La capacite a complexer des ions metalliques constitue l'une des potentialites importantes du chitosane. Ce polymere a montre vis-a-vis des ions testes, une selectivite de complexation qui depend du cation envisage. La capacite a fixer des ions varie de 0,02 mmol/g du chitosane pour Co 2+ . Ca 2+ a 1.2 pour Cu 2+ . Cet ordre selectif est confirme en utilisant les methodes de potentiometrie et de spectroscopie. Des essais de recuperation des metaux ont ete realises sur des effluents reels. Les premiers resultats permettent de confirmer les potentialites de ce polymere en tant qu'agent de depollution.

In this paper, from many new examples, our approach on the preparation of chitins and chitosans with controlled physico-chemical characteristics was presented. The chitosan samples were prepared from α-chitin from crustacean shells and β-chitin from squid pens. The chitin deacetylation was carried out according to two methods using, respectively, as alkaline agent, the aqueous sodium hydroxide solution and anhydrous potassium hydroxide. The role of the source and of the process on the N-deacetylation reactions is confirmed. The effect of the addition of sodium borohydride or thiophenol within the reaction medium was studied. One of the parameters conditioning the physico-chemical characteristics of chitosan being in relation with the nature and the quality of original chitin, the role of this parameter was examined and the isolation process was discussed to put in evidence its advantages compared to other processes quoted in the literature by relying on new results.

The complexation of copper ions by chitosan and its oligomers is investigated using potentiometric and spectrophotometric methods to study the nature of the complexes involved and the role of the degree of polymerisation. Two complexes are demonstrated. Their structure is proposed, the pH range in which they are respectively stable is determined and their stability constants calculated. Finally a degree of polymerisation of 6 appeared as the threshold value for an efficient complexation of copper ions by chitosan oligomers.

The capacity of the chitosan to complex metallic ions is one of its most important potentialities. This polymer shows a selectivity according to the considered cation. In the case of divalent ions the capacity to fix the metallic ions increases from 0.02 mmol/g of chitosan for Co2+, Ca2+ to 1.2 for Cu2+ in the same external conditions. Considering trivalent ions this capacity is from 0.2 mmol/g of chitosan for Pr3+ and Cr3+ to 1.47 for Eu3+ and Nd3+. This selectivity seems to be independent on the size and the hardness of the ions. This order in the selectivity is confirmed using potentiometric and spectrophotometric methods and does not depend on the physical form of chitosan. Recovery tests of metals were carried out on real effluents. The first results obtained confirm the initial interest in using chitosan as a depolluting agent, especially as a film. (C) 2002 Elsevier Science Ltd. All rights reserved.

The capacity of the chitosan to complex metallic ions is one of its most important potentialities. This polymer shows a selectivity according to the considered cation. In the case of divalent ions the capacity to fix the metallic ions increases from 0.02 mmol/g of chitosan for Co2+, Ca2+ to 1.2 for Cu2+ in the same external conditions. Considering trivalent ions this capacity is from 0.2 mmol/g of chitosan for Pr3+ and Cr3+ to 1.47 for Eu3+ and Nd3+. This selectivity seems to be independent on the size and the hardness of the ions. This order in the selectivity is confirmed using potentiometric and spectrophotometric methods and does not depend on the physical form of chitosan. Recovery tests of metals were carried out on real effluents. The first results obtained confirm the initial interest in using chitosan as a depolluting agent, especially as a film.

Chitin was extracted from squid pens and the used conditions allow to obtain a completely N-acetylated β-chitin with a molecular weight large enough for the obtention of chitosans of high molecular weight. Deacetylation, leading to the obtention of chitosan, was performed according to two processes (Kurita and Broussignac conditions) and the physicochemical characteristics (degree of acetylation and molecular weight) of the obtained chitosans were compared. The influence of the reaction conditions (temperature, repetition of alkaline steps, etc.) is discussed in relation with the physicochemical characteristics of the chitosan. This will allow one to choose the best process for preparing chitosan so that it is suitable for its end use.

