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Synthesis of hypophosphate by ultraviolet irradiation of phosphite solutions
INORG.
NUCL,
CHEM. LETTERS
Vol. 9,
pp. 39-41,
1973.
Pergamon
Press. Printed
in
(~eet
Britain.
SYNTHESIS OF HYPOPHOSPHATE BY ULTRAVIOLET IRRADIATION OF PHOSPHITE SOLUTIONS Alan W. Schwartz and Matty van der Veen Department of Exobiology, University of Nijmegen, The Netherlands (Received 30 July 1972)
The synthesis of hypophosphate has been reported to occur in aqueous solutions of phosphite under the influence of 60Co ~,,m~ rays (I). We wish to report the observation of a similar synthesis by means of ultraviolet irradiation. Irradiations were carried out at 25 ° under nitrogen in an Hanovia one liter photochemical reactor, fitted with a low pressure mercury arc tube. The characteristics of the source are such that most of the energy is emitted at 25h and 185 nm. Preliminary identification of IkTPophosphate was made by means of thin layer chromatography on cellulose in the acid solvent described by Aurenge et el. (2). Comparison was made with an authentic sample of sodium hTpophosphate prepared from elemental phosphorus by the method of Leininger and Chulski (3). Purified product was isolated for purposes of identification from irradiated solutions by column chromatography on cellulose in a solvent consisting of water, ethanol, isobutanol, isopropanol and formic acid (30:35: 15:20:10 v/v). Aliquotes of a concentrated, irradiated solution were injected repeatedly into the solvent stream to the top of a hO cm by 5 cm 2 column of Whatman CC31. The trailing edges of the phosphite peaks of a series of runs were pooled and rechromatographed to yield purified product (peaks were located by conductivity monitoring). After evaporation of the solvent, the residue was taken up in water, passed through a columm of Dowex 50(H +) and evaporated over sodium hydroxide to
$9
ULTRAVIOLET IRRADIATION
40
Voi. 9, No. I
remove the last traces of formic acid. The resistance of the product to acid hydrolysis (relative to pyrophosphate) and its slow hydrolysis to a mixture of phosphate and phosphite were in accord with the known properties of hypophosphoric acid (4). The absence of a P-H stretching band in the region of 2300-2400 cm -I also eliminated such possibilities as isohypophosphate, pyrophosphite, or diphosphite (5). The identity of the product as hypophosphate was substantiated by means of the absorption spectrum of the complex formed with the molybdenum (V) - molybdenum (VI) reagent (6). Yield determinations were made by separation of a band of reaction product on thin layer plates and analysis of the eluted product band for hypophosphate by the method of Yoza and Ohashi (6). The yield of hypophosphate as a function of time and pH is presented in FIG. I.
L--
® 50 .==w
--" 40 o E "--'30 (D =,..
~o 2 0
1
2
3
4
5
6
7
8, 9 10 11 12 13 l& 15
Hours of Irradiation FIG. 1 Yield of hypophosphate as a function of time and pH. All solutions were I0-3M in phosphite and were prepared by mixing appropriate proportions of NaH2FO 3 and Na2HPO 3. o, pH 3.4; A, pH 3.9; o, pH 4.9 and l, pH 8.0 (Na2HP03).
Vol. 9, No. 1
ULTRAVIOLET IRRADIATION
41
The progress curves extrapolate to a point on the abscissa corresponding to about one hour of irradiation. This observation is in qualitative agreement with that of Matsuura et al. of a similar effect in ggmm--radiolysis
(I). The
influence of pH on the reaction rate may be related to the higher extinction coefficients of aqueous solutions of disodium phosphite at 185 nm as compared to that of sodium hydrogen phosphite (7); or, alternatively, to the stability of the hypophosphate radical-ion in aqueous solution. The reaction is quite efficient, more than 10% of Na2HPO 3 being converted to Na4P206 in a few hours. Besides hypophosphate and phosphate, no other products were detected. We wish to thank D. Schoof and L. Fan de Leemput for technical assistance.
References I. N. Matsuura, M. Yoshimura, M. Takizawa and Y. Sasaki, Bull. Chem. Soc. Japan 44, 1027 (1971). 2. J. Aurenge, M. Degeorges and J. Normand, Bull. Soc. Chim. France 31, 508 (1964). 3. E. Leininger and T. Chulski, Inorganic Synthesis (J.C. Bailar, ed.), Vol, IV, p. 68. McGraw Hill, New York (1953): 4. N. Yoza, I. Koga and S. Ohashi, J. Inorg. Nucl. Chem. 33, 1435 (1971.) 5. D.E.C. Corbridge and E.J. Lowe, J. Chem. Soc. 1954, 493. 6. N. Yoza and S. Ohashi, Bull. Chem. Soc. Japan 37, 33 (1964). 7. H. Benderly and M. Halmann, J. Phys. Chem. 71, 1053 (1967).
