In Organic pigments, the molecules are made of carbon atoms along with
hydrogen, nitrogen or oxygen atoms. Organic pigments can be subdivided into
two subgroups:
Natural
Organic Pigments- Pigments of this category are derived from animal
products and plant products. The use of these pigments are rare due to their
poor lightfastness property.
Before the beginning of the modern era, the natural organic pigments were
considered as an important part of the historical pigments. Earlier these
are used for bodily ornaments, textile dyeing and cosmetics.
But, today a large number of the natural organic dyes have been replaced by
the synthetic organic dyes. Therefore, today, these pigments are remembered
by theirs quaint historical names. These pigments are being adopted by the
modern commercial paint companies to lend romance in their traditional
mixtures.
Synthetic
Organic Pigments- Pigments of this category are carbon based and these
are often made from petroleum compounds. Most of the Synthetic Organic
Pigments except Carbon Black are not stable and they will wear away at the
time of using as a pigment.
Under intense pressure or heat, carbon base molecules are manufactured from
petroleum, acids, and other chemicals and Synthetic Organic Pigments have
been formulated from these molecules.
These two subgroups of Organic Pigments have been depicted in the following
table.
| Natural Organic Pigments |
Synthetic
Organic Pigments |
Miscellaneous: e.g Rose-Madder,
Bone
Black,
Carbon Black |
Quinacrid
ones |
Phthaloc
yanines |
Perylenes |
Pyr
roles |
Ary
lamides |
Metal Complexes: e.g
Transparent Yellow,
New Gamboge |
Miscellaneous: e.g
Dioxazsine
in Danthrone. |
The entire concept of organic chemistry mainly depends on
carbon's atoms. These atoms have amazing flexibility and ability to form
many different structures. Due to this attribute, they are able to form
different combinations with other carbon atoms or atoms of other elements or
with other compounds. This facilitates it to form almost limitless molecular
variations. Out of these large number of carbon made molecules, intense
color variations attribute will come in these synthetic organic pigments.
Pigments which are formed out of these molecules, are the least toxic and
economically beneficial.
AZO Pigments along with other organic pigments are derived from water
soluble dyes.
Synthetic Organic Pigments are mainly derived from some selective elements
atoms. These are as follows:
Chromophore is a pair or group of atoms. This pair creates a complex and
dynamic clouding of the electrons within the respective electron shells in
single atom or more then one atoms. These chromophores are responsible
behind the color creation phenomena of the pigment's molecules.
(Image showing Chromophore groups in synthetic organic pigments)