66-98-8Relevant articles and documents
Degradation of fluorescent whitening agents in sunlit natural waters
Kramer,Canonica,Hoigne,Kaschig
, p. 2227 - 2234 (1996)
Stilbene-type fluorescent whitening agents (FWAs), such as the distyryl biphenyl (DSBP) and the diaminostilbene types (DAS 1 and DAS 2), are commonly used in detergents and papers. They are not readily biodegradable, but due to their ability to absorb part of the terrestrial sunlight, they can be photochemically degraded in natural surface waters. Following a fast preceding photoisomerization, the three compounds are degraded by direct photochemical processes yielding mainly aldehydes and alcohols. Their degradation quantum yields are similar, about 10"SUP -4" . Nevertheless, in samples of a eutrophic Swiss lake water, DSBP is photochemically degraded three times faster (t"SUB 1/2" =87 min) in summer noon terrestrial sunlight at 25 degrees C than DAS 1 and DAS 2 (t"SUB 1/2" =278 and 313 min) because of a higher rate of sunlight absorption by the DSBP isomer mixture. All FWAs are degraded faster if the oxygen concentration is increased. Dissolved natural organic material partly inhibits the degradation of DSBP in the reaction with molecular oxygen. The behavior of these compounds illustrates the influence of a preceding isomer equilibrium on degradation rate coefficients. (Authors)
Pd-catalyzed oxidative homocoupling of arylboronic acids in WEPA: A sustainable access to symmetrical biaryls under added base and ligand-free ambient conditions
Appa, Rama Moorthy,Lakshmidevi, Jangam,Naidu, Bandameeda Ramesh,Venkateswarlu, Katta
, (2021/01/11)
Symmetrical and unsymmetrical biaryls comprises a diverse class of biologically eloquent organic compounds. We herein report, a quick and eco-friendly protocol for the synthesis of biaryls by an oxidative (aerobic) homocoupling of arylboronic acids (ABAs) using Pd(OAc)2 in water extract of pomogranate ash (WEPA) as an efficient agro-waste(bio)-derived aqueous (basic) media. The reactions were executed at ambient aerobic conditions in the absence of external base and ligand to result symmetrical biaryls in excellent yields. The use of renewable media with an effective exploitation of waste, short reaction times, excellent yields of products, easy separation of the products, unnecessating the external base, oxidant, ligand or volatile organic solvents and ambient reaction conditions are the vital insights of the present protocol.
Oxidative and Reductive Cross-Coupling Reactions Catalyzed by an Anionic "ligandless" Palladium Complex
Schroeter, Felix,Lerch, Swantje,Strassner, Thomas
supporting information, p. 1614 - 1621 (2019/01/04)
The anionic complex [NBu4][Pd(DMSO)Cl3], which can be synthesized on a gram scale in a single step starting from commercially available starting materials, has been shown to be an active catalyst in the Mizoroki-Heck reaction of aryl halides. We present two new catalytic applications of this complex: the base-free oxidative Heck reaction and the reductive homodimerization of aryl halides. This complex outperformed other palladium salts. In the latter reaction, the catalyst loading could be reduced to 0.01 mol %. The scope of the reactions has been explored, demonstrating the potential of the anionic palladium complex in these catalytic transformations.