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An iron-catalyzed synthesis of α,β-unsaturated carboxylic acids from alkynes and carbon dioxide was developed. This reaction proceeds through hydromagnesiation of alkynes followed by carbon dioxide insertion under atmospheric pressure and ambient temperature in the presence of iron and a Grignard reagent as a catalyst and hydride source, respectively. Several symmetrical and unsymmetrical alkynes were transformed into the corresponding acids in good to excellent yields. The methodology provides an efficient route to the synthesis of vinyl carboxylic acids. [ABSTRACT FROM AUTHOR]

Abstract: An aromatic triamine-based flame-retardant benzoxazine (3), which could not be prepared by the traditional approaches, was successfully prepared by a three-step procedure. The first step is the condensation of 2-hydroxybenzaldehyde with an aromatic triamine, forming intermediate (1) with an imine linkage. The second step is the reduction of the imine linkage by sodium borohydride, resulting in intermediate (2) with a secondary amine linkage. The third step is the ring closure condensation of (2), leading to benzoxazine (3). The structures of (1–3) were confirmed by IR, high-resolution mass, 1H and 31P NMR spectra. Benzoxazine (3) was copolymerized with commercial benzoxazines. According to the measurements, thermal properties, flame retardancy, dimensional stability of commercial polybenzoxazines were significantly improved via the incorporation of (3). [Copyright &y& Elsevier]

Two flame‐retardant epoxy curing agents, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐tris(4‐hydroxyphenyl)methane (1) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐ (4‐aminophenyl)‐bis(4‐hydroxyphenyl)methane (2), were prepared by a facile, economic, one‐pot procedure. The structures of the curing agents were confirmed by IR, high‐resolution mass, 1‐D, and 2‐D NMR spectra. A reaction mechanism was proposed for the preparation, and the effect of electron withdrawing/donating effects on the stabilization of the carbocation was discussed. (1‐2) served as curing agents for diglycidyl ether of bisphenol A (DGEBA), dicyclopentadiene epoxy (HP‐7200), and cresol novolac epoxy (CNE). Properties such as glass transition temperature, coefficient of thermal expansion, thermal decomposition temperature, and flame retardancy of the resulting epoxy thermosets were evaluated. The resulting epoxy thermosets show high Tg, low thermal expansion, moderate thermostability, and excellent flame retardancy. The bulky biphenylene phosphinate pendant makes polymer chains difficult to rotate, explaining the high Tg and low thermal expansion characteristic. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7898–7912, 2008 [ABSTRACT FROM AUTHOR]

The process is found to form the desired carboxylic acids with complete (E) selectivity except for substrate (XV), where an E/Z mixture is identified. [ABSTRACT FROM AUTHOR]