Volume 4 (2003)
Articles
TECHNIQUES D'ASSEMBLAGE DES 2-METHYL-4- ARYL-1,2,3,4-TETRAHYDROISOQUINOLEINES. APPLICATION A LA SYNTHESE DES ALCALOÏDES CHERYLLINE ET LATIFINE
LEBRUN STÉPHANE, COUTURE AXEL, GRANDCLAUDON PIERRE*
The purpose of this review is to compile the synthetic approaches to 2-methyl-4-aryl-1,2,3,4-tetrahydroisoquinolines focusing on the published literature from 1970 to present. The review is organized by bond formation and emphasis is particularly placed on the total synthesis, in racemic or enantiomerically pure forms, of the naturally occurring alkaloids cherylline and latifine.
ANALYSE MULTICONFORMATIONNELLE DES MACROLIDES SYMÉTRIQUES DE 12 À 28 CHAÎNONS BASÉE SUR LA MÉCANIQUE MOLÉCULAIRE
BELAIDI S.(1), LABBASSI M.(2), GRÉE R.(3) ET BOTREL A.(3)
In this paper, we studied the a,ß-unsaturated macrolides, which represent the binding structure for many antibiotic families from 12- to 28- membered rings. Our object is to determine preferred conformations of macrocycles and to examine the relative importance of different contributions to total steric energy. The strain energy per CH2 group is relatively higher for macrocycle 12 (m = 4) (E(st/n) = 4.77 Kcal/mol). An important decrease in the strain energy per CH2 group from m = 4 to m = 6 confirms perfectly the limit between the two classes of medium and large rings. For two adjoining macrolides the torsional energy is lower for (m) uneven as in the case of the strain energy for m= 6. The contribution of the Van der Waals energy E (VdW /m) is higher in all examined macrocycles in their stable conformers (m = 6). The most preferential conformer (m = 12) for rings with n even belongs to the F6 family, then for n uneven it belongs to the F5 family; where as for m >12, this one is family 4.
APPLICATION OF HYDROLASES TO THE ENZYMATIC SYNTHESIS OF COSMETIC INGREDIENTS
MAUGARD THIERRY
The cosmetic industry looks for substances able to preserve and take care of the skin. Biotechnology is one of the way to prepare substances able to satisfy the consumers needs. Lipases and glycosidases constitute enzymes families with strong potentialities for the synthesis of many ingredients. These enzymes work in synthesis as well as hydrolysis and catalyze chemio-, regio- and stereo-selectives reactions. Examples could be given such as the modification of antioxidants like vitamin A and C, the synthesis of natural dyes like indigoids, but also the synthesis of biosurfactants like glucamides.
SOME POLYURETHANES BASED ON UNSATURATED POLYESTERS
STELIAN VLAD, CIOBANU CONSTANTIN
The present paper discusses the synthesis of linear unsaturated polyesters by the polycondensation reaction of maleic anhydride with different glycols (ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butane diol, 1,6-hexane diol and neopenthyl glycol) with acidities less than 5 mg KOH/g of sample, and the possibility to decrease the cross-linking process during reaction. The polyester-diols with relatively high molecular weight (~2000) were characterized by IR, 1H-NMR, end - groups analysis, as well as by the double bond content determination. These unsaturated polyesters may be used alone or in combination with other diols or diamines in synthesis of segmented polyurethanes. The presence of the unsaturated polyester as soft segment in the polyurethane chain might result in potential applications in several domains such as synthesis of different block copolymers, thermosetting resins, plasticizers, biodegradable and controlled release systems, etc. The polyurethanes were characterized by infrared (IR) and 1H-NMR spectroscopy, stress-strain measurements and other technique.
VISCOSIMETRIC BEHAVIOR OF WATER-n-PROPANOL SOLUTIONS
LISA GABRIELA, SCUTARU A. M., IRIMIA MARINELA, APREUTESEI DANIELA, IONESCU GHEORGHE.
