Researches on substituted arylamides of thiocarboxylic acids

Heating monothio- and dithiomalonic acids with-bromoacetophenone in dry ethanol gives 2,3,4-substituted thiazole derivatives.For Part VI see [1].     

Condensed systems based on 4-amino-3-mercapto-1,2,4-triazole

1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazines, hydrazones, and -thio adducts were obtained by reactions of 4-amino-3-mercapto-1,2,4-triazole with -bromoacetophenones, aldehydes, and ,-unsaturated ketones. Conditions that promote the cyclocondensation of the -thio adducts to the previously undescribed 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazepines were found. The chemical and spectral properties of the compounds obtained are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 267–272, February, 1992.     

Third-Order Nonlinear Optical Response of a New PVA Composite with PbS Nanocrystals

High third-order nonlinear optical susceptibility (⁽³⁾(;, –,)=3.4·10 ^–16 m²/V²) in the visible spectral range may be achieved in PVA composites with narrow-gap PbS semiconductor nanocrystals with a large exciton diameter.     

Polarographic reduction of adenine and its 9-(α,ω-dihydroxy-2-alkyl) derivatives

The polarographic reduction of adenine and its 9-(,)-dihydroxy-2-alkyl) derivatives on a short-period mercury electrode in strongly acidic media is determined by the rate of diffusion of the corresponding cations and, at pH values that exceed the pK_a values, by the kinetics of surface protonation of the uncharged molecules; this was proved by the dependence of the limiting current on the height of the mercury column, the temperature, and the depolarizer concentration. The polarographic reduction of adenine, adenosine, 9-(,-di-hydroxy-2-alkyl)adenines, and the corresponding phosphates in acidic media proceeds with the loss of sic electrons per molecule. The similar trends of the change in the half-wave potentials and the numerical pK_a values is associated with the fact that the site of protonation is simultaneously the site of nucleophilic attack by the electron during electrical reduction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1675–1678, December, 1977.     

Nitration of some 2-substituted thionaphthenes

A study is made of the nitration of thionaphthene-2-aldehyde, its diacetate, and of 2-(-nitrovinyl)thionaphthene. UV and IR spectroscopy show that nitration of thionaphthene-2-aldehyde in acetic anhydride gives a mixture of 3-nitrothionaphthen-2-aldehyde diacetate, 4-nitrothionaphthene-2-aldehyde diacetate, and 6-nitrothionaphthene-2-aldehyde diacetate in the ratios 106624, while nitration of thionaphthene-2-aldehyde diacetate gives a mixture of 3-nitrothionaphthene-2-aldehyde diacetate, 4-nitrothionaphthene-2-aldehyde diacetate, and 6-nitrothionaphthene-2-aldehyde diacetate in the ratios 363826. Nitration of 2-(-nitrovinyl)thionaphthene gives 4-nitro-2-(-nitrovinyl)thionaphthene.     

Ionic hydrogenation of 2-(ω-diethylaminoalkyl)thiophenes

A method was developed for the ionic hydrogenation of 2-(-diethylaminoalkyl)thiophene with triethylsilane and trifluoroacetic acid; this method gives 2-(-diethylaminoalkyl)-thiophans, which are representatives of previously undescribed thiophan derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1206–1207, September, 1975.     

Synthesis of triaza-2- cyclohexene derivatives

Di- and trialkyl derivatives of 1,3,4-triaza-2-cyclohexene were synthesized by reaction of N,N'-dimethylethyleneaminohydrazine with monocarboxylic acid and their anhydrides, esters, amides, and hydrazides. Alkyl derivatives of ,-bis [2-(1,3,4-triaza-2-cyclohexenyl)]alkanes were obtained as a result of the reaction of N,N'-dimethylethyleneaminohydrazine with dicarboxylic acids and their derivatives. 1-Ammo-1,3,4-triaza-2-cyclohexene derivatives were obtained from ethylenedihydrazine and monocarboxylic acid esters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 127–129, January, 1977.     

Interpretation of AC Conductivity of Lightly Doped Conducting Polymers in Terms of Hopping Conduction

The ac conduction of most disordered materials shows a regime of constant dc conductivity (0) at low frequencies and a crossover to a frequency-dependent regime of the type A ^s at high frequencies. We discuss the physical origin of this behavior and the interpretation of the onset frequency of excess ac conduction, _c , in terms of models for hopping conduction of polaronic carriers in a disordered medium. We emphasize the central role of the critical hopping rate in the percolation lattice for determining both (0) and _c . We show the behavior of () for lightly doped polypyrrole samples at different stages of doping, and we discuss the significance of frequency dispersion effects for electrochemical measurements.     

