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Studies on the rare earths Shaw, Kenneth Noel Francis 1942

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5k STUDIES ON THE RARE EARTHS by Kenneth Noel Francis Shaw A Thesis submitted in Partial Fulfillment of The Requirements for the Degree of * :E&STER: OF ARTS : in the Department of CHEMISTRY The University of British Columbia SEPTEMBER, 1942 (i) FOREWORD This investigation was undertaken originally with the intention of attempting to-; synthesize organometallic rare earth derivativesj i.e. compounds of those elements with alkyl or aryl radicals, involving a direct metal-carbon linkage. For further detail, the reader i s referred to the author*s 1940 thesis submitted to the U.B.C. Dept. of Chemistry, in partial fulfillment of the requirements for the Bachelor of Arts degree. A preliminary survey, of relevant literature j, together with early experiments, brought to light several problems which the author considered could only confuse subsequent inexperienced investigators, and hence deemed expedient to eliminate before proceeding withtthe main investigation. Experimental study was made of the following: 1»_ Elimination of cerium from rare earth mixtures. 2. Preparation of anhydrous rare earth bromideB. _5j_ Quantitative determination of mixtures of rare earth elements in their salts. Suggested methods of synthesizing rare earth organometallic compounds, with a discussion of the unsuccessful attempts made at the University of Illinois have also been included. The author gratefully acknowledges the generous advice of Dr. J. Allen Harris rendered in the supervision of this research. I am also indebted to Dr. L.F. Audrieth for his many helpful suggestions, and for his account of parallel investigations at the University of I l l i n o i s . Thanks are due to the University of Illi n o i s Dept. of Chemistry for supplying the rare earth oxides used i n this investigation• (ii) Following axe the three mixtures useds X i mainly La g0 3 J, with small awaunts of Nd 20 3 and Pr0 2. Y : Nd203, with traces of Pr0 2 and Sm203. 2 : 60% La 20 3 + 40% Pr0 2, with traces of Nd 20 3 and Sm203. Subscript ^ denotes presence of varying amounts of Ce, as in X 1 ? I 1 P Z Kenneth F„ Shaw Sept., 1942. University of B.C. (iii) STUDIES ON THE RARE EARTHS» I. SEPARATION QF CERIUM 1 A» Bromination 1 B. Phosphate Precipitation 9 II. SYNTHESIS OF ANHYDROUS RARE EARTH BROMIDES9 n A, Sulfur Monochloride Process 11 B» Sublimation Process 12 G« Extraction Process 15 Hie QUANTITATIVE ESTIMATION OF RARE EARTHS'. ANP DETERMINATION OF MEAN EQUIVALENT WEIGHT WITH 24 8 - QUINOLINQL IV. QRGANQMETALLIC COMPOUNDS QF THE RARE EARTH 29 ELEMENTS. V, SUMMARY^  . 31 VI, BIBLIOGRAPHY. ILLUSTRATIONS, Apparatus for Aqueous Bromine Extraction of Rare Earth Oxides. Sublimation Apparatus for Removal of Excess Ammctitiim Bromide, Apparatus for HBr Ether Extraction of Anhydrous Rare Earth Benzoates. 1. STUDIES ON THE RARE EARTHS I. SEPARATION OF CERIUM. Rare earth materials used i n the research laboratory generally consist of oxide mixtures, the f i r s t step in the resolution of which is the removal of cerium. The great majority of current meithods employed for the separation of cerium involve oxidation to the tetravalent state, wherein the element manifests properties sharply distinguishing i t from other rare earth elements. Some of the more important methods are mentioned by Neckers and Kremers , others by Mellor, and by Levy . In the following, tv/o such processes have been examined with a view to increasing their efficiency, A. Bromination, The method of treating a suspension of rare earfcb oxides in KOH solution with C l 2 was f i r s t employed by Mosander^. Subsequent workers have described parallel use of Br 2 and I 2 . Several repetitions of the process were found necessary to completely remove cerium. J^£eri^ntai_ 1. 