Chemical Synthesis of α-Formylphenylacetic Acid, the Postulated Precursor of Tropic Acid

1981 ◽  
Vol 36 (7-8) ◽  
pp. 611-614 ◽  
Author(s):  
Georg G. Gross ◽  
Karl J. Koelen ◽  
Angelika Müller ◽  
Günter Schmidtberg
Keyword(s):  
Chemical Synthesis ◽  
Silica Gel ◽  
Aqueous Media ◽  
Organic Solution ◽  
Acid Biosynthesis ◽  
Tropic Acid ◽  
Ph Values ◽  
Biosynthetic Studies

Abstract a-Formylphenylacetic Acid, Phenylmalonic Semialdehyde, Tropic Acid Biosynthesis a-Formylphenylacetic acid, the postulated immediate precursor of tropic acid, has been synthesized by deacetalization of a-diethoxymethylphenylacetic acid in the presence of silica gel. The compound was reasonably stable in organic solution. In aqueous media, however, a pronounced lability of this semialdehyde was observed at various pH-values (t/2 = 4.5 min at pH 7.4). It is thus very unlikely that this compound can be employed successfully in biosynthetic studies.

Detection of a covalent-ionic carbinolamine intermediate in aqueous media by SDTLC on silica gel plates

2007 ◽  
Vol 20 (3) ◽  
pp. 227-230 ◽  
Author(s):  
Ana Reverdito ◽  
Mariano García ◽  
Alejandra Salerno ◽  
Oscar Locani ◽  
Isabel Perillo
Keyword(s):  
Silica Gel ◽  
Aqueous Media

scholarly journals Double-Cross-Linked Networks Based on Methacryloyl Mucin

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1706
Author(s):  
Elena Olăreț ◽  
Brîndușa Bălănucă ◽  
Andra Mihaela Onaș ◽  
Jana Ghițman ◽  
Horia Iovu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aqueous Solution ◽  
Chemical Modification ◽  
Structural Modification ◽  
Aqueous Media ◽  
Cross Linking ◽  
Ph Values ◽  
Acid Aqueous Solution ◽  
Reaction Media ◽  
Double Cross

Mucin is a glycoprotein with proven potential in the biomaterials field, but its use is still underexploited for such applications. The present work aims to produce a synthesis of methacryloyl mucin single-network (SN) hydrogels and their double-cross-linked-network (DCN) counterparts. Following the synthesis of the mucin methacryloyl derivative, various SN hydrogels are prepared through the photopolymerization of methacrylate bonds, using reaction media with different pH values. The SN hydrogels are converted into DCN systems via supplementary cross-linking in tannic acid aqueous solution. The chemical modification of mucin is described, and the obtained product is characterized; the structural modification of mucin is assessed through FTIR spectroscopy, and the circular dichroism and the isoelectric point of methacryloyl mucin is evaluated. The affinity for aqueous media of both SN and DCN hydrogels is estimated, and the mechanical properties of the systems are assessed, both at macroscale through uniaxial compression and rheology tests and also at microscale through nanoindentation tests.

scholarly journals Chemical synthesis of all-trans-β-retinoyl phosphate

1976 ◽  
Vol 159 (3) ◽  
pp. 799-801 ◽  
Author(s):  
J P Frot-Coutaz ◽  
L M de Luca
Keyword(s):  
Retinoic Acid ◽  
Chemical Synthesis ◽  
Cellulose Acetate ◽  
Silica Gel ◽  
Absorption Maximum ◽  
Ammonium Acetate ◽  
Deae Cellulose ◽  
Thin Layers ◽  
Molar Ratio ◽  
Chloroform Methanol

all-trans-β-Retinoic acid is phosphorylated to retinoyl phosphate by bis(triethylamine) phosphate with yields of 10-15%. The product is soluble in methanol and is eluted from DEAE-cellulose acetate at a concentration of 0.1M-ammonium acetate in 99% (v/v) methanol. Its phosphate/retinoic acid molar ratio is 1. Retinoyl phosphate has an absorption maximum at 360nm in methanol, whereas retinoic acid has a maximum at 350 nm. The compound is hydrolysed at pH2 and pH13 for 20 min at 37 degrees C, but is relatively stable under the same conditions at pH4, 6, 8 and 10. Retinoyl phosphate (RF 0.1) can be separated from retinyl phosphate (RF 0.2) by chromatography on thin layers of silica gel in chloroform/methanol/water (60:25:4, by vol.).

Synthesis and Characterization of Immobilized Nanometer Calcium Titanate and the Application in Speciation Analysis for Chromium

2010 ◽  
Vol 129-131 ◽  
pp. 724-727
Author(s):  
Dong Zhang
Keyword(s):  
Silica Gel ◽  
Sol Gel ◽  
Speciation Analysis ◽  
Environmental Water ◽  
Complete Separation ◽  
Calcium Titanate ◽  
X Ray Diffraction ◽  
Ph Values ◽  
Adsorption Capacities

Nanometer calcium titanate immobilized on silica gel G (SGCTO) was prepared by the sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR). Its application in speciation of Cr(III) and Cr(VI) from water was studied. Adsorption and elution were investigated under different conditions. The results showed that the nanometer calcium titanate was immobilized on the silica gel G firmly, becoming a new adsorbent. At normal temperature, two forms of chromium show different adsorption capacities at different pH values, that is, Cr (III) selectively retained at pH 8–14, but Cr(Ⅵ) can’t be adsorbed. Whereas Cr (VI) retained at pH 1, but Cr(Ⅲ) can’t be adsorbed. Hence complete separation of the two forms of chromium is possible. Retained Cr(III) and Cr(VI) were eluted with 1 mol•L−1 HCl and 2 mol•L−1NaOH, respectively. The Cr(III) and Cr(VI) concentration was measured by atomic absorption spectroscopy. The method was successfully applied for the speciation of chromium in environmental water samples.

