bluuebunny/crossref_metadata_2025 huggingface dataset:
Basic hydrolysis of cinnamyl chloride
Authors: Červený Libor , Křivská Marie , Marhoul Antonín , Růžička Vlastimil
Published: August 2011

Basic hydrolysis of 3-chloro-1-phenyl-1-propene (cinnamyl chloride) to 3-phenyl-2-propen-1-ol (cinnamyl alcohol) and 1-phenyl-2-propen-1-ol was studied. The effects of the base type, presence of triethylbenzylammonium chloride as a phase transfer catalyst, and temperature were examined.
Epoxidation of 4,4-dimethyl-A-homo-4a-cholestene derivatives and a study of electron impact mass spectra of the epoxidation products
Authors: Velgová Helena , Trka Antonín
Published: August 2011

The effect of the substituent in the position 3 on the epoxidation of some 4,4-dimethyl-A-homo-4a-cholestene derivatives was investigated. The stereochemistry of the epoxidation is affected mainly by sterical and conformational effects. The mass spectrometric behaviour of epoxides IV-XI, XV-XX, XXIII and XXIV and of 4a,5-unsaturated 3-ketones XXI and XXVI was also studied. The double-transannular cleavage represents a common and characteristic decomposition pathway of molecular ions of these compounds.
Temperature control in a chemical reactor through variable area of the heat transfer surface. Simulation analysis
Authors: Horák Josef , Valášková Zina
Published: August 2011

An algorithm has been developed and on a mathematical model analyzed to stabilize the reaction temperature of a batch reactor. The reaction has been a zero-order one and the reactor has been operated in a instable operating point. The action variable is the heat exchange surface whose area is increased if the temperature is above, or decreased if the temperature is below the set point. The following two-point regulators have been studied: An ideal relay, a relay with hysteresis and an asymmetric PD relay. The effect has been discussed of the parameters of the regulators on the quality of regulation. Stability analysis has been made of the stationary switching cycles and the domains of applicability have been determined for individual regulators with respect to the rate of change of the area of heat exchange surface.
The titanometric determination of azobenzene derivatives in mixed acetonitrile-methanol-water medium
Authors: Barek Jiří , Berka Antonín , Borek Vladimír
Published: August 2011

The possibility of titanometric determination of a number of azobenzene derivatives in a mixed acetonitrile-methanol-water medium, which ensures sufficient solubility of the substances determined, was studied. Trivalent titanium in the presence of sodium citrate was found to be optimal. Conditions were found for the automatic potentiometric titration of a number of azo-compounds using this reagent.
1,3-Dipolar cycloaddition of C-benzoyl-N-phenylnitrone with dihydrofuran derivatives. Investigation of endo-exo stereoselectivity
Authors: Fišera Lubor , Dandárová Miloslava , Kováč Jaroslav , Gáplovský Anton , Patúš Juraj , Goljer Igor
Published: August 2011

C-Benzoyl-N-phenylnitrone (Ia) reacts with dihydrofuran derivatives (2,3-dihydro- and 2,5-dihydrofuran, 2,5-dimethoxy- and 2,5-diacetoxy-2,5-dihydrofuran) via 1,3-dipolar cycloaddition to give diastereoisomeric pair of exo- and endo- cycloadducts. The endo-exo stereoselectivity of the reaction is discussed. Cycloaddition of C,N-diphenylnitrone (Ib) with 2,3-dihydrofuran is also described. The cycloaddition kinetics have been studied with the nitrone Ia and non-substituted dihydrofurans.
Determination of heats of vaporization and some other thermodynamic properties for four substituted hydrocarbons
Authors: Svoboda Václav , Charvátová Vladimíra , Majer Vladimír , Hynek Vladimír
Published: August 2011

The temperature dependence of heats of vaporization and some other derived thermodynamic properties were determined for four substituted hydrocarbons, viz. 2,2,4-trimethylpentane,1-octene, ethylbenzene and n-butylbenzene. The temperature dependence of heats of vaporization was measured and, on the basis of these data, the values of standard heats of vaporization, internal and cohesive energies, entropies of vaporization and the difference of heat capacities of liquid and vapour at constant pressure and along the saturated vapour pressure curve were computed.
Study of the transition states in the hydroxythallation of alkenes
Authors: Strašák Milan , Majer Jaroslav
Published: August 2011

The properties of the transition states in the hydroxythallation of alkenes are characterized by means of two mechanistic methods, viz. the structure-reactivity profile method and the internal comparison method. In the case of RCH=CH2 and R1R2C=CH2 alkenes the transition state species is supposed to be a cyclic activated complex possessing a high positive charge localized at the multiply substituted carbon atom, whereas in the case of hydroxythallation of branched internal alkenes an acyclic transition state approaching in nature a carbonium ion is assumed.
Iodometric determination of 2-mercaptobenzthiazole by coulometric titration
Authors: Kučera Zdeněk , Karlík Milan , Krofta Jiří
Published: August 2011

The optimum conditions were found for the determination of 2-mercaptobenzthiazole (MBT) by coulometric titration with the generated iodine using biamperometric indication of the titration end point. Use is made of the oxidation to the disulphide (n = 1) and to benzothiazole-2-sulphinate (n = 4) in the regions pH 4.5-8.5 and 10-12, respectively. Eight repeated titrations to the disulphide gave the relative standard deviations 0.27% and 1.23% in the determination of 1 675 and 33.5 μg MBT, respectively, seven repeated titrations of 419 μg MBT to benzothiazole-2-sulphinate afforded results with the relative standard deviation 0.34%.
Alkylation of ergoline derivatives at position N(1)
Authors: Šmidrkal Jan , Semonský Miroslav
Published: August 2011

N(1)-Alkyl-8β-ergolines I-XII were prepared by alkylation of 8β-ergoline derivatives XIII to XVIII with alkyl halides in dimethyl sulphoxide in the presence of potassium hydroxide. The compounds I-XII exhibited weak inhibition effects on the secretion of prolactin
D-1-Carboxymethyl-8β-carboxy-6-methylergoline and some 1,8-disubstituted ergolines derived from it
Authors: Šmidrkal Jan , Semonský Miroslav
Published: August 2011

