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Synthesis of methyldichlorophosphine and dimethylchlorophosphine
372
Notes
of precipitate does not always correspond to the amount of caesium captured, especially for precipitates produced in HCIO4. The best results with diheteropolyacids (1)-(4) were obtained with acids having a central P atom together with HNO3 and similarly Si with HC1, the worst results were obtained with the combinations of P with HC104, and of Si with HC104 or HNO3. Triheteropolyacids (5)-(13) generally give lower results than corresponding diacids. (Table 1.) TABLE l .--COPRECIPITATION OF CARRIER-FREE CAESIUM
Coprecipitated Cs ( ~ ) acid concentration ,-- 12 N
Heteropolyacid
HPW HPMo HSiW HSiMo HPWV HPMoV HSiWV HSiMoV HAsWV HAsMoV HSeWV HGeWV HBWV
HNO3
HC1
H~S04
HCI04
99'5 99'0
99"4 97"7 97'4 97'0 77"0 80'0
99"2 98"8 92"0 98 "2 50"0 73"0
83'0
40"0
91"8 97"8 77"0 78"0 86"0 83"0 62"0 36"0
80'0 97'0 33'0 21'0 88"0 49'0 5'0 6-0
Note. Detailed data, including the discussion, will be published later. Institute of Nuclear Research Czechoslovak Academy of Sciences Prague
Synthesis o f
V. KOUI~M
methyldichlorophosphine and dimethylchlorophosphine* (Received 15 October 1959)
METHYLDICHLOROPHOSPHINE(II) has been mentioned in numerous publications tl~ but the only reference to its synthesis is a footnote stating that it "was prepared by the reduction of the complex (CHaPC13)(A1C14) (I) in acetonitrile with aluminium", t2~ A more convenient laboratory synthesis is the reduction of the complex (I), prepared from methyl chloride, phosphorus trichloride and aluminium chloride, tg~ with phenyldichlorophosphine in the presence of phosphorus oxychloride. (CH3PCla)(A1C14) + ~PCI~ + POCla --~ CHaPCI~ + ~PCI4 + A1Cla'POCla I II Tributylphosphine is also a satisfactory reducing agent but gives a somewhat lower yield. * Contribution No. 570 from the Central Research Dept., Experimental Station E. I. du Pont de Ncmours and Company, Wilmington, Deleware. ua~ L. Z. SOBOROVSKIIand Yu. M. ZINOV'EV,Zh. Obshch. Khim. 24, 516 (1954); ~M L. D. QUIN and C. H ROLSTON,J. Org. Chem. 23, 1693 (1958). t2) F. W. HOFFMANNand T. R. MOORE,J. Amer. Chem. Soe. 80, 1150 (1958). ta~ j. p. CLAY,J. Org. Chem. 16, 892 (1951).
Notes
373
Dimethylchlorophosphine (IV) was prepared for the first time recently by cleavage of dimethylaminodimethylphosphine with hydrogen chloride. ~4~ Tetramethyldiphosphine disulphide (I/I), obtainable in 85 per cent yield from methylmagnesium bromide and thiophosphoryl chloride, ~6~ has now been converted to dimethylchlorophosphine in 46 per cent yield by simultaneous reduction and cleavage with phenyldichlorophosphine. (CHa)2P--P(CHs)2 + ~PC12 --* 2(CHa)2PC1 + (~PS) fl N Iv S S ]II
Experimental Methyldichlorophosphine. The complex (I) prepared by shaking 12 g of methyl chloride, 31 g of phosphorus trichloride and 29 g of aluminium chloride in a sealed glass tube ta~ was placed in a 200 ml flask connected to a 6 in. Vigreaux column. Addition of 21 ml of phosphorus oxychloride produced an exothermic reaction and most of the complex dissolved. Phenyldichlorophosphine (31 mi) was added and the mixture was heated to 130 °. At that temperature the mixture became homogeneous and 23 ml of a clear, colorless liquid distilled at 80-98 °. Redistillation in a nitrogen atmosphere gave 21 g (82 per cent) of methyldichiorophosphine, b.p. 80-84 °. The infra-red spectrum was identical to that of an authentic sample supplied by the U.S. Army Chemical Cows and contained a strong band for the methyl group at 7-75 p, as reported by CASON and BAXTER.tS~ The 31p magnetic resonance was a sha W peak at -- 191 p.p.m., relative to 85 per cent phosphoric acid (literature value tTj - 191-2 p.p.m.). Substitution of tributylphosphine for the phenyldichlorophosphine used in this experiment gave methyldichlorophosphine in only 61 per cent yield. Dimethylchlorophosphine. A mixture of 