Dan Boström

Indomethacin-saccharin cocrystal: design, synthesis and preliminary pharmaceutical characterization.

PurposeTo design and prepare cocrystals of indomethacin using crystal engineering approaches, with the ultimate objective of improving the physical properties of indomethacin, especially solubility and dissolution rate.Materials and MethodsVarious cocrystal formers, including saccharin, were used in endeavours to obtain indomethacin cocrystals by slow evaporation from a series of solvents. The melting point of crystalline phases was determined. The potential cocrystalline phase was characterized by DSC, IR, Raman and PXRD techniques. The indomethacin–saccharin cocrystal (hereafter IND–SAC cocrystal) structure was determined from single crystal X-ray diffraction data. Pharmaceutically relevant properties such as the dissolution rate and dynamic vapour sorption (DVS) of the IND–SAC cocrystal were evaluated. Solid state and liquid-assisted (solvent-drop) cogrinding methods were also applied to indomethacin and saccharin.ResultsThe IND–SAC cocrystals were obtained from ethyl acetate. Physical characterization showed that the IND–SAC cocrystal is unique vis-à-vis thermal, spectroscopic and X-ray diffraction properties. The cocrystals were obtained in a 1:1 ratio with a carboxylic acid and imide dimer synthons. The dissolution rate of IND–SAC cocrystal system was considerably faster than that of the stable indomethacin γ-form. DVS studies indicated that the cocrystals gained less than 0.05% in weight at 98%RH. IND–SAC cocrystal was also obtained by solid state and liquid-assisted cogrinding methods.ConclusionsThe IND–SAC cocrystal was formed with a unique and interesting carboxylic acid and imide dimer synthons interconnected by weak N−H⋯O hydrogen bonds. The cocrystals were non-hygroscopic and were associated with a significantly faster dissolution rate than indomethacin (γ-form).

The Regio‐ and Stereoselective Synthesis of trans‐2,3‐Dihydropyridine N‐oxides and Piperidines

Reactivity N-Own: Pyridine N-oxides can be used for the complete regio- and stereoselective synthesis of trans-substituted piperidines. The sequential addition of Grignard reagents and aldehydes or ketones to pyridine N-oxides yields a complete regio- and stereoselective trans 2,3-addition reaction in high yields, and the substituted 2,3-dihydropyridine N-oxide can be reduced to form 2,3-trans-substituted piperidines (see scheme).

New cocrystals of ezetimibe with L-proline and imidazole

The objectives of the study were to screen and prepare cocrystals of anti-cholesterol drug ezetimibe (EZT) with the aim of increasing its solubility and dissolution rate. Thermodynamic phase diagra ...

Ca10K(PO4)7 from single-crystal data

Crystals of decacalcium potassium heptakis(orthophosphate), Ca10K(PO4)7, were obtained from a melt. The structure of Ca10K(PO4)7 is isostructural with β-Ca3(PO4)2 and has been determined previousl ...

Combustion of Biosolids in a Bubbling Fluidized Bed, Part 1: Main Ash-Forming Elements and Ash Distribution with a Focus on Phosphorus.

This is the first in a series of three papers describing combustion of biosolids in a 5-kW bubbling fluidized bed, the ash chemistry, and possible application of the ash produced as a fertilizing agent. This part of the study aims to clarify whether the distribution of main ash forming elements from biosolids can be changed by modifying the fuel matrix, the crystalline compounds of which can be identified in the raw materials and what role the total composition may play for which compounds are formed during combustion. The biosolids were subjected to low-temperature ashing to investigate which crystalline compounds that were present in the raw materials. Combustion experiments of two different types of biosolids were conducted in a 5-kW benchscale bubbling fluidized bed at two different bed temperatures and with two different additives. The additives were chosen to investigate whether the addition of alkali (K2CO3) and alkaline-earth metal (CaCO3) would affect the speciation of phosphorus, so the molar ratios targeted in modified fuels were P:K = 1:1 and P:K:Ca = 1:1:1, respectively. After combustion the ash fractions were collected, the ash distribution was determined and the ash fractions were analyzed with regards to elemental composition (ICP-AES and SEM-EDS) and part of the bed ash was also analyzed qualitatively using XRD. There was no evidence of zeolites in the unmodified fuels, based on low-temperature ashing. During combustion, the biosolid pellets formed large bed ash particles, ash pellets, which contained most of the total ash content (54%–95% (w/w)). This ash fraction contained most of the phosphorus found in the ash and the only phosphate that was identified was a whitlockite, Ca9(K,Mg,Fe)(PO4)7, for all fuels and fuel mixtures. With the addition of potassium, cristobalite (SiO2) could no longer be identified via X-ray diffraction (XRD) in the bed ash particles and leucite (KAlSi2O6) was formed. Most of the alkaline-earth metals calcium and magnesium were also found in the bed ash. Both the formation of aluminum-containing alkali silicates and inclusion of calcium and magnesium in bed ash could assist in preventing bed agglomeration during co-combustion of biosolids with other renewable fuels in a full-scale bubbling fluidized bed.

