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Comparison of Functionalized Lithium Dihydrobis(azolyl)borates with Their Corresponding Azolates as Environmentally Friendly Red Pyrotechnic Coloring Agents
Author(s) -
Dufter Alicia M. W.,
Klapötke Thomas M.,
Rusan Magdalena,
Schweiger Alexander,
Stierstorfer Jörg
Publication year - 2020
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202000427
Subject(s) - boron , lithium (medication) , oxidizing agent , chemistry , lithium borate , strontium , inorganic chemistry , environmentally friendly , nitro , organic chemistry , medicine , ecology , borate glass , biology , endocrinology , alkyl
The recent awareness of the impact of strontium on health has stimulated research efforts on lithium‐based red pyrotechnic colorants. We have previously shown lithium dihydrobis(azolyl)borates to be promising candidates due to their favorable adjustment to a reductive and low‐temperature flame atmosphere. These compounds are assumed to be sufficiently stable only if the pK a values of the heterocycles are between 5 and 20. Apart from their acidities, functionalization of 1 H ‐tetrazole and 1 H ‐pyrazole with nitro or amino groups, respectively, tailors the oxygen balances of the resulting Lewis acid base adducts to enhance the fuel‐rich flame environment or to make them oxidizing agents. This work determines whether the lithium salts of dihydrobis(3‐nitropyrazol‐1‐yl)borate and dihydrobis(5‐aminotetrazol‐1‐yl)borate are suitable replacements for strontium‐containing color imparters. Furthermore, the influence of potentially green‐light‐producing boron is evaluated by comparing the emissions of the lithium borates and the corresponding lithium azolates.