Indigo and Indigo Colorants

Paul, Roshan; Blackburn, Richard S.; Bechtold, Thomas

doi:10.1002/14356007.a14_149.pub3

Cited by 13 publications

(16 citation statements)

References 54 publications

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“…Indeed, as early as 1896, indigo production from the Indigofera tinctoria plant allowed a yearly production of 9000 tons. [ 58 ] Since then, chemistry developments have allowed the production of indigo to increase significantly. Nowadays, indigo is principally made from a petroleum derivative namely aniline, at a rate of 70 000 tons annually following the Pfleger synthetic process developed in 1901.…”

Section: Natural Dyesmentioning

confidence: 99%

“…Nowadays, indigo is principally made from a petroleum derivative namely aniline, at a rate of 70 000 tons annually following the Pfleger synthetic process developed in 1901. [ 58 ] Nevertheless, natural indigo is still extracted from the Indigofera tinctoria leaves at the rate of 50–100 tons/year and employed as a natural dying product. However, the purity of natural indigo is low (20–50% range) and its price per kg is ten to 30 times that of the synthetic molecule.…”

Section: Natural Dyesmentioning

confidence: 99%

See 1 more Smart Citation

Biosourced Monomers: Toward Sustainable Conjugated Polymers for Organic Electronics

Boivin

Dupont

Gendron

et al. 2022

Macro Chemistry & Physics

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Organic electronic materials are starting to appear in various applications, but there are still hurdles to overcome before the average consumer can get them in their hands. Right now, most polymers in the field of organic electronics are made from petroleum derivatives. However, new sources of platform chemicals and monomers are being explored. This perspective article highlights ways that have been explored to avoid the use of petrochemicals and demonstrates new pathways that can be taken to increase the sustainability of conjugated polymers in organic electronics.

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Section: Natural Dyesmentioning

confidence: 99%

Section: Natural Dyesmentioning

confidence: 99%

Biosourced Monomers: Toward Sustainable Conjugated Polymers for Organic Electronics

Boivin

Dupont

Gendron

et al. 2022

Macro Chemistry & Physics

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“…The potential savings of a process which omits this step can be illustrated by the calculations given in Table 4 where the water and chemical consumption for a technical plant per day and within a year (250 working days), and for an annual production of 1.5 million tons of dyed warp yarn are shown [ 21 , 36 ].…”

Section: Process Balances—model Calculationsmentioning

confidence: 99%

“…10% of the annual cotton production, respectively 2.5 million tons, goes into jeans production. The vast majority of these products is dyed with synthetic indigo, which holds an annual production of 70,000 tons [ 21 ]. Due to this unique situation, a number of approaches to recycle denim pre- and post-consumer wastes have been presented in the literature.…”

Section: Introductionmentioning

confidence: 99%

Dope Dyeing of Regenerated Cellulose Fibres with Leucoindigo as Base for Circularity of Denim

et al. 2022

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Circularity of cellulose-based pre- and post-consumer wastes requires an integrated approach which has to consider the characteristics of the fibre polymer and the presence of dyes and additives from textile chemical processing as well. Fibre-to-fibre recycling is a condition to avoid downcycling of recycled material. For cellulose fibres regeneration via production of regenerated cellulose fibres is the most promising approach. Textile wastes contain dyes and additives, thus a recycling technique has to be robust enough to process such material. In an ideal case the reuse of colorants can be achieved as well. At present nearly 80% of the regenerated cellulose fibre production utilises the viscose process, therefore this technique was chosen to investigate the recycling of dyed material including the reuse of the colorant. In this work, for the first time, a compilation of all required process steps to a complete circular concept is presented and discussed as a model. Indigo-dyed viscose fibres were used as a model to study cellulose recycling via production of regenerated cellulose fibres to avoid downcycling. Indigo was found compatible to the alkalisation and xanthogenation steps in the viscose process and blue coloured cellulose regenerates were recovered from indigo-dyed cellulose. A supplemental addition of reduced indigo to the cellulose solution was also found feasible to adjust colour depth in the regenerated cellulose to the level required for use as warp material in denim production. By combination of fibre recycling and indigo dyeing the conventional yarn dyeing in denim production can be omitted. Model calculations for the savings in water and chemical consumption demonstrate the potential of the process. The proportion of the substitution will depend on the collection rate of denim wastes and on the efficiency of the fibre regeneration process. Estimates indicate that a substitution of more than 70% of the cotton fibres by regenerated cellulose fibres could be achieved when 80% of the pre- and post-consumer denim wastes are collected. Therefore, the introduction of fibre recycling via regenerated cellulose fibres will also make a substantial impact on the cotton consumption for jeans production.

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“…Aromatic amines are indispensable intermediates for a plethora of chemicals, including polymer precursors, pharmaceuticals, and dyes . It would be ideal to synthesize them directly from the corresponding arene and amine.…”

Section: Introductionmentioning

confidence: 99%

Cu-α-diimine Compounds Encapsulated in Porous Materials as Catalysts for Electrophilic Amination of Aromatic C–H Bonds

Emelen

Lemmens

Márquez

et al. 2022

ACS Appl. Mater. Interfaces

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Electrophilic amination has emerged as a more environmentally benign approach to construct arene C−N bonds. However, heterogeneous catalysts remain largely unexplored in this area, even though their use could facilitate product purification and catalyst recovery. Here we investigate strategies to heterogenize a Cu(2,2′-bipyridine) catalyst for the amination of arenes lacking a directing group with hydroxylamine-O-sulfonic acid (HOSA). Besides immobilization of Cu on a metal−organic framework (MOF) or covalent organic framework (COF) with embedded 2,2′-bipyridines, a ship-in-a-bottle approach was followed in which the Cu complex is encapsulated in the pores of a zeolite. Recyclability and hot centrifugation tests show that zeolite Betaentrapped Cu II (2,2′-bipyridine) is superior in terms of stability. With N-methylmorpholine as a weakly coordinating, weak base, simple arenes, such as mesitylene, could be aminated with yields up to 59%, corresponding to a catalyst TON of 24. The zeolite could be used in three consecutive runs without a decrease in activity. Characterization of the catalyst by EPR and XAS showed that the active catalytic complex consisted of a site-isolated Cu II species with one 2,2′-bipyridine ligand.

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Indigo and Indigo Colorants

Cited by 13 publications

References 54 publications

Biosourced Monomers: Toward Sustainable Conjugated Polymers for Organic Electronics

Biosourced Monomers: Toward Sustainable Conjugated Polymers for Organic Electronics

Dope Dyeing of Regenerated Cellulose Fibres with Leucoindigo as Base for Circularity of Denim

Cu-α-diimine Compounds Encapsulated in Porous Materials as Catalysts for Electrophilic Amination of Aromatic C–H Bonds

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