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Organic salts of lanthanide elements—II
J. Inorg. Nucl. Chem., 1963, Vol. 25, pp. 201 to 203. Pergamon Press Lid. Printed in Northern Ireland
ORGANIC SALTS OF LANTHANIDE ELEMENTS--II PREPARATION OF LANTHANUM AND CERIUM(II1) ACYLATES FROM A NON-AQUEOUS MEDIUM S. N. MISRA, T. N. MISRA, R. C. MEHROTRA* Chemical Laboratories, Gorakhpur University, Gorakhpur, India (Received 24 July 1962)
Abstract--The reactions of anhydrous lanthanum and cerium(III) chlorides have been studied with acetic acid, acetic anhydrideacetic acid and acetic anhydride. In all three reactions, tri-acetates are the final products in quantitative yield. The molecular weights, determined ebullioscopically in benzene, show them to be monomeric. Reactions of lanthanum and cerium(liD chlorides with palmitic acid have also been studied at different molar ratios in benzene and the mono-, di-, and tri-palmitates have been isolated. IN an earlier publication/1) the preparation o f the tri-laurates, palmitates, and stearates of lanthanum and cerium(lII) has been described and they have been shown to be stable, non-hydrolysable compounds. In a recent detailed study ~2) the reactions of lanthanum and n e o d y m i u m oxides with acetic acid and acetic anhydride have been shown to yield oxo-acetates with the formula ( A c O ) 2 M - - O - - M ( O A c ) 2 . 2 A c O H , which are converted to the tri-acetates only on prolonged refluxing with acetic anhydride. These tri-acetates have been given bridge structure of the type Ae
(AcO)~M~O~M(OAc)2 Ac on the basis of their behaviour in conductometric titrations with acids. Oxy-acylates o f this type have been reported in the case of titanium (3) f r o m the reactions of titanium oxide-alkoxide as well as titanium alkoxides and titanium tetrachloride, A similar detailed study in these laboratories ~4) of the reaction of alkyl borates with acetic anhydride has confirmed the bridged structure of boron acetate reported by GERRARD~5) and by LAUBENGAYER(6) and co-workers. In view o f the formation of non-hydrolysable cerium(III) and lanthanum soaps (~) from aqueous solutions and the formation of oxy-acetate products reported by SEATON et al. (2), it was considered worth while to study the reactions of lanthanum and cerium (III) chlorides with palmitic acid in a non-aqueous medium. It was found that these reactions are slow, more so in lanthanum chloride than in cerium(III) chloride but the mono-, di-, and tri-palmitates can be isolated by simple metathetic reactions, e.g. MC13 + x R C O O H -+ MCI(3_~I(RCOO)x ~- xHC1 * Present address: University Prof. and Head of Chemistry Dept. University of Rajasthan, Jaipur. (India). ~1~S. N. MmRA,T. N. MmRAand R. C. MEHROTRA,J. Inorg. Nuel. Chem., 25, 195 (1963). ~z)j. A. SEATON,F. G. SHERIFand L. F. AUDRIETH,J. lnorg. Nucl. Chem. 9, 222-231 (1955). (3) K. C. PANDEand R. C. MEHROTRA,Chem. and Ind., 114 (1957). t41 A. K. RAI and R. C. MEHROTRA,Private communication (1962). [5~ W. GERRARDand A. M. WHEELANS,Chem. and Ind. 758, (1954). (6) R. G. HAYTER,A. W. LAUBENGAYERand P. G. THOMPSON,J. Amer. Chem. Soe. 79, 4043, (1957). 201
202
S . N . MISRA, T. N. MISRA and R. C. MEHRO'IRA
