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Sailaja Geddam - One of the best experts on this subject based on the ideXlab platform.

  • A Diazonium Ion Cascade from the NitrosatIon of Tolazoline, An Imidazoline-Containing Drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO 2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH 2 Cl 2 as the transformatIon progresses. It nitrosates much more rapidly (50 x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxy-ethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 °C (k obs = 6.25 x 10 -5 s -1 in 0.5 M acetate buffer with a 10 * [NO 2 -] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons

  • A Diazonium Ion cascade from the nitrosatIon of tolazoline, an imidazoline-containing drug.
    Chemical research in toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Jianzheng Shi, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH2Cl2 as the transformatIon progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-( N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxyethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 degrees C ( kobs = 6.25 x 10 (-5) s (-1) in 0.5 M acetate buffer with a 10 * [NO2(-)] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons

  • a Diazonium Ion cascade from the nitrosatIon of tolazoline an imidazoline containing drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO 2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH 2 Cl 2 as the transformatIon progresses. It nitrosates much more rapidly (50 x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxy-ethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 °C (k obs = 6.25 x 10 -5 s -1 in 0.5 M acetate buffer with a 10 * [NO 2 -] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons <3 mM. Cursory examinatIon of the nitrosatIon chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.

  • a Diazonium Ion cascade from the nitrosatIon of tolazoline an imidazoline containing drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Jianzheng Shi, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH2Cl2 as the transformatIon progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-( N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxyethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 degrees C ( kobs = 6.25 x 10 (-5) s (-1) in 0.5 M acetate buffer with a 10 * [NO2(-)] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons <3 mM. Cursory examinatIon of the nitrosatIon chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.

Ajibola A Olaniyi - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis and spectroscopic characterizatIon of 4-carboxyl-2,6-dinitrophenylazohydroxynaphthalenes
    Dyes and Pigments, 2008
    Co-Authors: Olajire A Adegoke, Olakunle S Idowu, Ajibola A Olaniyi
    Abstract:

    Abstract A series of azo dyes was prepared by the reactIon of 4-carboxyl-2,6-dinitrobenzene Diazonium Ion (CDNBD) with two naphthols and three substituted naphthalene ether derivatives. UV, IR, 1 H, 13 C and 2D-NMR spectroscopy as well as mass spectral analyses were used to establish the structure of the new azo dyes. α-Naphthol and its ether gave para -substituted azo dyes while β-naphthol and its ethers provided ortho -substituted dyes. DealkylatIon of the naphthalene ether linkage was found to occur upon coupling with the Diazonium Ion, to form the corresponding naphthol in the final azo product.

  • improved colorimetric determinatIon of reserpine in tablets using 4 caboxyl 2 6 dintrobenzene Diazonium Ion cdnbd
    Tropical Journal of Pharmaceutical Research, 2007
    Co-Authors: Olajire A Adegoke, S O Idowu, Ajibola A Olaniyi
    Abstract:

    Purpose: To develop a simple, rapid and improved colorimetric method for the assay of reserpine in tablets Method: The method is based on the aromatic ring coupling of reserpine with 4-carboxyl-2,6dinitrobenzene Diazonium Ion with the consequent formatIon of an azo adduct. OptimizatIon of reactIon conditIons and validatIon were carried out and the method applied to assay of reserpine in tablets. Result: Reserpine coupled readily with CDNBD and optimizatIon of experimental conditIons showed the reactIon to be completed in 10 min at room temperature. A 1:1 drug to reagent stoichiometric ratio was obtained for the azo adduct formed. The adduct exhibited a bathochromic shift with respect to the drug and pronounced hyperchromic shift with respect to the reagent. Sample analyses were done using a colorimeter at 470 nm. The assays were linear and reproducible over the concentratIon range of 2.25 24 µg/mL. The new method was successfully applied in the assay of reserpine in tablets with a performance similar to the official (USP) spectrophotometric method (p > 0.05). This method represents a profound improvement on the previously reported colorimetric method for reserpine. ConclusIon: The method developed is rapid and could find applicatIon in in-process quality control of reserpine.