5g. oxide X x was simmered with 3ml e Br 2 + 100 ml.H20 t i l l Br 2 fumes ceased to evolve. The hot mixture was fi l t e r e d , the residue washed with a l i t t l e cold H20 and the washings united with the filtrate« This treatment was repeated 6x. The filtrates-were Tmited:'and.eonc©Btrated'rto 8§-'ml« Spectrum examination revealed the same heavy absorption bands charact-eristic of the original oxide .in- both the- concentrate ;aawl••in- HN03 solutioa of the -residue *• However^ -' on treatment with HgGg 4* dilute: NH4OH, the concentrated f i l t r a t e gave a negative test for Ce, whilst the HN03 solution of the residue .showed a higher concentration of Ce than did the original oxide, A sample of oxide Yx subjected to the same treatment reacted,in a like fashion* 2. 5g» oxide Z% were refluxed 18 hours with 10 ml. Br 2 + 300ml. H20 in a pyrex apparatus ©quipped with ^ ".ground joints (500 cc. flask, surmounted by 5 - 30 cm. condensers)/ After cooling, the mixture was filt e r e d and 25 ml. of the f i l t r a t e set aside for spectroscopic exam-ination. The filtrate-and residue were returned t© the flask with 5 ml. more Br s and refluxed for an additional 12 hour period. Considerable amounts of Br g remained at the end of the period. The cold mixture was filt e r e d and 25-ml. of the f i l t r a t e set aside for spectroscopic exam-ination. The-absorption spectrum- lines • of both f i l t r a t e s -we're-of the same approximate density indicating that no appreciable solvation had occured during the second refluxing. An HN03 solution of the residue showed the same absorption spectrum, indicating solvation to be incomplete. The f i l t r a t e s gave negative tests for Ce whilst the HNO^  solution of the residue gave a stronger Ce test than the original oxide mixture, A sample of oxide Y x subjected to the same treatment reacted in a like fashion. 3. 5g. oxide X x were refluxed 2 hours with 5 ml. Br 2 and 500 ml. Hs0* After--cooling.,; concentrated .NH^ OH was; -added- dropwise-until the brown color of Br 2 just disappeared. Refluxing was continued 1^ 2 hour more, then the mixture was cooled, fi l t e r e d , and the f i l t r a t e evaporated to 25 ml. As before, the f i l t r a t e showed the absorption spectrum lines of the original oxide, but in this instance also gave a positive Ce test. The HN03 solution of the residue behaved in the same manner, 4» gg. ©xMe Xj; was 'refluxed 2 hours- with 5 ml. Br 2 and 300 ml. HgO, 26 ml. 49 % aqueous HBr were then slowly added and refluxing continued 1/2 hour longer. The mixture was cooled, fi l t e r e d , and the fi l t r a t e evaporated t© 25 ml© The-filtrate .showed tfae^usuaf. :-afeB©rption*;spectrum?'and-aiso gave a-positive-Ga test® .-A&'M0'3.s^  a:. -positive Ce • test - but showed BO absorption,'' spectrum® . -"' -7»§g;i. © x i ^ was seated atop, a- .leagth• of - l w ; 'diameter -glass- rodih ;-a- pyrex Soxhlet extractorj equipped-:with-JL joints and surmounted by 3 - 30 cm. condensers^ "6 mI-;. -Br6: were <mr«fully poured into-the' thimble and 300 ml. H20 into the -fMsk..and heating.-eommenced-with'-aavelectric-rhotplate.^-. The-' author 'found that i f -the-Br.2were^iBitial3y-mixed with-the Hg© in--the: f ^ - - - . ' . ' • • ' ' - . - ' - # • ' . ' ' " - -f a l l i n g to the bottom-and--entering ;the"-siphon- tmb©i~ -where--by- virtue- of i t s higher density, the- Hg0 subsequently-distilling-;-over flooded above the thimble- and ran-.down the vapor- inlet-tube*- -Unles s - t e a t l ^ condensation- of" water oceured, with-ensiaJ^. - w Furtherj excessive ebullition of Br g therein- tended---to::eject the so l i d into the - extraction- liquors' therefore,, ' the optimum -quantity- of' Br 2 must be experimentally found. Due to the fine porosity of the alundum 4. •! thimble, extraction proceeded at a very slow rate, siphoning occurring : once every hour with the above precautions. It was necessary to add a r! l i t t l e Br 2 from time to time to offset losses sustained through f: volatilisation* . - After IS hours -t extraction was discontinued* The walls | of the extraction- flask were coated- with- a-: pale -yellow • gummy - residue } and the extraction- liquor; was1- -turbid* The .liquor was filtered-^ and the fine precipitate thus obtained washed back into the flask, where addition | ..' - of a few ec. 48% 'HBr: produced &• clear- solution*- Since both the .filtrate I and the HBrsolution-gave negative--tests--emporated-to :25: mli^:The'-v-resultamtX:-solutio&y .pa€e~---'green"'-i3^ o^o;lorf''d'ae to i presence-of small -amounts of Er^ showed-the -same-absorption-spectra as |; ,.