( M -----l a n t h a n u m or cerium(III), x = 1, 2 or 3). The f o r m a t i o n o f an oxygen-bridged c o m p o u n d could n o t be detected at a n y stage in the a b o v e reactions. In view Of their form a t i o n in the r e a c t i o n between t i t a n i u m tetrachloride a n d acetic acid, it was considered o f interest to study the r e a c t i o n between a n h y d r o u s l a n t h a n u m a n d cerium(III) chloride a n d acetic acid, acetic a c i d - a c e t i c a n h y d r i d e mixture a n d acetic a n h y d r i d e . I n all these cases quantitative yields o f the tri-acetates were o b t a i n e d as final p r o d u c t s . M e a s u r e ments o f the m o l e c u l a r weights o f these c o m p o u n d s in benzene showed t h e m to be m o n o m e r i c , in sharp c o n t r a s t to the b r i d g e d structure suggested on the basis o f their p h y s i c o - c h e m i c a l properties. EXPERIMENTAL Material Anhydrous acetic acid (E. Merck) was dehydrated by refluxing with acetic anhydride~ followed by fractionation. Acetic anhydride (B.D.H.) was purified by fractionation and the distillate collected at 138-140°C. Palmitic acid (B.D.H.) was purified by distillation under reduced pressure. Benzene (B.D.It.) was purified as in our earlier work c1~. Anhydrous lanthanum chloride, prepared from lanthanum oxide (E. Merck, 99 per cent), was dissolved in hydrochloric acid (A.R.) and evaporated to dryness. This process was repeated four times and the anhydrous salt was prepared by heating in a closed tube in dry hydrogen chloride. Anhydrous cerium(III) chloride was obtained from a hydrated sample (B.D.H.) by removing the water azeotropically with benzene and ethanol. The final product was freed from volatile solvents under reduced pressure. Methods Molecular weights were determined ebullioscopically in dry benzene as in Part I ~1~. Analyses Lanthanum and cerium(liD in the acetates were estimated by igniting a weighted quantity at 900°C to the respective oxides. Carbon and hydrogen contents of the acetates were estimated by standard methods. In the chloride acylates, lanthanum and cerium were estimated by precipitation as the oxinates. Preparation of chloride acylates of lanthanum and cerium(liD (i) Reaction of lanthanum chloride and palmitic acid (molar ratio 1:1). Freshly-distilled palmitic acid (1-294 g) was added to powdered anhydrous lanthanum chloride (1"25 g) in 30 g of dry benzene, and the contents were refluxed. After several hours refluxing evolution of hydrogen chloride gas had not stopped completely, although it had become very slow. The product was filtered and washed repeatedly with dry methanol, in which both lanthanum chloride and palmitic acid are soluble. After washing, the compound was dried under reduced pressure (0"05 mm) at 30°C for 3 hr. (Yield 1"506 g Found: La, 30.49; CI, 16.28. Calc. for La(C15H31COO)C12: La, 30"1; C1, 15.24~o). (ii) Reaction of cerium(III) chloride and palmitic acid (molar ratio 1 : 1). Cerium (III) chloride (1"34 g), palmitic acid (1"33 g) and benzene (30 g) were refluxed in a bath at 110°C. The compound was filtered and washed several times with dry methanol, dried under reduced pressure and analysed (Yield: 1"29 g Found: Ce, 30.49; CI, 16-4. Calc. for Ce(ClsHaxCOO) C12: Ce, 29.95; CI,1 15.2~.) (iii) Reaction of lanthanum chloride and palmitic acid (molar ratio 1 : 2). Lanthanum chloride (1"489 g), palmitic acid (3.304 g) and benzene (25 g) were refluxed at a bath temperature of I10°C. Hydrogen chloride was not detected before 8 hr refluxing. The reaction was stopped after several hours and the product filtered, washed thoroughly with dry methanol, and dried under reduced pressure (0-05 mm) at 30°C. (Yield: 1-89 g Found: La, 21"2; C1, 4"8. Calc for La (C15HalCOO)zCl: La, 20"4; C1, 5"18~). (iv) Reaction of cerium (110 chloride and palmitic acid (molar ratio 1:2). Cerium(Ill) chloride (1-35 g), palmitic acid (2-70 g) and benzene (35 g) were refluxed in a bath at 115°C and after 15 hr. refluxing hydrogen chloride