Reaction of D-8β-carboxy-6-methylergoline (I) with ethyl bromo acetate gave D-1-carboxy-8β-carboxy-6-methylergoline (II), whose dimethyl ester III was reduced with sodium borohydride, either selectively to D-1-(2-hydroxyethyl)-8β-methoxycarbonyl-6-methylergoline (IV) or completely to D-1-(-2-hydroxyethyl)-8β-hydroxymethyl-6-methylergoline (V). Derivatives VI-XV of compounds IV and V have also been prepared.
3-Aminoalkyl- and 3-benzyl-4(3H)-quinazolinones
Authors: Roubínek František , Vavřina Josef , Buděšínský Zdeněk
Published: August 2011

Reaction of 3-(2,3-epoxypropyl)-4(3H)-quinazolinone and/or its 6,7-dichloro- and 7-bromo-6-chloro-derivatives (Ib, Ic) with 5-diethylamino-2-pentylamine, 3-diethylaminomethyl-4-hydroxyaniline, 3,4-methylenedioxyaniline and 4-dimethylaminoaniline gave the corresponding substituted 4(3H)-quinazolinones, IIa, IIIb, IVb, Vc and VIc. Reactions of 3-(2-chloroethyl)-4(3H)-quinazolinones with the substituted anilines, pyridine and pyrrolidine gave rise to 3-(2-amino-ethyl)-4(3H)-quinazolinones VIIIa-VIIIj, IX and X. The piperidine derivative XI was obtained by the action of 1-(2-chloroethyl) piperidine on 4(3H)-quinazolinone. Reactions of 2-chlorobenzyl chloride 4-chlorobenzylchloride and 3,4,5-trimethoxybenzoyl chloride with 4(3H)-quinazolinone afforded 3-(2-chlorobenzyl)-, 3-(4-chlorobenzyl)-4(3H)-quinazolinone and 3-(3,4,5,-trimethoxybenzoyl)-4(3H)-quinazolinone (XII, XIII, XIV). All the compounds were screened for coccidiostatic and antihelmintic activity.
Components of Senecio pancicii DEGEN var. arnautorum (VELEN.) STOJ., STEF. et KIT. and S. Pancicii DEGEN var. pancicii
Authors: Jizba Josef , Buděšínský Miloš , Vaněk Tomáš , Boeva A. , Dimitrova Kalinka , Šantavý František , Novotný Ladislav
Published: August 2011

In Senecio pancicii var. arnautorum and var. pancicii a mixture was found of paraffinic hydrocarbons C25-C33, paraffinic alcohols C24-C30, phytosterols, palmitic acid, esters of fatty acids C12, C14 and C16 with dihydroxytriterpenes (among which one was identified as faradiol)and senecio alkaloids senecionine and seneciophylline.
Spectrophotometric study of the effect of tensides on triphenylmethane dyes
Authors: Škarydová Vlasta , Čermáková Ludmila
Published: August 2011

The effect of cation-active tenside 1-carbethoxypentadecyltrimethylammonium bromide (Septonex) on the absorption spectra of selected triphenylmethane dyes, eriochromcyanine R and bromopyrogallol red, was studied. The effect of the micelle aggregates of the tenside on the spectrophotometric characteristics of the individual dissociated forms of the dyes was demonstrated and the influence of strong electrolytes (NaCl, NaNO3) was studied. The interaction of both dyes with the micelle form of the nonionic tenside Triton X-100 was studied under similar experimental conditions.
The reliability of MINDO method for characterizing the transition state structures in radical addition reactions
Authors: Ponec Robert , Málek Jaroslav
Published: August 2011

The additions of the methyl radical and hydrogen atom to ethylene were chosen to test the reliability of MINDO method for predicting the transition state structures. It has been shown that the structures obtained at the level of the MINDO method differ markedly from the ab initio calculated structures.
Configuration and conformation of amidoximes. N,N-Dialkyl derivatives
Authors: Exner Otto , Motekov Nedelko
Published: August 2011

Dipole moments of N,N-dialkylamidoximes Ia-Ie and of substituted O-benzoyl-N,N-dimethyl-benzamidoximes IIa-IIe were measured in benzene or dioxan, respectively. The results with the latter set of compounds allow to assign in an independent and unambiguous way the E-configuration which was found previously for all N,N-dialkylamidoximes investigated in the crystalline state; our reasoning does not involve bond moment values within the amidoxime functional group. The fundamental difference in the stereochemistry between unsubstituted amidoximes and their N,N-dialkyl derivatives has thus been confirmed. On the other hand, the configuration of simple N,N-dialkylamidoximes (e.g. Ia-Ie) cannot be deduced from their dipole moments in a straightforward manner. The reason is that the conjugation within the N=C-N chain requires a mesomeric correction term which cannot be neglected and is not equal in either configuration. The example shows very clearly limitations of the bond moment approach if applied to conjugated molecules.
Hydrogenation of aromatic nitro compounds on copper-modified platinum catalysts
Authors: Červený Libor , Paseka Ivo , Stuchlý Vladimír , Růžička Vlastimil
Published: August 2011

The gas and liquid phase hydrogenations of nitrobenzene and liquid phase hydrogenation of p-chloronitrobenzene on Pt-Cu catalysts were studied. The effect of the copper content on a catalyst was examined, and a relationship was sought between the degree of occupation of the platinum surface by copper and the decrease in the hydrogenation activity in the liquid phase hydrogenation of nitrobenzene. The mechanism of this reaction is discussed.
Preparation of 7-oxabicyclo[4.3.0]nonanes and 2-oxabicyclo[4.4.0]decanes specifically labelled with deuterium
Authors: Tureček František
Published: August 2011

trans-Annulated 7-oxabicyclo[4,3,0]nonanes, labelled with deuterium at C(1), C(6), C(8) and C(9), and cis-annulated isomers labelled at C(1) and C(6) were prepared by cyclization of the corresponding labelled 2-(2-hydroxyethyl)-cyclohexanols. cis- Annulated 7-oxabicyclo[4,3,0]nonanes labelled at C(5), C(8) and C(9) were prepared by oxymercuration-reduction of labelled 2-(3-cyclohexenyl)ethanols. 2-Oxabicyclo[4.4.0]decanes labelled at C(1), C(3) and C(6) were prepared by cyclization of the corresponding 2-(3-hydroxypropyl)cyclohexanols. cis-Annulated 2-oxabicyclo[4,4,0]decanes labelled at C(4), C(5) and C(10)were obtained by oxymercuration-reduction of 3-(3-cyclohexenyl)-propanols. Conformation of the cis-annulated isomers is discussed.
A study of the reaction of 2-pyridyl isothiocyanate with azoimide
Authors: Marchalín Miroslav , Považanec František , Martvoň Augustin
Published: August 2011

