scholarly journals UV radiation and the reaction between ammonium and thiocyanate under prebiotic chemistry conditions

2010 ◽  
Vol 75 (10) ◽  
pp. 1381-1389 ◽  
Author(s):  
Santana de ◽  
Leidimara Pelisson ◽  
Diogo Janiaski ◽  
Cássia Zaia ◽  
Dimas Zaia
Keyword(s):  
Uv Radiation ◽  
Prebiotic Chemistry ◽  
Ammonium Thiocyanate ◽  
Nitrogen Atmosphere ◽  
Primitive Earth ◽  
Ph Values ◽  
Ft Ir ◽  
Uv Lamp ◽  
Hydrolysis Of ◽  
Ft Ir Spectroscopy

The reaction between ammonium and thiocyanate under prebiotic chemistry conditions was studied using FT-IR spectroscopy. Ammonium thiocyanate (1.0 10-3 mol L-1) was dissolved in sodium chloride solution (28.57 g L-1) at two different pH values (5.30 and 7.20). FT-IR results showed that it was possible that some compound that resembles dithiooxamides was synthesized when samples of ammonium thiocyanate were exposed to UV radiation under a regular atmosphere, as UV radiation in the presence of oxygen leads to the formation of perchlorate ions (ClO4-) due to the presence of Cl- ions as well. After acid hydrolysis of the samples of ammonium thiocyanate irradiated under a nitrogen atmosphere, yellow and white compounds were obtained, which could not be identified. These results were different from those reported in the literature, where other authors found methionine. However, they used higher concentrations of ammonium thiocyanate and a different type of UV lamp. On the other hand, in the present study, a lower concentration of ammonium thiocyanate was used, which probably resembled more the concentration of ammonium thiocyanate of primitive earth.

Hydrolysis of Titanium Tetrabutoxide. Study by FT-IR Spectroscopy

1999 ◽  
Vol 32 (2) ◽  
pp. 289-304 ◽  
Author(s):  
M. J. Velasco ◽  
F. Rubio ◽  
J. Rubio ◽  
J. L. Oteo
Keyword(s):  
Ir Spectroscopy ◽  
Ft Ir ◽  
Titanium Tetrabutoxide ◽  
Hydrolysis Of ◽  
Ft Ir Spectroscopy

scholarly journals Adsorption of nicotine from aqueous solutions on montmorillonite and acid-modified montmorillonite

2019 ◽  
Vol 51 (1) ◽  
pp. 93-100
Author(s):  
Irena Ilic ◽  
Natasa Jovic-Jovicic ◽  
Predrag Bankovic ◽  
Zorica Mojovic ◽  
Davor Loncarevic ◽  
...  
Keyword(s):  
Isotherm Model ◽  
Kinetics Of Adsorption ◽  
Nicotine Concentration ◽  
Ph Values ◽  
Modified Montmorillonite ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Kinetics Of ◽  
Ft Ir Spectroscopy

Montmorillonite (Mt) and acid modified montmorillonite (MtA) were tested as nicotine adsorbents. The samples were characterized using FT-IR spectroscopy and low temperature nitrogen physisorption. Nicotine adsorption was performed with respect to contact time, pH and initial nicotine concentration. The kinetics of adsorption obeyed the pseudo-second-order kinetics. The optimal pH values for nicotine adsorption were 6 and 9 for Mt and MtA, respectively. The isotherms related to adsorption on Mt at pH = 6 and 9 as well as for MtA at pH=6 were best fitted with Sips isotherm model, while adsorption onto MtA at pH=9 obeyed Langmuir isotherm model.

scholarly journals Synthesis of Biopolymers by Condensed Histidine Imide Derivatives with Some Acid Anhydride and Their Crosslink with Acrylonitrite

2014 ◽  
Vol 5 (1) ◽  
pp. 27-41
Author(s):  
Dr. Firyal. M.A ◽  
Assel K. M.
Keyword(s):  
Chemical Resistance ◽  
Basic Medium ◽  
Direct Polycondensation ◽  
Visible Spectroscopy ◽  
Bioactive Polymers ◽  
Ph Values ◽  
Ft Ir ◽  
Rate Of Hydrolysis ◽  
Uv Visible ◽  
Hydrolysis Of

