Synthetic dye

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1. Presentation Topic: Synthetic dyes Department: Chemistry Presented by: Muhammad Ahsan

2. Introduction Dyes are colored organic compounds that are used to impart color to various substrates, including paper, leather, fur, hair, drugs, cosmetics, waxes, greases, plastics and textile materials . A Dye is a colored compound, normally used in solution, which is capable of being fixed to a fabric.

3. Evolution of Dyes:- The preparation and application of dyestuffs is one of the oldest forms of human activities. There is also mention of it in the Bible and other works of classical antiquity. It was in 2600 BC when earliest written records of the use of dyestuffs were found in China. First humanmade organic dye that was discovered by William Henry Perkin in the year 1856. The first synthetic dye, picric acid, was prepared in the year 1771 from the natural pigment, indigo.

4. William Perkin an 18 years old student was working on chemical synthesis of natural products. In a classic case of serendipity, the young William Perkin chanced upon his now famous 'Aniline Mauve' dye while he was attempting to synthesize quinine, the only cure for malaria. Perkin named his colour Mauveine , after the French name of nonfast colour which was made of natural dyes. So "Mauve" (a basic dye) was the first synthetic dye stuff. Mauve was a derivative of coal tar. It was the first mass produced dye, that was commercially available and the idea was born that a colour could be made in the factory. It was indeed a revolution.

5. Properties of good dye:- Dyes  must possess the following four properties: ­ 1.  Colour 2.  Solubility in water 3. Ability to be absorbed and retained by  fibre ( substantivity ) or to be chemically combined with it (reactivity).  4.  Ability to withstand washing, dry  cleaning  and exposure to  light. 

6. Classification There are several ways for classification of dyes. Each class of dye has a very unique chemistry, structure and particular way of bonding. While some dyes can react chemically with the substrates forming strong bonds in the process, others can be held by physical forces. Some of the prominent ways of classification are: Classification based on the source of materials classification of the Dyes- Based on the nature of their respective chromophores . Classification by methods of application.

7. Classification based on the source of materials A very common classification of the dyestuff is based on the source from which it is made. Accordingly the classification could be :  Natural Dyes  Synthetic Dyes

8. Natural Dye Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources. E.g. roots , berries, bark, leaves, and wood. O ther organic sources include fungi and lichens .

9. Wool Fabric Natural Fabrics Silk Fabric Flax Fabric Cotton Fabric Linen Fabric Hemp

10. Synthetic Dyes Almost all the colors that you see today are Synthetic dyes. Synthetic dyes are used everywhere in everything from clothes to paper, from food to wood.  This is because   they are cheaper to produce, brighter, more color-fast, and easy to apply to fabric. E.g. Acid Dyes, Azo Dyes, Basic Dyes, Mordant Dyes, etc Azo dye testing

11. Classification based on the Chromophore present Dyes may be classified according to the type of chromophores present in their structures. Nitro and Nitroso Dyes Azo Dyes Triarylmethane Dyes Anthraquinone Dyes Indigo dyes

12. Azo Dyes Azo dye is a large class of synthetic organic dyes that contain nitrogen as the azo group −N=N− as primary chromophore their molecular structures. More than half the commercial dyes belong to this class. These dyes are highly coloured and are prepared by diazotizing an aromatic amine and coupling with suitable aromatic compound. Para Red

13. Methyl Orange Congo Red Bismarck Brown Azo dyes account for approximately 60-70% of all dyes used in food and textile manufacture.  In theory, azo dyes can supply a complete rainbow of colours , but yellow/red dyes are more common as blue/brown dyes. 

14. Triarylmethane Dyes Triarylmethane dyes  are synthetic organic compounds containing triphenylmethane backbones . T hese compounds are intensely colored and are produced industrially. In triarylmethane dyes a central carbon is bonded to three aromatic rings, one is in the quinoid form. Auxochromes areNH 2 , NR 2 and OH. Malachite Green

15. Malachite Green is used as a direct dye for wool and silk. Phenolphtalein is used as acid base indicator Phenolphthalein

16. Anthraquinone Dyes Anthraquinone dye,   any of a group of organic dyes having molecular structures based upon that of  anthraquinone .  Alizarin is the main ingredient for the manufacture of the madder lake pigments known to painters as Rose madder and Alizarin crimson . Alizarin is also used commercially as a red textile dye. Alizarin