-<-• that-of the--orig-iaal •••©xide,"-;-" r . The-apparatus-8-was •'oieaBed-'-thorou^^ j remaining i n the thimble was reextracted with E r g + H20 for 12 hours more. I ! • The extraction liquor, treated as before, resembled that of the f i r s t I extraction 'in^appearance^--ab8orption^«pectrwa&'and-'test' for-'-Ge*-As a small portion of the residue remaining i n the thimble s t i l l showed absorption bands on spectroscopic examination of i t s HN03 + H30g solution (indicating presence of undissolved Br, Nd, and necessarily La), extraction was continued for a further 15 hours with fresh quantities of Br 2 +• H20. Once again, the extraction liquor gave a negative Ce test and exhibited the characteristic absorption spectrum* However, an HN03 + H 20 2 solution of the residue from the thimble showed no absorption spectrum, thereby indicating complete solvation of a l l earths-but ceria. A.sample of oxide J X treated in the same manner behaved in a similar fashion. The-method was abandoned because of the slow speed of f i l t r a t i o n through the alundum thimble and lack of a satisfactory substitute, . 6. With the object of developing a rapid extraction process, the following apparatus was devised* 1, 3-30 cm. condensers. Z* 1 graduated'inlet tube.. Si. 1 extraction flask. -4v :-l.adapter* " 5. 1 - 3 legged glass cupj 30 em» long. The extraction flask was constructed from a lJ.L. pyrex -erlenmeyer^v pyrex- tubing and a pyrex -8 joint®. The extraction cup consisted of a pyrex tube, sealed at one end, with 3 short lengths of 7mm. tubing blown into the sealed end for drainage purposes. Use of 3 condensers served to miaimiEe--extensive loss- of Br 3 otherwise sustained through volatilisation, • A-baH.-of;-'-g^ «s-;;wo0l>-waS/pacieid--int-o the base of the cup and sprinkled lightly with acid-washed asbestos. The ease of flow was tested by f i l l i n g the cup with H20 and noting the drainage rate. M f a i r l y fast -flow-- is- desirable-yet- sufficient asbestos- must be present to prevent subsequent passage of the rare earth oxides.. GaleuMtioas were- made-- on-the -assumption that solvation of the oxides proceeded on the basis of the following equations,based upon the reactions of other metal oxides. CSX.) APPARATUS FOR Aqueous BROMINE: EXTRACTION OF RARE- EARTH Oxmsrs, 6 La 20 3 + 3Br 2 •+• LaBr 3 + La(OBr) 3 5La(0Br), - • Ia(BrO,K + 2LaBr., or 3La 20 3 + 9Br 2 -* La(Br0 3) 3 + 5LaBr3 Cerium remains i n the tetravalent state as insoluble Ce(OH)4. . . lOg. oxide X x were placed i n the cup and washed to the bottom with the aid of a wash bottle. When the drainage was too slow, or when the oxide tended to pass through the asbestos pack|i the material was removed, and a new pack prepared, as previously described, u n t i l a,, satisfactory one was obtained* 6--ml.-Br3(excess-over theoretical) and 300 ml. H20 were placed i n the extraction flask, the apparatus assembled as shown, and heating commenced over a Meker burner whose flame was so adjusted to permit steady extraction without overflow of the cup. Extraction was-continued for 12 hours, after which the extraction liquor was treated with a few ml. 48% HBr to dissolve the gummy suspensbid and evaporated to 25 ml. i n a beaker. Tests performed on the resultant solution showed complete absence.of Ce, but showed the usual absorption spectrum. The residue remaining in the cup was dissolved i n H 20 2 .+ concentrated,HN03. ..The..clear solution obtained thereby, showed no absorption spectrum and gave a heavy brown precipitate on treatment with . M$®E: +• H 20 2, thus-, indicating - it- consisted wholly- ©f.