was detected at the top of the condenser. After prolonged refluxing a glassy solid separated from the lower, unreacted cerous chloride. Refluxing was continued until the evolution of hydrogen chloride had slowed down considerably. The compound was filtered through a sintered funnel (G-4), washed thoroughly with methanol, and dried under reduced pressure (Yield: 1-28 g Found: Ce, 20"8; C1, 5-4 Calc. for Ce(CI~H3~COO)aCI: Ce, 20'36; Cl, 5'14~o). (v) Reaction of lanthanum chloride andpalmitic acid (molar ratio 1:3). Finely powdered lanthanum chloride (1.0 g), freshly-distilledpalmitic acid (.3.10 g) and anhydrous benzene (30-0 g) were refluxed in a bath kept at 115°C for several hours. It was evident from the speedof evolution of hydrogen chloride
Organic salts of lanthanide elements--II
203
that this reaction was faster than those with 1 : 1, and 1:2 molar ratios. After several hours' refluxing the reaction was terminated when evolution of hydrogen chloride gas had ceased. The compound was filtered, washed several times with methanol, and dried under reduced pressure (0.05 ram) at 30°C. (Yield: 2.01 g Found: La, 16.3; C1~H31COO (palmitate), 83-5. Calc. for La(C15H31COO)3: La, 15-54; C15H31COO, 84.46~). (vi) Reaction of cerium(Ill) chloride with palmitic acid (molar ratio 1 : 3). Cerium(Ill) chloride (1"63 g, palmitic acid (5'19 g) and benzene (30 g) were refluxed at a bath temperature of 115°C for several hours. The reaction was terminated after several hours' refluxing. The product was filtered, washed repeatedly with dry methanol, and dried under reduced pressure. (Yield: 3"25 g Found: Ce, 14-98; Cl~H3tCOO (palmitate), 84"3. Calc. for Ce(C15H31COO)3: Ce, 15-48; C15H3tCOO, 84.52 ~).
Preparation of rare earth acetates (i) Reaction of lanthanum chloride and acetic acid. Lanthanum chloride (2"34 g) and acetic acid (60 g) were refluxed on an oil bath (135°C) for several hours. Hydrogen chloride was detected at the top of the condenser just after refluxing had started. The evolution of hydrogen chloride was very rapid initially, but gradually became slower. After half an hour the lanthanum chloride had dissolved completely in the solvent, and after a few hours' refluxing a white crystalline solid separated from the solution. When reaction was complete as shown by the absence of hydrogen chloride at the top of the condenser, the product was filtered, washed several times with dry acetic acid and dried under reduced pressure at 70°C. (Yield: 2"98 g Calc. yield: 3.02 g Found: La, 43"89; C, 22.84; H, 2'90. Calc. for La(CH3COO)3: La, 44.11; C, 22.74; H, 2.86~). (ii) Reaction of cerium(Ill) chloride and acetic acid. Cerium(III) chloride (2"53 g) acetic acid (30 g) were reftuxed in an oil-bath (135°C); the reaction began immediately with vigorous evolution of hydrogen chloride. As refluxing proceeded a white solid separated. When the reaction was complete this was filtered, washed thoroughly with acetic acid, and dried at 60°C under reduced pressure. (Yield: 2'73 g Calc. yield: 2.8 g Found: Ce, 44'4; C, 22.8; H, 2"85. Calc. for Ce(OOCCH3)3: Ce, 44.16; H, 2.85; C, 22.7~). (iii) Reaction of lanthanum chloride with acetic acM acetic anhydride. Acetic acid (30 g), acetic anhydride (30 g) and lanthanum chloride (3"28 g) were refluxed an oil-bath for several hours. It was only after 4 hr refluxing that hydrogen chloride was detected, indicating that this reaction was slower than that with acetic acid. Once reaction had begun, hydrogen chloride was liberated at an appreciable rate and the reaction was complete after several hours. The solid, which started to separate as soon as