Martius Yellow

Dinitro-l-naphthol (Martius Yellow) [605-69-6] M 234.2, m 81-82°. Crystd from benzene or aqueous EtOH. 

Colouring Matters.—In Italy butter may be coloured, but not with certain prohibited colouring matters, such as Martius yellow, Victoria yellow and metanil yellow. As a rule annatto is used, but sometimes also saffron or turmeric, and rarely carotin coal-tar colours (aniline yellow, butter yellow) are also employed. 

Extraneous Colouring Matters.—Most of the products in question are coloured a more or less deep yellow by means of organic colouring matters or, sometimes, saffron, the depth of colour depending on whether enhancement of the natural colour of the flour or imitation f the colour imparted by eggs is desired. In Italy the use of picric acid, Victoria yellow, Martius yellow and metanil yellow for this purpose is prohibited. 

Non-sulphonated nitro-phenols (Picric acid Victoria yellow Martius yellow)... 

Naphthol yellow S, Martius yellow, naphthylamme yellow, naphthalene yellow, citronine A, etc. Solution Ibecomcs colourless or very pale yellow. 

Martius Yellow.—In a similar way the nitro naphthalenes are only faintly colored and are not valuable as dyes while the mixed nitro and hydroxy naphthalenes are colored compounds. One of these is a yellow dye which was formerly used to dye wool and silk but is now principally used in dyeing soaps. It is the 2-4-di-nitro i-naphthol which in the form of its sodium, calcium or ammonium salt is known as Martius yellow. 

The commercial product consists of the potassium salt, which is sparingly soluble. On wool and silk it dyes the same shades as Martius yellow, but is to be preferred as yielding much faster d ves. 

It may be distinguished from Martius yellow by treating its solution with acids Martius yellow is immediately precipitated, while naphthol yellow S gives no reaction. 

NO,—>—NH,. An example is the reduction of Martius Yellow as the ammonium salt to 2,4-diamino-l-naphthol. ... 

The sources of dyes used by man include animal, vegetable, and mineral. Sir William Henry Perkins, in 1856, synthesized the first aniline dye. In 1860, a triphenylmethane dye, fuch-sine, was used by the French to color wine. On August 2, 1886, the U.S. Congress authorized the addition of color to butter. On June 6, 1896, Congress approved colorants in cheese, and by 1900 colorants were added to catsup, jellies, cordials, candies, sausage and noodles. However, there were some concerns by the public. For example, chrome yellow, martius yellow and quicksilver Vermillion were added to foods to hide poor quality or to increase weight. There was no control over the purity of colorants used. For example, it has been noted that rejected textile dyes were sometimes added to foods. Use of arsenic acid and mercury in the manufacture of colorants also created some concerns. 

Yellow needles from hot EtOH or CHCL. M.p, 137-5° (132°). Spar, sol. Et,0, EtOH, CgHg. Prac. insol, H5O. Non-volatile in steam. Sn -J- HCl —>- 2 4-manuno-l-naphthol. Ale. NHj at 200° —> 2 4-dinitro-l-naphthyl-amine. Na salt is the dyestuff Martius Yellow. 

Naphthalene was first isolated from coal tar in 1819 by Alexander Garden it represents about 10% of this complex mixture of aromatics. The industrial importance of naphthalene dates from the latter half of the last century, owing mainly to the ease with which it can be converted into sulfonic adds and thence also to the naphthols, for use as dyestuffs intermediates. However, the first synthetic naphthalene-based dye was a nitro-derivative, Martius Yellow (Add Yellow 24), which was patented in 1864 by Carl Alexander Martius. 

Martius yellow n. Calcium derivative of naphthalene yellow. 

Other Names Acid Yellow 24 1-Naphthol, 2,4-dinitro- l-Hydroxy-2,4-dinitronaphthalene 2,4-Dinitro-l-naphthol 2,4-Dinitronaphthol Martinsgelb Martius yellow Manchester Yellow NSC 6148... 

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