Benzotriazole

Last updated
Benzotriazole
Benzotriazole - numbered.png
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Names
Preferred IUPAC name
1H-1,2,3-Benzotriazole
Other names
1H-Benzotriazole; 1,2,3-Benzotriazole; BTA; BtaH
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.177 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 202-394-1
PubChem CID
RTECS number
  • DM1225000
UNII
  • InChI=1S/C6H5N3/c1-2-4-6-5(3-1)7-9-8-6/h1-4H,(H,7,8,9) Yes check.svgY
    Key: QRUDEWIWKLJBPS-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C6H5N3/c1-2-4-6-5(3-1)7-9-8-6/h1-4H,(H,7,8,9)
    Key: QRUDEWIWKLJBPS-UHFFFAOYAH
  • n1c2ccccc2[nH]n1
Properties
C6H5N3
Molar mass 119.127 g·mol−1
AppearanceWhite solid
Density 1.369 g/cm3 [1]
Melting point 100 °C (212 °F; 373 K) [2]
Boiling point 350 °C (662 °F; 623 K) [2]
20 g/L [2]
Acidity (pKa)8.2 [3] [4]
Basicity (pKb)> 14 [4]
Hazards
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-pollu.svg
Warning
H302, H319, H332, H411, H412
P261, P264, P270, P271, P273, P280, P301+P312, P304+P312, P304+P340, P305+P351+P338, P312, P330, P337+P313, P391, P501
Related compounds
Related compounds
 Benzimidazole, Tolyltriazole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Benzotriazole (BTA) is a heterocyclic compound with the chemical formula C6H4N3H. It can be viewed as the fusion of a benzene and triazole rings. It is a white solid, although impure samples can appear tan. It is used as a corrosion inhibitor for copper. [5]

Contents

Structure and synthesis

Benzotriazole synthesis 01.svg

Benzotriazole features two fused rings. It can in principle exist as tautomers, but X-ray crystallography establishes the depicted structure. The N=N and HN-N distances are 1.306 and 1.340 Å. [1]

Benzotriazole can be prepared by the monodiazotization of o-phenylenediamine using sodium nitrite and acetic acid. [6] [7] [8]

Reactions

Acid-base behavior

Structure of ZnCl2(BTA)2 CSD CIF BISNUM.png
Structure of ZnCl2(BTA)2

BTA is a weak Bronsted acid with a pKa = 8.2. [3] It is a weak Brønsted base, as indicated by the low pKa < 0 of its conjugate acid, [HBTA]+. [4]

It is also a Lewis base, binding Lewis acids at the C-N=N center. A variety coordination complexes are known such as the tetrahedral 2:1 derivative with zinc chloride, ZnCl2(BTA)2. [9] In some complexes, BTA binds metals as its conjugate base forming polymers and oligomers. [10] It binds to copper surfaces, serving as a corrosion inhibitor. [11]

N-alkylation

AlkylnBTA.svg

Deprotonation of BTA followed by treament with alkyl halides gives a mixture of 1- and 2-alkyl derivatives. [12] Aromatic aldehydes (ArCHO) in the presence of ethanol gives benzotriazole-based N,O-acetals:

ArCHO + BtH + EtOH → ArCH(OEt)(Bt) + H2O

These acetals are susceptible to deprotonation, giving access to acylsilanes [13] and acylboranes.

N-amination of BTA with hydroxylamine-O-sulfonic acid gives 1-aminobenzotriazole. Oxidation of this amine with lead(IV) acetate affords benzyne, which rapidly dimerises to biphenylene. [14]

Dehydrobenzol aus Aminobenztriazol.svg

Applications

Benzotriazole has been used as a restrainer (or anti-fogging agent) in photographic emulsions or developing solutions, and as a reagent for the analytical determination of silver. More importantly, it has been extensively used as a corrosion inhibitor in the atmosphere and underwater. BTA can be used as antifreezes, heating and cooling systems, hydraulic fluids, and vapor-phase inhibitors as well.[ citation needed ]

Corrosion inhibition

Benzotriazole is an corrosion inhibitor for copper. It is known that a passive layer, consisting of a complex between copper and benzotriazole, is formed when copper is immersed in a solution containing benzotriazole. The passive layer is insoluble in aqueous and many organic solutions. There is a positive correlation between the thickness of the passive layer and the efficiency of preventing corrosion. [15] BTA is used in heritage conservation, notably for the treatment of bronze disease.

