Red, Sodium Salt

Other Names Phenol, 4,4 -(3H-2,l-benzoxathiol-3-ylidene)fcli[2-chloro-, 5,5-dioxide, monosodium salt Chlorphenol red, sodium salt 

CAS Registry Number 123333-64-2 Merck Index Number Not listed Chemical Structure 

Chemical/Dye Class Sulfonephthalein Molecular Formula Ci9HuCl205SNa Molecular Weight 445.26 pH Range 4.8-6.4 

Physical Form Brown crystals Solubility Soluble in water, ethanol UV-Visible ( max) 575 nm Melting Point 250°C Synthesis Synthetic methodssz 

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Pigment Red 57, discovered in 1903 by R. Gley and O. Siebert at AGFA, developed into one of the most important organic pigments in the market. It was first supplied in the form of its yellowish red sodium salt, to be converted to the calcium or barium salt by the consumer. 

Congo Red.1—Dissolve 4-6 g. of benzidine in a hot mixture of 12 c.c. of concentrated hydrochloric acid and 100 c.c. of water, add 150 c.c. more water, cool the clear solution to 2°-3°, and diazotise with 3-6 g. of sodium nitrite in 20 c.c. of water, added within the space of one minute. Leave the tetrazo -solution for five minutes and then pour it with stirring into a solution of 16 g. of sodium naph-thionate and 20 g. of crystallised sodium acetate in 250 c.c. of water. When a sample of the liquid, on warming with hydrochloric acid, no longer evolves nitrogen, dissolve the blue-black precipitate of the dye-acid by warming with sodium carbonate and so produce the red sodium salt filter and salt out the product from the filtrate with common salt (not too much). Collect the precipitate at the pump and wash with brine. The blue acid can be precipitated from the solution of the sodium salt with hydrochloric acid. 

Other coloured flames follow similar physico-chemical phenomena but operate in different regions of the spectrum. Consequently, the maker of the coloured lance has at his disposal copper salts for blue, strontium salts for red, sodium salts for yellow and barium salts for green, as shown in Table 10.2. 

Methyl Red sodium salt [845-10-3] red-yellow-orange 0.05 (in water)... 

Experiment Dissolve some o-nitrophenol in a solution of sodium carbonate by warming the scarlet red sodium salt is formed. 

Part bromcresol green (sodium salt) 0.1% in water 1 chlorphenol red (sodium salt) 0.1% in water e,. yellow-green blue-violet Blue-green at pH = 5.4 blue with violet tinge at 5.8 blue-violet at 6.2... 

Part bromthymol blue (sodium salt) 0.1% in water 1 phenol red (sodium salt) 0.1% in water 7.5 ti (1 Dirty green at 7.2 pale violet at 7.4 intense violet at 7.6 excellent indicator... 

Methyl red Methyl red sodium salt Chlorophenol red Hematoxylin Litmus extra pure Bromophenol red Bromocresol purple 4-Nitrophenol Bromoxylenol blue Alizarin 4.4 t- V ... 

Dissolve 0.1 g methyl red (sodium salt) in 100 ml of 96 % ethanol Sodium thiosulphate solution ... 

Other Names C.I. Acid Red 2, sodium salt Methyl red sodium salt o-Methyl red sodium salt... 

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