the reaction had commenced, was filtered, washed thoroughly with acetic acid and acetic anhydride and dried at 70°C under reduced pressure. (Yield: 4.1 g Calc. yield: 4"22 g Found: La, 44-3; C, 22.75; H, 2.91. Calc. for La(OOCCH3)3: La, 44'11; C, 22.76; H, 2.85~). (iv) Reaction of cerium(Ill) chloride with acetic acid-acetic anhydride. Cerium(III) chloride (3.42 g), acetic acid (30 g) and acetic anhydride (30 g) were refluxed for several hours in a bath at 130°C. On prolonged refluxing the chloride dissolved, but on cooling a crystalline solid separated in amounts whichincreased with increasing time of refluxing. After completion of the reaction the solid was filtered, washed thoroughly with acetic anhydride-acetic acid and dried under reduced pressure at 65°C. (Yield: 4'34 g Calc. yield: 4'5 g Found: Ce, 44.34; C, 22.74; H, 2.94. Calc. for Ce(OOCCH3)3: Ce, 44.16; C, 22-75, H, 2-85~). (v) Reaction of lanthanum chloride and acetic anhydride. Lanthanum chloride (2.18 g) and acetic anhydride (60 g) were refluxed for several hours; hydrogen chloride was only detected after 10 hr refluxing; dissolution of lanthanum chloride was also slower in this case. When hydrogen chloride was no longer detectable the product was filtered, washed thoroughly with acetic anhydride and dried under reduced pressure at 70°C. (Yield: 2-75 g Calc. yield: 2'80 g Found: La, 44.3; C, 22"95; H. 2.75. Calc. for I_.a(OOCCHa)3: La, 44.11; C, 22.76; H, 2"85~). (vi) Reaction of cerium(Ill)chloride with acetie anhydride. Cerium(III) chloride (3.14 g), and acetic anhydride (40 g) were refluxed at a bath temperature of 140°C for several hours. This reaction was also slow and hydrogen chloride could only be detected after 9 hr refluxing. The product was filtered, washed with acetic anhydride several times, and dried under reduced pressure at 65°C. (Yield : 3-94 g Calc. yield: 4 g Found: Ce, 44.38; C, 22.98; H, 2.7. Calc for Ce(OOCCHs)3: Ce, 44-16; C, 22.75; H 2-85 o/). Acknowledgement--Two of us (S. N. M., T. N. M.) are grateful to the Atomic Energy Establishment, Bombay, for the award of research fellowships.
ORGANIC SALTS OF LANTHANIDE ELEMENTS--II PREPARATION OF LANTHANUM AND CERIUM(II1) ACYLATES FROM A NON-AQUEOUS MEDIUM S. N. MISRA, T. N. MISRA, R. C. MEHROTRA* Chemical Laboratories, Gorakhpur University, Gorakhpur, India (Received 24 July 1962)
Abstract--The reactions of anhydrous lanthanum and cerium(III) chlorides have been studied with acetic acid, acetic anhydrideacetic acid and acetic anhydride. In all three reactions, tri-acetates are the final products in quantitative yield. The molecular weights, determined ebullioscopically in benzene, show them to be monomeric. Reactions of lanthanum and cerium(liD chlorides with palmitic acid have also been studied at different molar ratios in benzene and the mono-, di-, and tri-palmitates have been isolated. IN an earlier publication/1) the preparation o f the tri-laurates, palmitates, and stearates of lanthanum and cerium(lII) has been described and they have been shown to be stable, non-hydrolysable compounds. In a recent detailed study ~2) the reactions of lanthanum and n e o d y m i u m oxides with acetic acid and acetic anhydride have been shown to yield oxo-acetates with the formula ( A c O ) 2 M - - O - - M ( O A c ) 2 . 2 A c O H , which are converted to the tri-acetates only on prolonged refluxing with acetic anhydride. These tri-acetates have been given bridge structure of the type Ae
