Indigo and Indigo Colorants

Steingruber, Elmar

doi:10.1002/14356007.a14_149.pub2

Cited by 33 publications

(22 citation statements)

References 19 publications

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“…[5] The organic constituent of the hybrid, indigo (Figure 1 a), has been known for 4000 years, and it is still the most heavily exploited organic blue dye. [6] Intra-and intermolecular hydrogen bonds account for the poor solubility of pure, crystalline indigo. [7] Inserted into palygorskite layer interspaces, the visible absorption of indigo provides the optical function to make Maya Blue a colorant with a blue to turquoise tint.…”

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confidence: 99%

Laponite Blue: Dissolving the Insoluble

et al. 2012

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The neutral organic dye indigo forms an inorganic-organic hybrid material with nanoclays (see picture; blue circles on disks symbolizing indigo, spheres indicating liberated cations) and can thus be transferred into aqueous solution. Solids recovered from these solutions resemble the ancient Maya Blue pigment. The method can also be applied to other hydrophobic species and may open the gate for novel solution chemistry, including photonic and catalytic applications.

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Laponite Blue: Dissolving the Insoluble

et al. 2012

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“…Very recently, Lubell and coworkers reported the continuous flow intensification of the Heumann indole synthesis. This transformation was initially proposed for the preparation of indigo, a relevant dyestuff, although a different protocol was selected for the industrial preparation of this molecule, the so-called Heumann−Pfleger method [ 87 ]. Almost forgotten, in the following decades, the Heumann indole synthesis has been sporadically utilized for the preparation of substituted indoles [ 88 , 89 , 90 , 91 , 92 , 93 , 94 ].…”

Section: Synthesis Of Indole Ring Under Continuous Flow Conditionsmentioning

confidence: 99%

Continuous Flow Synthesis of Heterocycles: A Recent Update on the Flow Synthesis of Indoles

2020

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Indole derivatives are among the most useful and interesting heterocycles employed in drug discovery and medicinal chemistry. In addition, flow chemistry and flow technology are changing the synthetic paradigm in the field of modern synthesis. In this review, the role of flow technology in the preparation of indole derivatives is showcased. Selected examples have been described with the aim to provide readers with an overview on the tactics and technologies used for targeting indole scaffolds.

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“…Whereas the replacement of Y in 2 (X = O) by sulfur and selenium [ 10 – 11 ] or even tellurium [ 12 – 13 ] has been known for some time, derivatives of “phosphaindigo” (Y = various substituted phosphorus derivatives) have only been described more recently [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Attempts to prepare an all-carbon indigoid system

Yildizhan¹,

Hopf²,

Jones³

2015

Beilstein J. Org. Chem.

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SummaryFirst attempts are described to prepare a precursor for an all-carbon analog of indigo, the tetracyclic triene 4. Starting from indan-2-one (9) the α-methylene ketone 13 was prepared. Upon subjecting this compound to a McMurry coupling reaction, it dimerized to the bis-indene derivative 17, rather than providing the tetramethyl derivative of 4, the hydrocarbon 14. In a second approach, indan-1-one (18) was dimerized to the conjugated enedione 21 through the bis-1-indene dimer 19. All attempts to methylenate 21 failed, however. When 19 was treated with the Tebbe reagent, the dimer 23 was produced, presumably through a Cope reaction of the intermediately generated isomer 22. The bis-indene derivative 23 can be alkylated with 1,2-dibromoethane to produce a 1:1 mixture of the spiro compounds 24 and 25. Although 9 could be reductively dimerized to 30, the conversion of this olefin to 14 failed.

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Indigo and Indigo Colorants

Abstract: The article contains sections titled: 1. Physical Properties 2. Chemical Properties … Show more

Cited by 33 publications

References 19 publications

Laponite Blue: Dissolving the Insoluble

Laponite Blue: Dissolving the Insoluble

Continuous Flow Synthesis of Heterocycles: A Recent Update on the Flow Synthesis of Indoles

Attempts to prepare an all-carbon indigoid system

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