandavar, Mallayan
, p. 87 - 94 (2012/02/03)
A few iron(III) 3,5-di-tert-butylcatecholate (DBC2-) adducts of the type [Fe(L)(DBC)(CH3OH)], where L is a tridentate substituted monophenolate ligand such as 2-((N-benzylpyrid-2-ylmethylamino)methyl)phenol (H(L1)), 2-((N-benzylpyrid-2-ylmethylamino)-methyl)-4,6-dimethylphenol (H(L2)), 2-((N-benzylpyrid-2-ylmethylamino)methyl)-4,6-di-tert-butylphenol (H(L3)) and 2-((N-benzylpyrid-2-ylmethylamino)methyl)-4-nitrophenol (H(L4)), have been isolated and characterized by elemental and ESI-MS analysis. The spectral and electrochemical properties and dioxygenase activities of the adducts have been studied in methanol solution. Upon varying the substituents on the phenolate ring from electron-releasing to electron-withdrawing, the redox potential of DBSQ/DBC2- couple is shifted to a more positive value indicating an increase in covalency of iron(III)-catecholate bonds. All the complexes elicit cleavage of DBC2- using molecular oxygen to afford both intra- (I) and extradiol (E) cleavage products with the product selectivity (E/I) varying in the range 0.3-1.9. Interestingly, the incorporation of electron-withdrawing substituents facilitates the regioselective extradiol cleavage of catechol while that of electron-releasing substituents facilitate the regioselective intradiol cleavage.
Synthesis of 3,4-dihydro-2H-1,3-benzoxazines by condensation of 2-hydroxyaldehydes and primary amines: Application to the synthesis of hydroxy-substituted and deuterium-labeled compounds
Andreu,Ronda
, p. 2316 - 2329 (2008/09/21)
We report the synthesis of several substituted 3,4-dihydro-2H-1,3- benzoxazines by simple ring closure of 2-hydroxybenzylamines with paraformaldehyde. The facile synthesis of the benzylamine precursors from commercially available salicylaldehyde derivativ
Generation and application of o-Quinone methides bearing various substituents on the benzene ring
Sugimoto, Hiromichi,Nakamura, Satoshi,Ohwada, Tomohiko
, p. 669 - 679 (2008/02/09)
o-Quinone methides (o-QMs) are highly reactive, short-lived intermediates, which have potential synthetic applicability. However, few studies on the generation of o-QMs bearing an electron-withdrawing group have been reported. Herein we present a general method for the generation of o-QMs, particularly those substituted with an 0lectrophilic substituent, from new precursors, 4H-1,2-benzoxazines 2. We have also studied systematically the Diels-Alder reactions of o-QMs with various dienophiles, such as vinyl ethers, enamines and imines. The reactions provide a versatile route to substituted chromans, phenols and 3,4-dihydro-2H-benzo[e]-[1,3]oxazines (3,4-dihydro-1,3-benzoxazines). Furthermore, we applied the new method to the derivatization of some natural products.
