研究目的
The objective of the present work is to use Raman spectroscopy for characterizing, the fate of phenyl-derivatives, from phenyl-amines to aryl-diazonium derivatives (ADD).
研究成果
The work consisted in a Raman characterization of synthesized diazonium salts, comparing them with Raman spectra provided for amines. Raman investigation of synthesized diazonium salts confirmed the stretching of the N≡N bond in the expected spectral range of 2285-2305 cm-1. The disappearance of the H-N-(ring) symmetric stretching observed in the range 3299-3361 cm-1 for the primary amines, is another evidence of the effectiveness of salt synthesis. Moreover, our results indicate that the very strong band related to the combination of both CH in-plane bending for mono- and para-substituted benzenes as well as C-N stretching in the range 1073-1080 cm-1, constitutes an actual spectral signature of the phenyl-derivatives stemming from diazonium salts.
研究不足
The study focused on the characterization of phenyl-derivatives from primary amines to diazonium salts using Raman spectroscopy. The influence of the substituent located in the para-position was discussed, but the mesomeric effect induced by electron-donating groups (+M) was not investigated.
1：Experimental Design and Method Selection:
The study involved the synthesis of four aryl-diazonium derivatives (ADD) from their corresponding amines and their characterization using Raman spectroscopy. DFT calculations were also performed to support the experimental findings.
2：Sample Selection and Data Sources:
Four ADD were synthesized: benzene diazoniumtetrafluoroborate (DS), 4-decyl benzene diazoniumtetrafluoroborate (DS-C10H21), 4-carboxybenzene diazoniumtetrafluoroborate (DS-COOH), and 4-(aminoethyl) benzene diazoniumtetrafluoroborate (DS-(CH2)2NH2).
3：2).
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Raman measurements were recorded on pure chemicals with a Labram HR800 Raman microspectrometer (HORIBA Jobin Yvon SAS). A robust laser diode at 691 nm (Ondax) was used. NMR measurements were recorded using a Bruker Avance III 400 MHz instrument.
4：Experimental Procedures and Operational Workflow:
Diazonium salts were obtained by oxidation of the corresponding aryl-amine at 0°C and using sodium nitrite. Raman measurements were recorded on pure chemicals with a Labram HR800 Raman microspectrometer.
5：Data Analysis Methods:
The vibrational wavenumbers and normal modes were calculated within their harmonic approximation. A scaling factor of 0.976 was chosen on the basis of previously published work.
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