17. Indigo Dyes Indigo dye is an organic compound with a distinctive blue color Historically , indigo was a natural dye extracted from plants. But today n early all indigo dye  is produced   synthetically. It contains carbonyl chromophore. The primary use for indigo is as a dye for cotton yarn, which is mainly for the production of denim cloth for blue jeans  Small amounts are used for dyeing  wool  and silk. Indigo

18. Classification based on the Dyeing method:- According to the dyeing methods , there are following types. Cationic (Basic) Dyes: Anionic ( Acid) Dyes: Direct Dyes. Disperse Dyes:

19. Acid Dyes water-soluble anionic dyes applied to fibers such as silk, wool, nylon and modified acrylic fibers Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber . Stick to fibers by hydrogen bonding, Van der Waals force, and ionic bonding Structure is made up of Azo dyes, Triphenylmethane , and Anthraquinone

20. Basic Dyes water-soluble cationic dyes applied to acrylic fibers , but find some use for wool and silk soluble in acid and insoluble in basic solution Bonded by ionic bonds

21. Direct (substantive) Dyes Bright and deep colors can be azo compounds, stilbenes , oxazines , or phtalocyanines Contain solubilising groups (mainly sulphonic acid groups) in an aqueous solution dye molecules being held in place mainly through Van der Waals forces and hydrogen bonds

22. Disperse Dyes: Water-insoluble non-ionic dyes for application to hydrophobic fibers from aqueous dispersion. Used predominantly on polyester and to a lesser extent on nylon, cellulose, cellulose acetate, and acrylic fibers. Used in Thermal transfer printing and dye diffusion thermal transfer processes for electronic photography.

23. A number of other classes of dyes have also been established, that includes the following: Fluorescent Dyes -  A very innovative dye. Used for application in sports good etc. Fuel Dyes -  Used in fuels. Leather Dyes -  Used for leather. Leuco Dyes -  Has a wide variety of applications including  electronic industries  and papers. Other important dyes:-

24. Other important dyes:- Inkjet Dyes -  Writing industry including the inkjet printers. Oxidation Dyes -  Used mainly for hair. Optical Brighteners -  Used primarily for textile fibres and paper. Smoke Dyes -  Used in military activities. Sublimation Dyes -  For application in textile printing.

25. What makes the Dyes coloured ? which is explained by the presence of a substance called Chromophore in the dyes. By definition dyes are basically aromatic compounds. Their structures have aryl rings that has delocalised electron systems. These structures are said to be responsible for the absorption of electromagnetic radiation that has varying wavelengths, based upon the energy of the electron clouds. It is actually because of this reason that chromophores do not make dyes coloured . Rather it makes the dyes proficient in their ability to absorb radiation. Chromophores acts by making energy changes in the delocalised electron cloud of the dye. This alteration invariably results in the compound absorbing radiation within the visible range of colours and not outside it. Human eyes detects this absorption, and responds to the colours .

26. How can the colour of the Dyes be altered? The Modifiers. Colour modifiers like methyl or ethyl groups can actually alter the colour of dyes. They do so by altering the energy in the delocalised electrons. It has been found that by addition of a particular modifier there is a progressive alteration of colour . An example can be given for methyl violet series. The following diagram explains what happens to the colour of the dyes when modifiers are added.

27. Step A: When no methyl group is added the original dye Pararosanil as it is called is red in colour . Step B: As Four Methyl groups are added the reddish purple dye Methyl Violet is got.

28. Step C: With the addition of more groups a purple blue dye Crystal Violet is obtained. It has in it six such groups.

29. Disadvantage of synthetic dyes:- synthetic dyes have harmful effects on the environment and human beings. First off , synthetic dyes are made up of chemical compounds that can be harmful to humans, especially those who work in their production. Some of the chemicals found in synthetic dyes are mercury, lead, chromium,copper , sodium chloride, toluene, and benzene. Exposure to large doses of these substances can be toxic and can have severe effects in the human body.

30. Water pollution can also result from manufacturing synthetic dyes when untreated dye effluent is dumped directly on bodies of water.

31. TOPIC HAIR DYE :

32. MEANING OF HAIR DYE:- Hair dye or hair colouring is the practice of changing the hair colour . The main reason for this are cosmetic : To cover gray hairs or to change the colour of hair which is regarded as more fashionable or desrablein todays world.