(AcO)~M~O~M(OAc)2 Ac on the basis of their behaviour in conductometric titrations with acids. Oxy-acylates o f this type have been reported in the case of titanium (3) f r o m the reactions of titanium oxide-alkoxide as well as titanium alkoxides and titanium tetrachloride, A similar detailed study in these laboratories ~4) of the reaction of alkyl borates with acetic anhydride has confirmed the bridged structure of boron acetate reported by GERRARD~5) and by LAUBENGAYER(6) and co-workers. In view o f the formation of non-hydrolysable cerium(III) and lanthanum soaps (~) from aqueous solutions and the formation of oxy-acetate products reported by SEATON et al. (2), it was considered worth while to study the reactions of lanthanum and cerium (III) chlorides with palmitic acid in a non-aqueous medium. It was found that these reactions are slow, more so in lanthanum chloride than in cerium(III) chloride but the mono-, di-, and tri-palmitates can be isolated by simple metathetic reactions, e.g. MC13 + x R C O O H -+ MCI(3_~I(RCOO)x ~- xHC1 * Present address: University Prof. and Head of Chemistry Dept. University of Rajasthan, Jaipur. (India). ~1~S. N. MmRA,T. N. MmRAand R. C. MEHROTRA,J. Inorg. Nuel. Chem., 25, 195 (1963). ~z)j. A. SEATON,F. G. SHERIFand L. F. AUDRIETH,J. lnorg. Nucl. Chem. 9, 222-231 (1955). (3) K. C. PANDEand R. C. MEHROTRA,Chem. and Ind., 114 (1957). t41 A. K. RAI and R. C. MEHROTRA,Private communication (1962). [5~ W. GERRARDand A. M. WHEELANS,Chem. and Ind. 758, (1954). (6) R. G. HAYTER,A. W. LAUBENGAYERand P. G. THOMPSON,J. Amer. Chem. Soe. 79, 4043, (1957). 201
202
S . N . MISRA, T. N. MISRA and R. C. MEHRO'IRA
( M -----l a n t h a n u m or cerium(III), x = 1, 2 or 3). The f o r m a t i o n o f an oxygen-bridged c o m p o u n d could n o t be detected at a n y stage in the a b o v e reactions. In view Of their form a t i o n in the r e a c t i o n between t i t a n i u m tetrachloride a n d acetic acid, it was considered o f interest to study the r e a c t i o n between a n h y d r o u s l a n t h a n u m a n d cerium(III) chloride a n d acetic acid, acetic a c i d - a c e t i c a n h y d r i d e mixture a n d acetic a n h y d r i d e . I n all these cases quantitative yields o f the tri-acetates were o b t a i n e d as final p r o d u c t s . M e a s u r e ments o f the m o l e c u l a r weights o f these c o m p o u n d s in benzene showed t h e m to be m o n o m e r i c , in sharp c o n t r a s t to the b r i d g e d structure suggested on the basis o f their p h y s i c o - c h e m i c a l properties. EXPERIMENTAL Material Anhydrous acetic acid (E. Merck) was dehydrated by refluxing with acetic anhydride~ followed by fractionation. Acetic anhydride (B.D.H.) was purified by fractionation and the distillate collected at 138-140°C. Palmitic acid (B.D.H.) was purified by distillation under reduced pressure. Benzene (B.D.It.) was purified as in our earlier work c1~. Anhydrous lanthanum chloride, prepared from lanthanum oxide (E. Merck, 99 per cent), was dissolved in hydrochloric acid (A.R.) and evaporated to dryness. This process was repeated four times and the anhydrous salt was prepared by heating in a closed tube in dry hydrogen chloride. Anhydrous cerium(III) chloride was obtained from a hydrated sample (B.D.H.) by removing the water azeotropically with benzene and ethanol. The final product was freed from volatile solvents under reduced pressure. Methods Molecular weights were determined ebullioscopically in dry benzene as in Part I ~1~. Analyses Lanthanum and cerium(liD in the acetates were estimated by igniting a weighted quantity at 900°C to the respective oxides. Carbon and hydrogen contents of the acetates were estimated by standard methods. In the chloride acylates, lanthanum and