Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

13-15

Authors: Alexandru Ciocarlan, Pavel F. Vlad, Mihai Coltsa, Edu Carolina, Andrei Biriiac, Alina Nicolescu and Calin Deleanu

The current communication represents an extended abstract of the presentation delivered on the joint Moldo-Italian seminar “New frontiers in natural product chemistry”, held in the Institute of Chemistry, Academy of Sciences of Moldova on 30 September. An overview of the synthetic methods oriented to the synthesis of C6 and C7 functionalized euryfurans is provided.

19-23

Authors: Margherita Gavagnin

The current communication is an extended abstract of the presentation delivered on the joint Moldo-Italian seminar “New frontiers in natural product chemistry”, held in the Institute of Chemistry, Academy of Sciences of Moldova on 30th September. An overview of the recent studies conducted by our group on opisthobranch molluscs from distinct geographical areas is briefl y presented.

27-29

Authors: Emiliano Manzo, Maria Letizia Ciavatta, Dario Pagano and Angelo Fontana

The current communication represents an extended abstract of the presentation delivered on the joint Moldo-Italian seminar “New frontiers in natural product chemistry”, held in the Institute of Chemistry, Academy of Sciences of Moldova on 30 September. A simple and effi cient strategy for the synthesis of galactoglycerolipids is provided.

36-44

Authors: Valerian Cerempei

The article studies the corrosive activity of the monatomic alcohol (ethanol, butanol) - gasoline mixtures on the materials from which the internal combustion engines are made. The corrosive infl uence of these blends was determined in dependence of their composition. It was established that the addition of butanol and triethylamine in the ethanol-gasoline mixture essentially reduces the corrosive activity of this mixture.

48-52

Authors: I. Povar, V. Cerempei and B. Pintilie

The infl uence of added alcohols, ethanol and butanol, on the main biofuel properties, as the specifi c gravity, Reid saturated vapour pressure and distillation curves have been investigated. These properties are intimately related to the fuel composition and their prediction relies on the knowledge of its components characteristics. This research proves the possibility of obtaining fuels with different levels of resistance to detonation, using gasoline with different chemical components and various fractions of alcohols.

53-64

Authors: Tudor Lupaşcu, Alexandru Gonţa

Studies of the antioxidant activity of polyphenolic compounds extracted from grape seeds are of considerable interest currently. The compound Enoxil is a mixture of polyphenols, esthers, and carboxylic acids, which could be involved in reducing the risk of diseases associated with oxidative stress. The results of the investigation of antioxidant activity for the compound Enoxil and its forms are presented in this paper. Two distinct methods were used to assess the antioxidant properties of the tested compounds: the radical monocation of 2,2′-azinobis-(3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS•+ test) and the DPPH method (2,2-diphenyl-1-picrylhydrazyl radical). It can be concluded that acetone-Enoxil has a higher antioxidant activity that other tested compounds.

70-72

Authors: Ştefan Manole, Maria Cocu

We have researched the color properties of coordination compounds synthesized by us previously [1] (8-(1′,2′-naphthyl)-1-R3-methyl-6-thiomethyl-4,5,7-triazaocta-1,3,5,7-tetraenato-1,1′-diolato(-)O, O′, N4, N7-M(II), where R=CH3, C6H5, M=Ni, Co, Cu), which can be used for coloring thermoplastic masses. They meet the requirements for use as a pigment for coloring thermoplastic masses [2]. Colors of colored products have a high photostability (7 points), thermostability (>250 °C) and intensity of color that give a low consumption (0.004 to 0.008 g medium tone, a 0.040-0.080 g to 100 g polystyrene intense tone and 0.002 to 0.008 g medium tone and 0.010-0.030 g intense tone for 100 g polyethylene). Compounds of nickel (II) stained polystyrene and polyethylene in red, cobalt (II) - in green with a yellow tinge, copper (II) - in deep red with a yellow tint.

79-83

Authors: Andrei Bîrîiac

Starting with the methyl 11-homodrim-8-ene-7-oxo-12-oate a two steps synthesis of methyl-11-homodrim-6,8(9)- diene-12-oate was accomplished in 87% overall yield, which on photooxygenation in the presence of tetraphenylporphyrin gave a mixture of methyl esters of 11-homodrim-7-ene-6α,9α-peroxy-12-oic and 11-homodrim-5,8-diene-7-oxo-12-oic acids 21% and 54% yields, respectively.