Cyclization of substituted 1, 4-diphenylthiosemicarbazides to thiazole derivatives

Heating together substituted 1, 4-diphenylthiosemicarbazides and-bromoacetophenone in ethanol gives new bases and quaternary salts of 2, 3, 4-substituted thiazole.     

Oxidative Transformations of Polyprenols

Oxidative transformationsinvolving the hydroxylsand -methylsof polyprenolsisolated from birch greenery (7-9 isoprene units in the chain) were used to produce ,-diols, diesters, aldehydoalcohols, and hydroxyacids. The products are of interest as potential anti-inflammatory, antiulcer, hepatoprotective, and cardio-active preparations.     

Syntheses of methyl-2-furylketones

, -Dibromomethyl-2-furylketone and its 5-nitro derivatives are prepared by brominating the appropriate ketones in CCl₄.,-diiodomethyl-2-furylketone and its 5-nitro derivative are synthesized by the action of iodine on the appropriate diazoketones, and in the case of the 5-nitro derivative along with the diiodoketone is isolated the corresponding glyoxal. 5-Nitro-2-furylglyoxal is also obtained by the action of dimethylsulfoxide on bromomethyl-5-nitro-2-furylketone.For Part XII see [1]     

Synthesis of 2-amino-3-(ω-aminoalkyl)indoles

2-Amino-3-(-phthalimidoalkyl)indoles have been obtained by the rearrangement of -phthalimido acid -phenylhydrazides under the action of POCl₃. The possibility has been studied of eliminating the phthalyl protective group from these compounds and a convenient method has been developed for obtaining 2-amino-3-(-aminoalkyl)indole dihydrochlorides. The behavior of the 2-amino-3-(-phthalimidoalkyl) indoles in alkylation reactions has been investigated.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 484–488, April, 1980.     

Synthesis of prenols ωt2c2sOH and ωt3c2sOH related to dolichols

Conclusions A stepwise synthesis of two prenols t₂c₂sOH and t₃c₂sOH, related to dolichols, from geranyllinalool and isoprenoid cis-and saturated hydroxysulfones was carried out.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 817–821, April, 1987.     

Concerning the enantiomerization barrier of hypericin

Summary The Syntheses of -(R)-menthyl and ,-bis-(R)-menthyl derivatives2 and3 of hypericin were achieved, and the corresponding diastereomers could be separated. The equilibria between the respective diastereomers are slightly displaced in favor of the chromatographically faster moving ones. Kinetic measurements on these easily equilibrating diastereomers of2 and3 provided anArrhenius activation energy for the interconversion barrier between the two propeller conformers of 83 and 89 kJ/mol. It could be shown that the -menthyl residues are of minor relevance to the height of this barrier, as is also the case for thebay hydroxyl ionization and quinone tautomerization equilibria. It was thus concluded that the intrinsic barrier for the propeller conformer enantiomerization of hypericin is in the order of 80 kJ/mol. These results are in accord with those obtained from semiempirical calculations.

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Zur Enantiomerisierungsbarriere von Hypericin

Zusammenfassung Nach Synthese der -(R)-Menthyl- und ,-bis-(R)-Menthylderivate2 und3 des Hypericins konnten die entsprechenden Diastereomerenpaare getrennt werden. Die Gleichgewichte sind etwas zugunsten der chromatographisch rascher wandernden Diastereomeren verschoben. Kinetische Messungen an diesen leicht äquilibrierenden Diastereomeren von2 und3 führten zu einerArrheniusschen Aktivierungsenergie für die Interkonversionsbarriere zwischen den beiden Propellerkonformeren von 83 und 89 kJ/mol. Es konnte gezeigt werden, daß die -Menthylreste für die Höhe dieser Barriere nur geringfügige Bedeutung haben, ebenso wie dasbay-Hydroxyl-Ionisierungsgleichgewicht und das Tautomeriegleichgewicht. Daraus wurde geschlossen, daß die intrinsische Barriere für die Enantiomerisierung der beiden Hypericinpropellerkonformeren in der Größenordung von 80 kJ/mol liegt. Dieses Resultat stimmt mit den Ergebnissen semiempirischer Rechnungen überein.

