indigo - Introduction: Indigo is an organic molecule that...

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Introduction: Indigo is an organic molecule that gives off a blueish color. It comes from a plant from the pea family and is used to dye cotton and wool fabric. The color of blue jeans comes from the source of indigo. Sir William Henry Perkins in 1865 synthetically made the indigo molecule, and by 1897 it was commercially made. A quick way to make indigo is to react between 2- nitro-benzaldehyde and acetone in the presence of strong base, NaOH. 2C 7 H 5 NO 3 + 2C 3 H 6 O C 16 H 10 N 2 O 2 + 2 CH 3 CO 2 H +2H 2 O Indigo is insoluble in water, which makes it easy to collect. Enable to dye cloth blue, Indigo has to be reduced to leucoindigo with an appropriate reagent and dissolved in water. C 16 H 10 N 2 O 2 + 2H + +2e - C 16 H 12 N 2 O 2 When the cloth is taken out of the dye, oxygen in the air oxidizes the leucoindigo to indigo. With the use of vacuum filtration, Vat dyeing, and spectrophotometer techniques one can make indigo, dye a cloth and find the absorbance, wavelength and concentration of indigo.
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This note was uploaded on 04/02/2008 for the course CHEM 104B taught by Professor Staff during the Spring '07 term at University of Arizona- Tucson.

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indigo - Introduction: Indigo is an organic molecule that...

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