From the reaction mixture of 2-pyridyl isothiocyanate with azoimide in dioxane 5-(2-pyridyl-amino)tetrzole, 2-pyridylthiourea and elemental sulfur were isolated instead of the expected 5-(2-pyridylamino)-1,2,3,4-thiatriazole. The mechanism of the reaction mentioned was studied on the basis of the synthesis of the assumed intermediates and the isolation of the intermediates by means of compounds with an activated acetylenic or ethylenic bond.
Reaction of 2-propenoic acid and of derivatives of 1-phenyl-2-propen-1-one with 1-acetoxy-2-phenoxyethane in polyphosphoric acid
Authors: Zvara Ivan , Lukáč Ivan , Hrdlovič Pavol , Chmela Štefan
Published: August 2011

2-Propenoic acid when reacted with 1-acetoxy-2-phenoxyethane in polyphosphoric acid at room temperature gives intermolecular acylalkylated produkt I. Probably owing to a rapid subsequent reaction the acylated intermediary product could not be detected. Therefore alkylation of a model compound, 1-acetoxy-2-phenoxyethane, with derivatives of 1-phenyl-2-propen-1-one was investigated, which led to compound I-IV.
CO2 Laser-induced and BCl3-sensitized decomposition of hexafluoroacetone. Comparison with high temperature thermochemistry
Authors: Pola Josef , Engst Pavel , Horák Milan
Published: August 2011

The cw CO2laser-induced decomposition of hexafluoroacetone sensitized with boron trichloride (total pressure 5.3-8.0 kPa) yields along with perfluorinated hydrocarbons trifluoroacetyl fluoride, carbon monoxide and carbonyl fluoride. The same carbonyl compounds are also formed by conventional thermal decomposition of hexafluoroacetone on tungsten filament at temperatures 950-2 100°C but their distribution during reaction progress is different. Features of both reactions are discussed.
Synthesis and absolute configuration of three isomeric spiro-bis(2-pyrrolidinones)
Authors: Kajtár Márton , Hollósi Miklós , Kinski Klaus , Majer Zsuzsanna
Published: August 2011

Syntheses are described for three isomeric spiro-bis-(2-pyrrolidinones): 2,7-diazaspiro[4,4]nonane-3,8-dione (II), 2,7-diazaspiro[4.4]nonane-1,8-dione (IV) and 1,7-diazaspiro[4,4]nonane-2,8-dione (IV). All the syntheses were carried out starting from 3-carboxy-5-oxo-3-pyrrolidineacetic acid (VIII) of known configuration, allowing the assignation of absolute configuration to compounds II, IV and VI synthesized through stereochemically unequivocal reaction steps.
Tricyclic psychotropic agents containing two chalcogen atoms in the central ring: Derivatives of 11H-dibenz[b,f]-1,4-oxathiepin
Authors: Šindelář Karel , Holubek Jiří , Ryska Miroslav , Dlabač Antonín , Metyšová Jiřina , Svátek Emil , Hrubantová Marta , Protiva Jiří , Protiva Miroslav
Published: August 2011

Reactions of 2-bromobenzyl bromide and its analogues XVII and XXV with 2-hydroxythiophenol resulted in 11H-dibenz[b,f]-1,4-oxathiepin (Ia) and its 2-chloro (Ib) and 2-trifluoromethyl derivative (IC). Treatment of the lithium compounds derived from Ia and Ib with carbon dioxide and dimethylaminoalkyl chlorides gave compounds IIa, Va and VIab; modification of side chains led to amines IVa, VIIa and VIIIa. 11-(1-Methyl-4-piperidyl) derivatives Xbc were obtained by chlorination of compounds Ibc with sulfuryl chloride or N-chlorosuccinimide and the following treatment with 1-methyl-4-piperidylmagnesium chloride. Compound Ib was transformed by oxidation to the sulfone XX affording by treatment with sodium hydride and tert-aminoalkylchlorides the basic sulfones XXI and XXII. While the nuclearly unsubstituted amines with the aliphatic side chains (IVa and VIIa) have intensive antireserpine activity and are potential antidepressants, the 11-(1-methyl-4-piperidyl) derivatives with a substituent in position 2 of the skeleton (Xbc) are potential neuroleptics; the trifluoromethyl derivative Xc especially has outstanding cataleptic and antiapomorphine efficacy.
(6,11-Dihydrodibenzo[b,e]thiepin-11-yl)methylamine, (4-methoxy-6,11-dihydrodibenzo[b,e]thiepin-11-yl)-methylamine and derivatives; Synthesis and pharmacological screening
Authors: Valenta Vladimír , Metyš Jan , Protiva Miroslav
Published: August 2011

Using the Curtius reaction, the acids VIa and VIv were transformed to the carbamates IVa and IVb which afforded by alkaline hydrolysis the primary amines Ia and Ib. The N-methyl derivatives IIab were obtained by reduction of the carbamates IVa with lithium aluminium hydride. The N,N-dimethyl derivatives IIIab resulted by methylation of the primary amines Iab with formaldehyde and formic acid. The synthesis of the acid VIb was carried out from phthalide and 2-methoxythiophenol in seven steps. The amines Iab-IIIab showed clear thymoleptic properties in the test of reserpine ptosis in mice and by inhibition of the perphenazine catalepsy in rats. The acid VIb has antiinflammatory activity.
4-β-D-Ribofuranosyl-1,2,4-triazin-3,5(2H,4H)-dione and 4-β-D-ribofuranosyl-6-methyl-1,2,4-triazin-3,5(2H, 4H)-dione
Authors: Hřebabecký Hubert
Published: August 2011