The goal of the paper is the determination of the dynamic viscosity (?) for water-n-propanol solutions, for various concentrations and temperatures. On the basis of the experimental data, the applicability of the Guzman-Andrade and Walther-Ubbelhode equations, regarding the dependence of the dynamic viscosity on the temperature has been tested. Also, starting from the primary experimental data, the activation parameters of viscous flow: variation enthalpy (?Hm#), variation entropy (?Sm#) and free Gibbs’ energy (?Gm#) using the Eyring equation have been calculated. The characterization of the viscous flow involves also the determination of the dependence of dynamic viscosity versus the concentrations of the solutions. For the studied solutions, the excess viscosities have been calculated and it was established the type of deviation from the ideal behavior. This study and the involved parameters are used in projection but also for the complex description of the phenomenon.
SYSTEME POLYMERE-MEDICAMENT A BASE DE 1-(2-HYDROXYETHYLE)-2-METHYLE-5-NITROIMIDAZOLE IMMOBILISE SUR POLY(METHYLE METHACRYLATE-CO-ACIDE ACRYLIQUE)
POPA MARCEL, DUMITRIU CORINA LAVINIA
RÉSUMÉ: L’objet de l’étude est l’obtention et la caractérisation d’un système polymère-médicament capable a libérer d’une manière contrôlée le principe actif, par une réaction d’hydrolyse suivie de sa diffusion. Le polymère support utilisé est le poly(méthyle méthacrylate-co-acide acrylique), tandis que le médicament est le 1-(2-hydroxyéthyle)-2 méthyle- 5-nitroimidazole. Le système a été réalisé par estérification du copolymère avec le médicament en présence du dicyclohexyle carbodiimide comme activateur. Une étude de l’influence de certains paramètres du processus sur l’efficacité de la réaction a été effectuée. Les paramètres étudiés sont: les rapports médicament/support, activateur/support, et le volume de solvant. Le produit de couplage avec un contenu maximum de médicament a été caractérisé par des méthodes spectrales, du point de vue du comportement thermique, ainsi que de la capacité de libération du médicament dans des conditions qui simulent celles du tube gastro-intestinal.
TURBIDIMETRIC STUDY OF THE DEMIXING PHENOMENON IN LIQUID – LIQUID SYSTEM POLYURETHANE – DIMETHYLFORMAMIDE - WATER
UNGUREANU SIMONA, BĂLĂU LUMINIŢA, CIOBANU CONSTANTIN, POPA MARCEL, APOSTU M. O.*, MELNIG V.*
The present research relates to liquid – liquid demixing phenomena encountered in polyurethane (PU)/N,N’-dimethylformamide (DMF)/water system. The cloud – points were determined by turbidimetric titration for various initial concentrations of PU in DMF. It was experimentally observed that a small amount of water is needed to induce liquid – liquid demixing. The cloud – points were determined by turbidimetric titration for PU/DMF different concentrations between 1÷20 %. The obtained phase diagram is a useful tool for the preparation of membranes with controlled morphology. Morphology and structure of the membranes was studied by Scanning Electronic Microscopy (SEM) technique and by Angular Total Reflection Fourier Transform InfraRred (ATR-FTIR) method. The paper reveals that the morphology of the asymmetric membranes can be anticipated with the help of phase diagram and controlled by casting parameters such as: polymer concentration, coagulation bath composition and temperature.
STUDY OF THE EXTRACTION IN A CONTACTOR EQUIPPED WITH A NEW TYPE OF PACKING
KONCSAG CLAUDIA IRINA, MAIORU GETA SIMONA, TOIU ANCA, ZAHARIA ANIŞOARA ARLEZIANA
A new type of structured packing made of corrugated metal gauze was tested in a liquid - liquid countercurrent contactor at the extraction of some mercaptans (Ethanethiol, 1-Propanethiol and 1-Butanethiol) from gasoline with NaOH solutions (5%, 10% and 15% wt). The study was made in a laboratory installation, comparatively with the contactor without packing, acting as a dispersion column. The new packing has a great void fraction but a small specific area. However, it has sensibly better efficiency in the extraction process, proved by increasing up to 56% the mass transfer coefficients.
LEVURES À VIN EN PANIFICATION
STURZA RODICA, DESEATNICOV O., SUBOTIN IU.