Alkaline modified oil shale fly ash: optimal synthesis conditions and preliminary tests on CO2 adsorption.

Environmentally friendly product, calcium-silica-aluminum hydrate, was synthesized from oil shale fly ash, which is rendered so far partly as an industrial waste. Reaction conditions were: temperature 130 and 160°C, NaOH concentrations 1, 3, 5 and 8M and synthesis time 24h. Optimal conditions were found to be 5M at 130°C at given parameter range. Original and activated ash samples were characterized by XRD, XRF, SEM, EFTEM, (29)Si MAS-NMR, BET and TGA. Semi-quantitative XRD and MAS-NMR showed that mainly tobermorites and katoite are formed during alkaline hydrothermal treatment. Physical adsorption of CO(2) on the surface of the original and activated ash samples was measured with thermo-gravimetric analysis. TGA showed that the physical adsorption of CO(2) on the oil shale fly ash sample increases from 0.06 to 3-4 mass% after alkaline hydrothermal activation with NaOH. The activated product has a potential to be used in industrial processes for physical adsorption of CO(2) emissions.

Pharmaceutical Salts of Fluoroquinolone Antibacterial Drugs with Acesulfame Sweetener

Novel organic salts of norfloxacin and ciprofloxacin with artificial sweeteners such as saccharin and acesulfame were prepared. The two salts 1 and 2 were characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Finally, the crystal structures were solved by single crystal X-ray diffraction data and the structures were analyzed in terms of supramolecular synthons. In norfloxacin acesulfamate 1, two norfloxacin cations and two acesulfame anions form an eight membered cyclic tetramer supramolecular synthon. The salt, ciprofloxacin acesulfamate 2, has a similar structure as salt 1. This study contributes the importance of crystal engineering and supramolecular chemistry to the pharmaceutical applications in terms of interactions and structural correlations in the design of new solid phases. Supplemental materials are available for this article. Go to the publishers online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.

Monohydrous dihydrogen phosphate salts of norfloxacin and ciprofloxacin

Norfloxacin and ciprofloxacin crystallize with phosphoric acid in aqueous solution to give the salts 4-(3-carboxy-1-ethyl-6-fluoro-4-oxo-1,4-dihydro-7-quinolyl)piperazinium dihydrogenphosphate monohydrate, C16H19FN3O3(+) x H2PO4(-) x H2O, and 4-(3-carboxy-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-7-quinolyl)piperazinium dihydrogenphosphate monohydrate, C17H19FN3O3(+) x H2PO4(-) x H2O, respectively. In the crystal structures, the phosphate anions and the piperazine rings of norfloxacin or ciprofloxacin form a 12-membered supramolecular synthon, viz. R4(4)(12). The synthons R4(4)(12) and R2(2)(8) formed between adjacent phosphate anions result in the three-dimensional structures.

Chemo-bio catalyzed synthesis of R-1-phenylethyl acetate over bimetallic PdZn catalysts, lipase, and Ru/Al2O3. Part II

The effect of calcination and reduction temperature on the physical properties of PdZn/Al2O3 catalysts, prepared by co-precipitation deposition technique and characterized by XPS, XRD, and TEM methods are reported. The temperatures were varied in a range of 300–500°C. The catalyst calcined at 300°C and reduced at 400°C exhibited the metal particle size of 2–6 nm and contained the highest surface concentrations of Pd and Zn according to XPS measurements. The size and the fraction of large particles (above 10 nm) increased with increasing the calcinations and reduction temperatures.

TiO2 nanoparticles vs. TiO2 nanowires as support in hydrogen peroxide direct synthesis: the influence of N and Au doping

The performance of Pd on titania support were evaluated in the direct synthesis of hydrogen peroxide. The equipment used was a high pressure, semi-batch apparatus equipped with a special injection ...