- Thursday, July 1, 1999
- Published at:Not Found
- A new class of supported carbonyl manganese catalyst was prepared by treating the dimeric decacarbonyldimanganese(0), Mn2(CO)10, with insoluble aminated poly(siloxane) surface. Solid state FT-IR spectra indicated that the supported catalyst is a dimeric complex that is substituted with two amine ligands, one at each Mn atom. The supported manganese complex was investigated as catalyst for the hydrosilylation reaction of terminal olefins. Contrary to the homogeneous Mn2(CO)10 catalytic system, the supported manganese complex was completely selective toward the hydrosilylation reaction with no detectable olefin isomerization or other side-reaction products. Furthermore, the catalyst was selective to produce the linear hydrosilylation product rather than the branched one. No lowering in catalyst activity due to the support was observed. A good proportion of the catalyst activity after separation and reuse was retained for at least four times. Highly reproducible catalytic activity measurements were obtained with
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- Friday, January 1, 1999
- Published at:مجلة جامعة الأزهر بغزة - سلسلة العلوم الطبيعية، المجلد (1) ديسمبر 1999
- Dodecacarbonyltriruthenium(0), Ru3(CO)12, 1, has been chemically anchored to the aminated polysiloxane surface, 2. The resulting supported ruthenium complex, 3, was evaluated as catalyst for the olefin isomerization reactions. Contrary to its homogeneous catalyst counterpart, 1, the supported catalyst 3 showed exceptionally high selectivity towards 1-octene isomerization, and trans-2-octene was the sole product of the reaction mixture. The olefin isomerization reaction was markedly activated by the presence of the tertiary silane (EtO)3SiH. No hydrosilylation reaction products were detected. Preliminary kinetic study indicated catalysis by lower nuclearity catalytic species, where the cluster fragments during the reaction process. The effects of different reaction parameters on the rate of the reaction have been investigated.
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- Friday, November 1, 1996
- Published at:Not Found
- Supported tetra(-4-pyridyl)porphyrinato-manganese(III) [MnIII(TPyP)]+ and -tin(IV) [SnIV(TPyP)]2+ have been prepared. The solid support was iodonated poly(siloxane) surface prepared by condensation reactions of (EtO)4Si with (MeO)3Si(CH2)3I. The supported metalloporphyrins were employed as catalysts for the oxidation reactions of 1-octene and of cyclohexene. NaBH4 was used to reduce [MnIII(TPyP)]+ and [SnIV(TPyP)]2+ back to their catalytically active MnII and SnII forms, respectively. Contrary to their homogeneous counterparts, both of the supported metalloporphyrins catalysed the cyclohexene oxidation reaction to yield only 2-cyclohexen-1-one with no other products over a reaction time of 10 h. In addition to cyclohexene oxidation, the supported [MnIII(TPyP)]+ catalysed 1-octene oxidation as well, whereas the supported [SnIV(TPyP)]2+ was inactive for the oxidation of 1-octene.
Journal of Molecular Catalysis A: Chemical, Volume 113, Issues 1-2, 25 November 1996, Pages 35-44
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- Friday, April 1, 1994
- Published at:Not Found
- Decaying leaves have been found capable of resisting the effects of acid rain via their ability to buffer water.
In a previous study the buffering action of five common types of leaves (cypress, oak, pine, cinchona and ficus) was investigated. In the present study the effects of several factors on the buffering ability of these leaves have been studied. These factors are acidity, presence of foreign ions, concentration of leaves and location.
The studied factors have been found not to affect the pattern of variation of pH of the leaf suspensions with time but to affect the pH value reached by these suspensions.
Ficus leaves have shown a distinct copability of neutralizing acidic waters.
Journal of Environmental Science and Health, Part A, Volume 29, Issue 3 April 1994 , pages 467 - 475
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- Saturday, January 1, 1994
- Published at:An-Najah J. Res., Vol. II, No. 8 (1994)
- Isomerization and hydrosilylation reactions of terminal olefins have been reported under thermal and photochemical conditions using Ru3 (C0) 12, 1, and HRu3 (CO)!! , 2,11 '0 In a very recent work, we reported E LI that 1 catalyses both Isomerization and hydrosilylation reactions of 1-octene (eq. 1). It has been found that the isomerization reaction occurs via lower nuclearity catalytic species that result from fragmentation of the mother cluster 1. Evidence in favour of concurrent cluster catalysis was also reported. On the other hand, the hydrosilylation reaction occurred via cluster catalysis at first and after some-time fragment catalysis occurred.
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