Indigo Synthesis and Dyeing - Format: PDF

At an early date the manufacturers of dyestuffs placed depend ence upon scientific research, established extensive laboratories for the purpose, and encouraged the training of suitable personnel through the establishment of numerous fellowships in educational institutions. In 1934, 129 separately organized research labora tories were in operation, employing about 1,350 technically trained persons. Net cost of research for that year was about $8,000, 000 or 4% of the sales value of all synthetic organic chemicals.

Chemistry of blue jeans: Indigo synthesis and dyeing - Format: PDF

Keywords: Dye, chemistry, basics, information, reactions, synthesis

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The range of applications of synthetic and natural dyes (often, but not exclusively ) and colorants is extremely wide and affects virtually all areas of natural, industrial production and daily life. Equally great is the range of available dyes, perfectly suitable for the particular application and use. The use of dyes in certain areas subject to legal guidelines, such as in food or cosmetics. Here is the list of ingredients are often marked with special designations such as C.I. numbers or the INCI name. We should also mention the use of colors and dyes in the and in .

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Azo dyes are by far the largest group of disperse dyes and constitute about 60-70% of all commercial dyes in both number and amount produced. They are characterized by the typical nitrogen to nitrogen (-N = N-) bonds; which is the most common chromophore of azo dyes. They are fairly cheap, easy to apply and have a wide range of colours for both synthetic and natural fibres. The azo group is attached to two radicals (organic residues) of which at least one but, more usually, both are aromatic (carboxylic or heterocyclic). They exist in the trans form with a bond angle of ca. 120° and the nitrogen atoms are Sp2 hybridized (; ; ). The range of shades that could be obtained from azo dyes includes yellows, reds, oranges, violets, navy blues and blacks but green shades are limited. The depth of shades is usually influenced by the number of azo groups contained in the dye structure. Thus, the more the number of azo groups in the dye structure, the greater the depth of shade but the duller the brightness (; ; ).

About 14,000 tons of synthetic indigo are still produced per year to dye blue jeans.
In this study, fluorescein based dye was synthesized by three step reaction.

Synthesis and properties of bipyridyl-based dye-sensitizers

Among the many other methods of dye-stuff synthesis, de pendent upon the linking together of hydro-carbon nuclei into more complex molecules, may be mentioned the production of synthetic indigo. The raw materials in this case are aniline and chloro-acetic acid, which upon condensation give phenylglycine. This, upon fusion with caustic alkali, produces indoxyl and by air oxidation indigo :— The most complex molecular structures are those possessed by the vat dyes of the anthraquinone class. These are obtained by the linking together of two or more anthraquinone residues or by the fusion of these residues with other groups in such a way as to produce new carbon rings. The very fast indanthrene blue RS or duranthrene blue is obtained by heating (3-aminoanthra quinone with caustic alkalis and subsequent oxidation by air. The change is thus represented :— This method of dye-stuff synthesis has proved capable of wide application and is very suitable for technical employment, since it can be effected in cold aqueous solution, gives almost theo retical yields and allows of any required substituent being intro duced in prearranged position into the final dye-stuff. When applied to diamino-compounds such as benzidine, it gives rise to dyes containing three hydro-carbon residues (disazo-dyes), such as Congo red :— Disazo-dye-stuffs of another type are obtained by coupling diazo compounds with primary monoamino-derivatives, again diazo tizing the free amino-groups in these products and recoupling the diazo-compounds with suitable hydroxy or amino-derivatives. For example :— i3y applying a similar process to diamines, and also by making A still more complex example is the dye-stuff caledon jade green which has the structure :— It is obtained from anthraquinone, by first condensing with gly cerine, then fusing with caustic soda, oxidizing the product (dibenzanthrone), and finally introducing methyl groups in place of two hydrogen atoms. While initially all the alizarine or anthra quinone dyes were synthesized from anthracene, recently with the cheapening of phthalic anhydride, these dyes are also made by condensation of phthalic anhydride with benzene or its derivatives.

Son, Synthesis and Properties of Novel Rhodamine 6G Fluorescent Dye Compound, Textile Coloration and Finishing (J.

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III. Mordant and Chrome Dyes.—These are coloured comIii. Mordant and Chrome Dyes.—These are coloured com- pounds containing particular groups, usually OH or groups, capable of forming stable coloured lakes (co-ordinative com pounds) with metallic hydroxides, particularly with those of chromium, aluminium, iron and copper. The mordant dye-stuffs proper comprise many of the older natural colouring-matters, much as logwood, fustic, cutch, cochineal, Persian berries and brazilwood, but only a few synthetic dyes, which belong chiefly to the anthraquinone class (alizarine, purpurines, alizarine blue, ali zarine cyanines, anthragallol, etc.). Most of the mordant-dyeing colouring-matters of synthetic origin contain acid groups or or both) and may therefore be classified as acid-mordant colours. These are mainly used on a chromium mordant and are theref ore generally termed chrome colours. In wool dyeing the chromium mordant (sodium bichromate, chromium acetate or chromium fluoride) is applied to the wool either before or after dyeing, or even more frequently (metachrome or solochrome colours) both dye stuff and mordant (chromate) are added to gether to the dye-bath. The shades dyed with mordant and acid mordant dye-stuffs are generally much faster to alkalis and there fore to washing and milling than those obtained with ordinary acidic dyes, whilst the resistance to light, more particularly of those belonging to the anthraquinone group, is very good. Mor dant dyes are also employed in calico printing, in which case the solution of the dye-stuff suitably thickened is mixed with chromium acetate and acetic acid, printed upon the cotton cloth and steamed.

Synthesis of triphenylamine trisazo dye and study of ist uses in dye sensitized solar cells - Format: PDF

Synthesis and Absorption Spectra of Monoazo Dyes …

Both Caro and Perkin rushed to patent the process, but Caro’s patent issued 24 hours earlier, and Perkin had to license the new red synthetic dye from his rival.