Histidine as known amino acid was converted to its acid chloride [C1] with thionyl chloride at 0 oC, then reacted with ammonia, the corresponding imide-diamine [C2] was obtained, and then condensed with maleic or methylnadic anhydride. The two novel condensed polymers [C3, C4] were obtained with highly conversion percentage and modified to crosslinked polymers [C5, C6] with acrylonitrile monomer through vinylic group by free radical polymerization. The physical properties of all prepared polymers were studied and characterized by 1H-NMR, FT-IR and UV-visible spectroscopy. The swelling % was calculated. The new Polymers [C3, C4], were synthesized by direct polycondensation to give the new bioactive polymers. The rate of hydrolysis of the prepared polymers was studied in different pH values at 37 oC. Howeve, the crosslinked biopolymers [C5, C6] indicated much more chemical resistance than [C3, C4], and the sustained release was observed as good results in basic medium.

scholarly journals Dihydrogen Bonds in Salts of Boron Cluster Anions [BnHn]2− with Protonated Heterocyclic Organic Bases

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 330 ◽  
Author(s):  
Varvara V. Avdeeva ◽  
Anna V. Vologzhanina ◽  
Elena A. Malinina ◽  
Nikolai T. Kuznetsov
Keyword(s):  
Cluster Anions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Boron Cluster ◽  
Organic Bases ◽  
Dihydrogen Bonds ◽  
Reaction Solution ◽  
Ft Ir ◽  
Hydrolysis Of ◽  
Ft Ir Spectroscopy

Dihydrogen bonds attract much attention as unconventional hydrogen bonds between strong donors of H-bonding and polyhedral (car)borane cages with delocalized charge density. Salts of closo-borate anions [B10H10]2− and [B12H12]2− with protonated organic ligands 2,2’-dipyridylamine (BPA), 1,10-phenanthroline (Phen), and rhodamine 6G (Rh6G) were selectively synthesized to investigate N−H...H−B intermolecular bonding. It was found that the salts contain monoprotonated and/or diprotonated N-containing cations at different ratios. Protonation of the ligands can be implemented in an acidic medium or in water because of hydrolysis of metal cations resulting in the release of H3O+ cations into the reaction solution. Six novel compounds were characterized by X-ray diffraction and FT-IR spectroscopy. It was found that strong dihydrogen bonds manifest themselves in FT-IR spectra that allows one to use this technique even in the absence of crystallographic data.

scholarly journals In Vitro Study of MefenamateStarch as Drug Delivery System

2013 ◽  
Vol 10 (3) ◽  
pp. 954-964
Author(s):  
Baghdad Science Journal
Keyword(s):  
In Vitro Study ◽  
Controlled Drug Release ◽  
Gastric Fluid ◽  
Molar Ratio ◽  
Ph Values ◽  
Ft Ir ◽  
Uv Visible ◽  
The Stability ◽  
Hydrolysis Of

Mefenamic acid was esterified with starchwith[1:1] Molar ratio, as drug substituted with natural polymer, to prolongthe period of hydrolysis of drug polymer with other advantages. The new prodrug starch was characterized by FT-IR and UV-Visible and 1H-NMR spectroscopies. The physical properties were studied and controlled drug release was studied in different pH values at 37oC. The stability of drug was carried out by measuring the absorbance of mefenamic starch which hydrolyzed in HCl solution of pH 1.1 (artificial gastric fluid) and phosphate buffer of pH 7.4 (simulating intestinal fluid SIF) at 37oC for several days. The thermal analysis such as DSC was studied.

