The NO2 itself is a chromophore, i.e. it is a color-bearing group so it imparts color. For example, benzene is colorless & upon nitration “using HNO3 &H2SO4”, nitrobenzene is obtained. This product is pale yellow.
Assume that “an increase” in color is desired, then an auxochrome (e.g. –OH, -NH2, -CHO) is required to be present in the molecules. For example, phenol is a colorless acidic liquid which has –OH group. When phenol is nitrated by dilute HNO3, it gives 2 products: o-nitrophenol & p-nitrophenol. Both products have deep yellow color & they are separable. In this case, the molecules will have extended conjugation system. A conjugated system is a chromophore “such as what is found in beta-carotene or lycopene”.
Your research is a fertile one since one can head to many possibilities. You can nitrate the fatty acids or hydrate them & then nitrate. You can look for a way to attach an aldehyde group plus a nitro group or an amino group plus a nitro group on the fatty acids… I think this work will be a lengthy one but it is worth it.
Dr Sasho
I think answer by Mr Nizar is on the same line as i wrote. Gas itself is coloring . And in addition to it whe it reacts with fatty acid?, products may be colored.
Thank you very much for your kind answers, I really apprecitae that. Of course that NO2 groups are chromophore (and also nitro- compounds especially in molecules with conjugation), that is a widely known fact in the chemical sciences community. What I actually need is a prove (published articles) where nitrogen dioxide reacts with unsaturated fatty acids at room temperature and obtaining colored nitro- compounds. I especially need the possible mechanisms that are describing these kinds of reactions. Thank you once again.
Best regards,
Sasho
Some of our Research Gate colleagues added their publications to the RG site.
Here are 2 examples hoping that they are useful to your work.
https://www.researchgate.net/publication/13395142_Nitration_of_Unsaturated_Fatty_Acids_by_Nitric_Oxide Derived_Reactive_Nitrogen_Species_Peroxynitrite_Nitrous_Acid_Nitrogen_Dioxide_and_Nitronium_Ion
https://www.researchgate.net/publication/23987939_Convergence_of_Nitric_Oxide_and_Lipid_Signaling_Anti-Inflammatory_Nitro-Fatty_Acids
Article Nitration of Unsaturated Fatty Acids by Nitric Oxide-Derived...
Article Convergence of Nitric Oxide and Lipid Signaling: Anti-Inflam...
1=Rate-Determining Step in the NOx Reduction Mechanism on BaY Zeolites and the Importance of Long-Range Lattice Effects
Xiaoying Bao, Chun-Yi Sung, Randall Q. Snurr*, and Linda J. Broadbelt*
Department of Chemical and Biological Engineering and Institute for Catalysis in Energy Processes, Northwestern University, Evanston, Illinois 60208, United States
ACS Catal., 2012, 2 (3), pp 350–359
2=Theoretical study of the reaction mechanism and kinetics of
low-molecular-weight atmospheric aldehydes (C1eC4) with NO2
Yuemeng Ji a
, Yanpeng Gao a,b
, Guiying Li a
, Taicheng An a,*
a State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry,
Chinese Academy of Sciences, Guangzhou 510640, China
bGraduate School of Chinese Academy of Sciences, Beijing 100049, China
Atmospheric Environment 54 (2012) 288e295
3=Kinetics of Several Oxygenated Carbon-Centered Free Radical Reactions with NO2
Matti P. Rissanen*†‡, Suula L. Arppe†, and Raimo S. Timonen†
† Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
‡ Division of Atmospheric Sciences, Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki, Finland
J. Phys. Chem. A, 2013, 117 (19), pp 3902–3908
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