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Wpływ środowiska zasadowego na wydajność reakcji Hecka stosowanej do sieciowania kauczuku chloroprenowego

Dziemidkiewicz Anna, Maciejewska Magdalena

Elastomery

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2019

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T. 23, nr 3

163--174

PL

Celem przeprowadzonych badań było określenie wpływu trietanoloaminy (TEOA) na wydajność reakcji Hecka stosowanej do sieciowania kauczuku chloroprenowego (CR). Zaproponowany układ sieciujący jest nowym przykładem zastosowania, doskonale znanej w syntezie organicznej, reakcji Hecka [1]. Reakcja ta jest jedną z głównych metod tworzenia wiązań podwójnych węgiel–węgiel (C=C) w syntezie organicznej. Nie odnotowano jak dotąd żadnego wykorzystania reakcji Hecka w technologii elastomerów. Sporządzono mieszanki kauczukowe zawierające acetyloacetonian żelaza(II) (Fe(acac)2) jako nowy środek sieciujący z różną zawartością TEOA (1–5 cz. mas.). Dodatkowo mieszanki napełniono krzemionką (SiO2) pirogeniczną Aerosil 380 lub sadzą (CB) N550. Uzyskane wyniki wykazały, że zarówno ilość TEOA, jak i rodzaj napełniacza miały istotny wpływ na właściwości otrzymanych elastomerów. W przypadku kompozytów napełnionych CB aktywność Fe(acac)2 w procesie sieciowania wzrastała wraz z ilością TEOA. Potwierdziły to wysokie wartości przyrostu momentu obrotowego i stopnia usieciowania CR oraz krótsze czasy wulkanizacji. W przypadku mieszanek napełnionych SiO2 wpływ ilości TEOA na wydajność procesu sieciowania nie był tak jednoznaczny. Jednak biorąc pod uwagę przyrost momentu obrotowego, stopień usieciowania oraz optymalny czas wulkanizacji można stwierdzić, że użycie 3 cz. mas. TEOA skutkowało największą aktywnością Fe(acac)2.

EN

The aim of the study was to determine the effect of triethanolamine (TEOA) on the efficiency of Heck’s reaction used for the crosslinking of chloroprene rubber (CR). The proposed crosslinking system is a new example of the application of the Heck reaction, well known in organic synthesis [1]. This reaction is one of the main methods of creating carbon‑carbon double bonds (C=C) in organic synthesis. So far, no use of Heck’s reaction in elastomer technology has been reported. Rubber blends containing iron(II) acetylacetonate (Fe(acac)2) as a new crosslinking agent with different TEOA content (1–5 phr) were prepared. Additionally, the blends were filled with pyrogenic silica (SiO2) Aerosil 380 or carbon black (CB) N 550. The obtained results showed that both the amount of TEOA and the type of filler had a significant effect on the properties of the elastomers obtained. In case of composites filled with CB, the activity of Fe(acac)2 in the crosslinking process increased with the amount of TEOA. This was confirmed by high values of torque increment and degree of crosslinking of CR and shorter vulcanization times. In case of rubber compounds filled with SiO2, the effect of TEOA on the efficiency of crosslinking process was not so unambiguous. However, considering the increase in torque, the degree of crosslinking and the optimum vulcanization time, it can be stated that the use of 3 phr. TEOA resulted in the highest Fe(acac)2 activity.

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Wpływ hydroksylowych cieczy jonowych na reakcję Hecka katalizowaną związkami palladu

Tarnowicz S., Trzeciak A. M., Nowicki J.

Przemysł Chemiczny

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2016

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T. 95, nr 4

843--846

PL

Zaprezentowano wyniki użycia cieczy jonowych funkcjonalizowanych grupami hydroksylowymi jako kokatalizatorów w reakcji Hecka katalizowanej związkami palladu. Zbadano ciecze jonowe z anionami hydroksylowymi i dicyjanoimidkowymi. Zaobserwowano pozytywny wpływ obecności cieczy jonowych z tej grupy na wydajność reakcji Hecka. Najlepsze wyniki (54% i 60% cynamonianu butylu) uzyskano w obecności katalizatora [glymim]₂[PdCl₄] z solą [glymim]Cl.