Consequences of Fluoride Incorporation on Properties of Apatites

2006 ◽  
Vol 309-311 ◽  
pp. 697-700 ◽  
Author(s):  
Racquel Z. LeGeros ◽  
Dindo Q. Mijares ◽  
Fang Yao ◽  
John P. LeGeros ◽  
T. Bromage ◽  
...  
Keyword(s):  
Crystal Size ◽  
Chemical Properties ◽  
Calcium Deficiency ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Lower Solubility ◽  
Ft Ir ◽  
Hydrolysis Of ◽  
Ft Ir Spectroscopy

Fluoride, when incorporated in the apatite, stabilizes the structure. The purpose of this study was to determine the consequences of fluoride (F) substitution on the physico-chemical properties of apatites. F-containing apatites were prepared by precipitation or by hydrolysis of CaHPO4 in solutions containing different F concentrations and characterized using x-ray diffraction, FT-IR spectroscopy, scanning electron microscopy, thermogravimetry and chemical analyses. Results showed that F incorporation have the following effects: (a) decrease in a-axis dimension, (b) increase in crystal size and thickness, (c) decrease in calcium deficiency, and (d) lower solubility.

Thermal Behaviour of Candesartan Active substance and in pharmaceutical compounds

2017 ◽  
Vol 68 (8) ◽  
pp. 1895-1902
Author(s):  
Ioana Cristina Tita ◽  
Eleonora Marian ◽  
Bogdan Tita ◽  
Claudia Crina Toma ◽  
Laura Vicas
Keyword(s):  
Thermal Behaviour ◽  
Active Substance ◽  
Pharmaceutical Research ◽  
Pharmaceutical Product ◽  
Nitrogen Atmosphere ◽  
Pure Substance ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ft Ir

Thermal analysis is one of the most frequently used instrumental techniques in the pharmaceutical research, for the thermal characterization of different materials from solids to semi-solids, which are of pharmaceutical relevance. In this paper, simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) were used for characterization of the thermal behaviour of candesartan cilexetil � active substance (C-AS) under dynamic nitrogen atmosphere and nonisothermal conditions, in comparison with pharmaceutical product containing the corresponding active substance. It was observed that the commercial samples showed a different thermal profile than the standard sample, caused by the presence of excipients in the pharmaceutical product and to possible interaction of these with the active substance. The Fourier transformed infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRPD) were used as complementary techniques adequately implement and assist in interpretation of the thermal results. The main conclusion of this comparative study was that the TG/DTG and DSC curves, together with the FT-IR spectra, respectively X-ray difractograms constitute believe data for the discrimination between the pure substance and pharmaceutical forms.

scholarly journals The Preparation, Thermal Properties, and Fire Property of a Phosphorus-Containing Flame-Retardant Styrene Copolymer

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 127 ◽  
Author(s):  
Yu Sun ◽  
Yazhen Wang ◽  
Li Liu ◽  
Tianyuan Xiao
Keyword(s):  
Thermal Properties ◽  
Thermogravimetric Analysis ◽  
Flame Retardant ◽  
Oxygen Index ◽  
Limiting Oxygen Index ◽  
Chemical Structures ◽  
1H Nuclear Magnetic Resonance ◽  
Phosphorus Containing ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

A 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) acrylate, (6-oxidodibenzo [c,e][1,2] oxaphosphinin-6-yl) methyl acrylate (DOPOAA), has been prepared. Copolymers of styrene (St) and DOPOAA were prepared by emulsion polymerization. The chemical structures of copolymers containing levels of DOPOAA were verified using Fourier transform infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. The thermal properties and flame-retardant behaviors of DOPO-containing monomers and copolymers were observed using thermogravimetric analysis and micro calorimetry tests. From thermogravimetric analysis (TGA), it was found out that the T5% for decomposition of the copolymer was lower than that of polystyrene (PS), but the residue at 700 °C was higher than that of PS. The results from micro calorimetry (MCC) tests indicated that the rate for the heat release of the copolymer combustion was lower than that for PS. The limiting oxygen index (LOI) for combustion of the copolymer rose with increasing levels of DOPOAA. These data indicate that copolymerization of the phosphorus-containing flame-retardant monomer, DOPOAA, into a PS segment can effectively improve the thermal stability and flame retardancy of the copolymer.

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