2 Bromobenzoic Acid Synthesis Essay

Preferred IUPAC name

5,5'-Disulfanediylbis(2-nitrobenzoic acid)

Other names

3,3'-Disulfanediylbis(6-nitrobenzoic acid)
5-(3-Carboxy-4-nitrophenyl)disulfanyl-2-nitrobenzoic acid
Dithionitrobenzoic acid
5,5'-Dithiobis(2-nitrobenzoic acid)


CAS Number

3D model (JSmol)

ECHA InfoCard100.000.650



  • InChI=1S/C14H8N2O8S2/c17-13(18)9-5-7(1-3-11(9)15(21)22)25-26-8-2-4-12(16(23)24)10(6-8)14(19)20/h1-6H,(H,17,18)(H,19,20) Y
  • InChI=1/C14H8N2O8S2/c17-13(18)9-5-7(1-3-11(9)15(21)22)25-26-8-2-4-12(16(23)24)10(6-8)14(19)20/h1-6H,(H,17,18)(H,19,20)



  • c1cc(c(cc1SSc2ccc(c(c2)C(=O)O)[N+](=O)[O-])C(=O)O)[N+](=O)[O-]


Chemical formula

Molar mass396.34 g·mol−1
Melting point240 to 245 °C (464 to 473 °F; 513 to 518 K) (decomposes)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Y verify (what is YN ?)
Infobox references

Ellman's reagent (5,5'-dithiobis-(2-nitrobenzoic acid) or DTNB) is a chemical used to quantify the number or concentration of thiol groups in a sample.[2] It was developed by George L. Ellman.


In Ellman's original paper,[2] he prepared this reagent by oxidizing 2-nitro-5-chlorobenzaldehyde to the carboxylic acid, introducing the thiol via sodium sulfide, and coupling the monomer by oxidization with iodine. Today, this reagent is readily available commercially.

Ellman's test[edit]

Thiols react with this compound, cleaving the disulfide bond to give 2-nitro-5-thiobenzoate (TNB), which ionizes to the TNB2− dianion in water at neutral and alkaline pH. This TNB2− ion has a yellow color.

Reaction of DTNB with a thiol (R-SH).

This reaction is rapid and stoichiometric, with the addition of one mole of thiol releasing one mole of TNB. The TNB2− is quantified in a spectrophotometer by measuring the absorbance of visible light at 412 nm, using an extinction coefficient of 14,150 M−1 cm−1 for dilute buffer solutions,[3][4] and a coefficient of 13,700 M−1 cm−1 for high salt concentrations, such as 6 M guanidinium hydrochloride or 8 M urea.[4] Unfortunately the extinction coefficient for dilute solutions was underestimated in the original 1959 publication, as 13,600 M−1 cm−1, and as noted in a recent article, this mistake has persisted in the literature.[5] Commercial DTNB may not be completely pure, so may require recrystallization to obtain completely accurate and reproducible results.[4]

Ellman's reagent can be used for measuring low-molecular mass thiols such as glutathione in both pure solutions and biological samples, such as blood.[6] It can also measure the number of thiol groups on proteins.[6]


External links[edit]

  1. ^5,5′-Dithiobis(2-nitrobenzoic acid) at Sigma-Aldrich
  2. ^ abEllman GL (1959). "Tissue sulfhydryl groups". Arch. Biochem. Biophys. 82 (1): 70–7. doi:10.1016/0003-9861(59)90090-6. PMID 13650640. 
  3. ^Collier HB (1973). "Letter: A note on the molar absorptivity of reduced Ellman's reagent, 3-carboxylato-4-nitrothiophenolate". Anal. Biochem. 56 (1): 310–1. doi:10.1016/0003-2697(73)90196-6. PMID 4764694. 
  4. ^ abcRiddles PW, Blakeley RL, Zerner B (1983). "Reassessment of Ellman's reagent". Meth. Enzymol. Methods in Enzymology. 91: 49–60. doi:10.1016/S0076-6879(83)91010-8. ISBN 978-0-12-181991-0. PMID 6855597. 
  5. ^Riener CK, Kada G, Gruber HJ (2002). "Quick measurement of protein sulfhydryls with Ellman's reagent and with 4,4'-dithiodipyridine". Anal Bioanal Chem. 373 (4–5): 266–76. doi:10.1007/s00216-002-1347-2. PMID 12110978. 
  6. ^ abRiener, Christian K.; Kada, Gerald; Gruber, Hermann J. (2002-07-01). "Quick measurement of protein sulfhydryls with Ellman's reagent and with 4,4′-dithiodipyridine". Analytical and Bioanalytical Chemistry. 373 (4-5): 266–276. doi:10.1007/s00216-002-1347-2. ISSN 1618-2642. 


2-bromobenzoic acid



InChI Key


Canonical SMILES


MeSH Synonyms

2-bromobenzoic acid

Depositor-Supplied Synonyms

2-BROMOBENZOIC ACID, o-Bromobenzoic acid, 88-65-3, Benzoic acid, 2-bromo-, Benzoic acid, o-bromo-, 2-Bromo-benzoic acid, Bromobenzoic acid, Benzoic acid, bromo-, UNII-AZ789TZS4L, XRXMNWGCKISMOH-UHFFFAOYSA-N, NSC 6976, EINECS 201-848-6, SBB058412, BRN 0971266, AI3-03699, 25638-04-4, o-bromobenzoicacid, o-bromo benzoic acid, 2-bromo benzoic acid, PubChem3739, ACMC-1BKGP, AC1L1NN1, AC1Q5U5E, AZ789TZS4L, SCHEMBL49806, KSC202O4D, ORTHO-BROMOBENZOIC ACID, 137677_ALDRICH, AC1Q721X, ARONIS008730, CHEMBL115950, RARECHEM AL BO 0014, 16320_FLUKA, CTK1A2741, NSC6976, ATTERCOP-CHM AT111657, MolPort-000-151-734, NSC-6976, STR04298, ANW-39124, AR-1D9583, BBL025932, LABOTEST-BB LT01143292, LABOTEST-BB LT03329502, LABOTEST-BB LT03330984, LABOTEST-BB LT03408090, STK399786, AKOS000119014, AB00223, AC-3084, AM81263, AS00760, LS10336, MCULE-3239222085, PS-5299, RP25821, RP25824, RTR-027891, AJ-16268, AK-77301, AN-13329, KB-21678, LS-36194, SC-07180, TL806152, AB1003393, DB-020710, ST2409734, TR-027891, B0552, FT-0600392, ST45045473, M-6066, AB01330856-02, AE-641/00396046, I01-0406, T5883849, 3B3-034896, InChI=1/C7H5BrO2/c8-6-4-2-1-3-5(6)7(9)10/h1-4H,(H,9,10

Removed Synonyms

2-Bromobenzoate, null, Telmisartan, CID6940, 4-27-00-07537 (Beilstein Handbook Reference), 144701-48-4, 94-41-7


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