4-β-D-Ribofuranosyl-1,2,4-triazin-3,5(2H,4H)-dione (IX) and 4-β-D-ribofuranosyl-6-methyl-1,2,4,-triazin-3,5(2H,4H)-dione (XI) were prepared by cyclization of (Z)-4-β-D-ribofuranosyl-semicarbazones of methyl glyoxylate (VI) and methyl pyruvate (VIII) in the methanolic solution of sodium methoxide. A mixture of (E)- and (Z)-ribosylsemicarbazones III and IV was prepared by condensation of the ribosylsemicarbazide I with methyl dimethoxyacetate and a mixture of (E)-and (Z)-isomers V and VIII was obtained on condensation of I with methyl pyruvate. The (Z) isomer VI was prepared on acid-catalyzed isomerisation of the (E)-isomer III while the (Z)-isomer VIII was obtained on the UV-irradiation of isomer V.
Estimation of the vapour-liquid equilibrium data of N-component system by a modified method of binary contributions
Authors: Medlík Vladimír , Voňka Petr , Novák Josef P.
Published: August 2011

A method is proposed making it possible to calculate excess quantities of a multicomponent system on the basis of knowledge of this excess quantity for the constituent binary systems. The method is applied to the calculation of vapour-liquid equilibrium data of multicomponent systems.
Heats of mixing of the ternary systems 1-propanol-n-alkane-cyclohexane
Authors: Veselý František , Dohnal Vladimír , Prchal Miloslav
Published: August 2011

Heats of mixing HE were measured at the temperature of 298 15 K in the ternary system 1-propanol-n-hexane-cyclohexane, 1-propanol-n-heptane-cyclohexane and 1-propanol-n-octane cyclohexane along three pseudobinary chorids and in the binary system 1-propanol-n-hexane. The measured values of the ternary excess enthalpies were correlated by the Scatchard equation for one polar component and by the SSF equation in pseudobinary mixtures. A very good agreement with the experiments was attained on computing the enthalpies of mixing by the group-contribution method. Qualitatively the same results were found on applying the modified Renon-Prausnitz model of continuously associated solution. The combination of the Renon-Prausnitz model with the group-contribution method did not yield a more conspicuous improvement.
A contribution to evaluation of influence of medium in electronic and infrared spectroscopy
Authors: Bekárek Vojtěch , Juřina Jan
Published: August 2011

Dependence of ET(30) of solvent parameters on relative permittivity (ε) and refractive index (n) of solvent has been found for forty solvents in the form ET(30)=29.87 + 72.03 (ε - 1/(2ε + 1)-29.16(ε - 1) (n 2 - 1)/(2ε + 1) (2n2 + 1), the correlation coefficient being 0.958. Relation has been discussed between ET(30) and π solvent parameters and significance of the term (ε - 1). (n2 - 1)/(2ε + 1) (2n2 + 1) has been tested for evaluation of solvent effects in electronic spectra.>
Conversion of 2,3:4,6-di-O-isopropylidene-L-sorbose to 2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid by catalytic oxidation with oxygen on platinum
Authors: Nondek Lubomír , Žďárová Dana , Málek Jaroslav , Chvalovský Václav
Published: August 2011

The kinetics of the oxidation of 2,3:4,6-di-O-isopropylidene-L-sorbose to 2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid by oxygen were determined in the aqueous alkaline medium and over platinum on carbon as the catalyst. The most adequate kinetic equation suggested on the basis of non-linear regression was that of the Langmuir-Hinshelwood type. The corresponding most probable reaction mechanism involved an equilibrium single-site adsorption of the substrate, a dissociative dual-site adsorption of oxygen and a surface reaction between oxygen and the substrate to form aldehyde in the rate determining step; in the aqueous alkaline medium the aldehyde is oxidized in the next step to give the anion of 2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid. This mechanism appears to be generally applicable to the catalytic transformations of primary alcohols into carboxylic acids by oxygen or air under the above reaction conditions. A linear correlation of the relative reactivities of a series of water-soluble primary aliphatic alcohols with the Taft σ constants shows the polar substituent effect to play the predominant role. However, ethanol is approximately twenty times as reactive as 2,3:4,6-di-O-isopropylidene-L-sorbose and this indicates that in the oxidation of the latter compound also strong steric effects should apply.
Synthesis, IR spectra and antimicrobial activity of 1,4-dialkylpiperazine dioxides
Authors: Devínský Ferdinand , Lacko Ivan , Mlynarčík Dušan , Krasnec Ľudovít
Published: August 2011

Preparation of 1-alkylpiperazines, 1-alkyl-4-methylpiperazines, 1,4-dialkylpiperazines, 1-alkyl-4-methylpiperazine dioxides, and 1,4-dialkylpiperazine dioxides is described. IR spectra of dioxides were interpreted. Antimicrobial activity of dioxides against Staphylococcus aureus, Escherichia coli and Candida albicans was determined.
The complexes of iminodiacetic acid with divalent manganese and iron
Authors: Lukeš Ivan , Šmídová Ivana , Ebert Miroslav
Published: August 2011

Complexes of the type M2[Me(IDA)2] and MeIDA.n H2O, where M = H+, Li+, Na+, K+, 1/2 Ba2+, Me = Mn2+, Fe2+ and IDA = [NH(CH2COO)2]2- were prepared in the solid state. The magnetic properties, thermal stability and electron and infrared spectra of these substances were studied. It followed from the results that both prepared types of complex have a high spin octahedral configuration. In contrast to M2[Me(IDA)2] type complexes, complexes of the Me IDA . nH2O type have polymeric character.
Vibration spectra of mixed crystals Sc(PO4, VO4) and Y(PO4, VO4)
Authors: Muck Alexander , Smrčková Olga , Hájek Bohumil
Published: August 2011