cerium were estimated by precipitation as the oxinates. Preparation of chloride acylates of lanthanum and cerium(liD (i) Reaction of lanthanum chloride and palmitic acid (molar ratio 1:1). Freshly-distilled palmitic acid (1-294 g) was added to powdered anhydrous lanthanum chloride (1"25 g) in 30 g of dry benzene, and the contents were refluxed. After several hours refluxing evolution of hydrogen chloride gas had not stopped completely, although it had become very slow. The product was filtered and washed repeatedly with dry methanol, in which both lanthanum chloride and palmitic acid are soluble. After washing, the compound was dried under reduced pressure (0"05 mm) at 30°C for 3 hr. (Yield 1"506 g Found: La, 30.49; CI, 16.28. Calc. for La(C15H31COO)C12: La, 30"1; C1, 15.24~o). (ii) Reaction of cerium(III) chloride and palmitic acid (molar ratio 1 : 1). Cerium (III) chloride (1"34 g), palmitic acid (1"33 g) and benzene (30 g) were refluxed in a bath at 110°C. The compound was filtered and washed several times with dry methanol, dried under reduced pressure and analysed (Yield: 1"29 g Found: Ce, 30.49; CI, 16-4. Calc. for Ce(ClsHaxCOO) C12: Ce, 29.95; CI,1 15.2~.) (iii) Reaction of lanthanum chloride and palmitic acid (molar ratio 1 : 2). Lanthanum chloride (1"489 g), palmitic acid (3.304 g) and benzene (25 g) were refluxed at a bath temperature of I10°C. Hydrogen chloride was not detected before 8 hr refluxing. The reaction was stopped after several hours and the product filtered, washed thoroughly with dry methanol, and dried under reduced pressure (0-05 mm) at 30°C. (Yield: 1-89 g Found: La, 21"2; C1, 4"8. Calc for La (C15HalCOO)zCl: La, 20"4; C1, 5"18~). (iv) Reaction of cerium (110 chloride and palmitic acid (molar ratio 1:2). Cerium(Ill) chloride (1-35 g), palmitic acid (2-70 g) and benzene (35 g) were refluxed in a bath at 115°C and after 15 hr. refluxing hydrogen chloride was detected at the top of the condenser. After prolonged refluxing a glassy solid separated from the lower, unreacted cerous chloride. Refluxing was continued until the evolution of hydrogen chloride had slowed down considerably. The compound was filtered through a sintered funnel (G-4), washed thoroughly with methanol, and dried under reduced pressure (Yield: 1-28 g Found: Ce, 20"8; C1, 5-4 Calc. for Ce(CI~H3~COO)aCI: Ce, 20'36; Cl, 5'14~o). (v) Reaction of lanthanum chloride andpalmitic acid (molar ratio 1:3). Finely powdered lanthanum chloride (1.0 g), freshly-distilledpalmitic acid (.3.10 g) and anhydrous benzene (30-0 g) were refluxed in a bath kept at 115°C for several hours. It was evident from the speedof evolution of hydrogen chloride
Organic salts of lanthanide elements--II
203
that this reaction was faster than those with 1 : 1, and 1:2 molar ratios. After several hours' refluxing the reaction was terminated when evolution of hydrogen chloride gas had ceased. The compound was filtered, washed several times with methanol, and dried under reduced pressure (0.05 ram) at 30°C. (Yield: 2.01 g Found: La, 16.3; C1~H31COO (palmitate), 83-5. Calc. for La(C15H31COO)3: La, 15-54; C15H31COO, 84.46~). (vi) Reaction of cerium(Ill) chloride with palmitic acid (molar ratio 1 : 3). Cerium(Ill) chloride (1"63 g, palmitic acid (5'19 g) and benzene (30 g) were refluxed at a bath temperature of 115°C for several hours. The reaction was terminated after several hours' refluxing. The product was filtered, washed repeatedly with dry methanol, and dried under reduced pressure. (Yield: 3"25 g Found: Ce, 14-98; Cl~H3tCOO (palmitate), 84"3. Calc. for Ce(C15H31COO)3: Ce, 15-48; C15H3tCOO, 84.52 ~).
