Organische Schwefelverbindungen, LIV. Synthesen von Thiocarbonylverbindungen durch Einwirkung von Kaliumxanthogenat oder Thioharnstoffen auf gem. Dichloride

Schönberg, Alexander; Frese, Emil

doi:10.1002/cber.19681010241

Cited by 33 publications

(6 citation statements)

References 16 publications

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“…Thioketone 7 was then used in the key step in the synthesis of the motor molecule (Scheme 4): introduction of the central olefin through a Barton-Kellogg reaction sequence. [18,19] Although several protocols for the formation of sterically overcrowded alkenes have been developed, [28] advantages of the Barton-Kellogg reaction include the possibility to selectively form unsymmetrical alkenes by using two distinct building blocks, and the gradual increase in steric strain in the molecule through several highly exothermic steps. These steps begin with a 1,3-dipolar cycloaddition, followed by ring contraction from a five-to a three-membered ring with extrusion of N 2 , and finally extrusion of sulfur to give the olefin.…”

Section: Resultsmentioning

confidence: 99%

“…Since each tether contains an oxygen-sensitive thiol group, it is must be attached at a late stage of the synthesis, preferably on a deprotected form of model motor molecule 5. Second, we anticipated that the key step in the synthetic sequence would be the Barton-Kellogg coupling reaction, [18,19] because this method introduces the steric strain gradually over three con- secutive steps starting from high-energy intermediates. The precursors required for the Barton-Kellogg reaction are the known hydrazone 6 and a thioketone of lower half 7.…”

Section: Introductionmentioning

confidence: 99%

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Light‐Driven Rotary Molecular Motors on Gold Nanoparticles

Pollard

Wiel

Delden

et al. 2008

Chemistry A European J

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We report the synthesis of unidirectional light-driven rotary molecular motors based on chiral overcrowded alkenes and their immobilisation on the surface of gold nanoparticles through two anchors. Using a combination of (1)H and (13)C NMR, UV/Vis and CD spectroscopy, we show that these motors preserve their photochemical and thermal behaviour after they have been attached to gold nanoparticles. Furthermore, we describe the synthesis of (2)H- and (13)C-labelled derivatives that were used to verify the unidirectionality of the rotary cycle of these motors both in solution and while grafted to gold nanoparticles. Taken together, these data support the conclusion that these motors maintain their unidirectional rotary cycle when grafted to the surface of small (ca. 2 nm) gold nanoparticles. Thus, continuous irradiation of the system under appropriate conditions leads to unidirectional rotation of the upper half of the molecules relative to the entire nanoparticle.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Light‐Driven Rotary Molecular Motors on Gold Nanoparticles

Pollard

Wiel

Delden

et al. 2008

Chemistry A European J

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“…Infrared spectra were measured on a Perkin-Elmer System 2000 FT-IR spectrometer. Thiobenzophenone, [41] 4,4Ј-bis(dimethylamino)thiobenzophenone, [41] 3,3,5,5-tetraphenyl-1,2,4-trithiolanes, [42] dibenzosuberenethione, [43] and xanthione [43] were prepared according to literature procedures. Solvents and Fe 3 (CO) 12 were purchased from Sigma-Aldrich; all sol-vents were dried and distilled prior to use according to standard methods.…”

Section: Methodsmentioning

confidence: 99%

Reactions of Selected Aromatic Thioketones with Dodecarbonyltriiron

et al. 2010

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Dodecacarbonyltriiron reacts with 3,3,5,5‐tetraphenyl‐1,2,4‐trithiolanes (1e) to give the ortho‐metalated complex Fe2(CO)6[κ,μ‐S,η2‐(C13H10S)] (9a), complexes of the type (Ph2C)S2Fe2(CO)6 and the well known trinuclear complex Fe3S2 (CO)9 as by‐products. Complex 9a can also be obtained from the reaction of Fe3(CO)12 with thiobenzophenone (2a). In a similar way, 4,4′‐bis(dimethylamino)thiobenzophenone (2b) reacts with Fe3(CO)12 to give Fe2(CO)6[κ,μ‐S,η2‐(C17H20N2S)] (9b). The cyclic aromatic thioketones such as dibenzosuberenethione (2c) and xanthione (2d) react with Fe3(CO)12 to give the cyclometalated products Fe2(CO)6[κ,μ‐S,η2‐(C15H12S)] (9c) and Fe2(CO)6[κ,μ‐S,η2‐(C13H8OS)] (9d), respectively, and a small amount of Fe3S2(CO)9. Complexes 9a–d have been characterized by IR and NMR spectroscopies, elemental analyses, and X‐ray single crystal structure analyses.

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“…The protected catechol carboxylic acids 27 and 28 employed as coupling partners in the key amide‐forming reaction (Scheme 1) were prepared starting from 5‐nitro‐ 33 6a or 5‐bromo‐2,3‐dihydroxybenzoic acid ( 34 )12 by acid‐catalyzed esterification to give methyl esters 35 and 36 (Scheme 2). Subsequent protection with dichloro(4,4′‐dimethoxydiphenyl)methane, generated in situ from 4,4′‐dimethoxybenzophenone and oxalyl chloride,13 provided 37 and 38 in good yields (64 % and 80 %, starting from 33 and 34 , respectively). Substitution of the phenyl rings in the ketal moiety by electron‐donating methoxy groups was introduced to facilitate the acid‐catalyzed catechol deprotection in the last step of the ligand synthesis.…”

Section: Resultsmentioning

confidence: 99%

Separation of astaxanthin from cells of Phaffia rhodozyma using colloidal gas aphrons in a flotation column

Dermiki

Bourquin

Jauregi

2009

Biotechnology Progress

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The aim of this study is to investigate the separation of astaxanthin from the cells of Phaffia rhodozyma using colloidal gas aphrons (CGA), which are surfactant stabilized microbubbles, in a flotation column. It was reported in previous studies that optimum recoveries are achieved at conditions that favor electrostatic interactions. Therefore, in this study, CGA generated from the cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) were applied to suspensions of cells pretreated with NaOH. The different operation modes (batch or continuous) and the effect of volumetric ratio of CGA to feed, initial concentration of feed, operating height, and flow rate of CGA on the separation of astaxanthin were investigated. The volumetric ratio was found to have a significant effect on the separation of astaxanthin for both batch and continuous experiments. Additionally, the effect of homogenization of the cells on the purity of the recovered fractions was investigated, showing that the homogenization resulted in increased purity. Moreover, different concentrations of surfactant were used for the generation of CGA for the recovery of astaxanthin on batch mode; it was found that recoveries up to 98% could be achieved using CGA generated from a CTAB solution 0.8 mM, which is below the CTAB critical micellar concentration (CMC). These results offer important information for the scale-up of the separation of astaxanthin from the cells of P. rhodozyma using CGA.

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Organische Schwefelverbindungen, LIV. Synthesen von Thiocarbonylverbindungen durch Einwirkung von Kaliumxanthogenat oder Thioharnstoffen auf gem. Dichloride

Cited by 33 publications

References 16 publications

Light‐Driven Rotary Molecular Motors on Gold Nanoparticles

Light‐Driven Rotary Molecular Motors on Gold Nanoparticles

Reactions of Selected Aromatic Thioketones with Dodecarbonyltriiron

Separation of astaxanthin from cells of Phaffia rhodozyma using colloidal gas aphrons in a flotation column

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