Brazilin

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Brazilin
Skeletal formula of brazilin
Space-filling model of the brazilin molecule
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
ECHA InfoCard
 100.006.799 Edit this at Wikidata
EC Number
  • 207-477-6
KEGG
UNII
  • InChI=1S/C16H14O5/c17-9-1-2-10-14(4-9)21-7-16(20)6-8-3-12(18)13(19)5-11(8)15(10)16/h1-5,15,17-20H,6-7H2/t15-,16+/m0/s1 checkY
    Key: UWHUTZOCTZJUKC-JKSUJKDBSA-N checkY
  • InChI=1/C16H14O5/c17-9-1-2-10-14(4-9)21-7-16(20)6-8-3-12(18)13(19)5-11(8)15(10)16/h1-5,15,17-20H,6-7H2/t15-,16+/m0/s1
    Key: UWHUTZOCTZJUKC-JKSUJKDBBS
  • C1C2=CC(=C(C=C2[C@H]3[C@@]1(COC4=C3C=CC(=C4)O)O)O)O
  • Oc1cc3c(cc1O)[C@@H]2c4c(OC[C@]2(O)C3)cc(O)cc4
Properties
C16H14O5
Molar mass 286.283 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Brazilin is a naturally occurring, a

alkaline preparation it will appear red. Brazilin is closely related to the blue-black dye precursor hematoxylin, having one fewer hydroxyl group. Brazilein, the active dye agent, is an oxidized form of brazilin.[2][1]

Sources of brazilin

Brazilin is obtained from the wood of

over-exploitation. Brazilwood is now classified as an endangered species.[3]

Extraction and preparation

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 in lye (which produces a deep, purplish red) or a hot solution of alum (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 of lake 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 of SnCl
2 or SnCl
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 in

glair or a solution of gum arabic
. Alum is added to help develop and fix the color, which can then be used as a transparent ink or paint.

As with

hematein
, brazilin can be used for staining cell nuclei in histological preparations when combined with aluminium. The nuclei are then colored red instead of blue.

Notes

  1. ^
    PMID 25893688
    .
  2. doi:10.1016/S0924-2031(01)00138-2
    .
  3. doi:10.2305/IUCN.UK.1998.RLTS.T33974A9818224.en
    .

References

  • The Merck Index, 12th Edition. 1392
  • Armstrong, Wayne P. (1994). "Natural Dyes". HerbalGram. 32: 30.
  • Thompson, Daniel V. The Materials and Techniques of Medieval Painting, Dover Publications, Inc. New York, NY. 1956.

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Brazilin&oldid=1180548482"