Fermentation is an important stage in the formation of volatile substances which determine aroma and taste of bread. The use of wine leaven in bread baking could contribute to enrichment of the aroma of bread, but this would lengthen technology process, because the potential for fermentation of wine leaven is lower than that of brewer’s yeast. The goal of this study is obtaining of a liquid preferment (concentrate of taste) on the basis of natural or commercial wine leaven, which further will be introduced in the standard process of fast bread baking. The composition and conditions of fermentation of liquid preferment, obtained from same wine yeast samples (2 natural and 2 commercial) were studied. The process was optimized on the basis of gas volume, accumulated during the process of fermentation and on the basis of content of volatile components in the crumb and crust of obtained bread. It was found out that the duration of fermentation is the most considerable factor, while temperature, the amount of leaven and the content of flour play a small role in the formation of the aroma of bread.
THE SUPERIOR USE OF CEREAL RESOURCES FOR THE OBTAINING OF THE DIETETIC BAKERY PRODUCTS OBTAINING THE DOUGH WITH BARLEY FLOUR ADDITION
CIOBANU DOMNICA, LEONTE MIHAI, PĂDURARU LACRĂMIOARA, CHIRIŢĂ MIHAELA
This research program was done in order to obtain bakery products with barley flour addition. It confirms the complex effect of barley flour about reological and quantitative features of dough.
THE SUPERIOR USE OF CEREAL RESOURCES FOR THE OBTAINING OF THE DIETETIC BAKERY PRODUCTS BAKING OF BAKERY PRODUCTS WITH BARLEY FLOUR ADDITION
LEONTE MIHAI, CIOBANU DOMNICA, PĂDURARU LACRĂMIOARA
The utilization of a well-proportioned mixture of wheat flour and barley flour, allows the obtaining of dietetic bakery products, with a reduced content of gluten, wealthy in fiber and in B and PP vitamins. The most propitious dough can be obtained of 12 % barley flour of total mixture, when baking temperature is 180 °C and baking time is 35 minutes. In these conditions the acidity degree is 3.8 and the Core / Crust ratio is 1.2.
CONTRIBUTIONS VIEWING THE REDUCTION OF THE POLLUTING DEGREE FOR SULPHATE WASTE WATERS THROUGH THE PROCESS OF LIGNIN FLOCCULATION WITH PHOSPHORIC ACID AND DIAMMONIUMPHOSPHATE
IFRIM IRINA, CIOBANU DOMNICA, ANDRIOAI GABRIELA
The following technological stages, naming: the wood griding, washing and screening as well as the recovery of the sodium salts, generate sulphate waste waters which are characterized by a highly polluting chemical composition and high biodegradable because of the presence of lignin components. The reduction of the polluting degree is possible because of the flocculation technologies applied in acid medium with a mixture of reacting substances like phosphoric acid and diammonium phosphate.
THE PHOSPHORIC ACID INFLUENCE ON THE DEPOLLUTION OF THE WASTE WATERS ORIGINATED IN THE PRODUCTION OF KRAFT PULP
IFRIM IRINA, CIOBANU DOMNICA, ANDRIOAI GABRIELA
The obtaining of kraft pulp from softwood through the leaching of lignine in a highly alkaline environment leads to the pollution of the environment because of the existence of the alkalilignin and the tiolignin in the waste waters.
MICROBIOLOGICALLY INDUCED CORROSION AND IT’S MITIGATION IN COOLING CYCLES
GAVRILĂ LUCIAN(1), GAVRILĂ DANIELA(2), SIMION ANDREI(1)
The paper presents the data obtained by monitoring the cooling cycles of different industrial plants: ammonia plants, urea plants, power plants, fluid catalytic cracking units, desulphurization units. The typical bacterial populations for each system type and their action against the equipment are presented. The use of oxidizing and nonoxidizing biocides in cooling water treatment is emphasized.
RELIABILITY OF THE PAPER TYPE FOOD – SUPPLIES PACKAGE, AN ESSENTIAL CONDITION IN REDUCING THE ENVIRONMENTAL POLLUTION
CIOBANU DOMNICA*, RUSU BRANDUŞA**, STANCIU CONSTANTIN***
The reliability of the paper package is directly influenced by the conditions of the depositing area and by the nature of the package material. The usefulness of the food – supplies package, vegetal parchment type, used to pack goods having a high greasy level can not overpass 100° C temperature, 70% humidity and a period of 50 hours.