temperatures to generate a diradical [ 2 , 3 ]. If the aryl groups are properly substituted, this provides a ready means of introducing a flame-retarding unit into the main chain of a vinyl polymer [ 4 ]. The diols may be readily prepared by reductive coupling
Authors:Łukasz Komsta, Rafał Pietraś, Ewelina Bartuzi, Robert Skibiński, and Anna Gumieniczek
Thin-layer chromatography (TLC) on two adsorbents (RP18 and CN) and with six modifiers (acetonitrile, acetone, dioxane, propan 2-ol, methanol, and tetrahydrofurane), followed by classical RM value extrapolation (previous results), was chemometrically compared with new one-run gradient high-performance liquid chromatography (HPLC) (C18, C18e, CN, and DIOL columns, acetonitrile, and methanol as modifiers) and, additionally, with seven computational algorithms (ALOGPs, AClogP, ALOGP, MLOGP, KOWWIN, XLOGP2, and XLOGP3) as a lipophilicity assessment tool on 35 model compounds with known lipophilicity. The statistical significance of intercepts and slopes of Collander equation (log P — retention dependence) and their values were compared. Whole results data set was subjected to scaled principal component analysis, which allowed exploring two main trends in these data. It can be concluded that one-run gradient HPLC does not outperform TLC in lipophilicity determination. Very good correlations were obtained between real log P and computational approaches; however, this is not a surprise for such simple molecules.
Authors:Kristóf Bagdi, Kinga Molnár, Béla Pukánszky, and Béla Pukánszky
Polyurethanes were prepared from 4,4′-methylenebis (phenyl isocyanate) (MDI), 1,4-butanediol (BD), and poly(tetrahydrofurane)
polyether polyol (PTHF) by melt polymerization. The –OH functional group ratio of polyol/total diol was kept constant at 0.4,
while the ratio of the isocyanate and hydroxyl groups (NCO/OH) changed between 0.940 and 1.150. The thermal analysis of the
polymers by DSC and DMTA measurements indicated several transitions. The three glass transition temperatures observed were
assigned to the relaxation of the aliphatic –CH2– groups of the polyol, and to that of the soft and hard segments, respectively. The glass transition temperature of the soft
and hard phase changed with the NCO/OH ratio indicating changes in phase structure and composition confirmed also by the maximum
in the number of relaxing soft segments. Changes in the relatively small number of end-groups result in considerable modification
of mechanical properties. Strength is determined by molecular mass and interactions, while stiffness depends mainly on phase
structure. Surprisingly enough, –OH excess yields stiffer polymers, since the interaction of the –OH groups results in a decrease
in the amount of the soft phase. A unique correlation was found between tensile modulus and the number of relaxing soft segments.
New simple TLC methods with densitometry and videoscanning have been developed for the quantitation of bezafibrate in Bezamidin tablets and ciprofibrate in Lipanor capsules. Analysis was performed on HPTLC Diol F
plates with hexane-tetrahydrofuran, 8 + 2, as mobile phase. Detection was performed by densitometry at
= 227 nm and videoscanning at
= 254 nm. Calibration plots were constructed in the range 5–30 µg per spot for both drugs. The calibration data were tested using several regression models and the optimum models were selected (quadratic for videoscanning and nonlinear
was always >0.995). The active substances were extracted from tablets with methanol. The linearity of the method was tested by spotting different amounts of extracted solution (15–30 mg). The recovery function was always sufficiently linear, with an insignificant intercept and slope very close to unity. Accuracy was tested by quantitating three fortified samples (50, 100, and 150%); this resulted in homogeneous results without significant differences. Recovery measured by use of densitometry was 100.3% (
7.84%) for bezafibrate and 98.01% (
6.12%) for ciprofibrate. Videodensitometry resulted in recovery of 96.16% (
9.8%) and 97.8% (
11.2%), respectively. The
-test for two means showed there was no significant difference between the precision and accuracy of the methods.
Authors:F. Z. Biber, P. Unak, H. Enginar, T. Ertay, E. I. Medine, C. Tasci, and H. Durak
An estrogen derivative, β-estradiol or 1,3,5,(10)-estratriene-3,17β-diol) attached to diethylenetriamine pentaacetic acid
(DTPA) was synthesized in six experimental steps. At the end of these steps, a DTPA-attached estradiol derivative called deoxy-demethyl
homoestradiolyl-diethylenetriamine-pentaacetic acid (ESTDTPA) was obtained. The synthesized compounds were labeled with 99mTc. Thin layer radio chromatography (TLRC) was used to determine radiochemical yields and stabilities.Structural investigations
confirmed the structures. The labeling yield was satisfactory (about 95%), and 99mTc-ESTDPTA was stable in neutral medium at room temperature for 5 hours. Biodistribution studies were performed on normal
and DMBA-induced, tumor bearing female Albino Wistar rats. The activity per gram tissue was calculated, and time-activity
curves were plotted. ESTDTPA uptake by uterus reached a level of 20.73% dose/g, showing a maximum within 5 minutes after injection.
