Organic chemistry

By Sonianto Kuddi

40420060017 / 1EMB1

UPH-Teachers college11/12/2008

Dyes and pigmentsChemical structure and color

The history of indigo in Indonesia

Introduction

Colorants are characterized by heir ability to absorb or emit light in the visible range

(Zollinger, 2003, p. 1). Light of a given wavelength is perceived as the indicated color. The

perception of color by the human eye does not solely depend on absorption wavelength, although

it is crucial, but also on the shape of the bands involved. Man has used natural colorants long

years ago. Substances that impart color to a material are dyes and pigments. In term of chemical

structure, colorants can be inorganic or organic compounds. Both groups can be subdivided into

natural and synthetic representatives. (Christie, 2001, p. 24).

Colorants classified in to two separate ways, either according to their chemical structure

or according to the method of application, they are dyes and pigments. Every color is

representative of light that is at a particular wavelength or frequency. For example, what we

consider as red is light that has approximately 780 - 620 nm wavelength (Christie, 2001, p. 24).

When light interacts with molecules, the molecules absorb the energy from that

particular light. This energy can do something to the molecule. For example, certain wavelengths

can make molecules vibrate, make the bonds rotate, or make the electrons within the molecule

become more energetic. Certain molecules can only absorb certain energies. (Argonne National

Laboratory, 2005).

Dyes and Pigments

Dyes are applied to various substrates from a liquid in which they are completely or at

least partly soluble. They must possess specific affinity to a given substrate, which might be a

textile, paper, leather, hair, or other materials. Dyes may be natural or synthetic. Natural dyes

come from animals, minerals, and plants. Plants of the species Indigofera, Polygonum,

Lonchocarpus, Marsdenia, Strobilanthes, and Isatis. (Parramon, 1989, p. 76).

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Picture of Indigofera plant:

A dye must be colored, but it must also able to impart color to something else on a

reasonably permanent basis before it can be considered as a dye. Most dye contains considerable

unsaturation, and some part of the dye is usually in the form of aromatic rings with nitrogen

unsaturation of several types common to many dyes. Many correlations have been made between

chemical structure and color. Color result from electronic transitions between molecular orbitals.

A dye consists of a color production structure, the chromogen (electron acceptor), and a

part to regulate the solubility and dying properties, the auxochrome (electron donor). Without

both parts, the material is simply a colored body. The chromogen is an aromatic body containing

a color called chromophore. Some molecules lose their colors when the chromophore group are

saturated. Dyes are almost invariably applied to the textile materials from an aqueous medium,

so that they are generally required to dissolve in water. (Parramon, 1989, p. 76).

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A pigment is a material that changes the color of light it reflects as the result of selective

color absorption (Wikipedia, 2008). Pigment is a particulate solid dispersed into a medium

without significant solution or other interactions. Pigments are among the most important

components of historical paintings and textiles and their nature provides the unique character of

color. They can be divided into two main groups: inorganic and organic, extracted from plants or

animals.

Pigments consist of small particles that are practically insoluble in the medium in which

they are applied and have to be attached to substrate (Zollinger, 2003, p. 1). They coloring

materials that are required to be completely insoluble in the medium into which they are

incorporated. The principal traditional applications of pigments are in paints, printing inks and

plastics, although they are also used more widely, for example, in the coloration of building

materials, such as concrete and cement, and in the ceramics and glass. Applied into a medium by

a dispersion process, which reduces the clusters of solid articles into more finely divided form,

but they do not dissolve in the medium.

According to Chandravathanam (Chandravathanam, 2005) the difference between pigments and

dyes are:

Pigments are dispersions in the medium but dyes are solutions.

Pigments possess the particulate properties, while dyes do not.

Pigments are far more durable and resistant to fading than dyes.

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Pigment:

(Taken from: Chandravathanam, 2005)

Dye:

(Taken from: Chandravathanam, 2005)

Chemical structure and color

Since the Kekule’s proposal concerning the structure of benzene in 1865, organic

chemistry made significant and rapid progress as a science and almost immediately, theories

concerning the influence of organic structure on the color of molecules began to appear in the

literature. In 1867 one of the earliest observations was due to Graebe and liebemann. They

concluded some justification, that the dyes were unsaturated compounds and that this

unsaturation was destroyed by reduction (Christie, 2001. p. 26). The most organic dyes and

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pigments, in roughly decreasing order of importance, belong to the azo (-N=N-), carbonyl

(C=O), phthalocyanine, arycarbonium ion, sulfur, polymethine and nitro chemical classes.

(Parramon, 1989, p. 75).