Chemical structure of the coordination polymer from benzotriazolate and copper(I), the active ingredient in the BT-derived corrosion inhibition PolyCubtri.svg
Chemical structure of the coordination polymer from benzotriazolate and copper(I), the active ingredient in the BT-derived corrosion inhibition

Environmental relevance

Benzotriazole is fairly water-soluble, is not readily degraded, and has a limited sorption tendency. It is only partly removed in wastewater treatment plants and a substantial fraction reaches surface water such as rivers and lakes. [16] It is of low toxicity and a low health hazard to humans although exhibiting some antiestrogenic properties. [17] Benzotriazole (and tolyltriazole) is a common "polar organic persistent pollutant", often detected at >0.1 μg/L. [18] One source of this pollution is their use as anti-icing/deicing agents in airports. [19]

Benzotriazole derivatives

Many modifications of benzotriazole have been reported. [12] [20] [21] [22] Alizapride is a commercial drug containing a benzotriazole ring system.

Tolyltriazole is a mixture of isomers or congeners that differ from benzotriazole by the addition of one methyl group attached somewhere on the benzene ring. Tolyltriazole has similar uses, but has higher solubility in some organic solvents.[ citation needed ]

References

Commons-logo.svg Media related to Benzotriazole at Wikimedia Commons

  1. 1 2 Krawczyk, Sławomir; Gdaniec, Maria (2005). "Polymorph β of 1 H -benzotriazole". Acta Crystallographica Section E: Structure Reports Online. 61 (9): o2967 –o2969. doi:10.1107/S1600536805025523.
  2. 1 2 3 1H-Benzotriazole Archived September 27, 2007, at the Wayback Machine , SRC PhysProp Database
  3. 1 2 Katritzky, A. R.; Rachwal S.; Hitchings G. J. (14 January 1991). "Benzotriazole: A novel synthetic auxiliary". Tetrahedron. 47 (16–17): 2683–2732. doi:10.1016/S0040-4020(01)87080-0.
  4. 1 2 3 Katritzky, A. R. "Adventures with Benzotriazole" (PDF). Lecture presented at various locations in 2002. Florida Center for Heterocyclic Compounds. Archived from the original (PDF) on 26 April 2012. Retrieved 23 November 2011.
  5. ↑ "1,2,3-BENZOTRIAZOLE | CAMEO Chemicals | NOAA". cameochemicals.noaa.gov. Retrieved 2023-01-17.
  6. ↑ Robert A. Smiley "Phenylene- and Toluenediamines" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a19_405
  7. ↑ Damschroder, R. E.; Peterson, W. D. (1940). "1,2,3-Benzotriazole". Organic Syntheses. 20: 16. doi:10.15227/orgsyn.020.0016.
  8. ↑ Pereira, Claudio M. P.; Stefani, Helio A.; Guzen, Karla P.; Orfao, Aline T. G. (2007-07-31). "Improved Synthesis of Benzotriazoles and 1-Acylbenzotriazoles by Ultrasound Irradiation" . ChemInform. 38 (31). doi:10.1002/chin.200731104. ISSN   0931-7597.
  9. ↑ Søtofte, Inger; Nielsen, Kurt; Trysberg, Lennart; Uggla, Rolf; Nielsen, P. H. (1981). "Benzotriazole Complexes. II. The Crystal Structures of Benzotriazolium Tetrachlorocobaltate(II), Bis(benzotriazole)dichlorozinc(II) and Polymeric Tetrakis(benzotriazolato)dizinc(II)". Acta Chemica Scandinavica. 35a: 739–745. doi:10.3891/acta.chem.scand.35a-0739.