Infrared spectra of mixed crystals Sc(PO4, VO4) and Y(PO4, VO4) have been studied from the point of view of group analysis. These systems form substitution mixed crystals in tetragonal space group D194h. The anions having proper symmetry Td or D2d in site symmetry D2d exhibit in spectra lowering of the site symmetry to effective C2 as a result of lattice vibrations of the type T(B2).
Study of the electrochemical oxidation of manganese(II) ions to manganese dioxide and its cathodic stripping using rotating disk and rotating ring-disk electrode
Authors: Kostihová Eva , Beran Přemysl
Published: August 2011

This work deals with the cathodic stripping peaks of manganese dioxide deposited on a disk electrode by pre-electrolysis. Coulometric and spectrophotometric methods and electrochemistry using a rotating ring-disk electrode are used to explain the formation of the more positive peak as a result of the reduction of nonstoichiometric oxygen formed in the manganese dioxide film on the disk electrode.
Hydrogenation of 2-phenyl-1-propene and 1-hexene on platinum black surface modified by Pb, Tl and Bi atoms
Authors: Paseka Ivo , Červený Libor , Šmigolová Dagmar , Růžička Vlastimil
Published: August 2011

Hydrogenation of 2-phenyl-1-propene and 1-hexene in ethanol, toluene and benzene was studied on platinum black modified by ad-atoms of lead, thallium, and bismuth. The experimental dependences of the specific hydrogenation rate on the degree of coverage by the metal ad-atoms are interpreted under the assumption that the substrate and hydrogen take part in the reaction and at low degree of the coverage, the organic substance is adsorbed on the modified and non-modified surfaces to the same extent.
Heteroanalogues of 1-triacontanol
Authors: Kocián Oldřich , Stránský Karel , Závada Jiří
Published: August 2011

A synthesis of twelve heteroanalogues II-XIII of the plant growth stimulator 1-triacontanol (I), derived from the parent alcohol by a replacement of 1-4 methylene units by heteroatoms O, S, NH and/or by a replacement of 1-2 ethylene units by -CO-O-, -CO-NH- or epoxy groups is reported. Spectral and gas-chromatographic properties (Kováts retention indices) of the compounds are described.
Tricyclic psychotropic agents containing two chalcogen atoms in the central ring: Synthesis of 6-(aminoalkyl) derivatives of 6H-dibenz[b,e]-1,4-oxathiepin
Authors: Šindelář Karel , Holubek Jiří , Svátek Emil , Ryska Miroslav , Dlabač Antonín , Protiva Miroslav
Published: August 2011

Heating of 2-(2-hydroxyphenylthio)benzoic acid (XX) with acetic anhydride gave dibenz[b,e]-1,4-oxathiepin-6-one (XXII). Demethylation of 2-(2-methoxyphenylthio)benzyl bromide (XI) with boron tribromide and the following treatment with aqueous sodium hydroxide in dimethyl sulfoxide afforded 6H-dibenz[b,e]-1,4-oxathiepin (I) which was halogenated with chlorine or N-bromosuccinimide only to the undesirable 2-halogeno derivatives II and III. A reaction of 2-(2-methoxyphenylthio)benzaldehyde (XII) with chloroform and 50% aqueous sodium hydroxide in the presence of triethylbenzylammonium chloride led to the α-chloro acid XIX whose demethylation with boron tribromide and the following cyclization with sodium hydroxide in dimethyl sulfoxide gave a mixture with prevailing 6H-dibenz[b,e]-1,4-oxathiepin-6-carboxylic acid (IV). Amino alcohols XXV-XXVIII were obtained by reactions of 2-(2-fluorophenylthio)benzaldehyde (XXIV) with the corresponding Grignard reagents and the products were cyclized with sodium hydride in dimethylformamide to the title compounds V-VIII. While compounds V and VI showed antireserpine effects and can be considered as potential antidepresants, compound VIII has a strong central depressant activity, brings about ataxia, hypothermia and potentiates the cataleptic action of neuroleptics (properties of a tranquillizer).
Estimation of excess volume and density of ternary liquid mixtures of non-electrolytes from binary data
Authors: Cibulka Ivan
Published: August 2011

Several methods for estimating the excess volume and density of ternary liquid mixtures of non-electrolytes from binary data are tested using 27 sets of data from the literature. The mean error of the excess volume estimation is lower than 0.1 cm3 mol-1. The use of the tested methods for estimating the density of ternary mixtures results in a significant reduction of the error compared to the stimation when the mixture is considered to be ideal. In decisive majority of the data sets, the maximum error in the density estimation is lower than 0.1%.
Some information on calculating the liquid-liquid equilibrium of ternary systems. an improvement of prediction of liquid-liquid equilibrium in ternary systems from binary equilibrium data
Authors: Surový Július , Dojčanský Ján , Bafrncová Soňa
Published: August 2011

A possibility is described of improving the prediction of ternary liquid-liquid equilibrium data from binary ones by using three-parameter equations for calculating activity coefficients. The parameters for completely miscible pairs of liquids were determined from their vapour-liquid equilibrium data and those for partially miscible pairs of liquids from their mutual solubilities and from one limiting activity coefficient. A quantitatively correct prediction of the liquid-liquid equilibrium data was achieved in all cases by means of three different equations (NRTL equation, Redlich-Kister equation and Wilson equation modified by Novák and coworkers) in four hydrocarbon-hydrocarbon-polar solvent systems investigated.
The effect of sulphur compounds on hydrodenitrogenation of nitrogen compounds on a nickel-tungsten catalyst
Authors: Černý Mirko
Published: August 2011

Hydrodenitrogenation of pyridine on a sulphided NiO-WO3/Al2O3 catalyst has been studied in the presence of ethanethiol, propanethiol, thiophene and hydrogen sulphide and the amount of pentane, 1-methylpiperidine, 1-ethylpiperidine and piperidine has been determined. It was found that in the presence of all the sulphur compounds but hydrogen sulphide, the conversion of pyridine was lower than in their absence. The presence of hydrogen sulphide increased pyridine conversion.
Distribution of velocity components and liquid holdup in short vertical tubes with swirl bodies in the inlet part of the tube at cocurrent gas-liquid flow
Authors: Winkler Kurt , Kaštánek František
Published: August 2011

