255. Alizarine Yellow R

Nomenclature

CAS number: 2243-76-7
2-Hydroxy-5-[2-(4-nitrophenyl)diazenyl]benzoic acid; 5-(p-nitrophenylazo)salicylic acid; p-nitrobenzeneazosalicylic acid; Alizarine Yellow RW; C.I. Mordant Orange 1; C.I. 14030.
C13H9N3O5; mol wt 287.23.
C 54.36%, H 3.16%, N 14.63%, O 27.85%.

Description and references

Prepd by coupling diazotized p-nitroaniline with salicylic acid: Armento, US 2746955 (1956 to General Aniline and Film); Colour Index vol. 4 (3rd ed., 1971) p 4058.

Chemical structure

Properties

Orange-brown needles from dil glacial acetic acid, dec 253-254°. Sol in water, alc; slightly sol in acetone, Cellosolve; practically insol in other org solvents.

Derivative

Sodium salt.

Nomenclature

Mordant Yellow 3R.
C13H8N3NaO5; mol wt 309.21.
C 50.50%, H 2.61%, N 13.59%, Na 7.44%, O 25.87%.

Properties

Brownish yellow powder. Sol in water.

Use

Sodium salt used as indicator in 0.1% aq soln pH: yellow to red, range 10.2 to 12.0.