  10. ↑ Wang, Yan; Hu, Man-Cheng; Zhai, Quan-Guo; Li, Shu-Ni; Jiang, Yu-Cheng; Ji, Wen-Juan (2009). "Synthesis, structure and luminescent properties of an Organic–Inorganic hybrid solid based on unprecedented flower-basket-shaped [] clusters with 1,2-bis(benzotriazole)ethane ligands". Inorganic Chemistry Communications. 12 (4): 281–285. doi:10.1016/j.inoche.2009.01.003.
  11. ↑ Sease, Catherine (May 1978). "Benzotriazole: A Review for Conservators". Studies in Conservation. 2. 23 (2): 76–85. doi:10.2307/1505798. JSTOR   1505798.
  12. 1 2 Katritzky, Alan R.; Rachwal, Stanislaw (2010). "Synthesis of Heterocycles Mediated by Benzotriazole. 1. Monocyclic Systems". Chemical Reviews. 110 (3): 1564–1610. doi:10.1021/cr900204u. PMID   19799386.
  13. ↑ Katritzky, Alan R.; Wang, Zuoquan; Lang, Hengyuan (1996). "Novel and Convenient Synthesis of Aroyl-, Heteroaroyl-, Alkenoyl-, and Alkynoylsilanes". Organometallics. 15 (2): 486–490. doi:10.1021/om950712b.
  14. ↑ Campbell, C.D.; Rees, C.W. (1969). "Reactive intermediates. Part I. Synthesis and oxidation of 1- and 2-aminobenzotriazole". J. Chem. Soc. C . 1969 (5): 742–747. doi:10.1039/J39690000742.
  15. ↑ Finšgar, M.; Milošev I. (11 March 2010). "Inhibition of copper corrosion by 1,2,3-benzotriazole: A review". Corrosion Science. 52 (9): 2737–2749. Bibcode:2010Corro..52.2737F. doi:10.1016/j.corsci.2010.05.002.
  16. ↑ Giger, W; Schaffner, C; Kohler, HP (2006). "Benzotriazole and tolyltriazole as aquatic contaminants. 1. Input and occurrence in rivers and lakes". Environmental Science & Technology. 40 (23): 7186–92. doi:10.1021/es061565j. PMID   17180965.
  17. ↑ Farré, Marinel la; Pérez, Sandra; Kantiani, Lina; Barceló, Damià (2008). "Fate and toxicity of emerging pollutants, their metabolites and transformation products in the aquatic environment". TrAC Trends in Analytical Chemistry. 27 (11): 991–1007. doi:10.1016/j.trac.2008.09.010. ISSN   0165-9936.
  18. ↑ Loos, Robert; Locoro, Giovanni; Comero, Sara; Contini, Serafino; Schwesig, David; Werres, Friedrich; Balsaa, Peter; Gans, Oliver; Weiss, Stefan; Blaha, Ludek; Bolchi, Monica; Gawlik, Bernd Manfred (2010). "Pan-European survey on the occurrence of selected polar organic persistent pollutants in ground water". Water Research. 44 (14): 4115–4126. Bibcode:2010WatRe..44.4115L. doi:10.1016/j.watres.2010.05.032. PMID   20554303.
  19. ↑ Castro, Sigifredo; Davis, Lawrence C.; Erickson, Larry E. (2005). "Natural, cost-effective, and sustainable alternatives for treatment of aircraft deicing fluid waste". Environmental Progress. 24 (1): 26–33. Bibcode:2005EnvPr..24...26C. doi:10.1002/ep.10059.
  20. ↑ Katritzky, Alan R.; Rachwal, Stanislaw (2011). "Synthesis of Heterocycles Mediated by Benzotriazole. 2. Bicyclic Systems". Chemical Reviews. 111 (11): 7063–7120. doi:10.1021/cr200031r. PMID   21894899.
  21. ↑ Akter, Monalisa; Rupa, Kavuri; Anbarasan, Pazhamalai (2022). "1,2,3-Triazole and Its Analogues: New Surrogates for Diazo Compounds". Chemical Reviews. 122 (15): 13108–13205. doi:10.1021/acs.chemrev.1c00991. PMID   35852917.
  22. ↑ Katritzky, Alan R.; Lan, Xiangfu; Yang, Jason Z.; Denisko, Olga V. (1998). "Properties and Synthetic Utility of N -Substituted Benzotriazoles". Chemical Reviews. 98 (2): 409–548. doi:10.1021/cr941170v. PMID   11848906.
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