Chemical Database

Benzenesulfonic acid, 4-((2-hydroxy-1-naphthalenyl) azo)-, monosodium salt


  • CAS Number: 633-96-5
  • Synonyms/Related:
    • 1-p-Sulfophenylazo-2-naphthol, monosodium salt
    • 11550 Orange
    • 2-naphthol orange
    • 2-Naphthol Orange II
    • 4-((2-Hydroxy-1-naphthalenyl) azo) benzenesulfonic acid monosodium salt
    • 4-((2-Hydroxy-1-naphthalenyl) azo) benzenesulfonic acid, monosodium salt
    • 4-((2-Hydroxy-1-naphthyl) azo) benzenesulfonic acid, sodium salt
    • Acid Leather Orange Extra
    • Acid Leather Orange Extra G
    • Acid Leather Orange Extra PRW
    • Acid Leather Orange PRW
    • Acid Orange
    • Acid orange 7
    • Acid Orange A
    • Acid orange ii
    • Acilan Orange II
    • Airedale Orange II
    • Amacid Orange Y
    • Atul Acid Orange II
    • Benzenesulfonic acid, 4-((2-hydroxy-1-naphthalenyl) azo)-, monosodium salt
    • beta-Naphthyl orange
    • Betanaphthol Orange
    • Brasilan Orange A
    • Bucacid Orange A
    • Calcocid Orange Y
    • Certiqual Orange II
    • CI 15510
    • Colacid Orange
    • Curol Orange
    • D & C Orange no. 4
    • D and C Orange No. 4
    • D&C Orange 4
    • D&C Orange No. 4
    • Diacid Orange II
    • Erio Orange II
    • Fenazo Orange
    • Hidacid Orange II
    • Hispacid Orange AF
    • Java Orange II
    • Kayaku Acid Orange II
    • Kiton Orange II
    • Kromon Lake Orange Toner
    • Lake Orange A
    • Lake Orange II YS
    • Leather Orange Extra
    • Lurazol Orange E
    • Lutetia Orange 3JR
    • Mandarin G
    • Mitsui Acid Orange II
    • Naphthalene Lake Orange G
    • Naphthalene Orange G
    • Naphtocard Orange II
    • Neklacid Orange II
    • Nitto Acid Orange II
    • No. 177 Orange Lake
    • Nubilon Orange R
    • Orange 2 sodium salt
    • Orange Extra N
    • Orange Extra P
    • Orange II
    • Orange II for Lakes
    • Orange II Special For Lacquer
    • Orange IIC
    • Orange IIP
    • Orange IIS
    • Orange IISM
    • Orange No. 205
    • Orange Toner GRT
    • Orange Y
    • Orange YA
    • Orange YZ
    • Oranz kysela 7 [Czech]
    • p-((2-Hydroxy-1-naphthyl) azo) benzenesulfonic acid sodium salt
    • Peeracid Orange II
    • Perca Orange GR
    • Persian Orange
    • Persian Orange Lake
    • Persian Orange X
    • Pure Orange II S
    • Rifa Acid Orange II
    • Sanyo Gum Orange A
    • Sodium 4-((2-hydroxy-1-naphthyl) azo) benzenesulphonate
    • Solar Orange
    • Special Orange GR
    • Special Orange H
    • Symuler Orange Lake 43
    • Symulon Acid Orange II
    • Takaoka Acid Orange II
    • Tangarine Lake X-917
    • Tertracid Orange II
    • Tropaeolin OOO
    • Tropaeolin OOO 2
    • Tropaeolin OOO No. 2
    • Tropoclin OOO2 (Indicator)
    • Vondacid Orange II
    • Wool Orange A


  • Boiling Point: K °C °F
  • Flammability:
    • Explosive Limits:
      • Lower Explosive Limit: 0%
      • Upper Explosive Limit: 0%
    • Flammable Limits:
      • Lower Flammable Limit: 0%
      • Upper Flammable Limit: 0%
    • Flash Point K °C °F
    • Autoignition Temperature: K °C °F
  • Melting Point: K °C °F

Related Resources

  • USDOT Hazardous Materials Table 49 CFR 172.101
    An online version of the USDOT's listing of hazardous materials from 49CFR 172.101. This table can be sorted by proper shipping name, UN/NA ID and/or by primary hazard class/division.
  • 2008 ERG (Emergency Response Guidebook)
    Have you ever wondered what those four digit numbers on the placards on the side of trucks and rail cars mean? Our online 2008 ERG will give you your answer. This is an online version of the guidebook produced by the USDOT for first responders during the initial phase of a Dangerous goods/HazMat incident. ERG data last verified/updated Oct. 2, 2011
  • US DOT Hazardous Materials Transportation Placards
    Hazardous materials placards (DOT placards) are required when shipping hazardous materials in the United States, Canada and Mexico. These pages provide US DOT definitions for each hazmat placard.
  • Guide for Handling Household Chemicals
    Things you can do to make your home safer.
  • Molarity, Molality and Normality
    Introduces stoichiometry and explains the differences between molarity, molality and normality.
  • Molar Mass Calculations and Javascript Calculator
    Molar mass calculations are explained and there is a JavaScript calculator to aid calculations.
  • Periodic Table of Elements
    Provides comprehensive data for each element of the periodic table of elements including up to 40 properties, names in 10 languages and common chemical compounds. Information also provided for 3,600 nuclides and 4,400 nuclide decay modes.

Editor's note: Some chemicals in this database contain more information than others due to the original reason this information was collected and how the compilation was accomplished.

While working with material safety data sheets (MSDS), I found that manufacturers sometimes used obscure names for constituent chemicals and I didn't always have a good idea of what I was dealing with. To resolve this problem, over the years, I compiled chemical names and identifiers into a personal database, cross referencing regulatory and health safety information when possible. Colleagues and friends eventually started suggesting that I make my data available on this website so that others could benefit from my efforts -- which I finally did in 2004. The more common, regulated and/or hazardous a chemical is, the more information I will have likely collected it.


If you are aware of any synonyms listed above that are registered trademarks, please contact us with relevant information so that trademarks can be appropriately noted.

Notes about mixtures

Some chemicals listed in this database or not pure chemical compounds, rather they are mixtures/solutions of chemicals. It is not uncommon for wide range of molar ratios of a mixture to be lumped together as "synonyms" of the same "chemical". In some instances chemicals that are very similar from a health & safety and/or regulatory standpoint also may have been lumped together.

Reference Sources

Data for this database was compiled from: hundreds of Material Safety Data Sheets (MSDS) of common industrial and household products; the Hazardous Materials Table from the United States "Code of Federal Regulations" title 49 section 172.101; the National Institute for Occupational Safety and Health Pocket Guide to Chemical Hazards; the US DOT 1996, 2000 & 2004 Emergency Response Guidebooks; U.S. National Library of Medicine and many other related resources.


WARNING: These pages are for general reference and educational purposes only and MUST NOT be relied upon as a sole source to determine regulatory compliance or where matters of life and health are concerned. This site and the author do not warrant or guarantee the accuracy or the sufficiency of the information provided and do not assume any responsibility for its use.

To ensure regulatory compliance when transporting hazardous materials or dangerous goods, one must receive proper training and certification from a qualified instructor and refer to the current year's Code of Federal Regulations Title 49 (49CFR) or your country's shipping regulations. In matters regarding workplace safety, refer to current OSHA regulations (29CFR) and NIOSH guidelines or your own country's health and safety regulations. No one should ever enter into a hazardous environment without proper training from qualified instructors.

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