9.3 g of tetramethyldiphosphine disulphide and 20"3 ml of phenyldichlorophosphine was heated in a nitrogen atmosphere until the mixture became homogeneous at about 200 °. The clear, yellow solution was distilled to give 6.8 ml of a clear, colorless liquid b.p. 62-70 °. Redistillation gave 4"2 g (46 per cent) of clear, colorless dimethylchlorophosphine, b.p. 77 °, m.p. --4 to 0 ° (literature values: c~> b.p. 73 °, m.p. --1.4 to --1'0°). The infra-red spectrum contained bands assignable to saturated CH bonds at 3.35/~ and to a methyl group at 7.75/~. The proton magnetic resonance contained a symmetrical doublet in the methyl region. The 31p magnetic resonance was a single, sha W peak with a chemical shift of --93.0 p.p.m., relative to 85 per cent phosphoric acid. The mass spectrum contained major peaks at 81, 83, 96 and 98 units in the proper ratio for the presence of one chlorine atom in the molecule. Central Research Department Experimental Station E. I. du Pont de Nemours and Company Wilmington, Delaware
G . W . PARSHALL
~4~A. B. BURGand P. J. SLOTA,J. Amer. Chem. Soc. 80, 1107 (1958). tsJ H. REINHARDT,D. BIANCHIand D. MOLLE,Ber. 90, 1657 (1957). ¢6) j. CASONand W. N. BAXTER,J. Org. Chem. 23, 1303 (1958). iv} N. MULLER,P. C. LAUTERBURand I. GOLDENSON,J. Amer. Chem. Soc. 78, 3557 (1956).
A source of error in the determination of uranium-235 by gamma-spectrometry (Received 14 September, 1959; in revisedform 15 October 1959) URANIUM-235 emits y-rays at 184 keV which can easily be resolved from other y-rays emitted by uranium by using a scintillation spectrometer; data on radiation emitted by uranium and its daughters are given in the Table 1. A number of workers have measured the intensity of y-rays in an energy band at 184 keV to determine ~ssU concentrations in uranic samples.
Notes
of precipitate does not always correspond to the amount of caesium captured, especially for precipitates produced in HCIO4. The best results with diheteropolyacids (1)-(4) were obtained with acids having a central P atom together with HNO3 and similarly Si with HC1, the worst results were obtained with the combinations of P with HC104, and of Si with HC104 or HNO3. Triheteropolyacids (5)-(13) generally give lower results than corresponding diacids. (Table 1.) TABLE l .--COPRECIPITATION OF CARRIER-FREE CAESIUM
Coprecipitated Cs ( ~ ) acid concentration ,-- 12 N
Heteropolyacid
HPW HPMo HSiW HSiMo HPWV HPMoV HSiWV HSiMoV HAsWV HAsMoV HSeWV HGeWV HBWV
HNO3
HC1
H~S04
HCI04
99'5 99'0
99"4 97"7 97'4 97'0 77"0 80'0
99"2 98"8 92"0 98 "2 50"0 73"0
83'0
40"0
91"8 97"8 77"0 78"0 86"0 83"0 62"0 36"0
80'0 97'0 33'0 21'0 88"0 49'0 5'0 6-0
Note. Detailed data, including the discussion, will be published later. Institute of Nuclear Research Czechoslovak Academy of Sciences Prague
Synthesis o f
V. KOUI~M
methyldichlorophosphine and dimethylchlorophosphine* (Received 15 October 1959)
METHYLDICHLOROPHOSPHINE(II) has been mentioned in numerous publications tl~ but the only reference to its synthesis is a footnote stating that it "was prepared by the reduction of the complex (CHaPC13)(A1C14) (I) in acetonitrile with aluminium", t2~ A more convenient laboratory synthesis is the reduction of the complex (I), prepared from methyl chloride, phosphorus trichloride and aluminium chloride, tg~ with phenyldichlorophosphine in the presence of phosphorus oxychloride. (CH3PCla)(A1C14) + ~PCI~ + POCla --~ CHaPCI~ + ~PCI4 + A1Cla'POCla I II Tributylphosphine is also a satisfactory reducing agent but gives a somewhat lower yield. * Contribution No. 570 from the Central Research Dept., Experimental Station E. I. du Pont de Ncmours and Company, Wilmington, Deleware. ua~ L. Z. SOBOROVSKIIand Yu. M. ZINOV'EV,Zh. Obshch. Khim. 24, 516 (1954); ~M L. D. QUIN and C. H ROLSTON,J. Org. Chem. 23, 1693 (1958). t2) F. W. HOFFMANNand T. R. MOORE,J. Amer. Chem. Soe. 80, 1150 (1958). ta~ j. p. CLAY,J. Org. Chem. 16, 892 (1951).
