Talk:Indigo dye
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[edit] Dying Process
- Should something be mentioned about how fabric is dyed? Indigo is insoluble in water...I believe it is reduced into something water soluble (it's yellow in color at that point), applied to fabric, then oxidized back to indigo. Just a thought :-) 71.242.135.83 05:20, 29 June 2006 (UTC)
[edit] Page move
- I suggest moving Indigo dye to Indigo and the color article from Indigo to Indigo (color). Whether this is done or not, the dis-ambiguation page will remain at Indigo (disambiguation). At this moment, take, for example, Gold, which isn't titled "Gold (element)" despite the color, Gold (color), that was named after it. 66.245.1.229 20:02, 6 Nov 2004 (UTC)
- Good as it is, IMO; colors and underlying substances are too much of a mixed bag for a consistent naming formula; in this case the color is what most people think of first, if only because of Mood Indigo. --Jerzy(t) 05:00, 2005 Feb 9 (UTC)
[edit] Chemistry
Why just an empirical formula, which is of little interest? I don't know that we need a structure diagram (tho i dare say we could get one drawn for the article), but even if it's one of those multi-ring structures where an "edge" is shared between two ring polygons (something that i'm not sure i could grasp in a structural formula) it shouldn't be that cryptic to count the rings and specify their individual structures. --Jerzy(t) 05:00, 2005 Feb 9 (UTC)
[edit] FD&C Blue 2
The FD&C regulation lists CAS numbers for the different forms of indigotine that are allowed in food, but when I tried to find them, all except for 860-22-0 drew a blank. What is going on here? Did the FDA screw up here, have the numbers changed, or does PubChem just not have the others? Here is the quotation from the page:
- (a) Identity. (1) The color additive FD&C Blue No. 2 is principally the disodium salt of 2-(1,3-dihydro-3-oxo-5-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid (CAS Reg. No. 860-22-0) with smaller amounts of the disodium salt of 2-(1,3-dihydro-3-oxo-7-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid (CAS Reg. No. 54947-75-0) and the sodium salt of 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid (CAS Reg. No. 605-18-5). Additionally, FD&C Blue No. 2 is obtained by heating indigo (or indigo paste) in the presence of sulfuric acid.
Also, I will be adding a section on the food use of the dye here. --Slashme 07:36, 23 December 2005 (UTC)