  • 4-Carboxyl-2, 6-dinitrobenzene Diazonium Ion (CDNBD): a new Diazonium for the detectIon of phenol ether homologues
    Journal of Pharmacy & Bioresources, 2006
    Co-Authors: Olajire A Adegoke, Olakunle S Idowu, Monsurat O Lawal, Ajibola A Olaniyi
    Abstract:

    Pharmaceutical phenol ethers are a heterogeneous group of compounds possessing ether linkage to an aromatic nucleus. Diazo coupling is rare with these compounds and no physicochemical method of analysis has been reported based on the reactIon of these ethers with a Diazonium Ion. The high reactivity of 4-carboxyl-2,6-dinitrobenzene Diazonium Ion (CDNBD) is therefore investigated in this work. Comparative coupling reactIon was done with two other Diazonium Ions (derived from p-nitroaniline and sulphanilic acid). Twenty-two phenol ethers were selected for evaluatIon of their reactivity with the three Diazonium Ions. Such ethers consist of those with naphthalenes, indole and bridged rings. Spot tests were used to establish coupling at room and elevated temperatures. Visual inspectIon and thin layer chromatographic (TLC) analysis of the reactIon mixture provided evidence of coupling or otherwise. UV-VIS absorptIon spectra were used to characterize brightly coloured adducts, as a preliminary test for the estimatIon of these ethers by spectrophotometry. Of all the ethers screened, fourteen gave instant and distinct colour from CDNBD while seven of these gave colours of deeper intensity at elevated temperature. Only three of the ethers gave instant colour with diazotized p-nitroaniline while one compound gave instant colour with diazotized sulphanilic acid. UV absorptIon spectral analysis reveals the superiority of CDNBD for the detectIon and possible estimatIon of these ethers. CDNBD is shown to be a highly reactive areneDiazonium Ion with the possibility of finding usefulness for the determinatIon of phenol ethers by ultraviolet/visible spectrophotometry and precolumn derivatizatIon in high performance liquid chromatographic (HPLC) analysis. Journal of Pharmacy & Bioresources Vol. 2(2) 2005: 146-161

  • rapid colorimetric assay of diclofenac sodium tablets using 4 carboxyl 2 6 dinitrobenzene Diazonium Ion cdnbd
    Pakistan Journal of Pharmaceutical Sciences, 2006
    Co-Authors: Olakunle S Idowu, Olajire A Adegoke, Bolaji A Oderinu, Ajibola A Olaniyi
    Abstract:

    This study describes a novel simple, rapid and sensitive colorimetric assay method for diclofenac sodium tablets. The method is based on a simple aromatic ring derivatizatIon technique using newly developed 4-carboxyl-2, 6-dinitrobenzeneDiazonium Ion (CDNBD) as chromogenic derivatizing reagent with subsequent formatIon of an azo dye. The diazo coupling reactIon was carried out between CDNBD and diclofenac. OptimizatIon studies for time and temperature was conducted using the method of steepest ascent. The UV absorptIon spectrum was recorded and the stoichiometric ratio for the drug and reagent was done by continuous variatIon method. Optimal calibratIon range was fixed (1-way ANOVA) and then the method was applied to dosage form analysis. Comparison of dosage form analysis was done with the BP HPLC method. The diazo coupling reactIon is very fast and optimizatIon studies established an optimal reactIon immediately after mixing the reactIon mixture in a vortex mixer for 10 sec. A new absorptIon maximum (lambdamax) at 470 nm was selected as analytical wavelength. The assays were linear over 1.35-10.8 microg/ml of diclofenac and the reactIon required a 2:1 reagent/drug stoichiometric ratio. The new method has a low limit of detectIon of 0.27 microg/ml, and was reproducible over a three-day assessment of precisIon (RSD 2.31%). The method has been successfully applied to the assay of diclofenac sodium slow-release tablets and found to be of equivalent accuracy (p>0.05) with the official (B.P 1998) HPLC method. The new method has distinct advantages of speed, simplicity, sensitivity, and more affordable instrumentatIon and could find applicatIon as a rapid analytical method for diclofenac sodium tablets.

