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Benzotriazole

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Benzotriazole
Skeletal formula of benzotriazole
Space-filling model of the benzotriazole molecule
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 Edit this at Wikidata
EC Number
  • 202-394-1
RTECS number
  • DM1225000
UNII
  • InChI=1S/C6H5N3/c1-2-4-6-5(3-1)7-9-8-6/h1-4H,(H,7,8,9) checkY
    Key: QRUDEWIWKLJBPS-UHFFFAOYSA-N checkY
  • 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
Appearance White 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:
GHS07: Exclamation markGHS09: Environmental hazard
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).
☒N verify (what is checkY☒N ?)

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]

Structure and synthesis

[edit]
Synthesis of benzotriazole

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][9]

Reactions

[edit]

Acid-base behavior

[edit]
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.[10] In some complexes, BTA binds metals as its conjugate base forming polymers and oligomers.[11] It binds to copper surfaces, serving as a corrosion inhibitor.[12]

N-alkylation

[edit]

Deprotonation of BTA followed by treament with alkyl halides gives a mixture of 1- and 2-alkyl derivatives.[13] 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[14] 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.[15]

Synthesis of Benzyne and Biphenylene from 1H-Benzotriazole

Applications

[edit]

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

[edit]

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.[16] 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

Environmental relevance

[edit]

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.[17] It is of low toxicity and a low health hazard to humans although exhibiting some antiestrogenic properties.[18] Benzotriazole (and tolyltriazole) is a common "polar organic persistent pollutant", often detected at >0.1 μg/L.[19] One source of this pollution is their use as anti-icing/deicing agents in airports.[20]

Benzotriazole derivatives

[edit]

Many modifications of benzotriazole have been reported.[13][21][22][23] Vorozole and alizapride are commercial drugs. Benzotriazole esters are used as mechanism-based inactivators to treat severe acute respiratory syndrome (SARS) by inhibiting the SARS 3CL protease of the SARS-CoV-1 virus.[24]

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

[edit]

Media related to Benzotriazole at Wikimedia Commons

  1. ^ a b 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. ^ a b c 1H-Benzotriazole Archived September 27, 2007, at the Wayback Machine, SRC PhysProp Database
  3. ^ a b 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. ^ a b c 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. ^ "Benzotriazole - Chemical Supplier Distributor Chemceed".
  10. ^ 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.
  11. ^ 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.
  12. ^ Sease, Catherine (May 1978). "Benzotriazole: A Review for Conservators". Studies in Conservation. 2. 23 (2): 76–85. doi:10.2307/1505798. JSTOR 1505798.
  13. ^ a b 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.
  14. ^ 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.
  15. ^ 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.
  16. ^ 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.
  17. ^ 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.
  18. ^ 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.
  19. ^ 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.
  20. ^ 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.
  21. ^ 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.
  22. ^ 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.
  23. ^ 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.
  24. ^ Kale, Raju R.; Virendra Prasad; Prabhu P. Mohapatra; Vinod K. Tiwari (6 March 2010). "Recent developments in benzotriazole methodology for construction of pharmacologically important heterocyclic skeletons". Monatsh Chemistry. 141 (11): 1159–1182. doi:10.1007/s00706-010-0378-1. S2CID 93911988.
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