15N NMR study of azo-hydrazo tautomerism: Past and present
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F62690094%3A18470%2F23%3A50019968" target="_blank" >RIV/62690094:18470/23:50019968 - isvavai.cz</a>
Result on the web
<a href="https://www.sciencedirect.com/science/article/pii/S014372082200818X" target="_blank" >https://www.sciencedirect.com/science/article/pii/S014372082200818X</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.dyepig.2022.110896" target="_blank" >10.1016/j.dyepig.2022.110896</a>
Alternative languages
Result language
angličtina
Original language name
15N NMR study of azo-hydrazo tautomerism: Past and present
Original language description
5N NMR data (1J(15N, 1H) coupling constants and 15N chemical shifts) seem to be the most suitable ones to characterize azo-hydrazo tautomerism quantitatively. The reason is that nitrogen atoms of –Ndouble bondN−/−NH-N = fragments are directly involved in azo-hydrazo equilibrium.First data was measured and published in 1970 and 15N selectively enriched compounds had to be prepared since electro magnets were used in NMR spectrometers at that time providing very low resonance frequencies (from 60 to 100 MHz for protons) and have had, consequently, very low sensitivity. Moreover, a choice of 15N enriched 15N anilines was very limited and these compounds were relatively very expensive.At present, the situation is completely different. There has been a huge increase of NMR spectrometer frequencies used for measurement of NMR spectra and even routinely used NMR spectrometers having 400–600 MHz proton frequencies are sufficiently sensitive to provide 1J(15N, 1H) coupling constants and 15N chemical shifts at the natural abundance level of 15N. Inverse detection of resonances is now routinely used. The lower magnetogyric ratio of appropriate nucleus the higher signal enhancement is achieved: this is the very case of the 15N isotope. Theoretical enhancement factor obtained for inverse detection of 15N compared with direct one is ca 300! Application of cryoprobes where electronics is chilled either by liquid nitrogen or even liquid helium reducing electric noise allows to reduce time of accumulation from 8 to 16 times!Some representative examples are presented both from past to present demonstrating the fact that thorough analyses of NMR spectra allow determining the proper constitutions of compounds studies and excluding the wrong ones.
Czech name
—
Czech description
—
Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10401 - Organic chemistry
Result continuities
Project
—
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Dyes and pigments
ISSN
0143-7208
e-ISSN
1873-3743
Volume of the periodical
209
Issue of the periodical within the volume
B
Country of publishing house
GB - UNITED KINGDOM
Number of pages
7
Pages from-to
"Article Number: 110896"
UT code for WoS article
000913167600004
EID of the result in the Scopus database
2-s2.0-85142311251