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Treningi kompetencji praktycznych, weryfikujących teorię z praktyką bezpiecznej pracy w laboratorium, są ofertą znacznie okrojoną w stosunku do szkoleń. W trakcie takich zajęć można zdiagnozować szereg problemów związanych z przygotowaniem i oceną bezpiecznego stanowiska pracy. Jednym z nich jest projektowanie laboratorium bez barier dla osób niepełnosprawnych. Praca przedstawia proces kształtowania stanowiska pracy dla osób z dysfunkcją ruchu na przykładzie pracowni dydaktycznej.
Training of practical competence, verify the theory and practice of safe work in the laboratory, they offer significantly reduced compared to training. Over the course of such activities, one can assess a series of potential problems, connected with preparation and estimation of a safe workplace. Planning a laboratory without barriers for disabled people is one of them. The work presents the creation process of a workplace, on the basis of an educational workshop, for people afflicted with reduced mobility.
Witnessed within the last decades rapid development of the chemistry of Group 4 metals can be ascribed to the interesting structural properties of such complexes, as well as to wide range of their industrial applications. Species of titanium and zirconium bonded to aryloxo ligands are very good fodder for asymmetric organic syntheses, are very often used as base compounds for material engineering and catalysts or initiators for different kind of polymerization processes, and also for production of biodegradable materials. A carefully chosen ligand plays a crucial role in construction of potential candidates for these applications. Aryloxides form a big family of mono-, bis- and poliaryloxo ligands. They are very versatile since their structure and electronic properties are easily modified by changing of ring substitution patterns [10, 11], introducing of O, S, NR, Se, Te heterogroups [21] between aromatic rings [12-14], changing their numbers [15, 16] or even linking them by carbon chains [17, 18]. All those modifications can influence the structure and catalytic activity of formed complexes. Apart from aryloxides, also amino- and iminoaryloxides form the second group of ligands successfully utilized in chemistry of Group 4 metals. Chemical properties of these ligands can be easily modified through changing aromatic rings by using substituents influencing electronic properties and steric demands. For example, nitrogen atom changed by introduction of a group containing additional centre of coordination results in obtaining tridendate ligand [43]. Mannich condensation is the main synthetic method for obtaining these compounds [47]. Usage of primary, secondary or tertiary amine, as well as a change in reaction stechiometry or even a condition can lead to amine-aryloxide, amine-bisaryloxide or benzoxazine. Syntheses of transition metal compounds with aryloxide or amine/iminearyloxide species are generated by direct ligand reaction with a metal precursors MRn, M(OR)n, M(NR2)n, MCln (R = alkyl). Monodendate aryloxo ligands have a tendency to form ?-bridges between metal centres, which result in formation of oligomeric compound [M(OAr)n]m. Reactions of bisaryloxo ligands H2(LEtBu,Me) (E = -, CH2, C2H4) with chosen titanium and zirconium precursors produce heteroleptic, monomeric and tetrahedral complexes [12, 19, 20]. Change of a bridging group between phenyl rings to C2H4 increases the size of chelating ring in formed complexes [MX2(LC2H4tBu,Me)] [20, 35, 36] and at the same time decreases the inversion barrier which is the reason for relatively easy conformation changes in solutions. Imine-aryloxide complexes of Group 4 metals have been known since 1960 [44], but mainly in last decade we can witness the rapid development of this group. Here, one of the most interesting species are complexes with tetradendate amino-bisaryloxo ligands. These compound can adapt a different symmetry which depends on a ligand structure, with additional electron pair donor D [10]. First literature reports on the use of titanium complexes in polymerization of cyclic esters are from 1958 [61]. Mono-, and bisaryloxide complexes were reported to act as initiators for that reaction but the highest activity was obtained when heteroleptic titanium compounds supported by tridendate ligand (H2LN-R'tBu) [48] were used. Catalytic activity in lactide polymerization on titanium and zirconium complexes strongly depends on metal and aromatic rings substituents . Transition metal complexes of Group 4 metals stabilized by aryloxo and imine/aminearyloxo ligands play a very important role among relatively new non-metalocene catalysts for olefin polymerization. Monoaryloxide complexes are not effective in that process [66], titanium and zirconium species with bisaryloxo ligands, in which aromatic rings are linked by CH2 are less effective in ethene [68, 69] polymerization when compared to cyclopentadienyls [70]. Zirconium and hafnium amine-bisaryloxides are highly effective in 1-hexene polymerization and structure of a ligand plays here a key role [15]. Additional donor of electron density is also an important factor influencing molecular mass and polymer tacticity. Imine-aryloxide species with bulky groups in ortho- or NO2, OMe in para- positions are highly effective in polyethylene production. In asymmetric syntheses titanium and zirconium species are used for different processes, for example enantioselective oxidation, reduction, nucleophilic addition, cycloaddition and many others [81-84].
Content available remote Związki magnezu z ligandami aryloksanowymi : inicjatory polimeryzacji laktydów
Magnesium alkoxides and aryloxides are systematically explored in various kinds of chemical processes and among other, their use as reagents in organic transformations [1-5], supports or catalyst components in polyolefin industry [6, 7], chemical precursors for advanced materials [8-10], as well as initiators for the polymerization of cyclic esters [11, 12] are worth mentioning. Over the past few years we have witnessed an increasing research on the use of magnesium aryloxides in the synthesis of new, biodegradable polymers, which have been preferential candidates for applications in medicine, pharmacy and production of eco-friendly bulk packing materials [13-15, 54-56]. Ready availability of monomers from inexpensive, renewable resources and the fact that resulted materials do not degrade the environment are an additional asset. Biodegradable polymers for the biomedical applications are preferably obtained using initiators containing non-toxic metals, and aryloxides of metals such as magnesium are especially interesting in this context. Despite the high utility limited number of magnesium alkoxides and aryloxides reported in the literature have a well-defined structure proved by X-ray analysis, which is required to design "single-site" catalysts. However, it is possible to identify and characterise certain types of frameworks. Homoleptic magnesium bis-aryloxides depending on synthesis procedures and ligand structure can crystallise as monomers [12, 40, 44], dimers [47, 48], trimers [47, 48] and tetramers [47, 48] with the coordination number ranging from three to six. Among them candidates of primary importance for the application in the ring-opening polymerization (ROP) of cyclic esters are monomeric compounds. Up to now, however, only few examples of such species displaying the certain activity in living polymerization have been published [60-63]. Extremely important are homoleptic compounds able to act as initiators for ROP in presence of exterior alcohols which form end-groups in the resulting polymer [12, 50]. This constitutes a chance for the polymer chain modyfication achieved by simple introduction of functional groups and enable to obtain new drug-polymer complex.
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