D. Mendeleyev University of Chemical Technology of Russia

Transcription

1 D. Mendeleyev University of Chemical Technology of Russia N.R. Antipkin, G.A. Biljalova, M.A. Bogorodskaya, A.O. Bogorodsky, A.B. Sazonov, A.S. Chagovets Non-stoichiometric synthesis of rhenium heptasulfide hydrosol 7 th International Symposium On Technetium and Rhenium Science and Utilization Moscow Miusskaya square, Moscow 12547, Russia Tel (495) fax (495) mab8@mail.ru Re 2 application Catalysis : 1)±H 2 hydrogenation and dehydrogenation 2)Organic synthesis of complex organic compounds, reduction 3)Rheniforming C 17 H 35 COOH + 3H 2 S Re 2 Re 2 н-c 7 H H 2 C 17 H 35 CH 2 SH + 2H 2 O + 2S CH 3 R, nm S sp, m 2 /g

2 Re 2 application Nuclear medicine: nanoparticles labeled by radionuclides can be used in nuclear medicine for diagnostic and therapeutic purposes. Recently the nanocolloids of technecium 99m have been widely adopted in the technique of intraoperational visualization. Re 2 99m TcO 2 radionuclide generator 99 Mo/ 99m Tc 2Na 99m TcO 4 + 3SnCl 2 + 2H 2 O 2 99m TcO 2 + 3SnO 2 + 2NaCl + 4HCl 3 Objective of the research: to find optimal conditions for the Re 2 nanoparticles formation to determine kinetic parameters of the reaction Characteristics of disperse phase depend on concentration of reagents their ratio order of mixing synthesis time temperature method of stopping reaction 4

3 R E A C T I O N S Re 2 synthesis Na 2 S 2 О 3 + 2HCl Re Na 2 SO NaCI + H 2 O Possible elementary reaction The formation of intermediate substances 4 + Na 2 S 2 O 3 3 S+ Na 2 SO 4 etc other water-soluble forms of Re are formed Side reaction of hyposulfite decomposition Na 2 S 2 O 3 + 2HCl 2NaCl + SO 2 + S coll + H 2 O 5 Continuous medium (ReCM) Re2S7 Re2S7 Dispersoid (ReD) 4 3 S etc. Re2S7 S Primary precipitate Re 2 (RePP) Re 2 S 6

4 Mixing of reactants in ice bath Transferring to the reactor, synthesis 2 min End of synthesis and cooling sample preparation for spectrophotometry Transferring into the centrifuge tubes sample preparation for spectrophotometry 8 Re 2 dissolving techniques and reduced rhenium coloured compounds,5 D,3, λ, nm,3 1) Re 2 + H 2 O 2 + NH 3 2) HCl + Na 2 S 2 O 3 + SnCl 2 D,8,6 D ε 41 = 1,6 1 4 M-1 cm-1, ε 52 =,8 1 4 M-1 cm-1, C(Re) mg/l 1 1) Re 2 + HNO 3 + HCl 3 HCl + HNO 3 2 [Cl] + NOCl + 2 H 2 O 2) HCl + Na 2 S 2 O 3 + SnCl 2 2 NOCl 2NO + Cl 2 8

5 Re 2 dissolving techniques and reduced rhenium coloured compounds,5 D,3, λ, nm,3 1) Re 2 + H 2 O 2 + NH 3 2) HCl + Na 2 S 2 O 3 + SnCl 2 D,8,6 D ε 41 = 1,6 1 4 M-1 cm-1, ε 52 =,8 1 4 M-1 cm-1, C(Re) mg/l 1 1) Re 2 + HNO 3 + HCl 3 HCl + HNO 3 2 [Cl] + NOCl + 2 H 2 O 2) HCl + Na 2 S 2 O 3 + SnCl 2 2 NOCl 2NO + Cl 2 8 Re 2 dissolving techniques and reduced rhenium coloured compounds,5 D,3, λ, nm,3 1) Re 2 + H 2 O 2 + NH 3 2) HCl + Na 2 S 2 O 3 + SnCl 2 D,8,6 D ε 41 = 1,6 1 4 M-1 cm-1, ε 52 =,8 1 4 M-1 cm-1, C(Re) mg/l 1 1) Re 2 + HNO 3 + HCl 3 HCl + HNO 3 2 [Cl] + NOCl + 2 H 2 O 2) HCl + Na 2 S 2 O 3 + SnCl 2 2 NOCl 2NO + Cl 2 8

6 Influence of acidity on heptasulfide yield %, Re Finding optimal acidity ReD -RePP - ΣRe 2 -CM C opt (HCl) = 5 М 1 C(HCl), M Finding optimal synthesis time Prolonged heating in acidic conditions provokes sol coagulation τ opt = 2 3 min 1

