Purification of Organic Chemicals

Armarego, W. L. F.

doi:10.1016/b978-075067571-0/50008-9

Cited by 506 publications

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“…Solvents were purified according to literature procedures, 36 and distilled prior to use. Petroleum ether refers to that fraction distilling in the range 338343 K. Suspensions of compound Na[W 2 Cp 2 (-PCy 2 )(-CO) 2 ] (1) in THF were prepared as described previously.…”

Section: Experimental Section General Procedures and Starting Materialsmentioning

confidence: 99%

Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W₂Cp₂(μ-PCy₂)(μ-CO)₂]⁻

et al. 2014

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ARTICLEThis journal is © The Royal Society of Chemistry 2013 J. Name., 2013, 00, 1-3 | 1 12 in stark contrast with the exclusive bridging disposition found for its dimolybdenum analogue. 9 Then, it was of interest to further explore the potential of ditungsten anion 1 to build new unsaturated hydrides and related species, which is the main purpose of this work. In this paper we give full details of the protonation reactions of 1, which we have now extended to other Brönsted acids and also to H + -related electrophiles such as gold(I) complexes [AuCl(PR 3 )] and organometal chlorides ClEPh 3 (E = Sn, Pb). As it will be shown below, most of these reactions involve the addition of the corresponding electrophile at the dimetal site of the anion, to give new unsaturated compounds related to those obtained for the dimolybdenum analogue of 1. In contrast, only the ditungsten anion 1 is able to undergo double protonation to give stable dihydride derivatives, which are relatively stable towards dehydrogenation in the absence of coordinating anions. Scheme 1 Results and Discussion Protonation of compounds 1 and 2The sodium salt of anion 1 is easily protonated in tetrahydrofuran solution by weak acids such as [NH 4 and another one bearing only terminal hydrides [W 2 Cp 2 (H) 2 (-PCy 2 )(CO) 2 ]X (3T and 3T')] (Scheme 2). These isomers seem to be also in equilibrium in solution, and a ratio of ca. 6:5 was found in both cases. Unfortunately, these species could not be isolated as pure solids and decomposed progressively upon attempted purification, but their structures are well supported by spectroscopic data and DFT calculations (see below). In any case we note that the nature of the metal (W instead of Mo) is having a critical role in the stability of these products, because protonation of the Mo 2 analogue of 2 fails to yield any observable dihydrides and leads instead to complex mixtures of products that could not be isolated or characterized. Scheme 2To gain further insight into the role of the external anion in these reactions, we also examined reactions of 2 with some acids having coordinating anions. In particular, we have used three carboxylic acids of increasing acidity: acetic, benzoic and trifluoroacetic acid. No reaction was observed for the weaker acetic acid, but reaction of 2 with a slight excess of benzoic or trifluoroacetic acid gave the corresponding carboxylate-bridged complexes [W 2 Cp 2 (-PCy 2 )(-O:O´-O 2 CR)(CO) 2 ] [R = Ph(4a), CF 3 (4b)] (Chart 1), with the latter reaction taking place instantaneously at room temperature, while the former one requires thermal activation (completed within 30 min in refluxing toluene). There are two points of interest in these reactions: first, their rates correlate with the relative strength of these acids (CF 3 CO 2 H >> PhCO 2 H > CH 3 CO 2 H), which suggests that initial protonation to give cations analogous to 3 might be the first step of the process; secondly, the formation of the carboxylate complexes 4a,b requires release of hydrogen, likely occurring at...

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Section: Experimental Section General Procedures and Starting Materialsmentioning

confidence: 99%

Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W₂Cp₂(μ-PCy₂)(μ-CO)₂]⁻

et al. 2014

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“…All the chemicals and reagents were procured either from Aldrich (USA) or Ranbaxy (India) and were purified according to the standard procedure prior to use [5]. The TiO 2 paste consisting of 20 nm sized TiO 2 particles procured from Solaronix.…”

Section: Methodsmentioning

confidence: 99%

Durable Unsymmetrical Zinc Phthalocyanine for Near IR Sensitization of Nanocrystalline TiO<sub>2</sub> Films with Non-Volatile Redox Electrolytes

Giribabu

Kumar

Raghavender

et al. 2008

JNanoR

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Abstract. We are presenting our results based on unsymmetrical zinc phthalocyanine by adopting 'push-pull' concept for the nanocrystalline dye-sensitized solar cells. Using this sensitizer in combination with nonvolatile organic-solvent-based electrolytes, we obtained a photovoltaic efficiency of 1.52% under standard global AM 1.5 sunlight and compared the results with volatile organic-solvent based electrolyte. These devices exhibit admirable stability when subjected to continuous thermal stress at 60 o C for 1000 h. The sensitizer is thermally stable up to 150 o C and can be useful for roof top applications.