The axial and tangential velocity components and local liquid holdup rates have been measured in vertical tubes with swirl bodies located in the inlet part of the tube. The tubes were of 70 mm I.D. and H/D = 10-23. The air-water flow was directed upward. Superficial gas velocity was wG = 14-35 m s-1 and specific liquid load QLE = 15-65 m3 m-2 h-1. In the experiments, the blade angle of the swirl body and the liquid inlet have been altered. The resulting centrifugal moments were correlated with friction factors.
Solubility correlations for ternary systems containing peroxodisulphates
Authors: Balej Jan
Published: August 2011

Correlations of solubility data previously measured on ternary systems containing peroxodisulphates of monovalent cations have been established using the method of relative activity coefficient expansion. The relationships obtained give a fairly good representation of experimental solubility curves for systems which do not form solid solutions. The general form of the correlation function is discussed in relation to the resultant ionic strength of saturated solution.
MO study of Td-D4h equilibrium in complexes of transition metals. Equilibrium in tetrachloro complexes of atoms of the first transition row
Authors: Pelikán Petr , Liška Marek
Published: August 2011

The CNDO method in UHF version has been used for study of equilibrium of configuration isomers of tetrahedral and square-planar tetrachloro complexes of the first transition row atoms in the oxidation degree II (Mn(II), Fe(II), Co(II), Ni(II), Cu(II)). From the results it follows that the ability (conditioned by electronic structure of the central atom) to form the square-planar complexes decreases in the series Mn(II) > Fe(II) > Co(II) > Ni(II) > Cu(II). Several authors state the fact that the most important task of quantum chemistry is to develop procedures for calculation of rate and equilibrium constants of chemical reactions1,2. At the same time it is emphasized that these procedures should be independent of experimental data. By this term the authors mean such experimental data which are in some way connected with the reaction studied, and not the general experimental experience which (after transformation into axioms) can represent a basis of the used method.
Tartrate complexes of molybdenum(VI)
Authors: Havlová Pavla , Havel Josef , Bartušek Miloš
Published: August 2011

The formation of MoO2(TH-1)24- and (MoO2)2(TH-2)24- complexes was proved in roughly neutral aqueous solutions and their equilibrium constants were determined by potentiometric neutralization titrations. The possible ways of bonding of the tartrate ligand to the central Mo(VI) atom and the compositions of the Mo(VI) tartrate chelates are discussed.
Information properties of an analytical system
Authors: Eckschlager Karel
Published: August 2011

The connection of information measures such as the uncertainty after analysis and the information gain with inputs and outputs or with input-output relations in the system in which an analysis runs through as a process of obtaining information is shown on examples of instrumental or chromatographic qualitative analyses and of quantitative and trace analyses.
Benzoannelated quinone methides
Authors: Koutek Bohumír , Píšová Milena , Krupička Josef , Lyčka Antonín , Šnobl Dobroslav , Souček Milan
Published: August 2011

On the basis of detailed study of UV, IR, 13C NMR and E1/2 data of quinone methides V-VII three dominant factors influencing the behaviour of benzoannelated compounds must be considered: 1) electronic effects of both the exocyclic carbon substituents and the fused rings, 2) the extent to which the substituents are displaced out of the plane of the exocyclic double bond through steric interference between the side-chain substituents and peri-hydrogens and 3) the extent of the angular distorsion of the quinone-like rings. The ground state charge separation (~0.2e) in nonannelated derivatives was found to be strongly minimized by annelation of two benzene units to the parent systems. Near parallelism with this phenomenon was also observed in both the carbonyl vibration frequency and 13C NMR data.
Biochemically important reactions of 2-furylethylenes. Characterization of the reactivity towards thiols
Authors: Baláž Štefan , Šturdík Ernest , Drobnica Ľudovít
Published: August 2011

Reactions of 1-(5-R1-2-furyl)-2-R2,R3-ethylenes with thiols were investigated in aqueous solutions at pseudomonomolecular conditions and 25 °C. The obtained kinetic dependences made it possible to calculate the second order rate constants (1 mol-1 s-1). The reactivity of the studied 2-furylethylenes increases with the increasing electron-accepting effect of substituents varying both in position 5 of the furan and 2 of the exocyclic double bond. The reactivity of thiols towards 2-furylethylenes was found to raise with their increasing basicity.
1,3-Dipolar cycloadditions of ylide of 5-nitro-2-furfurylpyridinium bromide in indolizine synthesis
Authors: Štetinová Jarmila , Dandárová Miloslava , Kováč Jaroslav , Mesárošová Darina , Leško Ján
Published: August 2011

Substituted 3-(5-nitro-2-furyl)indolizines III-X were synthesized by 1,3-dipolar cycloaddition reaction of the ylide II, generated from 5-nitro-2-furfurylpyridinium bromide (I), with acrylonitrile, ethyl acrylate, diethyl maleate, benzalacetophenone, ethyl 3-(5-nitro-2-furyl)acrylate, (5-nitro-2-furfurylidene)acetophenone, β-nitrostyrene and dimethyl acetylenedicarboxylate. The structure of these products is discussed on the basis of their 1H NMR and mass spectra.
Cyclization reactions of some o-acylphenylhydrazones
Authors: Slouka Jan , Bekárek Vojtěch , Lyčka Antonín
Published: August 2011

The hydrazones Ia-Id and IIa-IId have been prepared by azo coupling of ethyl cyanacetylcarbamate and cyanacetamide, respectively, with diazotized o-aminoacetophenone, o-aminobenzophenone, 2-(2-aminobenzoyl)benzoic acid and 1-amino-9,10-anthraquinone. The hydrazones Ia-Id have been alkaline or thermally cyclized to 2-aryl-4,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitriles IIIa-IIId. On boiling in strongly acidic medium the hydrazones I and II are cyclized to the corresponding 3-substituted indazoles Va-Vc and 2,6-dihydronaphtho[1,2,3-c,d]indazol-6-one (Vd). Three hours boiling in 20% hydrochloric acid does not affect the 1,2,4-triazine cycle of nitriles IIIa-IIId, the nitrile groups being only hydrolyzed to give the corresponding carboxylic acids IVa-IVd. On the contrary, boiling in aqueous pyridine causes splitting of the 1,2,4-triazine cycle and formation of arylhydrazonocyanacetamides IIa-IId. IR and NMR spectroscopy has been used to study the possibility of simultaneous hydrogen bond to the both carbonyl groups in hydrazones I and II.
The diffusion current/drop area relationship in pulse polarography
Authors: Bolzan Jorge Alfredo
Published: August 2011

