scholarly journals Synthesis and transformation of sphingosine analogue pinane-based 2-amino-1,3-diols

2021 ◽  
Author(s):  
Ákos Bajtel ◽  
Mounir Raji ◽  
Matti Haukka ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Alkaline Hydrolysis ◽  
2D Nmr ◽  
Ring Closure ◽  
Biologically Active ◽  
Reductive Alkylation ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Hydrolysis Of

A library of pinane-based 2-amino-1,3-diols, analogues of biologically active sphingosine, was synthesised in a stereoselective manner. Isopinocarveol prepared from (–)-α-pinene was converted to condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray technics. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from commercially available (1R)-(–)-myrtenol. Reduction or alkaline hydrolysis of oxazolidines followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.

scholarly journals Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

2021 ◽  
Vol 17 ◽  
pp. 983-990
Author(s):  
Ákos Bajtel ◽  
Mounir Raji ◽  
Matti Haukka ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Alkaline Hydrolysis ◽  
Stereoselective Synthesis ◽  
2D Nmr ◽  
Ring Closure ◽  
Spectroscopic Techniques ◽  
Reductive Alkylation ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Hydrolysis Of

A library of pinane-based 2-amino-1,3-diols was synthesised in a stereoselective manner. Isopinocarveol prepared from (−)-α-pinene was converted into condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray spectroscopic techniques. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from the commercially available (1R)-(−)-myrtenol (10). The reduction or alkaline hydrolysis of the oxazolidines, followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent a regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.

scholarly journals Characterization and Optimization of the Alkaline Hydrolysis of Polyacrylonitrile Membranes

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1843 ◽  
Author(s):  
Leyre Pérez-Álvarez ◽  
Leire Ruiz-Rubio ◽  
Isabel Moreno ◽  
José Luis Vilas-Vilela
Keyword(s):  
Mechanical Properties ◽  
Alkaline Hydrolysis ◽  
Photoelectron Spectroscopy ◽  
Reaction Times ◽  
Special Importance ◽  
X Ray ◽  
Carboxylic Acid Groups ◽  
Wide Range ◽  
Enhanced Properties ◽  
Hydrolysis Of

There is currently an increasing interest in the development of polyacrylonitrile (PAN)-based membranes with new and enhanced properties which are of special importance in the processes of pervaporation, purification, and water treatment. Thus, the optimization of the functionalization of PAN membranes and its effect on their morphology, hydrophilicity, and mechanical properties plays an essential role in a wide range of applications. In this paper, the alkaline hydrolysis of asymmetric PAN membranes was investigated in order to get carboxyl-enriched surfaces that are of a great interest for more demanding subsequent modifications. The process was monitored using –C=NH intermediate bonds, which could be observed during the hydrolysis reaction by X-Ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) before the formation of carboxyl and amide groups. The amount of introduced carboxylic acid groups could be determined by thermogravimetric analysis (TGA) and by the interaction with toluidine blue O (TBO) dye. Hydrolysis was revealed as a simple way to modulate hydrophilicity (decreasing contact angle from 60 to 0° for reaction times from 0–3 h) and the mechanical properties of PAN membranes.

A new insight on alkaline hydrolysis of calcium aluminate cement concrete: Part I. Fundamentals

1996 ◽  
Vol 11 (7) ◽  
pp. 1748-1754 ◽  
Author(s):  
S. Goñi ◽  
C. Andrade ◽  
J. L. Sagrera ◽  
M. S. Hernández ◽  
C. Alonso
Keyword(s):  
Calcium Aluminate ◽  
Alkaline Hydrolysis ◽  
Degradation Process ◽  
Calcium Aluminate Cement ◽  
X Ray Diffraction ◽  
Cement Concrete ◽  
X Ray ◽  
Concrete Part ◽  
Hydrolysis Of ◽  
Aluminate Cement

