Spectroscopic studies of the electrophilic activation of amides with triflic anhydride and pyridine

2001 ◽  
Vol 79 (11) ◽  
pp. 1694-1703 ◽  
Author(s):  
André B Charette ◽  
Michel Grenon
Keyword(s):  
Spectroscopic Studies ◽  
Initial Reaction ◽  
Spectroscopic Techniques ◽  
Nmr Study ◽  
Acidic Conditions ◽  
Electrophilic Activation ◽  
Tertiary Amides ◽  
Secondary Amides

The reaction of amides with trifluoromethanesulfonic (triflic) anhydride in the presence of pyridine was thoroughly investigated by NMR spectroscopic techniques. Different pyridinium intermediates were generated from secondary amides, tertiary amides with enolizable protons, and tertiary amides lacking enolizable protons. It was found that the actual triflating reagent is N-(trifluoromethylsulfonyl)pyridinium triflate 11 which is formed by the initial reaction of triflic anhydride with pyridine. The alcoholysis of these intermediates yields O-alkyliminium ethers which can then be easily hydrolyzed under mild acidic conditions to the corresponding esters.Key Words: amides, triflic anhydride, pyridinium intermediates, NMR study.

Synthesis and photophysical studies of non-covalently linked porphyrin dyads and triads

2007 ◽  
Vol 11 (02) ◽  
pp. 85-94 ◽  
Author(s):  
Punidha Sokkalingam ◽  
Sangita Santra ◽  
Ravikanth Mangalampalli
Keyword(s):  
Ring Current ◽  
Singlet State ◽  
Photophysical Properties ◽  
Spectroscopic Techniques ◽  
Current Effect ◽  
H Nmr ◽  
Nmr Study ◽  
Photophysical Studies ◽  
Ring Current Effect ◽  
Covalently Linked

Non-covalent porphyrin dyads and triads containing N 3 S porphyrin and RuN 4 porphyrin subunits were synthesized by treating meso-pyridyl-21-thiaporphyrin with RuTPP(CO)(EtOH) in toluene at refluxing temperature. The dyads and triads were characterized by various spectroscopic techniques and the properties were compared with the reported dyad containing N 4 and RuN 4 porphyrin subunits. The 1 H NMR study of dyads and triads indicated that the inner NH , β-heterocycle and meso-pyridyl protons of the 21-thiaporphyrin unit experienced large upfield shifts as compared to their corresponding monomeric meso-pyridyl-21-thiaporphyrins due to the ring current effect of RuTPP(CO) subunit. The singlet state photophysical properties of N 3 S porphyrin subunit in dyads and triads showed 50-80% quenching of fluorescence as observed previously for N 4- RuN 4 dyad due to heavy ruthenium ion(s).

Spectroscopic studies on the selective inclusion of amphiphilised porphyrin derivatives in micellar phases

2003 ◽  
Vol 07 (03) ◽  
pp. 181-190 ◽  
Author(s):  
Donato Monti ◽  
Alessandra Pastorini ◽  
Mariano Venanzi ◽  
Stefano Borocci ◽  
Giovanna Mancini
Keyword(s):  
Catalytic Activity ◽  
Aqueous Solutions ◽  
Spectroscopic Studies ◽  
Spectroscopic Techniques ◽  
Porphyrin Derivatives ◽  
Brij 35 ◽  
Porphyrin Macrocycle ◽  
Micellar Aggregates

The inclusion behavior of [5-(4-(3-trimethylammonium)propyloxyphenyl)-10,15,20-tryphenylporphyrin] chloride( 1H 2), 2-[2-(2-(4-(10,15,20-triphenyl-5-porphyrinyl)-phenoxy)-ethoxy)ethoxy]ethanol (2 H 2), and their Mn ( III ) derivatives, 1MnCl and 2MnCl, respectively, in micellar phases of CTAB and Brij 35 aqueous solutions has been studied by means of several spectroscopic techniques. The results obtained show that a suitable functionalisation of the periphery of the porphyrin macrocycle influences the specificity of their binding to different micellar aggregates. This, consequently, allows for a tuning of the location and the aggregation mode of inclusion. These findings give a sound basis for the interpretation of the, earlier reported, P450 biomimetic catalytic activity featured by 1MnCl and 2MnCl in the epoxidation of some probe olefins.