33. HISTORY:- Hair colour is the matter of chemistry. The first safe commercial hair colour was created in 1909 by French chemist Eugene Schuller , using the chemical paraphenylenediamine (PPD).

34. What is HAIR AND NATURAL HAIR COLOR ? Hair is mainly Keratin. The same protein found in skin and fingernails. The natural colour of hair depends on the ratio and quantities of two other proteins, Eumelanin and Phaeomelanin . Eumelanin is responsible for brown to black hair shade while Phaeomelanin is responsible for goldenblond , ginger and red colour . The absence of either type of melanin produces white/grey hair.

35. NATURAL HAIR COLOURANTS:- People have been coloring their hairs for thousands of year using plant and minerals. Some of these natural agents contain pigments ( e.g. : Henna, black walnut shells ) and other contain natural bleaching agents like vinegar. Natural pigments generally works by coating the hair shaft with color but they aren’t more gentle than modern formulations.

36. TYPES OF HAIR DYE:- Depending upon the deposition of various Dyes for suitable time limit, the dyes are classified into four categories. They are : 1.) PERMANENT HAIR DYE 2.) DEMI-PERMANENT HAIR DYE 3.) SEMI-PERMANENT HAIR DYE 4.) TEMPORARY HAIR DYE

37. PERMANENT HAIR DYE:- In order to deposit permanent hair dye, the outer layer of hair shaft i.e. Cuticle must be opened. Once the Cuticle is opened, the dye react with the inner portion of the hair i.e. Cortex to deposit or remove the color. Most permanent hair dyes use a two-step process, which first removes the original color of the hair and then deposits a new color.

38. Ammonia is the alkaline chemical that open the cuticle and allows the hair color to penetrate the Cortex of the hair. It also acts as a catalyst when the permanent hair color comes together with the peroxide. Peroxide is used as a developer or oxidizing agent. The developer removes pre-existing color. Peroxide breaks chemical bonds in hair, releasing sulfur, which accounts for the characterstic odor of hair color. As the melanin is decolorized, a new permanent color is bounded to the hair cortex. Various types of alcohols and conditioners may also be present in hair dye. The conditioners close the cuticle after coloring to seal in and protect the new color.

39. DEMI-PERMANENT HAIR DYE:- Demi -permanent hair dye are those which contains an alkaline agent other than ammonia (e.g. Ethanolamine, Sodium Carbonate etc. ) and always employed with a developer, the concentration of hydrogen peroxide in that developer may be lower than used with a permanent hair dye. Demi -permanent are much more effective at covering Grey Hair than Semi-permanent dye but less than permanent hair dye .

40. SEMI-PERMANENT HAIR DYE:- Semi-permanent hair dye may deposit acidic dye onto the hair shaft or may consists of small pigment molecules that can slip inside the hair shaft, using a small amount of peroxide. In some cases, a collection of several colorant molecules enter the hair to form a larger complex inside the hair shaft. Generally these products doesn’t contain ammonia and if contain then in very negligible amount.

41. TEMPORARY HAIR DYE:- This dye is available in various forms including shampoos, gels, sprays and foams. Temporary hair dye is typically brighter and more vibrant than Semi-permanent and Permanent hair dye. The pigment molecules in temporary hair dye are large and can’t penetrate the Cuticle layer. The colour particles remain adsorbed to the hair shaft and are easily removed with a single shampooing.

42. REACTIONS INVOLVED IN permanent HAIR DYE PROCESS 1.) The first step shows the oxidation of p- phenylenediamine to the Quinonediimine i.e. C 6 H 4 (NH) 2 .

43. 2.) The second step involves the attack of this Quinonediimine on the coupler. This reaction is Electrophilic aromatic substitution.

44. 3.) In third and final step, the product form the Quinonediimine coupler reaction which oxidizes to the final hair dye. It was believed that the dye forms in the above reaction bonds to hair permanently because it produces a larger dye molecule, which is locked inside the hair.

45. ADVERSE EFFECT:- Hair dye or hair coloring involves the use of Chemicals that are capable of removing, replacing or covering up pigments naturally found inside the hair shaft. Use of these Chemicals can result in a range of adverse effects including temporary skin irritation or allergy, hair breakage, skin discoloration etc.