NUCL,
CHEM. LETTERS
Vol. 9,
pp. 39-41,
1973.
Pergamon
Press. Printed
in
(~eet
Britain.
SYNTHESIS OF HYPOPHOSPHATE BY ULTRAVIOLET IRRADIATION OF PHOSPHITE SOLUTIONS Alan W. Schwartz and Matty van der Veen Department of Exobiology, University of Nijmegen, The Netherlands (Received 30 July 1972)
The synthesis of hypophosphate has been reported to occur in aqueous solutions of phosphite under the influence of 60Co ~,,m~ rays (I). We wish to report the observation of a similar synthesis by means of ultraviolet irradiation. Irradiations were carried out at 25 ° under nitrogen in an Hanovia one liter photochemical reactor, fitted with a low pressure mercury arc tube. The characteristics of the source are such that most of the energy is emitted at 25h and 185 nm. Preliminary identification of IkTPophosphate was made by means of thin layer chromatography on cellulose in the acid solvent described by Aurenge et el. (2). Comparison was made with an authentic sample of sodium hTpophosphate prepared from elemental phosphorus by the method of Leininger and Chulski (3). Purified product was isolated for purposes of identification from irradiated solutions by column chromatography on cellulose in a solvent consisting of water, ethanol, isobutanol, isopropanol and formic acid (30:35: 15:20:10 v/v). Aliquotes of a concentrated, irradiated solution were injected repeatedly into the solvent stream to the top of a hO cm by 5 cm 2 column of Whatman CC31. The trailing edges of the phosphite peaks of a series of runs were pooled and rechromatographed to yield purified product (peaks were located by conductivity monitoring). After evaporation of the solvent, the residue was taken up in water, passed through a columm of Dowex 50(H +) and evaporated over sodium hydroxide to
$9
ULTRAVIOLET IRRADIATION
40
Voi. 9, No. I
remove the last traces of formic acid. The resistance of the product to acid hydrolysis (relative to pyrophosphate) and its slow hydrolysis to a mixture of phosphate and phosphite were in accord with the known properties of hypophosphoric acid (4). The absence of a P-H stretching band in the region of 2300-2400 cm -I also eliminated such possibilities as isohypophosphate, pyrophosphite, or diphosphite (5). The identity of the product as hypophosphate was substantiated by means of the absorption spectrum of the complex formed with the molybdenum (V) - molybdenum (VI) reagent (6). Yield determinations were made by separation of a band of reaction product on thin layer plates and analysis of the eluted product band for hypophosphate by the method of Yoza and Ohashi (6). The yield of hypophosphate as a function of time and pH is presented in FIG. I.
L--
® 50 .==w
--" 40 o E "--'30 (D =,..
~o 2 0
1
2
3
4
5
6
7
8, 9 10 11 12 13 l& 15
Hours of Irradiation FIG. 1 Yield of hypophosphate as a function of time and pH. All solutions were I0-3M in phosphite and were prepared by mixing appropriate proportions of NaH2FO 3 and Na2HPO 3. o, pH 3.4; A, pH 3.9; o, pH 4.9 and l, pH 8.0 (Na2HP03).
Vol. 9, No. 1
ULTRAVIOLET IRRADIATION
41
The progress curves extrapolate to a point on the abscissa corresponding to about one hour of irradiation. This observation is in qualitative agreement with that of Matsuura et al. of a similar effect in ggmm--radiolysis
(I). The
influence of pH on the reaction rate may be related to the higher extinction coefficients of aqueous solutions of disodium phosphite at 185 nm as compared to that of sodium hydrogen phosphite (7); or, alternatively, to the stability of the hypophosphate radical-ion in aqueous solution. The reaction is quite efficient, more than 10% of Na2HPO 3 being converted to Na4P206 in a few hours. Besides hypophosphate and phosphate, no other products were detected. We wish to thank D. Schoof and L. Fan de Leemput for technical assistance.
References I. N. Matsuura, M. Yoshimura, M. Takizawa and Y. Sasaki, Bull. Chem. Soc. Japan 44, 1027 (1971). 2. J. Aurenge, M. Degeorges and J. Normand, Bull. Soc. Chim. France 31, 508 (1964). 3. E. Leininger and T. Chulski, Inorganic Synthesis (J.C. Bailar, ed.), Vol, IV, p. 68. McGraw Hill, New York (1953): 4. N. Yoza, I. Koga and S. Ohashi, J. Inorg. Nucl. Chem. 33, 1435 (1971.) 5. D.E.C. Corbridge and E.J. Lowe, J. Chem. Soc. 1954, 493. 6. N. Yoza and S. Ohashi, Bull. Chem. Soc. Japan 37, 33 (1964). 7. H. Benderly and M. Halmann, J. Phys. Chem. 71, 1053 (1967).