7 Activation energy of the main and side reactions Re 2 formation hyposulfite decomposition Na 2 S 2 О HCl Re Na 2 SO NaCI + H 2 O Na 2 S 2 O 3 + 2HCl 2NaCl + SO 2 + S + H 2 O Е акт = 73 ± 3 kj/mol γ = 2,5 Е акт = 16 kj/mol γ = 1,2 When temperature rises up from 2 to 1 o C the rate of Re 2 formation increases in 8 times the rate of Na 2 S 2 O 3 decomposition increases only in 4 times 11 Temperature dependences of the Re 2 and S yields % Na2S2O 4 = 2,2 C(НСl) = 5 М С жел = 2,2 % Time 2 min t opt = 1 o C 3 t o C 12

8 The order of reaction with respect to 4 and Na 2 S 2 O 3 n =1 n =1,35 13 There is a consecutive substitution of oxygen atoms by sulfur atoms iin the molecule of rhenium acid formed after perrhenation protonation. One of the possible reaction mechanism is: HReO 4 + H 2 S 2 O 3 = H[ReO 3 S] + H 2 SO 4 H[ReO 3 S] + H 2 S 2 O 3 = H[ReO 2 S 2 ]+ H 2 SO 4 H[ReO 2 S 2 ]+ H 2 S 2 O 3 = H[ReOS 3 ] + H 2 SO 4 H[ReOS 3 ] + H 2 S 2 O 3 = H[ReS 4 ] + H 2 SO 4 The last one is formation of a sulphidic bridge between rhenium atoms H[ReS 4 ] + H[ReOS 3 ] = Re 2 + H 2 O 14

9 %ma% s.re, Finding optimal concentration of gelatin 7 6 -ReD -RePP - ΣRe 2 5 -ReCM C ,5 1, 1,5 2, 2,5 3,,elgGelatine is necessary, but undesirable agent C opt (gel) = 1,2 % 15 Re 2 yield dependence from the ratio ati R % 9 8 ore, -ReD -RePP - ΣRe 2 7 -ReCM Na2S2O Na S O opt = 4,5 16

10 Particle size distribution (Unicor SP) Na2 S2O3 Na2 S2O3 < 3,5 > 3,5 4 4 Bimodal distribution (5±15nm and 5±2nm) denotes different formation mechanisms or different nature of the particles Large particles are sulphur Na S O = opt 4,5 17 Particle size determination Zeta Potential/ Particle Sizer Nicomp тм 38 ZLS и ТECNAI-12-3R Effective hydrodynamic diameter ø mass-average = 55±2 nm ø number-average = 35±15 nm Small discrepancy means that the distribution of particles over their sizes is narrow Diameter of a nanoparticle dense core (electron microscopy) ø = 1-2 nm The sample of high polydispersity (not ours) Nanoparticles easily pass through sterilizing filter Millipore.22 18

11 ReO 4 - Possible impurities HCl SO 4 2- SO 3 2- S 2- α-aminoacids Fe 3+ NRW-6 NRW-1 NRW-6 NRW-1 + NRW-6 ph>12 ph>9 ph=5-6 The hydrosol was deionized by mixed bed ion-exchange columns 19 Re 2 HYDROSOL Visually transparent hydrosol Tyndall effect shows dispersoid Coagulation after stabilizer destroying 2

12 Comparison of hydrosols, obtained by different methods : Experiment С о (Re), g/l Na2S2O 3 4 С(HCl), M С gel,% Time min ø, nm 1 «Coren» radiopharmaceutica l,36 6, 7,,7,11,81 3,5 1 2 Zabel P.L. 24,59 7,1 3,,125, <1 (6%) 1 2 (14%) 3 Tsopelas ,8 7,7 4, 3 5 <5 (2 %) 4 MUCTR,6 4,5 5 2,2 2 5±2 (1 %) 21 As a result of the work visually transparent non-opalescent deionized product, stable within a wide range of рн (1-9), not coagulating in saturated solutions of salts (including polyvalent cations) even at long heating up to 1 о С has been synthesized. Effective hydrodynamic diameter of the nanoparticles (PCS) is at least 2-3 times more than diameter of the dense core (TEM). Re 2 nanoparticles are irregular shaped, X-ray amorphous, stabilized by gelatin Polydispersity is low: 75% (mass) of the particles have hydrodynamic diameter between 35 to 75 nm. Deionized hydrosols can be stored in an inert atmosphere for indefinitely long time (years). This work may be helpful in developing synthesis of other metal sulfides hydrosols 22

13 Thank you for your attention