“Azo compounds are compounds bearing the function group R-N=N-R', in which R and

R' can be either aryl or alkyl” (Wikipedia, 2008).

Yellow azo dye (4-hydroxyphenylazobenzene). Taken from Encyclopedia, 2008.

Aryl azo compounds: Compounds that usually stable, crystalline species. Azobenzene is

the prototypical aromatic azo compound. It exists mainly as the trans isomer, but upon

photolysis, converts to the cis isomer. (Encyclopedia, 2008). Alkyl azo compounds: Aliphatic

azo compounds (R/ R' = aliphatic) are less commonly encountered than the aryl azo compounds.

One example is diethyldiazene, EtN=Net. At elevated temperatures or upon irradiation, the

carbon-nitrogen (C-N) bonds in certain alkyl azo compounds cleave with the loss of nitrogen gas

to generate radicals. In this case, some aliphatic azo compounds are utilized as radical initiators

(Encyclopedia, 2008). http://www.nationmaster.com/encyclopedia/Azo-compound

The backbones of all of these colored molecules consist of sequences of carbon atoms

linked to each other by alternating single and double bonds. Colored molecules have a

distinguishing feature: their backbones consist of sequences of carbon atoms linked to each other

by alternating single and double bonds. These alternating sequences are an essential structural

feature for an organic, carbon-based molecule to absorb light and appear colored.

(webexhibits.org, 2008).

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BASF is a multinational chemical manufacturing corporation and German chemical

products company. This company produced kinds of color. BASF (Badische Anilin & Soda-

Fabrik) was founded on April 6th, 1865 by Friedrich Engelhorn. (BASF chemical company,

2008). Aniline is one of the products of this company. Aniline is an organic compound with the

formula C6H7N. It is the simplest and one of the most important aromatic amines, being used as a

precursor to more complex chemicals. Its main application is in the manufacture of polyurethane

(Wikipedia, 2008).

Below are chemical structures with their color:

Green:

Structure of chlorophyll a

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Orange:

β-carotene

Blue:

Indigo

Purple:

Tyrian purple

Red:

Lycopene

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Red:

Canthaxanthin

Pink:

Astaxanthin

Purple in Indonesia: In indonesia, we will see much purple color that Indonesian people

use. They use this color because purple color is kingdom traditional color. And then this

traditional color is imitated by society. This color relate with social position in society. (Karin,

2000).

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Pigments and their color:

Yellow                     Orange                     Red

carotenoids                     carotenoids                      carotenoids

pterins                              pterins                               pterins

flavines                            ommochromes                  ommochromes

zooanthoxantines                                                       porphirins

                                                                                      echinocromes

                                                                                      hallacrome

                                                                                      anthraquinones

Green                                     Blue                               Violet

schemochrome + pigment yellow     schemocrhomes                     carotenoprotein

bile pigments                                       carotenoprotein                      ommochromes

carotenoprotein                                  bile pigment                             echinocromes

chlorocruorine

pheophorbides

Red - Brown                     Brown                     Black

pheomelanin                                pheomelanin                   melanin

melanin                                         melanin

Grey                                 White

melanin                                         schemochromies

(mixture of white and black)      (light reflection)

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Requirement for color:

The role of double bonds. Electrons no longer localized in a double bond between two

adjacent atoms, are free to range over the whole molecule and hence are delocalized. Delocalized

electrons, held in molecular orbital, can absorb visible light and so become a source of color. The

role of molecular size. The existence of the electrons in molecular orbital is one requirement for

color. The size of the molecule determines the size of the molecular. A molecule will only appear

color if it is an intermediate size, where the energy spacing. Conjugated system-in an organic

compound consists of alternating single and double bonds in a chain of atoms.

The history of indigo in Indonesia

Indigo is thought to be the oldest dye. It was found in mummy cloths over 5,000 years

old and in the garments of Tutankhamen. Indigo was mentioned in the histories of Herodotus

(circa 450 B.C.) and was a valued “spice” carried back to Europe during the Crusades. For

centuries, European dyers used the woad plant to achieve blues and woad growers fought the

influx of this cheaper, deeper blue dye. In 1598, indigo was prohibited in France and parts of

Germany, and dyers had to swear, often on the pain of death, that they would not use indigo.

By the 17th century, indigo was a chief trade article of both the Dutch and British East

India Companies. In 1744, indigo arrived in South Carolina, from which it traveled to other

states, including New York. In 1883, Adolph von Baeyer synthesized the indigo molecule and by

the early 1900s, the market for natural indigo collapsed. Indigo dye can be purchased in both its

natural and synthetic forms and is still popular in the dyer’s garden. (Cornell, Plants & textiles).