Effects of pH and Uranium Valence State on the Aqueous Dissolution of Brannerite

2003 ◽  
Vol 807 ◽  
Author(s):  
Y. Zhang ◽  
E. Loi ◽  
M. Blackford ◽  
T. McLeod ◽  
H. Li ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Valence State ◽  
Ph Dependence ◽  
Aqueous Media ◽  
Matrix Elements ◽  
Atmospheric Conditions ◽  
Ph Values ◽  
Surface Alteration ◽  
Effects Of Ph ◽  
Order Of Magnitude

ABSTRACTThe dissolution of the thorium analogue of brannerite (ThTi2O6-I) and U(IV)/U(V) doped Th-brannerite (Th0.97U0.03Ti2O6-II and Th0.955U0.03Ca0.015Ti2O6-III) in aqueous media under atmospheric conditions has been studied to elucidate the effects of pH and uranium valence state on the dissolution rate.The dissolution of I is nearly stoichiometric but slightly preferential release of U occurs for II and preferential release of Ca and U occur for III. The V-shape pH dependence previously observed for U-brannerite only occurs for U (not other matrix elements) for II, indicating that the pH dependence is related to the U oxidation state upon dissolution. The normalised U dissolution rates of III are nearly an order of magnitude higher than those of II for pH values over 3, suggesting brannerite is less durable with U(V) doping. TEM examination of specimens after leaching revealed few surface alteration products, which is consistent with the nearly stoichiometric dissolution of thorium brannerite.

Modification of silica gel by attachment of 2-mercaptobenzimidazole for use in removing Hg(II) from aqueous media: A thermodynamic approach

2007 ◽  
Vol 311 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Edésio F.C. Alcântara ◽  
Elaine A. Faria ◽  
Deyse V. Rodrigues ◽  
Sheila M. Evangelista ◽  
Edimar DeOliveira ◽  
...  
Keyword(s):  
Silica Gel ◽  
Aqueous Media ◽  
Thermodynamic Approach

scholarly journals Chemical synthesis and papain-catalysed hydrolysis of N-α-benzyloxycarbonyl-l-lysine p-nitroanilide

1985 ◽  
Vol 226 (2) ◽  
pp. 601-606 ◽  
Author(s):  
N E Mackenzie ◽  
J P G Malthouse ◽  
A I Scott
Keyword(s):  
Chemical Synthesis ◽  
Ph Dependence ◽  
Low Ph ◽  
Pka Values ◽  
Tetrahedral Intermediate ◽  
Ph Values ◽  
Km Value ◽  
Hydrolysis Of

The chemical synthesis of N-alpha-benzyloxycarbonyl-L-lysine p-nitroanilide (Z-Lys-pNA) is described in detail. The pH-dependence of the catalytic parameters kcat,' Km and kcat./Km for the papain-catalysed hydrolysis of Z-Lys-pNA are determined. kcat. and Km are pH-independent between pH 5 and pH 7.42, but the pH-dependence of kcat./Km is bell-shaped, decreasing at high and low pH values with pKa values of 7.97 and 4.40 respectively. The catalytic parameters and their pH-dependence are shown to be similar to those reported for other anilide substrates and it is concluded that the Km value of 0.01 mM previously reported [Angelides & Fink (1979) Biochemistry 18, 2355-2369] is incorrect. The possibility of accumulating a tetrahedral intermediate during the papain-catalysed hydrolysis of Z-Lys-pNA is discussed.

Effect of Acetic Acid/Water Ratio on the Microstructure and Properties of LaNiO3 Thin Films by Metal Organic Solution Deposition

2015 ◽  
Vol 815 ◽  
pp. 89-93
Author(s):  
Yuan Yuan Zhang ◽  
Xiao Dong Tang ◽  
Gen Shui Wang ◽  
Xian Lin Dong
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Acetic Acid ◽  
Ph Value ◽  
Precursor Solution ◽  
Organic Solution ◽  
Solution Deposition ◽  
Ph Values ◽  
Metal Organic ◽  
Acetic Acid Water

Highly (100)-oriented LaNiO3 (LNO) thin films were prepared on p-type Si (100) substrates by metal organic solution deposition (MOSD). The LNO thin films were driven by series precursor solutions with different ratio of acetic acid to deionized water (Raaw) and pH values. The dependences of viscosity, pH value and the thermal property of the gel-derived powders of the precursor solution on Raaw values were systematically investigated. AFM images showed that Raaw can dramatically influence the surface roughness. When Raaw changed from 7:1 to 1:1, the surface roughness decreased from 3.695 nm to 1.488 nm. The resistivities of all the films are less than 2.1×10-3Ω·cm. It shows that the precursor solution has strong effect on the microstructure of the thin films and relatively slight effect on the resistivity.

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