Armstrong acid

Chemical compound From Wikipedia, the free encyclopedia

Armstrong acid (naphthalene-1,5-disulfonic acid) is a fluorescent organic compound with the formula C10H6(SO3H)2. It is one of several isomers of naphthalenedisulfonic acid. It a colorless solid, typically obtained as the tetrahydrate.[1] Like other sulfonic acids, it is a strong acid. It is named for British chemist Henry Edward Armstrong.[2]

Quick facts Names, Identifiers ...
Armstrong's acid
Skeletal formula of Armstrong's acid
Ball-and-stick model of the Armstrong's acid molecule
Names
Preferred IUPAC name
Naphthalene-1,5-disulfonic acid
Other names
Armstrong's acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.001.199 Edit this at Wikidata
UNII
  • InChI=1S/C10H8O6S2/c11-17(12,13)9-5-1-3-7-8(9)4-2-6-10(7)18(14,15)16/h1-6H,(H,11,12,13)(H,14,15,16) checkY
    Key: XTEGVFVZDVNBPF-UHFFFAOYSA-N checkY
  • InChI=1/C10H8O6S2/c11-17(12,13)9-5-1-3-7-8(9)4-2-6-10(7)18(14,15)16/h1-6H,(H,11,12,13)(H,14,15,16)
    Key: XTEGVFVZDVNBPF-UHFFFAOYAR
  • O=S(C2=CC=CC1=C(S(=O)(O)=O)C=CC=C12)(O)=O
  • O=S(=O)(O)c1cccc2c1cccc2S(=O)(=O)O
Properties
C10H8S2O6
Molar mass 288.299 g/mol
Appearance colorless solid
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 corrosive
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production and use

It is prepared by disulfonation of naphthalene with oleum:

C10H8 + 2 SO3 → C10H6(SO3H)2

Further sulfonation gives The 1,3,5-trisulfonic acid derivative.[1]

Reactions and uses

Fusion of Armstrong acid in NaOH gives the disodium salt of 1,5-dihydroxynaphthalene, which can be acidified to give the diol. The intermediate in this hydrolysis, 1-hydroxynaphthalene-5-sulfonic acid, is also useful. Nitration gives nitrodisulfonic acids, which are precursors to amino derivatives.

The disodium salt is sometimes used as a divalent counterion for forming salts of basic drug compounds, as an alternative to the related mesylate or tosylate salts. When used in this way such a salt is called a naphthalenedisulfonate salt, as seen with the most common salt form of the stimulant drug CFT. The disodium salt is also used as an electrolyte in certain kinds of chromatography.[3]

References

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