Bonding with ColorChemistry and OutreachOpportunities of Tie Dye
Anne E. MoodyTruman State [email protected]
AEMoody: Truman State U
Natural Dyes
Tyrian Purple From Shellfish
N
NO
OH
H
Br
Br
Kermesic Acid From Insects
HOOC
HO
CH3 O
O OH
OH
OH
AEMoody: Truman State U
Molecular Structure Determines Color of Matter
Note extended conjugated pi systems in these synthetic dyes:
OH
NN
SO3- Na+
Orange II
Martius Yellow
O- NH4+
NO2
O2N
AEMoody: Truman State U
Fiber Structure Determines Interactions with Dyes
N
H
CH
R
CO
NH CH
R'
CO
NH CH
R"CO
n
Wool has many reactive sites in its structure:
AEMoody: Truman State U
Cheaper Fabric Structures
• In Cotton, R = H• In Acetate Rayon, R= C(O)CH3
O
OO
HOOR
CH2OH
OO
CH2OH
OHRO
n
AEMoody: Truman State U
Vat Dyes depend on Mechanical Retention and
Redox Chemistry
N
NO
OH
H
Na2S2O4 + NaOH
O2 N
N
H
H
O- Na+
O- Na+Indigo Indigo white
blue form, H2O insoluble Leuco form, H2O soluble
AEMoody: Truman State U
Fiber Reactive DyesIn General: W-D-Q-RG-X
Where: W = water solubilizing groupsD = Chromophore of DyeQ = Bridging GroupRG = Reactive GroupX = Leaving Group
AEMoody: Truman State U
Procion Synthetic Dye Example
• Fiber Reactive Dye • Covalently Bonds to Fabric
NN
NCl
ClSO3
-Na+
NH
SO3-Na+
O
ONH
Procion Blue
AEMoody: Truman State U
“Stylized” Procion Dye Reaction with Cotton
OH OH OH OH OH
Base
O O O O O
Dye-Cl
O O O O O
Dye Dye Dye Dye Dye
Pretend this is cotton:
Deprotonated "cotton":
Dye BONDED to "cotton":
AEMoody: Truman State U
Closer Look at Dye-Fabric Bond Formation
NN
NWDQ Cl
Cl
O CelNN
NWDQ Cl
Cl
OCel
NN
NWDQ OCel
Cl
+ Cl
AEMoody: Truman State U
Hydrolysis of C-Cl of Dye
NN
NWDQ Cl
Cl
O HNN
NWDQ Cl
Cl
OH
NN
NWDQ OH
Cl
+ Cl
AEMoody: Truman State U
Acid-Base Chemistry Inactivates Dyes
NN
NN Cl
Cl
O H
WD
H
NN
NN Cl
Cl
WDH OH
NHN
NN Cl
Cl
WD+ HO
unreactive
AEMoody: Truman State U
Today’s Experiment
• Your T-shirt starts out very clean and dry!
• It goes into our bucket of base solution and now it is very wet and basic.
• We’ll wring it out when we give it to you!
AEMoody: Truman State U
Your Task for Today• Twist and fold the damp, basic
shirt in particular patterns; secure it with rubber bands.
• Apply the dyes using squirt bottles….
• Place wet, dyed shirt in zip-lock bag and let reactions proceed.
AEMoody: Truman State U
Patience with the Experiment!• Wait 24 hours!
• Wash in hot water with dish soap; dry in hot dryer.
• Enjoy cool shirt! ;-)