-Ce(OH)4: free of other rare-;ea»ths« The apparatus was considered unsatisfactory due to the trouble .involved-ia-^feparing. a satisfactory,asbestos f i l t e r - f o r use i n the extraction cup. See discussion for suggested improvements. 7. The extensive work of Prandtl, Rauchenberger and Losch 5 7. has shown that rare earth oxides are soluble in solutions of ammonium salts, to an extent varying according to the conditions employed. It was thought that such treatment combined with simultaneous halogenation might permit rapid separation of Ce from the other earths, by means of reactions expressed by the following equations i - 41a g0 3 +-6M&4Br-,+^  4La 20 3 + 6NH4NO3 + 9Br 2 2La(N0~) + 6LaBr3 + 12H20 + SN2 These -. equations -ar@-;-based- upoa'-the • i&et--- thatsolutions - of. ammonium salts 6 are- slowly oxidised' by - Br a -.wither elease-: o f . % gas,"" • As.- a-;-rough' qualitative" tests • the. jpocedure outlined, in. the following was carried out* 15g. oxide X x + 25g. NH4N03 (excess) was • simmered- g.ent3y-''-wi^ --i60''.:mli H20 %?7mli:.Br2/ (excess;) -until 'most of the Br 2 had vaporised. The hot mixture was filtered and evaporated to 25 ml. The -residue-was. washed with- a- little-H2©j, dried-in a hot a i r oven at 130?, weighed (8g.) and dissolved in concentrated HN03 + Hg02, Both the- filtrate-'and -'the-'«olution\of-;the;-residue.-showed the.: usual^ absorption-: spectrums-OB' spectroscopic; exaainationi. however^ whilst: the residue--solution-gave-a-'heavy'brown-flocculent precipitate with-,-HH4OH- +: Hps*,.-.the-filtrate-gave-only a. faint yellow- coloration, indicating relatively good elimination of Ce, Lack of time did -not-' permitfurther' investigation along this line* -.•,-,,!•'• • " • -r-discussion-Contrary to-the ideas-of-early investigators., i t i s evident from the foregoing that an alkaline medium i s not an essential pre-requisite for separation of ceria from congener earths by bromination. 8. The acidity of the hot Br 2 ~ H20 mixture i s sufficient to dissolve La, Pr, Nd, Sm» etc.., but does not affect tetravalent Ce. It is apparent z that reaction involves equilibria expressed by the equationss Br 2 + H20 «* HOEr + H4' + B£r K 2 S ° = 5.8 x K f 9 - HGBr */ H + + OBr" Kg 5° = 2,06 s l o " 9 In-.- the- -hot -solutions--employed-,--equilibria-: ;are--:pr^omid3|^3j^p:'t;he-''left due to decreasing solubility of Br 2 with rising temperature. Further, as the earths are dissolved to form bromates and bromides (ef• equations, p*6), the increasing- .value;- of, [Br~] -displaces-equilibria^-to--the l e f t and solvation i s brought to a standstill. For this reason^ refluxing can not be expected-to-result .in- eomplet©--;Separation--:©f- Ge- froa-.other rare -earth elements* whereas-- - extraction,;-- involving, removal of .the:-products formed from the sphere of action, should do so. Such has been shown experimentally true>- However, "i&€^ <:ex^  employed :-is impractical due to the time and precautionary measures required. It is suggested that sintered glass thimbles used with the apparatus described--under -section §• might: y i ^ Lack of -same prevented further study i n this direction. Solvations^of Ce noted-under section?S- i s due to the formation- of ammonium- salts,-solutions - of which- dissolve rare - earth 6 oxides.- Introduction of HBr into the aqueous Br 2 medium induces similar solvation-of Ge dU&>.to -the----high--{fifl,. -, The alundum thimbles employed for the Soxhlet extractions are unaffeoted by Br 2 + H20, as shown by blank runs performed under the conditions already described. The result of the qualitative test of reaction between rare earth oxides, Br 2, ammonium salts and H20 indicate that further Sir : . study along this line would be advantageous• The quantity of NH4N03 employed was almost twice that required by the equation, hence the very slight solvation of Ce, due to the action of NH4N03 solution on Ce02 (as shown by Prandtl et a l ^ ) i s to be expected. However, i t is evident that the presence of ammonium salts i n the reaction mixture produces a consid-erable increase in the rate of solvation ©f the other- earths, due to formation of a volatile product, without materially affecting Ce02. It i s suggested that the study of-extraction methods be extended to.