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m Changed it from saying it lowers the pKa by a million fold to saying it raises the Ka by a million fold. If the pKa changes from 9.9 to 3.4 that's a 3 fold change in the pKa and a million fold change in the Ka Tags: Visual edit Mobile edit Mobile web edit |
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Chloride salts of diazonium cation, traditionally prepared from the aniline, sodium nitrite, and [[hydrochloric acid]], are unstable at room temperature and are classically prepared at 0 – 5 °C. However, one can isolate diazonium compounds as [[tetrafluoroborate]] or [[tosylate]] salts,<ref>{{Cite journal|last1=Filimonov|first1=Victor D.|last2=Trusova|first2=Marina|last3=Postnikov|first3=Pavel|last4=Krasnokutskaya|first4=Elena A.|last5=Lee|first5=Young Min|last6=Hwang|first6=Ho Yun|last7=Kim|first7=Hyunuk|last8=Chi|first8=Ki-Whan|date=2008-09-18|title=Unusually Stable, Versatile, and Pure Arenediazonium Tosylates: Their Preparation, Structures, and Synthetic Applicability|journal=Organic Letters|language=EN|volume=10|issue=18|pages=3961–3964|doi=10.1021/ol8013528|pmid=18722457|issn=1523-7060}}</ref> which are stable solids at room temperature.<ref name="Mihelač-2021">{{cite journal | author1=Mihelač, M. |author2=Siljanovska, A. |author3=Košmrlj, J. |title=A convenient approach to arenediazonium tosylates |journal=[[Dyes Pigm.]] |year=2021 |volume=184 |pages=108726 |doi=10.1016/j.dyepig.2020.108726 |doi-access=free}}</ref> It is often preferred that the diazonium salt remain in solution, but they do tend to [[Supersaturation|supersaturate]]. Operators have been injured or even killed by an unexpected crystallization of the salt followed by its detonation.<ref name=supersat>{{cite web|url=http://www.crhf.org.uk/incident71.html|title=UK CRHF Incident Report – Supersaturated Diazonium salt causes Fatality|publisher=UK Chemical Reaction Hazards Forum|access-date=13 May 2010|archive-url=https://web.archive.org/web/20181006095115/http://www.crhf.org.uk/incident71.html|archive-date=6 October 2018|url-status=dead}}</ref>
Due to these hazards, diazonium compounds are often not isolated(not necessarily). Instead they are used ''in situ''. This approach is illustrated in the preparation of an arenesulfonyl compound:<ref>{{cite journal |journal=[[Org. Synth.]] |author= R. V. Hoffman |title= m-Trifluoromethylbenzenesulfonyl Chloride |volume= 60 |pages= 121 |year= 1981 |doi= 10.15227/orgsyn.060.0121}}</ref>
:[[File:Preparation of m-trifluoromethylbenzenesulfonyl chloride.svg|500px]]
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