In the case of pulse polarography theoretical considerations show that the diffusion current, either instantaneous or average, is proportional to the drop area, which in turn is a function of time to the 0.691 power. Experimental evidence collected from successive drops in the plateaus is presented. The depletion in the vicinity of the drop which prevents the use of others than the first drop in classical polarography does not seem to occur in pulse polarography to any noticeable extension because of the short electrolysis time inherent to this technique.
Continuous polarographic control of the concentration of industrial solution components by computer-aided solid renewable electrode and camac apparatus
Authors: Kletenik Yu. B. , Beck R. Yu. , Sorkin G. N. , Kiriushov V. N. , Novitskii S. P. , Burenkov I. I.
Published: August 2011

The peculiarities and technical characteristics are reported of the polarographic sensor having a renewable solid electrode and ensuring the performance of no less than 105 cycles. The sensor and special measurement-control apparatus are shown to allow the rapid check of the content of industrial electrolytes.
EPR spectra and defect states in glasses of the GexS100-x system
Authors: Frumar Miloslav , Plesch Gustáv , Černošková Eva , Černý Václav , Tichý Ladislav , Tichá Helena
Published: August 2011

Glasses of the GexS100-x system were studied in the region of 30 ⪬ x ⪬ 45. The concept of magnetically active defect centres was employed to account for the EPR spectra of pure samples as well as those doped with silver or iodine, prepared in different temperature conditions. In terms of this concept a consistent interpretation of the experimental data could be given for the composition region applied.
Reaction of 1-bromobutane with potassium cyanide under conditions of three-phase catalysis: Activity of new polymeric catalysts
Authors: Janout Václav , Čefelín Pavel
Published: August 2011

Six new polymeric catalysts active in the reaction between 1-bromobutane and potassium cyanide under conditions of liquid-solid-liquid three-phase catalysis (L-S-L TC) were prepared. The catalysts are based on a crosslinked polystyrene carrier of polar and dipolar functional groups of the type of quaternary ammonium and phosphonium, and also thioether , sulphoxide and sulphone groups. With respect to catalytic activity, an essential difference has been proved to exist between polymers where functional groups of the thio ether, sulphoxide, and sulphone type are bound as pendent on the polymer chain, and those where similar functional groups are part of the network. Compared with the water-toluene system, the water-chlorobenzene system usually gives higher yields.
Kinetics and mechanism of oxidation of allyl and crotyl alcohols by sodium N-chlorobenzenesulphonamide in hydrochloric acid medium
Authors: Yathirajan H. S. , Rangaswamy  , Mahadevappa D. S.
Published: August 2011

CHYBI ABSTRAKT !!!!
Derivatives of benzo(c)fluorene: II. Synthesis and biological effect of basic ethers of 7-oxo-7H-benzo(c)fluorene
Authors: Křepelka Jiří , Vančurová Iva , Holubek Jiří , Mělka Milan , Řežábek Karel
Published: August 2011

Alkylation of phenols IIa-IIc with ω-(N,N-dialkylamino)alkyl chlorides IIIa-IIId in an aqueous and/or a two-phase (toluene and aqueous potassium hydroxide) medium, and reactions of phenols IId-IIf with isopropylamine, gave rise to ethers IV-XIX. Compounds IV and V were used to prepare derivatives XX-XXVI. Reduction of the 7-oxo group in the compound V by the action of sodium borohydride produced the 7-hydroxy derivatives XXIV-XXVI, whereas reduction under conditions of the Wolf-Kishner reaction led to derivatives XXVII and XXVIII, respectively, which were also obtained by alkylation of XXIX with IIIa in an anhydrous medium. The compound XXIX was prepared by reduction of compound IIa. Most the of compounds prepared had marked antineoplastic effects, particularly compounds IV and V. Compounds V, VII, IX and XVIII exhibited antibacterial effects, and compounds XVI, XVIII and XXIII were as efficacious in subcutaneous application against encephalomyocarditis virus as Tiloron, used as standard.
Derivatives of benzo(c)fluorenes. III. Synthesis and biological action of some dibasic derivatives of 7-oxo-7H-benzo(c)fluorene
Authors: Vančurová Iva , Křepelka Jiří , Šmejkal František
Published: August 2011

Alkylation of phenols IIa-IIc by the action of ω-(N,N-dialkylamino)alkyl chlorides IIIa-IIId in an anhydrous or a two-phase medium (toluene-aqueous potassium hydroxide) gave rise to the dibasic derivatives IV-XI. In the two-phase medium, alkylation of IIa with IIIc produced the basic ether XII as the main product, a decarboxylation product, and compound VII. In biological test compound IV showed the strongest antibacterial effects on four kinds of bacteria, was efficacious in vivo against the viruses of encephalomyocarditis and vaccinia, and induced the formation of interferon to the same extent as Tiloron. The antineoplastic effects of the compounds were weaker than those observed with compound I (Benfluron) administered to animals with experimental, transplantable tumours.
Quantum-chemical study of rearrangement of vinyl alcohol into acetaldehyde. Intramolecular sigmatropic [1,3] shift of hydrogen
Authors: Žáková Mária , Leška Jaroslav
Published: August 2011