  • Novel colorimetric assay of indomethacin using 4-carboxyl-2,6-dinitrobenzene Diazonium Ion.
    Acta pharmaceutica (Zagreb Croatia), 2006
    Co-Authors: Olajire A Adegoke, Olakunle S Idowu, Ajibola A Olaniyi
    Abstract:

    A simple, sensitive and direct colorimetric method for the determinatIon of indomethacin either in pure form or in capsules has been developed. The method is based on the diazo coupling reactIon between indomethacin and a highly reactive areneDiazonium Ion, 4-carboxyl-2,6-dinitrobenzene Diazonium Ion, with the consequent formatIon of an azo dye. The reactIon is fast and gave an orange azo dye in ethyl acetate. The assay was carried out at 470 nm and the azo adduct was stable for three hours. Beer’s law is obeyed in the concentratIon range of 3.3–11 µg mL –1 of indomethacin. OptimizatIon studies established an optimum reactIon time of 20 minutes at 30 °C and the drug-to-reagent ratio of 1:2 for optimal detector response. The method developed has a low limit of detectIon of 0.90 µg mL –1 and is precise (RSD 2.3%). The new method has been successfully applied to the determinatIon of indomethacin in capsules and the method is of equivalent accuracy as the official (BP) spectrophotometric method. The new method could find applicatIon as a simple analytical method for the assay of indomethacin in capsules.

John C. Jewett - One of the best experts on this subject based on the ideXlab platform.

  • Suzuki Coupling of Protected Aryl Diazonium Ions: Expanding the Knowledge of Triazabutadiene Compatible ReactIons.
    Organic letters, 2021
    Co-Authors: Abigail J. Shepard, Julia Alma Townsend, Christopher Foley, Christopher Hulme, Michael T. Marty, John C. Jewett
    Abstract:

    Aryl Diazonium Ions are important in synthesis and chemical biology, and the acid-labile triazabutadiene can protect this handle for future use. We report a Suzuki coupling strategy that is compatible with the triazabutadiene scaffold, expanding the scope of synthetically available triazabutadienes. Shown herein, the triazabutadiene scaffold remains intact and reactive after coupling, as demonstrated by releasing the aryl Diazonium Ion to label a tyrosine-rich model protein.

  • Cu-Click Compatible Triazabutadienes To Expand the Scope of Aryl Diazonium Ion Chemistry
    Organic letters, 2016
    Co-Authors: Brandon M. Cornali, Flora W. Kimani, John C. Jewett
    Abstract:

    Triazabutadienes can be used to readily generate reactive aryl Diazonium Ions under mild, physiologically relevant conditIons. These conditIons are compatible with a range of functIonalities that do not tolerate traditIonal aryl Diazonium Ion generatIon. To increase the utility of this aryl Diazonium Ion releasing chemistry an alkyne-containing triazabutadiene was synthesized. The copper-catalyzed azide–alkyne cycloadditIon (“Cu-click”) reactIon was utilized to modify the alkyne-containing triazabutadiene and shown to be compatible with the nitrogen-rich triazabutadiene. One of the triazole products was tethered to a fluorophore, thus enabling the direct fluorescent labeling of a model protein.

  • Cu-Click Compatible Triazabutadienes To Expand the Scope of Aryl Diazonium Ion Chemistry
    2016
    Co-Authors: Brandon M. Cornali, Flora W. Kimani, John C. Jewett
    Abstract:

    Triazabutadienes can be used to readily generate reactive aryl Diazonium Ions under mild, physiologically relevant conditIons. These conditIons are compatible with a range of functIonalities that do not tolerate traditIonal aryl Diazonium Ion generatIon. To increase the utility of this aryl Diazonium Ion releasing chemistry an alkyne-containing triazabutadiene was synthesized. The copper-catalyzed azide–alkyne cycloadditIon (“Cu-click”) reactIon was utilized to modify the alkyne-containing triazabutadiene and shown to be compatible with the nitrogen-rich triazabutadiene. One of the triazole products was tethered to a fluorophore, thus enabling the direct fluorescent labeling of a model protein

Richard N. Loeppky - One of the best experts on this subject based on the ideXlab platform.

