Niro Matsuura

Hot-atom chemistry of polyphosphates—III: Reactions of 32P resulting from neutron activation of higher polymer

Abstract For the study of the reactions of 32 P in polymer phosphate during neutron activation, polyphosphates with mean chain lengths, n , of 10 and ∞ (Grahams salt) were used as target materials. The yield of recoil 32 P monomer was found to be much lower than that for tripolyphosphate. But three oxidation states of radiophosphorus of (+1), (+3) and (+5) were found in the recoil species. However, the distribution of the three states could be varied by changing the irradiation condition and target materials. The specific activity decreased with increase of polymer chain length. Bond breakage of polyphosphate during alkaline hydrolysis occurred in units of four (PO 3 ) − , and the accumulation of tetramer and the further hydrolysis of this species led to the conclusion that radioactive labelling occured only at the end atom of the long phosphorus chain.

Hot atom chemistry of tripolyphosphate—II: Reactions of 32P resulting from neutron activation

Abstract Sodium tripolyphosphate hexahydrate (Na 5 P 3 O 10 ·6H 2 O) and anhydrous salt (Na 5 P 3 O 10 ) were irradiated at reactor temperature of about 60°C, dry-ice temperature of about −76°C, in liquid state (aqueous solution) and in frozen state. The retention increased with increases of irradiation time at reactor temperature from a value of 30–50 per cent, yet at dry-ice temperature a constant but lower retention value of about 28 per cent was obtained. Water molecules, either as waters of hydration or solvent, play a very important role in the chemistry of the recoil species. The retention value was largely reduced by the presence of water molecules. Under the same experimental condition the retention value of anhydrous salt attained 48 per cent, while hexahydrate salt 38 per cent, frozen state (0·1 M aqueous solution) 8·5 per cent and liquid state (0·1 M aqueous solution) 1·0 per cent. The labeling position of 32 P in tripolyphosphate was determined by the limiting alkaline hydrolysis method and the radioactivity was found uniformly distributed among the three phosphorus atoms. Sodium pyrophosphates (Na 4 P 2 O 7 ·10H 2 O and Na 4 P 2 O 7 ) and sodium polymetaphosphate (NaP O 3 ) were irradiated in the same way as in tripolyphosphate and a similar trend of results was obtained.

Thermodynamic studies on thallium halides formation in N, N-dimethylformamide

Abstract The differences of the order of stability among halide ions for metal halogeno-complexes in nonaqueous solvents and water are examined by the thermodynamic constants for formation of thallium halides of transfer from water to N, N -dimethylformamide (DMF). The thermodynamic constants for formation of thallium halides were calculated from solubility products of thallium halides. The differences of the order of stability for thallium halides were found to be dependent mainly on the enthalpy changes for formation of thallium halides of transfer from water to DMF.

Hot-atom chemistry of polyphosphates—IV Radiation effect on the oxidation state of 32P in aqueous phase

Abstract Tripolyphosphate solution with various scavengers such as phosphite, hypophosphite, formate and benzene was irradiated in the reactor. The radioactive yields of hypophosphite ( 1 P), phosphite ( 3 P) and phosphate ( 5 P) as well as diphosphite ( 2 P− 4 P) and hypophosphate ( 4 P− 4 P) depended on the irradiation time and the scavenger used. The recoil 32 P species which had a mean oxidation state of +2 at zero γ-dose were mainly composed of 1 P and 3 P species, however, both H and OH radicals produced from the γ-radiolysis of water oxidized 1 P to 3 P and 3 P to 5 P through the intermediate states of 2 P and 4 p respectively. Based on these observations the reaction mechanism of 32 P in aqueous phase was also discussed.

酸素溶存0.8N硫酸溶液におけるリン(III)-鉄(II),ヒ素(III)-鉄(II)およびアンチモン(III)-鉄(II)系の放射線連鎖反応

第V族元素SIII(PIII,AsIII,SbIII)がFeIIと共存している溶液に放射線を照射するとSIII→SV,FeII→FeIIIの両反応が並行して進み,このときの両溶質の放射線収率G(FeIII)およびG(sV)の値はSIIIまたはFeIIがそれぞれ単独に溶存している場合のG値にくらべて異常に大となる。たとえばヒ素(II)-鉄(II)系ではヒ素(III)および鉄(II)の初濃度がともに2.0×10-4mol/lの場合,G(FeIII)=300,G(AsV)=150となる。これらの系におけるG値は二溶質の濃度によって複雑に変化をするが,一般に[FeII]0/[SIII]0の値が大きくなるにしたがってG(FeIII)とG(SV)はともに減少し,G(FeIII)/G(sV)の値は増大する傾向がある。これらの実験事実に基づいて連鎖反応を推定し,その伝播反応としてSIV+O2+H+→sV+HO2を含む機構を検討した結果,上述の伝播反応の進行に鉄(II)が重要な役割をはたしていることやいくつかの競合反応における競合の割合についての知見が得られた。またこれら二溶質系における連鎖反応進行の諸条件について考察した。