May, 1962
RADIATION INVUCED EXCHANGE OF PHOSPHORUS IN FCl3-POCIO
RADIATIOK INDUCED EXCE-IAKGE OF PHOSPHORUS IN THE SYSTEM'J
863 PCl,-POCl3
BY LEROYF. GRANTHAM AND HERBERT C. MOSER Department of Chemistry, Kansas State University, Manhattan, Kansas Received OctobeT 14, 1961
Phosphorus-32 was used as a tracer to measure the rate of radiation induced exchange of phosphorus in P C ~ S - P O C ~ binary solutions. Ultraviolet and y-radiation induced sufficient exchange to permit a study of the kinetics of the system, but exchange was not induced by visible light. The amount of phosphorus exchanged was found t o obey the equation M = k'bD k"abD, where a and b are concentrations of Pc13 and Poc13, respectively, and D is the gamma or ultraviolet dosage. Values for ky' and ky" were found t o be (3.18 i 0.16) x 10-10 rad-1 and (4.24 t 0.31) x lo-" g. mmole-1 rad-'. For y-rays the ratio k'/k'' was 15 times larger than it was for ultraviolet radiation.
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Introduction
that the samples were free of water and hydrolysis products. The y-irradiations were performed in the high level yExchange of phosphorus between its compounds facility a t Argonne National Laboratory which used spent does not occur generally, e.g., the P4-PCla system3t4 reactor fuel elements as the gamma source. Intensities or the PC13-PSCL s y ~ t e m although ,~ a slow ex- in the range of 0.9 X lo* to 3.7 X 104radsmin.+(inwater) used.'O The aqueous ferrous sulfate dosimetry change was found in the P-PCI, system dissolved in were of dosage made by Argonne National LaboraCSz.5 The exchange of chlorine in phosphorus measurements tory were corrected for density differences in the absorbing chlorides is This accounts far the media to obtain the y-ray dosages received by the samples. A Sylvania Gl5T8 Germicidal-A 15-watt mercury vapor phosphorus exchange found in the PC13-PCls lamp was used for the ultraviolet light source. The fused system.6 A y-ray induced exchange in the P*- silica ampoules were held adjacent t o the external surface of (white)-PC13 system was found,4 and a similarly the lamp. The ambient temperature of the samples during induced exchange of phosphorus between P0C13 irradiation was 50". Approximately 20% 2f the light and PCls was postulated to occur during reactor emitted by this lamp had a wave length of 2537 A. (4.9 e.v.). The mixtures were separated by distillation through irradiation of POCla.9 glass helix packed column (twelve theoretical plates). At Study of the y-ray induced phosphorus exchange least three PC!, and three POC& distillate fractions were in the PC13-POClr system was undertaken to help collected and radioassayed. If the results did not agree interpret the results of neutron irradiations of these within 2% the fractions were recounted along with other fractions of the same component. A graph illustrating compounds. the separating efficiency of this column was given in a Experimental previous publication .4 Radioassayci were made with a Tracerlab TGC5 Geiger Reagents.-Reagent grade Pel3 and P0C13 mere purified by double distillation through an &in. glass helig packed dipping tube in conjunction with a BerkeIey Decimal Scaler, column. Only the center fraction from each distillation was Model 2000. Bppropriate aliquots of radioactive materials kept. These purified reagents were stored in glass-stop- were used t o give. approximately 5000 counts per minute pered flasks and were redistilled if they were not used within after dilution t o 15ml. with xylene, a month after purification. The high boiling carrier in the separation procedure was n-decane. The first 100 ml. of Results decane was purified0 but in subsequent experiments the Rate of exchange (R) was determined from the commercial grade reagent was used. Purified grade xylene was used as a diluent in counting sample reparation. quantitative exchange law Phosphorus-32 labeled PC13 and P&Cls were prepared R = -ab In ( 1 - F ) / ( a b)t (1) by irradiating fused silica ampoules containing these materials in the Oak Ridge Graphite Reactor. The labeled where a; and b are the concentrations of PCI3 stock solutions were purified by distillution through a column having twelve theoretical plates.*P The results were inde- plus P3'C13 and POCla plus P320C1a,respectively, pendent of the compound initially labeled. Fis the fraction of exchange, and t is time. FracProcedure.-Large volumes (100 ml.) of mixtures con- tion of exchange was calculated from taining the correct concentrations of RCl, and POC13 were prepared by pi etting (in air) the carriers and labeled F = ( F - Po)/(l - Fo) (2) material into ggss-stoppered flasks. After the solutions were thoroughly mixed, 5-ml. aliquots were vacuum distilled where p is the apparent fraction exchange and Fo into previously outgassed, fused silica ampoules. The is the fraction exchange due to incomplete separaampoules were sealed under vacuum ( < S O p ) a t liquid nitrogen temperatures. Early experiments indicated that traoe tion. Values of Fo varied from 0.006 to 0.024 amounts of water enhanced the rate of exchange, therefore depending on the labeled stock solution used. during final encapsulation precaution was taken t o ensure Concentrations (a and b) are expressed in milli-
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(1) (a) Work supported by the Atomio Euergy Commission under Contraot AT 11-1-584; (b) Presented in part at the 138th National Meeting, American Chemical Society, New Y o r k , 1960. ( 2 ) From the Ph.D. Thesis of L. F. Grantham. (3) P. I