scholarly journals Pseudocapacitive Behavioral Testing of Iron Vanadate Nanoparticles Synthesized by Simple Co- Precipitation Method

2019 ◽  
Vol 9 (1S3) ◽  
pp. 374-378
Keyword(s):  
Electrochemical Impedance ◽  
Impedance Analysis ◽  
Spectroscopic Studies ◽  
Precipitation Method ◽  
Spectroscopic Techniques ◽  
Electron Microscopic ◽  
Electrochemical Behaviors ◽  
X Ray ◽  
Co Precipitation ◽  
Charge Discharge

Iron vanadate nanoparticles were prepared by simple co-precipitation method. The crystal structure and elemental composition of prepared material were confirmed using X-ray Diffraction analysis and Elemental Dispersive X- ray spectroscopic analysis respectively. Surface morphology of the sample was analyzed by Scanning Electron Microscopic techniques. Optical absorption and molecular vibrations were studied by UV-Vis. absorption spectroscopy and Fourier Transform Infrared spectroscopic techniques. Electrochemical behaviors such as redox property, charge-discharge mechanism and impedance analysis were examined with cyclic voltammetry, Galvanostatic charge-discharge and electrochemical impedance spectroscopic studies.

scholarly journals Detailed Spectroscopic Studies in the Aquatic Environment Using Synchrotron Radiation

2019 ◽  
Vol 21 ◽  
pp. 185
Author(s):  
N. Moraitis ◽  
K. Vassalos ◽  
T. J. Mertzimekis ◽  
A. Godelitsas ◽  
P. Gamaletsos ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Spectroscopic Studies ◽  
Coastal Sediments ◽  
Data Sets ◽  
Spectroscopic Techniques ◽  
Metals And Metalloids ◽  
Synchrotron Facility ◽  
Institute Of Technology ◽  
Karlsruhe Institute

The important role of metals and metalloids in the aquatic environment can be studied by means of Syn- chrotron Radiation (SR)-based X-ray spectroscopic techniques. In the present work, we have performed analyses of data sets (μ–XRF, μ–XANES and μ–EXAFS), for coastal sediments and marine precipitates, obtained at the ANKA Synchrotron Facility in Karlsruhe Institute of Technology (KIT, Germany). Prelim- inary results with regard to the distribution and speciation of toxic (Hg and As) and biocompatible (Fe) metals and metalloids are presented herein. It is therefore demonstrated that Fe is easily precipitated as FeIII oxyhydroxides, most likely related to As, as well as ferrihydrite-type FeIII hydrated oxyhydroxides, whereas Hg is rather accumulated in the form of methyl-containing compounds.

scholarly journals GC-FID and NMR Spectroscopic Studies on Gamma Irradiated Walnut Lipids

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Vassilia J. Sinanoglou ◽  
Irini F. Strati ◽  
Katerina Kokkotou ◽  
Dimitra Lantzouraki ◽  
Constantinos Makris ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Irradiation Dose ◽  
Heart Diseases ◽  
Juglans Regia ◽  
Spectroscopic Studies ◽  
Protective Role ◽  
Spectroscopic Techniques ◽  
Coronary Heart Diseases

Walnuts have an excellent fatty acid profile, beneficial for coronary heart diseases. A diet rich in walnuts has shown to decrease the total and LDL cholesterol levels as well as lipoprotein levels. In this study, the effects of different doses ofγ-irradiation and different packaging conditions on proximate composition and fatty acid profile of walnuts (Juglans regiaL.) were investigated merging data from different spectroscopic techniques. Walnuts moisture, ash, fat, and protein content as well as fatty acid profile were evaluated immediately after irradiation. GC-FID results showed that SFA increased and MUFA and PUFA decreased with the increase of irradiation dose. Moreover, MUFA/SFA and PUFA/SFA ratios decreasedP<0.05compared to control samples. Furthermore, NMR spectroscopy was implemented to examine possible discrimination patterns based on irradiation dose and packaging. This approach revealed the role of PUFA decrease with the parallel increase of irradiation dose while indicating the protective role of vacuum and MAP compared to air packaging. In conclusion, at irradiation doses of up to 5 kGy, the walnuts retained the nutritional benefits of its fatty acids, in particular MUFA and PUFA. Concerning the different types of packaging, greater stability in the nuts was observed using MAP packaging.

Sign in / Sign up

Export Citation Format

Share Document