Ovary and breast showed similar biodistribution profiles. The kidneys, which are the primary organs of metabolism and excretion
of estrogen, showed a high 99mTc-ESTDTPA uptake. The imaging studies were performed on normal and tumor bearing female Albino Wistar rats using a Camstar
XR/T gamma-camera. Gamma-scintigraphy studies showed that tumors could be well visualized in a few minutes and clearly differentiated
from other organs, such as bladder and liver by 24 hours.
Authors:P. Ramanjaneyulu, Y. Sayi, V. Raman, and K. Ramakumar
Detailed investigations have been carried out on the well-known method of spectrophotometric determination of boron particularly
in uranium compounds as boron-curcumin complex after extraction into 2-ethyl hexane 1,3-diol (EHD) to understand a number
of parameters, which have not been addressed earlier in the literature. These include (i) effect of different acid media on
analytical results of boron which are employed for dissolution of nuclear fuel samples, (ii) effect of diluents namely ethyl
alcohol and N,N-dimethyl formamide on sensitivity of method which are employed for final dilution, and (iii) studies on loss
of boron, if any, during conversion of uranium compounds to U3O8. Based on the present studies, the existing procedure has been suitably modified to improve the sensitivity in the measurements.
In addition, this paper also describes about interference studies with Al, Cr, Mg, Ca, Fe, Mn, Mo, F− and W and amount of EHD on modified method. Absolute detection limit was found to be 10 ng. The precision and accuracy of
the method, is 3% at level 100 ng·g−1 of boron.
Authors:L. Abate, E. Badea, I. Blanco, D. D’Angelo, and G. Della Gatta
Molar heat capacities of twelve linear alkane-α,ω-diamides H2NOC-(CH2)(n-2)-CONH2, (n=2 to 12 and n=14) were measured by differential scanning calorimetry at T=183 to 323 K. Heat flow rate calibration of the Mettler DSC 30 calorimeter was carried out by using benzoic acid as reference
material. The calibration was checked by determining the molar heat capacity of urea in the same temperature range as that
of measurements. The molar heat capacities of alkane-α,ω-diamides increased in function of temperature and fitted into linear
equations. Smoothed values of Cp,m at 298.15 K displayed a linear increase with the number of carbon atoms. The Cp,m contribution of CH2 group was (22.6±0.4) J K−1 mol−1, in agreement with our previous results concerning linear alkane-a,ω-diols and primary alkylamides as well as the literature
data on various series of linear alkyl compounds.
Authors:Wojciech Prus, Mieczysław Sajewicz, and Teresa Kowalska
In our earlier papers we provided indirect experimental evidence strongly in support of our long-established hypothesis that aliphatic ligands on chemically bonded TLC-type stationary phases (i.e. RP-18, RP-8, CN, and Diol) are partially aromatized relatively easily at considerably elevated temperatures (i.e. much higher than 100°C). The first indication of such a possibility was apparent from
spectra obtained from these phases by use of a high-power laser-light source emitting in the NIR range. Irradiation of samples of the adsorbents with the NIR light caused their evident heating and the consequent appearance of a predominant
band in the so-called aromatic region of the spectra. Later this unexpected, and in some ways disturbing, phenomenon was utilized positively in a new method for
spectroscopic evaluation of the density of coverage of the silica matrix with octadecyl ligands.In this paper we report results from an experiment designed to provide more convincing and direct evidence in support of our hypothesis about this partial aromatization. To collect such evidence we had to re-design the procedure used to heat the samples of stationary phase, and to find the most efficient means of extracting and separating the aromatization products. It became obvious that to obtain readily measurable quantities of such products the samples should be heated in a closed system (e.g. in a sealed glass ampoule or in the stainless steel tube which forms part of the apparatus for accelerated solvent extraction, ASE) which prevents the compounds from escaping from the reaction system at high temperatures. We then used two advanced methods of solvent extraction — ultrasonic extraction and ASE — to separate the expected aromatization products from the solid matrix of the adsorbents investigated. Finally, analysis of the extracts obtained was performed by HPLC with diode-array detection. Our results furnish convincing evidence of an efficient aromatization process occurring equally with TLC-type octadecyl and octyl ligands heated at 170°C.
In general, these heterocycles may be prepared from the corresponding diols which are available from reductive coupling of the appropriate ketones (Scheme 2 ).
Reductive coupling of a substituted
Authors:Marcela Stoia, Paul Barvinschi, Lucian Barbu Tudoran, Mirela Barbu, and Mircea Stefanescu
[ 21 – 23 ] starting from metal nitrates and different organic diols. We have established that at temperatures around 100 °C, a redox reaction takes place between the metal nitrates and diol, resulting in its oxidation to dicarboxylate anions that