In this work a hypothesis to explain the alkaline hydrolysis degradation process of calcium aluminate cement concrete (CACC) is presented. The hypothesis is based on x-ray diffraction (XRD) data of some samples taken from real Spanish CACC structures. The identification from XRD data of a hydrated alkaline aluminate could serve as a guide to differentiate both processes of normal carbonation and alkaline hydrolysis.

scholarly journals The Hydrolysis of Phosphinates and Phosphonates: A Review

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2840
Author(s):  
Nikoletta Harsági ◽  
György Keglevich
Keyword(s):  
Alkaline Hydrolysis ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Reaction Conditions ◽  
Phosphonic Acids ◽  
Active Compounds ◽  
Hydrolysis Of

Phosphinic and phosphonic acids are useful intermediates and biologically active compounds which may be prepared from their esters, phosphinates and phosphonates, respectively, by hydrolysis or dealkylation. The hydrolysis may take place both under acidic and basic conditions, but the C-O bond may also be cleaved by trimethylsilyl halides. The hydrolysis of P-esters is a challenging task because, in most cases, the optimized reaction conditions have not yet been explored. Despite the importance of the hydrolysis of P-esters, this field has not yet been fully surveyed. In order to fill this gap, examples of acidic and alkaline hydrolysis, as well as the dealkylation of phosphinates and phosphonates, are summarized in this review.

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

Composition and Surface Topography Effects on Apatite-Forming Ability of Ceramic-Polymer Composites

2003 ◽  
Vol 774 ◽  
Author(s):  
Susan M. Rea ◽  
Serena M. Best ◽  
William Bonfield
Keyword(s):  
Surface Topography ◽  
High Density Polyethylene ◽  
High Density ◽  
Apatite Layer ◽  
Biologically Active ◽  
Human Blood Plasma ◽  
Apatite Formation ◽  
Polyethylene Matrix ◽  
Composite Surface ◽  
X Ray

AbstractHAPEXTM (40 vol% hydroxyapatite in a high-density polyethylene matrix) and AWPEX (40 vol% apatite-wollastonite glass ceramic in a high density polyethylene matrix) are composites designed to provide bioactivity and to match the mechanical properties of human cortical bone. HAPEXTM has had clinical success in middle ear and orbital implants, and there is great potential for further orthopaedic applications of these materials. However, more detailed in vitro investigations must be performed to better understand the biological interactions of the composites and so the bioactivity of each material was assessed in this study. Specifically, the effects of controlled surface topography and ceramic filler composition on apatite layer formation in acellular simulated body fluid (SBF) with ion concentration similar to those of human blood plasma were examined. Samples were prepared as 1 cm × 1 cm × 1 mm tiles with polished, roughened, or parallel-grooved surface finishes, and were incubated in 20 ml of SBF at 36.5 °C for 1, 3, 7, or 14 days. The formation of a biologically active apatite layer on the composite surface after immersion was demonstrated by thin-film x-ray diffraction (TF-XRD), environmental scanning electron microscopy (ESEM) imaging and energy dispersive x-ray (EDX) analysis. Variations in sample weight and solution pH over the period of incubation were also recorded. Significant differences were found between the two materials tested, with greater bioactivity in AWPEX than HAPEXTM overall. Results also indicate that within each material the surface topography is highly important, with rougher samples correlated to earlier apatite formation.

Influence of medium on alkaline hydrolysis of succinic acid monomethyl and monopropyl esters

1980 ◽  
Vol 45 (11) ◽  
pp. 2873-2882
Author(s):  
Vladislav Holba ◽  
Ján Benko
Keyword(s):  
Succinic Acid ◽  
Kinetic Parameters ◽  
Alkaline Hydrolysis ◽  
Specific Interactions ◽  
Nonaqueous Media ◽  
The Media ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of succinic acid monomethyl and monopropyl esters were studied in mixed aqueous-nonaqueous media at various temperatures and ionic strengths. The results of measurements are discussed in terms of electrostatic and specific interactions between the reactants and other components of the reaction mixture. The kinetic parameters in the media under study are related to the influence of the cosolvent on the solvation sphere of the reactants.

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