Modification of Hair Pigmentation Or, Chemistry of Vanity Mark Yurewicz and Kathryn Montgomery, msy4

1
Modification of Hair Pigmentation (Or, Chemistry
of Vanity) Mark Yurewicz and Kathryn
Montgomery, msy4707_at_rice.edu klm3907_at_rice.edu
Abstract Hair pigmentation can be understood thro
ugh the chemistry of dyes as well as the physical
properties of compounds within hair and dyes.
Historically, various natural compounds have been
used to alter the chemical nature (and physical
appearance) of hair by coating the cuticle with
dye. The advent of commercial chemistry brought
revolutionary change to hair dyes with the use of
oxidation-reduction reactions used to penetrate
the hair. And now, the natural progression of
science has led to even newer methods of
modifying and creating hair pigmentation.

• Melanin Two pigments
• The products used to derive melanins have been
  identified (see figure 2) as well as sites where
  the products bind to the hair follicle (indicated
  in red curves).
• The exact chemical environment and arrangement
  has not yet been determined.
  
• Eumelanin (fig. 2-A) creates brown and black
  pigmentation.
  
• Phaeomelanin (2-B) creates gold, ginger reddish
  shades.

• A Brief History
• Natural hair dyes (like henna) have been used for
  millienia.
  
• Without alkalizing agents, temporary natural
  dyes only attach to the cuticle.
  
• Eugene Schueller. Paris 1907 with
  p-phenylenediamine (fig.4 below), created
  permanent dyeing, embedding dye in the cortex.
  Formed LOreal.

• Dyes of the Future
• Biomimetics Companies like LOreal researching
  biosynthesis of melanin for use as a hair dye
  
• Eumelanin the only current replicable pigment
  (5,6-dihydroxyindole, see Fig. 2-A
  top)
  
• Currently, biosynthetic pigments do not bind well
  to hair

• Chemistry of Color dyes
• Light waves excite electrons in molecular
  orbitals to new specific energy states given the
  chemical environment.
  
• Larger molecules with conjugated alternating
  p-bonding systems have larger, lower energy
  orbitals.
  
• The first jump in energy electrons make from
  these levels is lower than for most bonds. Thus,
  these molecules absorb light with lower
  frequencies, in the visible electromagnetic
  spectrum.

..
..
..
..
Fig. 4 Above Hydrogen peroxide (H2O2), oxidizin
g agent Below p-phenylenediamine, common amine u
sed for dyeing
Conclusion Modern hair dyes are more complex than
tools for the fulfillment of vanity. They
involve complex chemical reactions within the dye
and with the hair itself. Permanent dyes make
use of exothermic oxidation-reduction reactions
to create colored compounds which enter the
cortex of a strand of hair in an alkaline
solution. New research has led to the potential
use of synthesized melanin for use in hair dyes.
Although the chemistry of hair dye cannot solve
the major problems of the world, there is no harm
in making the world a little more beautiful.
Fig. 3 HC Red No. 3 (4-Amino-2-nitrodiphenylami
ne)
A common red hair dye

• Permanent Hair Dyeing
• Bleaching The first step is bleaching
  (oxidation) the existing melanin, typically done
  by H2O2. When oxidized, melanin is colorless.
  
• Dyeing Amines, (like p-phenylenediamine in fig.
  4) acting as the alkalizing agent, open up the
  cuticle, expand the cortex and help the dyes bind
  to the keratin cortex.

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2006). Hair color chemistry. Retrieved April 10,
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/aa101203a.htm Spence, J. (2004). The chemistry
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