fabrics and dyes

alkenes

-C=C-

conjugated alkenes

-C=C-C=C-

azo

-N=N-

What kind of dye did we use in tie-dye?

Procion dyes.

What was the purpose of soaking our tie-dye shirts in soda ash? Write the reaction of a cotton monomer with soda ash to assist in your explanation.

The purpose of soda ash is that the base will weaken or break the O-H bonds

vat dyes

Water insoluble dyes such as indigo that require first converting (in indigo's case reducing) them to a water soluble form

What would have happened if you had spilled diothionite solution onto your blue jeans? What would Mrs. Kinner have told you to do in that case and why?

Diothionite would reduce the indigo in your jeans to the yellow leucoindigo form. Don't rinse with water! The leuco form is water soluble and the indigo dye in your jeans will wash away. Simply wait and let it air oxidize back to indigo on its own.

chromophores

Groups within an organic molecules that selectively absorb visible light

Where did we obtain the starting materials for synthetic dyes in the past and where do we get them now?

In the past the starting materials were often extracted from natural sources—usually plant sources or naturally occurring minerals, but sometimes even animal sources. Now we use mostly starting materials from crude oil refining.

mordants

A coupling agent—usually a metal ion—that attaches to both the dye and the fiber and forms a link between them. It can fix a dye that would otherwise come off in the wash

carbonyl

C=O

Explain why cotton and wool dyed so much darker than polyester in our indigo lab.

Cotton and wool have -OH and NH3+ groups for the negatively charged leuco form of indigo to hydrogen bond and ionic bond to. Polyester lacks these groups.

To what form must indigo be converted in the dying process and why? What's the process called?

Indigo must be reduced to the leuco base form so that it's water soluble in a process called vat dying.

dyes

Intensely colored molecule that strongly absorbs visible light and that directly bonds to textiles

what was the first synthetic dye? who synthesized it and how?

Mauve was the first synthetic dye synthesized on accident by William Perkin who was actually trying to synthesize quinine as a drug to treat malaria.

Why do the threads of many tie-dyed t-shirts remain white after dying?

Most of the time, the threads of t-shirts are made of polyester so that they do not dye with the rest of the cotton t-shirt.

nitro

NO2

What type of bonding occurs between fiber-reactive dyes and the fabric itself?

New covalent bonds.

fiber reactive dyes

Newest class of dyes that bond directly to fabric

pigments

colored minerals combined with a vehicle such as oil or mud to adhere to a surface

diagram, Quinoid, indigo (Benzene - Carbonyl - Alkene - Carbonyl - Benzene)

draw out