Several sea sources for chitin have been investigated, and the chitin content and crystallographic polymorph of the extracted chitin determined. Deacetylation of the chitin was carried out and the physicochemical characteristics of the resulting chitosan studied. The influence of the reaction parameters (reaction duration, temperature, nature of alkaline reagent, etc) was followed, Thus it became possible to determine adequate reaction conditions for obtaining chitosans with the required properties. The physicochemical characteristics of the obtained chitosan are closely related to the taxonomy of the source. New sea sources for chitin have been investigated and considered for industrial purposes, (C) 2000 Society of Chemical Industry.

La complexation du coeur 99mTcO3+ par le 2,10-diméthyl-4,8-dithiaundécane-2,10-dithiol 1 a été réalisée en utilisant un sel d'étain comme réducteur et a conduit à la formation d'une espèce I stable et neutre. Avec le 5-butyl-3,7-dithianonane-1,9-dithiol 2, la même réaction conduit à la formation d'un complexe II instable difficile à isoler. Les études biologiques sur la souris Swiss ont montré que seul I était intéressant (fixation myocardique supérieure à celle du RP 30). Dans le cas des complexes à coeur TcN, on obtient chaque fois deux espèces neutres, soit à partir de [99mTcNCl4]−, soit à partir de 99mTcNCl2[P(CH2CH2CN)3]2; il est possible, selon les conditions opératoires, de favoriser la formation de l'une ou l'autre espèce et de les isoler par purification. Les résultats biologiques se sont avérés assez décevants.

The following dithioetherdithiols: 2,10-dimethyl-4,8-dithiaundecane-2,10-dithiol 1, 5-butyl-3,7-dithianonane-1,9-dithiol 2 and 4,4,6,6-tetramethyl-3,7-dithianonane-1,9-dithiol 3 have been synthesized. These compounds are very attractive as potential precursors of technetiated radiopharmaceuticals. While the syntheses of compounds 1 and 2 have been achieved satisfactorily, that of 3 unfortunately could not be effected: the reaction of ethanedithiol (or of its monobenzylated or monobenzoylated derivatives) with 2,4-dimethylpentane-2,4-diol leads mostly to cyclization or fragmentation products.

L'ion [99mTcNCl4]− a été préparé en milieu chlorhydrique à partir de 99mTcO4− en utilisant NaN3 comme source d'azote. Une étude de sa stabilité en fonction du pH montre qu'il est transformé de façon notable en une nouvelle espèce au bout de 30 min dès un pH de 4. Pour un pH de 5 la transformation est pratiquement totale après le même temps. Il se forme l'ion pertechnétate: un certain nombre de réactions classiques de cet ion appliquées à la nouvelle espèce formée l'ont démontré sans ambiguīté.

ChemInformVolume 19, Issue 27 Preparative Organic Chemistry ChemInform Abstract: Synthesis of 15-(1,3-Dimercapto-2-propyl)pentadecanoic Acid, a Potential Complexing Agent for 99mTc. A. ALAGUI, A. ALAGUI Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorM. APPARU, M. APPARU Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorM. COMET, M. COMET Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorR. PASQUALINI, R. PASQUALINI Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorM. VIDAL, M. VIDAL Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this author A. ALAGUI, A. ALAGUI Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorM. APPARU, M. APPARU Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorM. COMET, M. COMET Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorR. PASQUALINI, R. PASQUALINI Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this authorM. VIDAL, M. VIDAL Univ. Sci. Technol. Med. Grenoble LEDSS, 38402 St-Martin-d'HeresSearch for more papers by this author First published: July 5, 1988 https://doi.org/10.1002/chin.198827112Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume19, Issue27July 5, 1988 RelatedInformation

The labelling of 1,3-n alkylpropanedithiols and of 15-/1,3-dimercapto 2-propyl/ pentadecanoic acid by99mTc has been performed by an exchange reaction with the hexachlorotechnetate ion99mTcCl 6 2− and by reduction of99mTcO 4 − with Sn/II/ in the presence of the ligand. The biological distribution of the exotechnetium complexes obtained by the latter method in mouse does not reveal a high tropism of these labelling compounds in relation to a particular tissue.