EN

1-(2,3-Dihydroxypropyl)-3-methylimidazolium hydroxide ([glymim]OH),1-hexyl-3-methylimidazolium hydroxide and 1-butyl-1,8-diazabicyclo[5.4.0]undec-7-ene hydroxide ionic liqs. were used as co-catalysts in the Pd-catalyzed Heck reaction of PhBr with CH₂=CHCOOBu. The highest yield of PhCH=CHCOOBu (60%) was obtained for [glymim]₂[PdCl₄] complex at 140°C in Me₂NCHO.

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Recykling metalokompleksowych katalizatorów immobilizowanych na nośnikach polimerowych

Bączek N., Strzelec K., Wąsikowska K.

Przemysł Chemiczny

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2013

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T. 92, nr 11

1969-1971

PL

Przedstawiono możliwość wykorzystania procesu enkapsulacji makrocząstek ferromagnetyka do otrzymywania efektywnych heterogenizowanych katalizatorów metalokompleksowych. W tym celu opiłki żelaza o średniej wielkości ziarna ok. 2 mm pokryto warstwą żywicy epoksydowej funkcjonalizowanej grupami tiolowymi. Pokazano możliwość wykorzystania tego typu nośników w procesie immobilizacji kompleksu palladu. Przygotowane ferromagenetyczne katalizatory wykazały dużą aktywność oraz stabilność w reakcji Hecka oraz w reakcji uwodornienia. Omówiono czynniki wpływające na właściwości katalityczne otrzymanych katalizatorów.

EN

Fe filings were encapsulated in a thiol groups-contg. epoxy resin, used as supports for immobilization of the PdCl2(PhCN)2 catalyst, and then for studying Heck reaction of PhI with CH2=CHCOOMe to trans-PhCH=CHCOOMe and hydrogenation reaction of PhCH=CHCHO to Ph(CH2)3OH. A high conversion of raw materials (71–98%) was achieved in both cases. The catalyst showed high activity and stability in the studied reactions and only small losses of Pd mass were obsd. after multiple use of the catalysts.

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Synthesis of the cross-linked humic acid supporting palladium catalyst and its catalytic properties for Heck reaction

Xu Q., Shi W., Cui Y.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 2

75-79

EN

Cross-linked humic acid supporting palladium (CL-HA-Pd) catalyst was prepared readily and characterized by infrared analysis (IR) and thermogravimetric analysis (TG). The catalyst could catalyze the Heck reaction of aryl halide or substituted aryl halide with vinyl compounds in N2 atmosphere; the yields were above 95%. The catalyst could be recovered and reused 7 times with the Heck reaction of iodobenzene with acrylic acid, and the yield was above 75.6%. The results showed that the catalyst had high catalytic activity even at low temperature of 62°C or with a small amount of the catalyst.

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Nanocząsteczkowe katalizatory palladowe w reakcjach tworzenia wiązań C-C

Trzeciak A. M., Ziółkowski J. J.

