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114510

Sigma-Aldrich

Methyl Orange

ACS reagent, Dye content 85 %

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Synonym(s):
4-[4-(Dimethylamino)phenylazo]benzenesulfonic acid sodium salt, Acid Orange 52, Helianthin, Orange III
Empirical Formula (Hill Notation):
C14H14N3NaO3S
CAS Number:
Molecular Weight:
327.33
Colour Index Number:
13025
Beilstein/REAXYS Number:
4732884
EC Number:
MDL number:
PubChem Substance ID:
NACRES:
NA.47

grade

ACS reagent

Quality Level

form

powder

composition

Dye content, 85%

technique(s)

titration: suitable

color

orange

pH

3.0-4.4, pink to yellow

visual transition interval

3.2-4.4, red to yellow

mp

>300 °C

λmax

505 nm

application(s)

diagnostic assay manufacturing
hematology
histology

storage temp.

room temp

SMILES string

[Na+].CN(C)c1ccc(cc1)\N=N\c2ccc(cc2)S([O-])(=O)=O

InChI

1S/C14H15N3O3S.Na/c1-17(2)13-7-3-11(4-8-13)15-16-12-5-9-14(10-6-12)21(18,19)20;/h3-10H,1-2H3,(H,18,19,20);/q;+1/p-1/b16-15+;

InChI key

STZCRXQWRGQSJD-GEEYTBSJSA-M

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1 of 4

This Item
68250199567861286
vibrant-m

114510

Methyl Orange

vibrant-m

68250

Methyl Orange

vibrant-m

199567

Ethyl Orange sodium salt

vibrant-m

861286

Orange G

grade

ACS reagent

grade

for microscopy (Hist.), indicator (pH 3.0-4.4)

grade

indicator grade

grade

certified by the Biological Stain Commission

color

orange

color

-

color

-

color

-

application(s)

diagnostic assay manufacturing
hematology
histology

application(s)

diagnostic assay manufacturing
hematology
histology

application(s)

diagnostic assay manufacturing
hematology
histology

application(s)

diagnostic assay manufacturing
hematology
histology

form

powder

form

powder

form

-

form

powder

λmax

505 nm

λmax

501.4 nm in H2O (acidified)

λmax

474 nm

λmax

475 nm

General description

Methyl orange (C.I. 13025) is the sodium salt of p-dimethylaminoazobenzenesulfonic acid.It is an orange-colored synthetic dye, which changes color depending on the pH of the solution. It develops a red color in acidic solution and yellow color in basic solution.

Application

Methyl orange is used as a-
  • pH indicator in the cell sap
  • counterstain to crystal violet in staining pollen tubes
  • component of a polychrome histological stain
  • solution indicator, such as in assays of oxalic and malonic acids
  • in other biomedical applications that include use in film dosimeters and as a reagent for the assay of bromide ions.

Biochem/physiol Actions

Methyl Orange is an azo dye which works as a pH indicator.

pictograms

Skull and crossbones

signalword

Danger

hcodes

Hazard Classifications

Acute Tox. 3 Oral

Storage Class

6.1C - Combustible, acute toxic Cat.3 / toxic compounds or compounds which causing chronic effects

wgk_germany

WGK 3

flash_point_f

Not applicable

flash_point_c

Not applicable

ppe

Eyeshields, Faceshields, Gloves, type P2 (EN 143) respirator cartridges


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