  • A Diazonium Ion Cascade from the NitrosatIon of Tolazoline, An Imidazoline-Containing Drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO 2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH 2 Cl 2 as the transformatIon progresses. It nitrosates much more rapidly (50 x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxy-ethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 °C (k obs = 6.25 x 10 -5 s -1 in 0.5 M acetate buffer with a 10 * [NO 2 -] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons

  • A Diazonium Ion cascade from the nitrosatIon of tolazoline, an imidazoline-containing drug.
    Chemical research in toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Jianzheng Shi, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH2Cl2 as the transformatIon progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-( N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxyethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 degrees C ( kobs = 6.25 x 10 (-5) s (-1) in 0.5 M acetate buffer with a 10 * [NO2(-)] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons

  • a Diazonium Ion cascade from the nitrosatIon of tolazoline an imidazoline containing drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO 2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH 2 Cl 2 as the transformatIon progresses. It nitrosates much more rapidly (50 x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxy-ethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 °C (k obs = 6.25 x 10 -5 s -1 in 0.5 M acetate buffer with a 10 * [NO 2 -] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons <3 mM. Cursory examinatIon of the nitrosatIon chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.

  • a Diazonium Ion cascade from the nitrosatIon of tolazoline an imidazoline containing drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Jianzheng Shi, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH2Cl2 as the transformatIon progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-( N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxyethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 degrees C ( kobs = 6.25 x 10 (-5) s (-1) in 0.5 M acetate buffer with a 10 * [NO2(-)] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons <3 mM. Cursory examinatIon of the nitrosatIon chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.

Charles L. Barnes - One of the best experts on this subject based on the ideXlab platform.

  • A Diazonium Ion Cascade from the NitrosatIon of Tolazoline, An Imidazoline-Containing Drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO 2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH 2 Cl 2 as the transformatIon progresses. It nitrosates much more rapidly (50 x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxy-ethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 °C (k obs = 6.25 x 10 -5 s -1 in 0.5 M acetate buffer with a 10 * [NO 2 -] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons

  • A Diazonium Ion cascade from the nitrosatIon of tolazoline, an imidazoline-containing drug.
    Chemical research in toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Jianzheng Shi, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH2Cl2 as the transformatIon progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-( N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxyethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 degrees C ( kobs = 6.25 x 10 (-5) s (-1) in 0.5 M acetate buffer with a 10 * [NO2(-)] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons

  • a Diazonium Ion cascade from the nitrosatIon of tolazoline an imidazoline containing drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO 2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH 2 Cl 2 as the transformatIon progresses. It nitrosates much more rapidly (50 x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxy-ethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 °C (k obs = 6.25 x 10 -5 s -1 in 0.5 M acetate buffer with a 10 * [NO 2 -] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons <3 mM. Cursory examinatIon of the nitrosatIon chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.

  • a Diazonium Ion cascade from the nitrosatIon of tolazoline an imidazoline containing drug
    Chemical Research in Toxicology, 2008
    Co-Authors: Richard N. Loeppky, Charles L. Barnes, Jianzheng Shi, Sailaja Geddam
    Abstract:

    Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformatIon when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are ratIonalized as arising from a cascade of reactive Diazonium Ions. N-Nitrosotolazoline can be isolated from the nitrosatIon reactIon in good yield when the mixture is extracted with CH2Cl2 as the transformatIon progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-( N-nitroso-2-imidazolinyl)benzylidene]hydroxylamine, which can also be produced in good yield from the reactIon of tolazoline with isopropyl nitrite. At low substrate and nitrite concentratIons, the main reactIon products are N-nitrosotolazoline, its decompositIon product N-2-hydroxyethylphenylacetamide, the above-mentIoned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosatIon rate in three buffer systems has been determined at pH 3.4 and 37 degrees C ( kobs = 6.25 x 10 (-5) s (-1) in 0.5 M acetate buffer with a 10 * [NO2(-)] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formatIon at nitrite concentratIons <3 mM. Cursory examinatIon of the nitrosatIon chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.

  • Crystal Structure of the Explosive Parent Benzyne Precursor: 2-Diazoniobenzenecarboxylate Hydrate
    Chemische Berichte, 1993
    Co-Authors: Christopher J. Horan, Charles L. Barnes, Rainer Glaser
    Abstract:

    The structure of the highly unstable benzyne precursor 2-diazoniobenzenecarboxylate (3) has been determined by single-crystal X-ray diffractIon. The structure is discussed in comparison to ab initio results for several conformers of 3, related aromatic Diazonium Ions, and phenyl catIon and also to crystal structures of simple Diazonium Ion salts and of benzoates. Structural features and characteristic distortIons are related to the electron density distributIons and to intra- and intermolecular interactIons between the neighboring functIonal groups.