91-95

Authors: Ion Dranca, Igor Povar and Tudor Lupascu

This research has been carried out in order to demonstrate the use of differential scanning calorimetry (DSC) in detecting and measuring α- and β-relaxation processes in amorphous pharmaceutical systems. DSC has been employed to study amorphous samples of poly (vinylpyrrolidone) (PVP), indomethacin (InM), and ursodeoxycholic acid (UDA) that are annealed at temperature (Ta) around 0.8 of their glass transition temperature (Tg). Dynamic mechanical analysis (DMA) is used to measure β- relaxation in PVP. Yet, the DSC has been used to study the glassy indomethacin aged at 0 and -10 oC for periods of time up to 109 and 210 days respectively. The results demonstrate the emergence of a small melting peak of the α-polymorph after aging for 69 days at 0°C and for 147 days at -10°C (i.e., ~55°C below the glass transition temperature) that provides evidence of nucleation occurring in the temperature region of the β-relaxation. The evolution of an endothermic recovery peak temperature features a plateau at longer annealing times, suggesting that the glass has made a signifi cant progress toward reaching the supercooled liquid state. It has been found that the melting peaks become detectable after the recovery peak reaches the plateau. The results highlight the importance of studying physical aging in the temperature region of the β – relaxation as a means of evaluating the physical stability of amorphous pharmaceutical materials.

10-28

Authors: Aculina Aricu

The presence of nitrogen in the molecule is usually accompanied either by the appearance of a new activity or the intensifi cation of original activity characteristic for the native terpenoids. This maintains alive the scientifi c interest in the synthesis of such compounds. The present communication put into discussion the recently elaborated methods for preparation of the nitrogen-containing terpenic compounds.

45-51

Authors: Gheorghe Nemtoi, Liliana Airinei, Tudor Lupascu and Alexandru Cecal

The corrosion process of some steels immersed in HNO3 solutions of different concentrations by means of voltammetric measurements was investigated. Even if the differences regarding the chemical composition of these steels were relatively low, it was succeeded to establish some electrochemical parameters (Rp, Ecorr, Epc, Ipc ,EF, Ipas, Estr and Dpas) with different values, in several experimental conditions. For different values of the corrosion potential, or of the contact time solid steel-aggressive medium, were proposed equations of the type: I = f ( E ) ,only for linear domains from the given voltammograms.

57-61

Authors: I. Povar, Nina Timbaliuc, Tatiana Cazac, Diana Shepel, Oxana Spinu and Ludmila Chiriac

An approach has been developed to determine the equilibrium model in heterogeneous aqueous systems containing a mixture of solid phases from the initial composition of the heterogeneous mixture and the equilibrium values of the pH. This approach allows to signifi cantly reduce the quantity of measured data, properly for solubility measurements. By using the new deduced equations it is possible to determine the solubility products of precipitates on the basis of the known composition of initial mixtures and pH values of saturated solutions avoiding some diffi cult experimental solubility measurements. The derived relations are useful for solving both direct and indirect equilibrium problems.

69-72

Authors: Valerian Cerempei

The article investigates phase stability of ethanol-gasoline mixtures depending on their composition, water concentration in ethanol and ethanol-gasoline mixture and temperature. There have been determined the perfect functioning conditions of spark ignition engines fueled with ethanol-gasoline mixtures.

77-80

Authors: T. Lupaşcu, M. Ciobanu, O. Bogdevici, V. Boţan

A large number of dyes have an important role not only in the textile and dye industries, but also in food, pharmaceuticals, cosmetics, and computers. These new applications bring a series of new problems in the purifi cation of waste water obtained from different technological processes, because colorants are microtoxic, mutagens and carcinogens.

86-89

Authors: Sîrbu Dumitru, Marin Ion

This article reports on the high yield synthesis and novel chalcones with isothiocyanate and imidazol groups. The synthesis was started from N,N-diphenilamine and fi nished with 4-(N,N-diphenylamino)-4’-(2-thioxoimidazolidin- 4-one)-chalcone, where the cheap and accessible reagents were used.

110-112

Authors: Veaceslav Kulciţki, Tatiana Sîrbu, Nicon Ungur

A selective rearrangement of a epoxi-homodrimanic substrate is described. Using fl uorosulfonic acid at low temperature leads by ring contraction to a perhydrindanic structure. On the contrary, using boron trifl uoridediethyl ether at r.t. selectively brings about angular methyl migration.