Notes
373
Dimethylchlorophosphine (IV) was prepared for the first time recently by cleavage of dimethylaminodimethylphosphine with hydrogen chloride. ~4~ Tetramethyldiphosphine disulphide (I/I), obtainable in 85 per cent yield from methylmagnesium bromide and thiophosphoryl chloride, ~6~ has now been converted to dimethylchlorophosphine in 46 per cent yield by simultaneous reduction and cleavage with phenyldichlorophosphine. (CHa)2P--P(CHs)2 + ~PC12 --* 2(CHa)2PC1 + (~PS) fl N Iv S S ]II
Experimental Methyldichlorophosphine. The complex (I) prepared by shaking 12 g of methyl chloride, 31 g of phosphorus trichloride and 29 g of aluminium chloride in a sealed glass tube ta~ was placed in a 200 ml flask connected to a 6 in. Vigreaux column. Addition of 21 ml of phosphorus oxychloride produced an exothermic reaction and most of the complex dissolved. Phenyldichlorophosphine (31 mi) was added and the mixture was heated to 130 °. At that temperature the mixture became homogeneous and 23 ml of a clear, colorless liquid distilled at 80-98 °. Redistillation in a nitrogen atmosphere gave 21 g (82 per cent) of methyldichiorophosphine, b.p. 80-84 °. The infra-red spectrum was identical to that of an authentic sample supplied by the U.S. Army Chemical Cows and contained a strong band for the methyl group at 7-75 p, as reported by CASON and BAXTER.tS~ The 31p magnetic resonance was a sha W peak at -- 191 p.p.m., relative to 85 per cent phosphoric acid (literature value tTj - 191-2 p.p.m.). Substitution of tributylphosphine for the phenyldichlorophosphine used in this experiment gave methyldichlorophosphine in only 61 per cent yield. Dimethylchlorophosphine. A mixture of 9.3 g of tetramethyldiphosphine disulphide and 20"3 ml of phenyldichlorophosphine was heated in a nitrogen atmosphere until the mixture became homogeneous at about 200 °. The clear, yellow solution was distilled to give 6.8 ml of a clear, colorless liquid b.p. 62-70 °. Redistillation gave 4"2 g (46 per cent) of clear, colorless dimethylchlorophosphine, b.p. 77 °, m.p. --4 to 0 ° (literature values: c~> b.p. 73 °, m.p. --1.4 to --1'0°). The infra-red spectrum contained bands assignable to saturated CH bonds at 3.35/~ and to a methyl group at 7.75/~. The proton magnetic resonance contained a symmetrical doublet in the methyl region. The 31p magnetic resonance was a single, sha W peak with a chemical shift of --93.0 p.p.m., relative to 85 per cent phosphoric acid. The mass spectrum contained major peaks at 81, 83, 96 and 98 units in the proper ratio for the presence of one chlorine atom in the molecule. Central Research Department Experimental Station E. I. du Pont de Nemours and Company Wilmington, Delaware
G . W . PARSHALL
~4~A. B. BURGand P. J. SLOTA,J. Amer. Chem. Soc. 80, 1107 (1958). tsJ H. REINHARDT,D. BIANCHIand D. MOLLE,Ber. 90, 1657 (1957). ¢6) j. CASONand W. N. BAXTER,J. Org. Chem. 23, 1303 (1958). iv} N. MULLER,P. C. LAUTERBURand I. GOLDENSON,J. Amer. Chem. Soc. 78, 3557 (1956).
A source of error in the determination of uranium-235 by gamma-spectrometry (Received 14 September, 1959; in revisedform 15 October 1959) URANIUM-235 emits y-rays at 184 keV which can easily be resolved from other y-rays emitted by uranium by using a scintillation spectrometer; data on radiation emitted by uranium and its daughters are given in the Table 1. A number of workers have measured the intensity of y-rays in an energy band at 184 keV to determine ~ssU concentrations in uranic samples.