The rearrangement mechanism of vinyl alcohol into acetaldehyde in the isolated molecule has been studied with respect to two possible different ways: the rearrangement in the plane of the molecule and in the plane perpendicular to the molecule. According to the Woodward-Hoffmann rules the former way is considered to be an allowed antarafacial [1,3] shift, and the latter way is a forbidden suprafacial shift. The reaction pathways have been studied by the method of reaction coordinate at the level of the semiempirical CNDO/2 and MINDO/3 methods by the technique of complete optimization. The reaction coordinates used for the study of reaction pathways in the plane of the molecule were the lengths of the bond being split between oxygen and hydrogen and that being formed between carbon and hydrogen and the angle formed by the three mentioned atoms (OHC). The reaction coordinates used for the perpendicular plane were the bond length between hydrogen and carbon (being formed) and those describing the way above the bonds. All the reaction pathways have to cross barriers, which means that the suprafacial shift is forbidden, and the antarafacial shift is geometrically difficult. Surprisingly the barrier of the suprafacial shift is lower than that of the antarafacial one, which has been explained by interaction of the migrating hydrogen atoms with bonds. This explanation is supported by the bond distance between the migrating hydrogen and central carbon atom in the transition state as well as by formation of hydrogen bond between oxygen, migrating hydrogen and double bond, which is indicated by the charge transfer connected with a considerable dipole moment. Existence of the relatively high barriers indicates that a spontaneous hydrogen shift in vinyl alcohol is impossible.
Simple theoretical models for elimination reactions on polar catalysts; Generalization of reactivities in series of chloroalkanes, alcohols, amines and thiols
Authors: Sedláček Jiří
Published: August 2011

CNDO/2 calculations have been made for simple models od adsorption of chloroalkane, alcohol, amine and thiol molecules on the surface of polar catalysts. The calculated values of selected quantum chemical quantities describing the properties of Cα-X and Cβ-HA bonds were correlated with reported experimental reactivities. Very good correlations with experimental data were obtained for quantum chemical quantities relating to the Cα-X bond. The results of calculations are discussed in relation to the reaction mechanism and the type of surface catalytic centres participating in the reaction.
Strontium and barium selenites. Synthesis and some properties
Authors: Ebert Miroslav , Havlíček David
Published: August 2011

The solubility, thermal analysis, powder X-ray diffraction, and infrared spectroscopy methods were applied to a study of selenites SrSeO3.n H2O (n = 0.6-1.0), anhydrous SrSeO3 (in two modifications), Sr(HSeO3)2, SrSe2O5, BaSeO3, and BaSe2O5. The conditions of their preparation and their bonding parameters are discussed in terms of comparison with magnesium and calcium selenites.
Reactions of gallocyanine methyl ester with gallium(III) and indium(III) ions
Authors: Kotouček Milan , Růžička Josef , Vaculíková Pavla
Published: August 2011

Reactions of gallocyanine methyl ester with gallium(III) and indium(III) ions in solutions in 15% (m/m) ethanol were studied spectrophotometrically. At pH 1.7-6.5, the GaL, GaL2, and Ga(OH)L3 complexes are formed; in the case of indium, the In(OH)2L2 and In(OH)L3 complexes appear at pH 4-6.5, and InL3B2 in tartrate solutions. The conditional stability constants and the equilibrium constants of the coordination equilibria were calculated, and procedures were worked out for a photometric determination of gallium and for a chelatometric determination of gallium and indium using gallocyanine methyl ester as metallochromic indicator.
Radiometric titrations based on the interaction of low-energy photons with matter
Authors: Havránek Emil , Nemčíková Angela , Bumbálová Alena
Published: August 2011

Argentometric titration with the indication of the point of equivalence based on the interaction of low-energy photons with the analyzed matter is described. The characteristic line of silver was excited by the combined source 147Pm/Sm; the samples were either in cuvettes or deposited on the chromatographic paper. The results are - within the limits of experimental errors - in agreement with the results of the classical argentometric titration with the visual indication of the point of equivalence.
Reaction of lithium aluminium hydride with 4,4-dimethyl-4a,5-epoxy-A-homocholestane derivatives and mass spectral fragmentation of some degradation products
Authors: Velgová Helena , Trka Antonín
Published: August 2011

Reductive opening of the epoxide ring of stereoisomeric 4,4-dimethyl-4a,5-epoxy-A-homocholestane derivatives with oxygen containing substituent (OH, OCOCH3, OCH3) in the position 3 was investigated. In the absence of other directing effects, than the stereoelectronic ones, the epoxide ring of 4aα,5α-epoxides is opened at the side of the less substituted carbon C(4a), under formation of 5α-hydroxy derivatives, while in the case of 4aβ,5β-epoxides both the cleavage of the C(4a)-O bond, leading to the formation of 5β-hydroxy derivatives, and the cleavage of the C(5)-O bond, leading to the formation of 4aβ-hydroxy-5,6-unsaturated derivatives take place. The participation of the substituent in the position 3 leads to an abnormal cleavage both in 4aα,5α-and 4aβ,5β-epoxides, i.e. to the cleavage of the C(5)-O bond under formation of 3,5-epoxides. The effect of the character of the substituent in the position 3 on the direction of the reductive cleavage of the epoxide ring is also discussed from the point of view of conformational and electronic effects. In mass spectrometry the main product of the fragmentation of the molecular ions of the 4a-hydroxy-3,5-epoxides XIII and XXV and the 4a-ketones XVII and XXVIII is the ion [C23H40O]+. which is formed after the breaking of the C(3)-O bond by the splitting off of the ring A. The fragmentation of the molecular ion of the semi-ketal XVIII is determined by the cleavage of the epoxide bond O-C(5).
C=O Stretching vibrations in Raman and infrared spectra of simple esters
Authors: Dybal Jiří , Štokr Jan , Schneider Bohdan
Published: August 2011

Infrared and Raman spectra of methyl acetate, tert-butyl acetate, methyl pivalate and tert-butyl pivalate were measured in the liquid and crystalline states and solutions of different dielectric constants. In these molecules, the bands of the C=O str. vibrations are not affected by conformational structure. The shape and position of the band of the C=O str. vibration in methyl acetate are primarily determined by intermolecular order created by interactions of the permanent dipoles of the molecules. In methyl pivalate and in tert-butyl acetate, the shape of the carbonyl band is mainly determined by Fermi resonance.