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| Names | |
|---|---|
| Preferred IUPAC name (6aS,11bR)-7,11b-Dihydroindeno[2,1-c][1]benzopyran-3,6a,9,10(6H)-tetrol | |
| Other names Brasilin; Natural Red 24; CI 75280 | |
| Identifiers | |
| |
3D model (JSmol) | |
| 4198570 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| ECHA InfoCard | 100.006.799 |
| EC Number |
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| KEGG | |
| UNII | |
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| Properties | |
| C16H14O5 | |
| Molar mass | 286.283 g·mol−1 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Brazilin is a naturally occurring,homoisoflavonoid, reddye obtained from the wood ofPaubrasilia echinata,Biancaea sappan,Caesalpinia violacea, andHaematoxylum brasiletto (also known asNatural Red 24 and CI 75280).[1] Brazilin has been used since at least the Middle Ages todye fabric, and has been used to make paints and inks as well. The specific color produced by the pigment depends on its manner of preparation: in anacidic solution brazilin will appear yellow, but in analkaline preparation it will appear red. Brazilin is closely related to the blue-black dye precursorhematoxylin, having one fewer hydroxyl group. Brazilein, the active dye agent, is an oxidized form of brazilin.[2][1]
Brazilin is obtained from the wood ofPaubrasilia echinata,Biancaea sappan (Sappanwood),Caesalpinia violacea, andHaematoxylum brasiletto.[1] The sappanwood is found inIndia,Malaysia,Indonesia andSri Lanka, the latter being a major supplier of the wood to Europe during the early Middle Ages. Later, discovery ofbrazilwood (Paubrasilia echinata) in the new world led to its rise in popularity with the dye industry and eventually itsover-exploitation. Brazilwood is now classified as anendangered species.[3]
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There are many ways to extract and prepare brazilin. A common recipe, developed in the Middle Ages, is to first powder the brazilwood, turning it into sawdust. Then, the powder can be soaked inlye (which produces a deep, purplish red) or a hot solution ofalum (which produces an orange-red color), either of which extracts the color better than plain water alone. To the lye extract, alum is added (or to the alum extract, lye) in order to fix the color, which will precipitate from the solution. The precipitate can be dried and powdered, and is a type oflake pigment.
Like many lake pigments, the exact colors produced depends on the pH of the mixture and the fixative used. Aluminium mordants used with brazilin produce the standard red colors, while the use of a tin mordant, in the form ofSnCl
2 orSnCl
4 added to the extract is capable of yielding a pink color.
An alternative preparation which produces a transparent red color involves soaking the brazilwood powder inglair or a solution ofgum arabic. Alum is added to help develop and fix the color, which can then be used as a transparent ink or paint.
As withhematein, brazilin can be used for staining cell nuclei in histological preparations when combined with aluminium. The nuclei are then colored red instead of blue.
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| Techniques |  | |
|---|---|---|
| Types of dyes | ||
| Traditional textile dyes | ||
| History | ||
| Craft dyes | ||
| Reference | ||
| Authority control databases: National |
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