Methyl Orange
Title: Methyl Orange
CAS Registry Number: 547-58-0
CAS Name: 4-[[(4-Dimethylamino)phenyl]azo]benzenesulfonic acid sodium salt
Additional Names: sodium p-dimethylaminoazobenzenesulfonate; helianthine B; C.I. Acid Orange 52; C.I. 13025; Orange III; Gold Orange; Tropaeolin D
Molecular Formula: C14H14N3NaO3S
Molecular Weight: 327.33
Percent Composition: C 51.37%, H 4.31%, N 12.84%, Na 7.02%, O 14.66%, S 9.80%
Literature References: Prepn from sulfanilic acid sodium nitrite + dimethylaniline: L. Gattermann, Die Praxis des Organischen Chemikers (de Gruyter, Berlin, 40th ed., 1961) pp 260-261. See also Colour Index vol. 4 (3rd ed., 1971) p 4043.
Properties: Orange-yellow powder or cryst scales. Sol in 500 parts water; more sol in hot water. Practically insol in alcohol.
Use: As indicator in 0.1% aq soln. pH: 3.1 red, 4.4 yellow. Employed for titrating most mineral acids, strong bases, estimating alkalinity of waters; useless for organic acids. In dyeing and printing of textiles.

Others monographs:
Sodium SulfideAmmonium Picrate3'-Methylphthalanilic AcidLotrifen
Trifluoroacetic AcidChloroacetic AcidNimesulideCatharanthine
SolasonineThorium OxideSulfanilic AcidSebacoin
d-Bornyl α-Bromoisovalerate2,2-Dichloroacetyl ChloridePicaridinMethyl Ethyl Ketone
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