Time filter

Source Type

Zielecka M.,Industrial Chemistry Research Institute
Polimery/Polymers | Year: 2011

Silica nanoparticles (NP's) with immobilized NP's of copper or silver were synthesized by means of sol-gel process. The optimization of silica NP's synthesis was carried out under different conditions of temperature and stirring rate. Our results confirmed that the stirring rate plays an important role in growth, polydispersity and stability of nanoparticles. The properties of nanosilica containing immobilized nanosilver or nanocopper were examined by scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), photon correlation spectroscopy (PCS) and zeta potential analysis. Source

Jamroz M.H.,Industrial Chemistry Research Institute
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The principle of operations of the VEDA program written by the author for Potential Energy Distribution (PED) analysis of theoretical vibrational spectra is described. Nowadays, the PED analysis is indispensible tool in serious analysis of the vibrational spectra. To perform the PED analysis it is necessary to define 3N- 6 linearly independent local mode coordinates. Already for 20-atomic molecules it is a difficult task. The VEDA program reads the input data automatically from the Gaussian program output files. Then, VEDA automatically proposes an introductory set of local mode coordinates. Next, the more adequate coordinates are proposed by the program and optimized to obtain maximal elements of each column (internal coordinate) of the PED matrix (the EPM parameter). The possibility for an automatic optimization of PED contributions is a unique feature of the VEDA program absent in any other programs performing PED analysis. © 2013 Elsevier B.V. All rights reserved. Source

In the article mentioned in the title, the authors challenged the hypothesis on shape-selective formation of 2,6-diisopropylnaphthalene (2,6-DIPN) in isopropylation of naphthalene over H-MOR catalysts. They claimed it was a myth, and there was no need to explain the high 2,6-DIPN selectivity with shape selectivity because it was in the range predicted by kinetics and thermodynamics. They also suggested that improper analysis of DIPN products could be a reason of the high 2,6-DIPN selectivity observed in the literature. However, in the current article I proved that some experimental results cannot be explained by kinetics, thermodynamics and analytical errors; therefore, shape-selective diisopropylation of naphthalene over H-mordenite is still the reality. © 2011 Elsevier Inc. All rights reserved. Source

Mazurek A.,Polish National Medicines Institute | Dobrowolski J.C.,Polish National Medicines Institute | Dobrowolski J.C.,Industrial Chemistry Research Institute
Organic and Biomolecular Chemistry | Year: 2013

New descriptors of the double bonded substituent effect, sEDA() and pEDA(), were constructed based on quantum chemical calculations and NBO methodology. They show to what extent the σ and π electrons are donated to or withdrawn from the substituted system by a double bonded substituent. The new descriptors differ from descriptors of the classical substituent effect for which the pz orbital of the ipso carbon atom is engaged in the π-electron system of the two neighboring atoms in the ring. For double bonded substituents, the pz orbital participates in double bond formation with only one external atom. Moreover, the external double bond forces localization of the double bond system of the ring, significantly changing the core molecule. We demonstrated good agreement between our descriptors and the Weinhold and Landis' "natural σ and π-electronegativities": so far only descriptors allowing for evaluation of the substitution effect by a double bonded atom. The equivalency between descriptors constructed for 5- and 6-membered model structures as well as linear dependence/independence of the constructed parameters was discussed. Some interrelations between sEDA() and pEDA() and the other descriptors of (hetero)cyclic systems such as aromaticity and electron density in the ring and bond critical points were also examined. © The Royal Society of Chemistry 2013. Source

Brzozowski R.,Industrial Chemistry Research Institute | Buijs W.,Technical University of Delft
Journal of Catalysis | Year: 2012

To finally dispel any doubts on the shape-selective formation of 2,6-diisopropylnaphthalene (2,6-DIPN) over H-MOR zeolites, naphthalene alkylation was carried out over high-silica H-MOR catalysts with propylene or isopropanol as an alkylating agent and with or without cyclohexane as a solvent. Isomeric composition of DIPN's, determined by one-dimensional GC analysis, was additionally confirmed with advanced two-dimensional GC × GC. Our results proved beyond any doubt shape-selective formation of 2,6-DIPN over these H-MOR catalysts from naphthalene and propylene and without cyclohexane as a solvent. The DIPN mixture contained 60-64% 2,6-DIPN, and the ratio of 2,6-DIPN/2,7-DIPN was in the range 2.5-2.8. We also showed that shape-selective formation of 2,6-DIPN over H-MOR catalyst was depressed by using isopropanol instead of propylene and in the presence of cyclohexane. © 2012 Elsevier Ltd. All rights reserved. Source

Discover hidden collaborations