Preparation of rare earth acetates (i) Reaction of lanthanum chloride and acetic acid. Lanthanum chloride (2"34 g) and acetic acid (60 g) were refluxed on an oil bath (135°C) for several hours. Hydrogen chloride was detected at the top of the condenser just after refluxing had started. The evolution of hydrogen chloride was very rapid initially, but gradually became slower. After half an hour the lanthanum chloride had dissolved completely in the solvent, and after a few hours' refluxing a white crystalline solid separated from the solution. When reaction was complete as shown by the absence of hydrogen chloride at the top of the condenser, the product was filtered, washed several times with dry acetic acid and dried under reduced pressure at 70°C. (Yield: 2"98 g Calc. yield: 3.02 g Found: La, 43"89; C, 22.84; H, 2'90. Calc. for La(CH3COO)3: La, 44.11; C, 22.74; H, 2.86~). (ii) Reaction of cerium(Ill) chloride and acetic acid. Cerium(III) chloride (2"53 g) acetic acid (30 g) were reftuxed in an oil-bath (135°C); the reaction began immediately with vigorous evolution of hydrogen chloride. As refluxing proceeded a white solid separated. When the reaction was complete this was filtered, washed thoroughly with acetic acid, and dried at 60°C under reduced pressure. (Yield: 2'73 g Calc. yield: 2.8 g Found: Ce, 44'4; C, 22.8; H, 2"85. Calc. for Ce(OOCCH3)3: Ce, 44.16; H, 2.85; C, 22.7~). (iii) Reaction of lanthanum chloride with acetic acM acetic anhydride. Acetic acid (30 g), acetic anhydride (30 g) and lanthanum chloride (3"28 g) were refluxed an oil-bath for several hours. It was only after 4 hr refluxing that hydrogen chloride was detected, indicating that this reaction was slower than that with acetic acid. Once reaction had begun, hydrogen chloride was liberated at an appreciable rate and the reaction was complete after several hours. The solid, which started to separate as soon as the reaction had commenced, was filtered, washed thoroughly with acetic acid and acetic anhydride and dried at 70°C under reduced pressure. (Yield: 4.1 g Calc. yield: 4"22 g Found: La, 44-3; C, 22.75; H, 2.91. Calc. for La(OOCCH3)3: La, 44'11; C, 22.76; H, 2.85~). (iv) Reaction of cerium(Ill) chloride with acetic acid-acetic anhydride. Cerium(III) chloride (3.42 g), acetic acid (30 g) and acetic anhydride (30 g) were refluxed for several hours in a bath at 130°C. On prolonged refluxing the chloride dissolved, but on cooling a crystalline solid separated in amounts whichincreased with increasing time of refluxing. After completion of the reaction the solid was filtered, washed thoroughly with acetic anhydride-acetic acid and dried under reduced pressure at 65°C. (Yield: 4'34 g Calc. yield: 4'5 g Found: Ce, 44.34; C, 22.74; H, 2.94. Calc. for Ce(OOCCH3)3: Ce, 44.16; C, 22-75, H, 2-85~). (v) Reaction of lanthanum chloride and acetic anhydride. Lanthanum chloride (2.18 g) and acetic anhydride (60 g) were refluxed for several hours; hydrogen chloride was only detected after 10 hr refluxing; dissolution of lanthanum chloride was also slower in this case. When hydrogen chloride was no longer detectable the product was filtered, washed thoroughly with acetic anhydride and dried under reduced pressure at 70°C. (Yield: 2-75 g Calc. yield: 2'80 g Found: La, 44.3; C, 22"95; H. 2.75. Calc. for I_.a(OOCCHa)3: La, 44.11; C, 22.76; H, 2"85~). (vi) Reaction of cerium(Ill)chloride with acetie anhydride. Cerium(III) chloride (3.14 g), and acetic anhydride (40 g) were refluxed at a bath temperature of 140°C for several hours. This reaction was also slow and hydrogen chloride could only be detected after 9 hr refluxing. The product was filtered, washed with acetic anhydride several times, and dried under reduced pressure at 65°C. (Yield : 3-94 g Calc. yield: 4 g Found: Ce, 44.38; C, 22.98; H, 2.7. Calc for Ce(OOCCHs)3: Ce, 44-16; C, 22.75; H 2-85 o/). Acknowledgement--Two of us (S. N. M., T. N. M.) are grateful to the Atomic Energy Establishment, Bombay, for the award of research fellowships.