Aromatization of cyclic ketones. II. Novel synthesis of substituted dihydroxybenzenes

Kablaoui, M. S.

doi:10.1021/jo00939a018

Cited by 11 publications

(4 citation statements)

References 3 publications

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Section: Discussionmentioning

confidence: 99%

“…This observation lends support to the assumption that brominated CHD serves as the sole source of Br - in a skeleton scheme of the CHD oscillator. Organic compounds like CHD are known to undergo aromatization during oxidation, yielding hydroquinone (H 2 Q) and finally quinone (Q) as products. − …”

Section: Discussionmentioning

confidence: 99%

“…Organic compounds like CHD are known to undergo aromatization during oxidation, yielding hydroquinone (H 2 Q) and finally quinone (Q) as products. [21][22][23] A simple skeleton scheme for the uncatalyzed CHD oscillator is This scheme neglects reactions of hydroquinone.An alternative simple scheme can be obtained by substituting reactions R11-R15 for reactions R6, R7, R9, and R10:Here HQ • is semiquinone. In reality, all the above reactions can take place, together with many others.…”

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confidence: 99%

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Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

et al. 1996

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We present a study of the bromate-1,4-cyclohexanedione-ferroin oscillating reaction in both well-stirred and reaction-diffusion systems. We investigate the dependence of the system dynamics on the initial reagent concentrations, with the initial concentration of ferroin varied from 0 to 5 × 10 -3 M, and show that the system behaves like a typical BZ oscillator if the concentration of ferroin exceeds 5 × 10 -5 M. We demonstrate spontaneous formation of spiral waves and transverse wave fronts in quasi-two-dimensional systems and formation of crossing wave patterns in thin layers of solution open to air. IntroductionThe Belousov-Zhabotinsky (BZ) reaction-diffusion system is perhaps the most commonly employed tool for experiments on chemical waves and pattern formation. [1][2][3][4][5][6][7] The ferroincatalyzed reaction with malonic acid as the initial reductant has been the most frequently used BZ system for this purpose. An important drawback of this reaction is the production of carbon dioxide, which results in the formation of bubbles that disturb the reaction-diffusion patterns and make it difficult to conduct lengthy experiments in either batch or open reactors. Attempts have been made to develop gas-free versions of the BZ reaction. 8 Unfortunately, these variants do not generate the range of chemical wave behavior found in the ferroin-malonic acid BZ reaction. Recently, showed that target patterns develop in the bromate-1,4-cyclohexanedione-ferroin reaction-diffusion system without formation of bubbles. They used ferroin at a concentration of 5 × 10 -4 M and considered it to be only an indicator, implying that the reaction is an uncatalyzed bromate oscillator (UBO). [9][10][11][12] Here we present further results related to both the uncatalyzed and the ferroin-catalyzed systems. We study the dependence of the system dynamics on the initial reagent concentrations, with that of ferroin varied from 0 to 5 × 10 -3 M, and show that the system behaves like a typical BZ oscillator if the concentration of ferroin exceeds 5 × 10 -5 M.The absence of bubbles and precipitate makes the present system an excellent tool for experiments on chemical waves and patterns. We demonstrate spontaneous formation of spiral waves and transverse wave fronts in quasi-two-dimensional systems and the formation of crossing wave patterns in thin layers of solution open to air.Some preliminary mechanistic considerations are also suggested. Experimental SectionMaterials. Stock solutions of 1.0 M NaBrO 3 (Janssen Chimica, 99+%), 0.3 M 1,4-cyclohexanedione (abbreviated as CHD) (Aldrich, 98%) dissolved in 1.0 M H 2 SO 4 by stirring the solution on a hot plate (40-50°C) for about 30 min, 0.025 M ferroin (prepared from the calculated amount of FeSO 4 ‚7H 2 O (Fisher, certified) and 1,10-phenanthroline (Aldrich, 99+%)), 0.2 M NaBr (Fisher, certified), and 1.0-10.0 M H 2 SO 4 were used to prepare the working solutions.Apparatus and Procedures. Batch experiments with the bromate-CHD and the bromate-CHD-ferroin systems were performed in a thermosta...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

et al. 1996

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“…4-(Benzyloxy)-2,5-dihydroxyacetophenone (81). Compound 81 was prepared by the oxidation of 80 as described , (39% yield).…”

Section: Methodsmentioning

confidence: 99%

Structure−Activity Requirements for Flavone Cytotoxicity and Binding to Tubulin

et al. 1998

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A series of 79 flavones related to centaureidin (3,6,4'-trimethoxy-5, 7,3'-trihydroxyflavone, 1) was screened for cytotoxicity in the NCI in vitro 60-cell line human tumor screen. The resulting cytotoxicity profiles of these flavones were compared for degree of similarity to the profile of 1. Selected compounds were further evaluated with in vitro assays of tubulin polymerization and [3H]colchicine binding to tubulin. Maximum potencies for tubulin interaction and production of differential cytotoxicity profiles characteristic of 1 were observed only with compounds containing hydroxyl substituents at C-3' and C-5 and methoxyl groups at C-3 and C-4'.

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Acetic Anhydride

Zibuck¹

2001

Encyclopedia of Reagents for Organic Synthesis

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Aromatization of cyclic ketones. II. Novel synthesis of substituted dihydroxybenzenes

Cited by 11 publications

References 3 publications

Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

Structure−Activity Requirements for Flavone Cytotoxicity and Binding to Tubulin

Acetic Anhydride

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