32977-06-3Relevant academic research and scientific papers
Synthesis and characterization of methoxybenzene-linked polyimides formed by 1,4-addition to bismaleimides
Hor, Seanghai,Koga, Nobuaki,Oyama, Kin-ichi,Tsukamoto, Masaki
, (2021/12/21)
Methoxybenzene-linked polyimides were synthesized by a trifluoromethanesulfonic acid (TfOH)-catalyzed 1,4-addition (Michael addition) reaction. Newly synthesized 1,3-bis(3,5-dimethoxyphenoxy)propane and known 5,5′-oxybis(1,3-dimethoxybenzene) as nucleophilic monomers were reacted with several bismaleimides in the presence of a catalytic amount of TfOH in m-cresol. Use of 1,3-bis(3,5-dimethoxyphenoxy)propane afforded polyimides with number average molecular weights (Mn)s of 8000–15000. However, polyimides with Mn of 4000 or less were obtained when 5,5′-oxybis(1,3-dimethoxybenzene) was employed as a monomer. The synthesized polyimides showed good thermostability as judged by 10% weight loss temperatures between 417 and 441 °C. Their glass transition temperatures were around 200 °C. These polymers featured a wide range of solubility in organic solvents such as m-cresol, DMF, pyridine, and chloroform.
Regioselective iron-catalyzed decarboxylative allylic etherification
Trivedi, Rushi,Tunge, Jon A.
supporting information; experimental part, p. 5650 - 5652 (2010/02/28)
[Chemical Equation Presented] An anionic iron complex catalyzes the decarboxylative allylation of phenols to form allylic ethers in high yield. The allylation is regioselective rather than regiospecific. This suggests that the allylation proceeds through π-allyl iron intermediates in contrast to related allylations of carbon nucleophiles that have been proposed to proceed via π-allyl complexes. Ultimately, iron catalysts have the potential to replace more expensive palladium catalysts that are typically utilized for decarboxylative couplings.
Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
Taskinen, Esko
, p. 1824 - 1834 (2007/10/03)
A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from -12 to -23 kJ mol-1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K-1 mol-1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol-1.
Iodothyronine Deiodinase Mimics. Deiodination of o,o'-Diiodophenols by Selenium and Tellurium Reagents
Vasil'ev, Andrei A.,Engman, Lars
, p. 3911 - 3917 (2007/10/03)
To better understand, and in the extension mimic, the action of the three selenium-containing iodothyronine deiodinases, o,o'-diiodophenols were reacted under acidic conditions with sodium hydrogen telluride, benzenetellurol, sodium hydrogen selenide, or benzeneselenol and under basic conditions with the corresponding deprotonated reagents. Sodium hydrogen telluride was found to selectively remove one iodine from a variety of 4-substituted o,o'-diiodophenols, including a protected form of thyroxine (T4). Thus, it mimics the D1 variety of the iodothyronine deiodinases. Sodium telluride was a more reactive deiodinating agent toward o,o'-diiodophenols, often causing removal of both halogens. Benzenetellurol and sodium benzenetellurolate sometimes showed useful selectivity for monodeiodination. However, the products were often contaminated by small amounts of organotellurium compounds. Sodium hydrogen selenide, sodium selenide, benzeneselenol, and sodium benzeneselenolate were essentially unreactive toward o,o'-diiodophenols. To gain more insight into thyroxine inner-ring deiodination, substituted 2,6-diiodophenyl methyl ethers were treated with some of the chalcogen reagents. Reactivity and selectivity for monodeiodination varied considerably depending on the substituents attached to the aromatic nucleus. In general, it was possible to find reagents that could bring about the selective mono- or dideiodination of these substrates.