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“…16 The probes MePMBr 2 , OcPMBr 2 , MeQMBr 2 , and ILs AlMeImCl, AlBuImCl and AlHxImCl were available from previous studies. 8,9,17 AlBuImCl and AlHxImCl are liquids at room temperature, AlMeImCl is a solid (mp 52-53 1C), once melted it crystallizes only over a period of several days.…”

Section: Experimental Section Materials and Synthesismentioning

confidence: 99%

Solvation in aqueous binary mixtures: consequences of the hydrophobic character of the ionic liquids and the solvatochromic probes

2012

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2012Solvation in aqueous binary mixtures:consequences of the hydrophobic character of the ionic liquids and the solvatochromic probes NEW JOURNAL OF CHEMISTRY, CAMBRIDGE, v. 36, n. 11, pp. 2353-2360, NOV, 2012 Information on the solvation in mixtures of water, W, and the ionic liquids, ILs, 1-allyl-3-R-imidazolium chlorides; R = methyl, 1-butyl, and 1-hexyl, has been obtained from the responses of the following solvatochromic probes: 2,6-dibromo-4-[(E)-2-(1-R-pyridinium-4-yl)ethenyl] phenolate, R = methyl, MePMBr 2 ; 1-octyl, OcPMBr 2 , and the corresponding quinolinium derivative, MeQMBr 2 . A model developed for solvation in binary mixtures of W and molecular solvents has been extended to the present mixtures. Our objective is to assess the relevance to solvation of hydrogen-bonding and the hydrophobic character of the IL and the solvatochromic probe. Plots of the medium empirical polarity, E T (probe) versus its composition revealed non-ideal behavior, attributed to preferential solvation by the IL and, more efficiently, by the IL-W hydrogen-bonded complex. The deviation from linearity increases as a function of increasing number of carbon atoms in the alkyl group of the IL, and is larger than that observed for solvation by W plus molecular solvents (1-propanol and 2-(1-butoxy)ethanol) that are more hydrophobic than the ILs investigated. This enhanced deviation is attributed to the more organized structure of the ILs proper, which persists in their aqueous solutions. MeQMBr 2 is more susceptible to solvent lipophilicity than OcPMBr 2 , although the former probe is less lipophilic. This enhanced susceptibility agrees with the important effect of annelation on the contributions of the quinonoid and zwitterionic limiting structures to the ground and excited states of the probe, hence on its response to both medium composition and lipophilicity of the IL.

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Purification of Organic Chemicals

Cited by 506 publications

References 0 publications

Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W₂Cp₂(μ-PCy₂)(μ-CO)₂]⁻

Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W₂Cp₂(μ-PCy₂)(μ-CO)₂]⁻

Durable Unsymmetrical Zinc Phthalocyanine for Near IR Sensitization of Nanocrystalline TiO<sub>2</sub> Films with Non-Volatile Redox Electrolytes

Solvation in aqueous binary mixtures: consequences of the hydrophobic character of the ionic liquids and the solvatochromic probes

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Purification of Organic Chemicals

Cited by 506 publications

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Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W2Cp2(μ-PCy2)(μ-CO)2]−

Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W2Cp2(μ-PCy2)(μ-CO)2]−

Durable Unsymmetrical Zinc Phthalocyanine for Near IR Sensitization of Nanocrystalline TiO<sub>2</sub> Films with Non-Volatile Redox Electrolytes

Solvation in aqueous binary mixtures: consequences of the hydrophobic character of the ionic liquids and the solvatochromic probes

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Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W₂Cp₂(μ-PCy₂)(μ-CO)₂]⁻

Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W₂Cp₂(μ-PCy₂)(μ-CO)₂]⁻