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I.

ABSTRACT

This experiment aims to make Martius yellow and its sodium salt. This was achieved via sequential sulfonation-nitration and acid-base reactions from α-naphthol. A fine orange powdery dye, the salt of the martius yellow, was formed and a fine bright yellow powdery dye, martius yellow, was also formed. The acidity of the martius yellow depends upon neutralizing it with H2SO4. The preparation of the Martius Yellow was observed comprehensively in this experiment.

II.

INTRODUCTION

Dye is a chemical compound used to produce long lasting colors in materials. It is used in textile, paper and plastic industries, for leather, ink, food, etc. It may not be capable of attaching itself to the material to be dyed, but it can retain its color on prolonged exposure to air, sunlight, temperature, soap or water. (Sarvesh ,2013)

Dye’s molecules are consisted of chromophores and auxochromes components where chromophores (OH, NH2, NHR, NR2, Cl and COOH) are responsible for the production of colours and auxochromes (NO2, NO, N=N) enhance the affinity of the dye toward the fibres.

Dyes can be produced from natural or synthetic sources

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Martius yellow is a yellow dye with a molecular formula C10H6N2O5 that is used as a biological stain. It is an example of a Friedel Craft Alkylation Reaction who was discovered by Karl Alexander von Martius in 1868. The following are the reactions involved in the preparation of Martius Yellow.

Figure 1

Figure 1 shows the reaction for the Preparation of Martius Yellow.

The exchange of groups occurs with remarkable ease, and it is not necessary to isolate the disulfonic acid. The identification of various intermediates and end products also imply that the degradation of martius yellow proceeds through multiple reaction pathways. The advantage of introducing the nitro groups in this indirect way is that 1-naphthol is very sensitive to oxidation and would be partially destroyed on

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direct nitration. Martius Yellow is prepared by reaction of the acidic phenolic group of 1 with ammonia to form the ammonium salt. A small portion of this salt (Martius Yellow) is converted by acidification and crystallization into pure 2,4-dinitro-1naphthol (1), a sample of which is saved. The rest is suspended in water and reduced to diaminonaphthol with sodium hydrosulfite

III.

EXPERIMENTAL SECTION

a-Naphthanol (1g) was mixed with conc. H2SO4 warmed until completely dissolved, then was cooled in an ice bath, the solution has a dark brown color. While cooling t-he anaphthanol solution a mixture of conc. HNO3 (2mL) and water (8mL) was mixed and placed in an icebath. When both tubes are cold, H2O was added with a-Naphthanol solution, shake and was poured in the dilute HNO3 solution. The mixture was warmed to a water bath with a temperature of 50oC, the solution turned to a bloody color. When the solution was darker the temperature was raised slowly with stirring until the reaction was complete, the solution turned to a yellow color that lookeed like a mud H2O (40mL) was added to the mixture, chilled thoroughly, filtered the dye and was wash with water. The dye was dissolved in a boiling water then a 8M NaOH was added in the solution until it turned alkaline, the solution turned alkalined when 45 drops of 8M NaOH was added. The solution was filterd through suction resulting to a filtrate and a precipitate (which is the salt from the Martius Yellow, the precipitate was a fine orange crystals) . For the filtrate, a NaCl (10g) was added then chilled, the filtrate was orange color that was same

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with tempra.A solution of free nithronaphanol was prepared by dissolving half of the salt of Martius Yellow and was neutralize with dilute H2SO4,it was chilled then filtered again through suction and was washed with water. The dyes were dried after the filtration process and was kept for the next experiment.

IV.

RESULTS AND DISCUSSIONS

The Martius Yellow produced is a bright yellow salt that are fine crystals and it is miniscule amount of it are enough to stain paper as well as skin bright yellow, while the Salt of the Martius Yellow is a dark orange color that are also fine crystals.

The Martius Yellow turned to a bright yellow color due to addition of the diluted H2SO4. The brighter the color this means that the solution was acidic

Figure 2.a.

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Figure 2.a. shows the structural formula of the Martius Yellow (C10H6N2O5).

Figure 2.b.

Figure 2.b. shows the structural formula of the salt of the Martius Yellow, Sodium Monohydrate.

V.

CONCLUSIONS

The experimenter was able to found out the Martius Yellow formed as well as the salt of the Martius Yellow. The formation of the Martius Yellow depends on the way of doing the experiment. There are times that not dissolving the a-naphthanol would result to a rusty color of the filtrate of the salt of the martius yellow than an orange one which would cause too much error. In the martius yellow adding a dilute H2SO4 if the solution has abrighter the color than the actual color it is more acidic.

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The experimenter recommend to check the temperature while doing the water bath to be able to monitor the darkening of the solution. A use of gloves is highly recommended for this experiment.

VI.

REFERENCES

1. Jaiswal, Sarvesh (2013, May 23). Dyes retrieved from https://www.scribd.com/document/143288180/Dyes

2. Dawood, Sara; Sen, Tushar K. (2013). Review on Dye Removal from Its Aqueous Solution into Alternative Cost Effective and Non-Conventional Adsorbents retrieved from http://www.jscholaronline.org/articles

3. Caberoy, Ruby Roy (2012, Jan. 14). Martius Yellow retrieved from https://www.scribd.com/document/78250075/Martius-Yellow

4. Singla, Ritu; Grieser, Franz; Ashokkumar, Muthupandian (2008, May 12). Sonochemical degredation of Martius Yellow dye in aqueous solution retrieved from https://www.sciencedirect.com/science/article/pii/S1350417708000898

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VII.

APPENDICES