Its primary uses are in cosmetics, as a laboratory indicator, and as the dye that makes blue jeans.

Indigo is still ubiquitous in blue jeans, although today it can be produced synthetically, as well as

through fermentation of the indigo plant (which is not itself blue).

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The species Indigofera tinctoria, native to Asia, has always been the most valuable

indigo species traded. Indigo became the "king of dye" early in history. The use of the plant's

blue dye for adornment, religious ritual, and as a symbol of political and social status occurred

independently in cultures around the world. The central role played by India is captured in the

word Indigo. Although the Sanskrit name for the dye came from nila, meaning dark blue, the

ancient Greeks referred to the product as the Indian dye, indikon. Asian cultures including India,

Indonesia, and China have a long tradition of using indigo to print, dye, and batik textiles (west,

2008).

Egyptian artifacts suggest that Indonesia was employed as early as 1600 BC and it has

been found in Africa, India, Indonesia, and China. The history of indigo in Indonesia divided

into several phase. As we know indigo are used to make batik. History of batik and indigo in

Indonesia sliver with the growth Majapahit monarchic and spreading Islam teaching in Java. In a

few note, development of batik many conducted at period of Mataram empire, then at period of

Solo empire and Yogyakarta.

So usages of indigo as colorant of batik in Indonesia have been recognized since period

of Majapahit Empire. As for starting the wide-spreading of batik artistry become property of

Indonesian people and especially Java tribe after final of XVIII century or early XIX century. All

batik that they yielded were batik write until early XX century and chop batik recognize newly

after First World War or about 1920 year. The bearing with spreading of Islam teaching in

Indonesia: many centre of making batik are Santri area andlater batik become appliance struggle

of economics by figures merchant of Moslem fight against economics of Dutch.

Artistry of batik is picture’s artistry above cloth and becoming one of the kings’ family

cultures in Indonesia. Initially batik done only in Kraton and its result for the king’s clothes,

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family and also follower. Because many follower of king which keep out Kraton, hence artistry

of this batik brought by them out of Kraton and done in them place. Later batiks are imitated by

people closest and hereinafter expend to become women’s work in their home. Hereinafter, batik

only for family clothes of keratin, later become people clothes for man and also for women.

Colorant materials medium consist of original flora Indonesia. For example Indigo, Soga and ect.

Batik that coloring by Indigo was very expensive because fade-proof and durable.

This is the process of how the industrial synthesis the indigo:

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Dictionary:

Pigment: is a material that changes the color of light it reflects as the result of selective color

absorption, particulate solid dispersed into a medium (a liquid) without significant

solution or other interactions.

Dye: is a colorant which soluble in water.

Indigo: Dye which imparts a beautiful blue color to material, obtained until about 1900

entirely from some species of the indigo plant (Indigofera tinctoria). Synthetic indigo has

replaced the natural dye; it is reduced chemically to the soluble yellow compound

leucoindigo, in which form it is applied to textile fibres and reoxidized to indigo.

Chromogen: a color production structure and as electron acceptor, aromatic body containing

a color called chromophore.

Auxochrome: a part to regulate the solubility, dying properties and as a electron donor.

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5 Question:

1. How we can identify color?

2. What the different between dyes and pigments? Explain your answer

3. Draw at least five chemical structures of pigments and what color that they yield?

4. Explain process of making blue jeans?

5. Explain history of indigo in Indonesia?

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Reference:

Parramon, J. (1989). Color theory. Watson-Guptill Publications: New York.

Streitwieser, A., Heathcock, Kosower. (1992). Introduction to organic chemistry: 4th edition. Macmillan publishing company: New York, Toronto.

Austin, G. T. (1984). Shreve’s chemical process industries: Fifth edition. McGraw-Hill: Washington.

Zollinger, H. (2003). Color Chemistry: Syntheses, properties, and applications of organic dyes and pigments. Helvetica Chimica Acta.

Christie, R. M. (2001). Colour chemistry. Royal Society of Chemistry: Britain.

Argonne National Laboratory. (2005). Color and Chemical Structure. Retrieved November 25, 2008 from http://www.newton.dep.anl.gov/askasci/chem03/chem03668.htm

Encyclopedia, 2008. Azo compounds. Retrieved December 16, 2008 from: http://www.nationmaster.com/encyclopedia/Azo-compound

BASF chemical company. (2008). BASF at a glance. Retrieved December 16, 2008 from: http://www.basf.com/group/corporate/en/content/about-basf/index

Karin. (2000). Kecubung the Indonesian Amethyst. Retrieved December 16, 2008 from: http://www.kecubung.com/indonesian/

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