Hydroxynaphthol blue

Hydroxynaphthol blue
Names
	Other names Hydroxynaphthol blue
Identifiers
CAS Number	63451-35-4 ;
3D model (JSmol)	Interactive image ;
ChemSpider	20157443 ;
ECHA InfoCard	100.058.343
PubChem CID	9576626 ;
UNII	VG5SKF7S6C ;
CompTox Dashboard (EPA)	DTXSID8069852 ;
	InChI InChI=1S/C20H14N2O11S3.3Na/c23-15-9-16(35(28,29)30)13-3-1-2-4-14(13)18(15)21-22-19-12-6-5-11(34(25,26)27)7-10(12)8-17(20(19)24)36(31,32)33;;;/h1-9,23-24H,(H,25,26,27)(H,28,29,30)(H,31,32,33);;;/q;3+1/p-3/b22-21+;;; Key: AUIINJJXRXMPGT-ZRUFZDNISA-K ; InChI=1/C20H14N2O11S3.3Na/c23-15-9-16(35(28,29)30)13-3-1-2-4-14(13)18(15)21-22-19-12-6-5-11(34(25,26)27)7-10(12)8-17(20(19)24)36(31,32)33;;;/h1-9,23-24H,(H,25,26,27)(H,28,29,30)(H,31,32,33);;;/q;3+1/p-3/b22-21+;;; Key: AUIINJJXRXMPGT-QWKJSYRZBJ;
	SMILES O=S(C(C=C4)=CC1=C4C(/N=N/C2=C3C(C=CC=C3)=C(S(=O)(O[Na])=O)C=C2O)=C(O)C(S(=O)(O[Na])=O)=C1)(O[Na])=O;
Properties
Chemical formula	C20H11N2Na3O11S3
Molar mass	620.46301 g/mol
Appearance	Black-violet Powder
Solubility in water	Soluble
Acidity (pKa)	6.44, 12.93
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Last updated June 08, 2025

Hydroxynaphthol blue is an azo dye. It is used for determining the endpoint in complexometric titrations/Metal Titration.

References

↑ Atuko Itoh; Keihei Ueno (1970). "Evaluation of 2-hydroxy-1-(20hydroxy-4-sulpho-1-naphthylazo)-3-naphthoic acid and hydroxynaphtol blue as metallochromic indicators in the EDTA titration of calcium" . Analyst. 95 (1131): 583–589. Bibcode:1970Ana....95..583I. doi:10.1039/an9709500583. ISSN 1364-5528.

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[1] Atuko Itoh; Keihei Ueno (1970). "Evaluation of 2-hydroxy-1-(20hydroxy-4-sulpho-1-naphthylazo)-3-naphthoic acid and hydroxynaphtol blue as metallochromic indicators in the EDTA titration of calcium" . Analyst. 95 (1131): 583–589. Bibcode:1970Ana....95..583I. doi:10.1039/an9709500583. ISSN 1364-5528.

[1]

Names

Other names Hydroxynaphthol blue
Identifiers
CAS Number	63451-35-4 ^Y
3D model (JSmol)	Interactive image
ChemSpider	20157443 ^N
ECHA InfoCard	100.058.343
PubChem CID	9576626
UNII	VG5SKF7S6C ^Y
CompTox Dashboard (EPA)	DTXSID8069852
InChI InChI=1S/C20H14N2O11S3.3Na/c23-15-9-16(35(28,29)30)13-3-1-2-4-14(13)18(15)21-22-19-12-6-5-11(34(25,26)27)7-10(12)8-17(20(19)24)36(31,32)33;;;/h1-9,23-24H,(H,25,26,27)(H,28,29,30)(H,31,32,33);;;/q;3+1/p-3/b22-21+;;;^N Key: AUIINJJXRXMPGT-ZRUFZDNISA-K^N InChI=1/C20H14N2O11S3.3Na/c23-15-9-16(35(28,29)30)13-3-1-2-4-14(13)18(15)21-22-19-12-6-5-11(34(25,26)27)7-10(12)8-17(20(19)24)36(31,32)33;;;/h1-9,23-24H,(H,25,26,27)(H,28,29,30)(H,31,32,33);;;/q;3+1/p-3/b22-21+;;; Key: AUIINJJXRXMPGT-QWKJSYRZBJ
SMILES O=S(C(C=C4)=CC1=C4C(/N=N/C2=C3C(C=CC=C3)=C(S(=O)(O[Na])=O)C=C2O)=C(O)C(S(=O)(O[Na])=O)=C1)(O[Na])=O
Properties
Chemical formula	C₂₀H₁₁N₂Na₃O₁₁S₃
Molar mass	620.46301 g/mol
Appearance	Black-violet Powder
Solubility in water	Soluble
Acidity (pK_a)	6.44, 12.93^[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references