     

Interpreting magic-number and evaporation effects in cluster size distributions

The Smoluchowski equations describe the coalescence of clusters to form larger clusters. If the kernels or rate constants in these equations are homogeneous, meaning thatK _{j, k} = ² K _jk (wherej andk are cluster sizes), it can be shown that the populationsn _k approachAk ^a e - ^bk for largek and large time, where the constantsa andb depend on the homogeneity parameter. Deviations of observed populations from this formula may be ascribed to magic-number and/or evaporation effects on the kernels. By integrating the Smoluchowski equations numerically for various choices of the kernels, we derive population distributions and show the effects of magic-number clusters and evaporation on the population distribution. Various methods are used to extract the value of, in order to determine the best way to extract the underlying value of from experimental data. Experimental populations for sodium metal clusters are then analyzed according to the same procedure, to extract the homogeneity parameter and explain the patterns in the population distribution.     

Synthesis and properties of an ω,ω′-appended eighteen carbon chains hypericin derivative

Summary An ,-appended eighteen carbon chains hypercin derivative (2) was synthesized starting from emodin. The overall yield of the seven step synthesis was 12%. The¹H and¹³C NMR, absorption, and emission spectroscopic properties were measured;2 can be dissolved even in apolar solvents and polyethylene.

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Synthese und Eigenschaften eines mit C₁₈-Ketten ,-substituierten Hypericinderivats

Zusammenfassung Ein in den Positionen , mit zwei C₁₈-Ketten substituiertes Derivat des Hypericins (2) wurde ausgehend von Emodin synthetisiert. Die Gesamtausbeute der siebenstufigen Synthese betrug 12%. Die¹H- und¹³C-NMR, absorptions- und emissionsspektroskopischen Eigenschaften wurden gemessen;2 kann sogar in apolaren Lösungsmitteln und Polyethylen gelöst werden.

     

Partition coefficients of ω-phenylalkanols between water and sodium deoxycholate micelles

The partition coefficient of -phenylalkanols [C₆H₅(CH₂)_mpOH, m _p =3–6] between water and micelles of sodium deoxycholate (NaDC) has been determined by a differential spectroscopic method at 25°C. The linear dependence of thestandard free energy change of transfer calculated from the partition coefficient on the alkyl chain length of the alkanols (m _p 4) yields the standard free energy change per methylene group [G^o(CH₂)]. G^o(CH₂) value for the present system, –3.21 kJ-mol ^–1 is larger in magnitude than that for sodium dodecylsulfate (SDS)--phenylalkanol system, –2.40 kJ-mol ^–1 . The result indicates that the alkyl chain of -phenylalkanols has higher affinity to NaDC micelles than to SDS micelles although the molecular structure of NaDC is more rigid and bulkier than that of SDS and the aggregation number of micelles of the former is much smaller than that of micelles of the latter. On the basis of the linear relation between the effect of added -phenylalkanols on the critical micelle concentration of NaDC (–dC_cmc/dC_a) and the partition coefficient, it is found that the degree of ionization of NaDC micelles is not influenced by solubilization of -phenylalkanols into the micelles.     

The synthesis of ω-thienylalkane acids from ω-chloroalkane acids

Summary We have worked out a preparative method for the synthesis of -thienylalkane acids by acylation of thiophene with -chloroalkane acid chlorides followed by conversion of the resulting -chloroalkyl(2-thienyl)ketones into the corresponding acids by reaction with sodium malonic ester or potassium cyanide, and reduction of the resulting products with their simultaneous hydrolysis.Here and later we mean -(2-thienyl)alkne acids.We take this opportunity to thank R. Kh. Freidlina, A. A. Beér, and M. A. Besprozvannii for giving us enough -chloroalkane acids.     

A new approach to arylaliphatic 1,5-, 1,6-, and 1,7-dicarbonyl compounds and their monoacetals based on direct anodic oxidation of 1-phenyl- and benzo[c]cycloalkenes

A new simple approach to -benzoylalkanals, 2-((-formylalkyl)benzaldehydes, and their monoacetals was developed based on direct anodic oxidation of I-phenylcycloalkenes and benzo[ccycloalkenes in methanol followed by acid hydrolysis of the electrolysis products. The target products are obtained in 53–72 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2044–2046, August, 1996.     

Bromination of 2-acetyl-5-methylfuran

The bromination of 2-acetyl-5-methylfuran by bromine and N-bromosuccinimide was studied. The action of N-bromosuccinimide on 5-methyl-2-acetylfuran in various solvents leads to mixtures of an -bromo ketone, a 5-bromomethyl derivative, and 5-bromomethyl--bromo ketone. The use of 2,2-azobisisobutyronitrile as activator of the radical process does not make the reaction selective but promotes bromination at the methyl group of the ring. A selective method for the synthesis of 2-(bromoacetyl)-5-methylfuran by the bromination of 2-acetyl-5-methylfuran with bromine was developed.Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 184–186, February, 1999.