Wiadomości Chemiczne

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2009

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[Z] 63, 1-2

1-15

EN

The important role of palladium nanoparticles has been recently demonstrated in many catalytic systems designed for C-C bond forming reactions [1-4]. There are examples of catalytic systems described earlier as homogeneous in which Pd(0) nanoparticles were now identified. In the article three different palladium catalytic systems are discussed. In the first one, Pd(0) nanoparticles, obtained by chemical reduction of PdCl2 and stabilized by polyvinylpyrrolidone, were used for Heck coupling in [Bu4N]Br medium. Decrease of nanoparticles size in reaction conditions was explained as a result of dissolution of Pd(0) colloid and simultaneous formation of catalytically active monomolecular anionic palladium complexes [33]. The second example presents application of Pd(II) and Pd(0) supported on alumina-based oxides in Suzuki-Miyaura reaction [36]. Reduction of Pd(II) to Pd(0) nanoparticles under reaction conditions was confirmed. In contrast to the first described case, in Suzuki-Miyaura reaction the size of Pd(0) nanoparticles was the same before and after the catalytic cycle. The catalytic activity of both palladium forms was quite high, however Pd(0) formed in situ was slightly more efficient as catalyst. In the third part of the article studies of palladium reduction in anionic complexes of [IL]2[PdX4] type are shown, where IL = imidazolium cation [37]. These complexes catalyzed well Suzuki-Miyaura cross-coupling, but they were not stable under reaction conditions and decomposed to Pd(0) nanoparticles and Pd black. Using ESI-MS method it was possible to identify polynuclear (Pd3, Pd5) intermediate forms, stabilized with imidazolium cations or N-heterocyclic carbenes. In all systems discussed in the article co-existence of Pd(0) nanoparticles and monomolecular complexes was observed. That is important for understanding of the nature of catalytically active forms in C-C bond forming reactions.

6

Catalytic performances of cross-linking humic acids supported Pd/Ni bimetallic catalyst for heck reaction

Xu Q., Zhang L., Shi W., Cui Y.

Polish Journal of Chemical Technology

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2009

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Vol. 11, nr 3

22-26

EN

The cross-linking humic acids (CL-HAs), epichlorohydrin as the cross-linking reagent and the supported Pd/Ni bimetallic catalysts (CL-HAs-Pd/Ni) were prepared and characterized by IR, AAS, XPS, TEM. The effects of reaction time, temperature, base, solvent and the amount of catalyst on the properties of the catalyst were studied. These catalysts could catalyze the Heck reaction of aryl halides and substituted aryl halides with acrylic acids or styrene successfully; the yields were all above 95%.

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Rola cieczy jonowych w reakcjach tworzenia wiązań C-C z udziałem katalizatorów palladowych : szczególny wpływ halogenków imidazoliowych

Trzeciak A. M.

Wiadomości Chemiczne

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2006

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[Z] 60, 11-12

819-843

EN

The strategy of modification in chemical processes in order to ensure a safer, cleaner environment in the future is one of the main goal of green chemistry. The basic twelve principles of green chemistry were formulated by P. Anastas and J.Warner in 1998 and accepted by society. Following these principles chemists designing a new process should pay special attention to select substrates and chemicals that minimize their harm to the environment and to human health. Also existing chemical technologies should be modified in a similar way. One approach to achieve this goal is replacement of traditional toxic solvents (mainly VOC,s volatile organic solvents) with ionic liquids presenting a group of liquids or low-temperature melting solid salts of no vapour pressure. Application of ionic liquids in processes catalyzed by transition metal complexes meets two (or in some cases even three) green chemistry rules. The presence of ionic liquids as a solvent in catalytic systems for C-C bond forming reactions like Heck, Sonogashira, Suzuki and carbonylation offers many spectacular advantages including facilitation of catalyst separation from organic products. Elimination even traces of metals from the products of C-C coupling reactions which are used as medicines or agricultural chemicals is extremely important. An article presents catalytic systems containing palladium catalyst precursors, both soluble and heterogenized complexes as well as palladium nanocolloids applied in C-C bond forming processes performed in ionic liquids. The applicability of ionic liquids and influence of their molecular structure on the reaction course is discussed. A special attention is paid to the reactions of ionic liquids with palladium precursors leading to the formation of new species and modification of catalytic properties of the system. It is shown that in many catalytic systems a strong inhibiting effect of imidazolium halides was observed. This fact can be explain on the basis of experimental data by the reaction of imidazolium halide with palladium - aryl intermediate leading to N-heterocyclic carbene complex of lower catalytic activity. Decomposition of palladium - aryl intermediates with formation of phosphonium salts in the presence of imidazolium halide was also observed. In both above mentioned cases a key intermediate in C-C bond forming reactions, that is palladium - aryl halide complex, is eliminated from the reaction mixture causing to decrease of the final product yield. An article presents a state of knowledge in the field of ionic liquids application in catalysis and formulates expectations for future designing of catalytically active and environmentally friendly palladium based systems for C-C bond forming reactions.