-rare earth carbonates-,- sulfates^ -phosphates;, and-also to sparingly soluble organic salts• Bs - Phosphate- Precipitation. Neokers and Kremers ~ developed a satisfactory method for quantitative separation < ©f - C© from: congener- earths - in- acid -solution by addition - o f s o l u b l e phosphate to-a - slightly acid - solution containing Ge(N0 3) 4, whence Ce precipitates completely as eerie phosphate, leaving the other rare earths- i n s©lution as-the-nitrates* The-oxides* which have f i r s t been- ignited - to ensure naximum- conversion- to • Ce02i) are dissolved-in sufficient -concentrated HNQ3 $©-give 5$-free-acid upte subsequent - dilution-1©; a 10$-- rare earth content.. Sodium - phosphate. solution i s slowly added at 8G°G u n t i l precipitation is complete. The f i l t r a t e i s - further • treated- with excess- sodium- phosphate - and titrated with Kfifa©^  u n t i l oxidation of Ge t© the tetravalent form and removal as phosphate i s complete. By this means, Neokers and Kremers succeeded in reducing the Ge content ©f the f i l t r a t e : t o 0*02$. xo Ejgerimental. Oxides Xx, Y x and Z| were treated according to the method of Neckers and Kramers withthe following variations» 1. The free acid content of the dilute rare earth nitrate solutions was reduced to 4$. 2. The temperature of admixture of the rare earth nitrate and sodium phosphate solutions was raised to 90-95°C8 Coprecipitation of up to 20% of the other rare earths with Ce, as fine phosphate precipitates which fil t e r e d only with considerable d i f f i c u l t y resulted. However, the nitrate f i l t r a t e of the other earths gave absolutely no coloration when a 5cc. portion was treated with dilute :ffl4©fr +--HS0S?-thereby- indicating - removal of >all Ce. Neckers and Kremers noted that 5% free HN03 sufficed to prevent precipitation of a l l rare earths but Ce l V as phosphates. Their inference that reduction of this acid content would cause coprecipitation of other earths is herein found true experimentally« The higher temp-erature of admixture of the solutions employed by the author probably favors such precipitation. One obvious advantage of the described changes of procedure is that the Ce content of the f i n a l f i l t r a t e i s reduced to <T0.00008$, the value of the sensitivity of the hydrogen peroxide test for Ge~ « • The endpoint of the titration of C e 1 1 1 to Ce I V with KMn04 solution i s reached sloy<rly and i s frequently vague, when sodium 9 phosphate is employed for precipitation. The finding— that H3P04,used as the precipitation agent,permits rapid attainment of a sharp endpoint can be advantageously applied. 11 II, SYNTHESIS OF ANHYDROUS -BARE EARTH BROMIDES.. Sine© anhydrous metallic bromides are frequently employed as i n i t i a l reagents in the preparation of organometallic compounds8 i t was necessary to investigate current modes of synthesising these salts of the rare earth elements» Most of the methods described in the • 10* 11 literature, * * involve - elevated temperatures, and ;are unsatisfactory for making large quantities of anhydrous rare earth bromides, .Further, the technique required i s usually elaborate and time consuming, frequently'p the products are contaminated- with- trying- quantities:'-.of the oxybromides, -Three representative- methods- have been studied in the following, A i SBlfar--Monochlbride • -.Process, :.. Bourion-^ p r e p ^ e d - b y . passage of dry HBr + S a01 g over the oxides at temperatures slightly below red heat. Some assistance was- given-by the--.author-1© B..B,- Tonks and to R.Ri Shinobu, who studied Bourion's Process in partial fulfillment of the requirements for their Bachelor of Arts degrees at the U,B.0i in 1940 and 1941 respectively. The interested reader is referred to their theses for details-,-of the---experiments: carried out, "Jggssssiss* Bourion*s Process was found unsatisfactory in this laboratory .for synthesis--- of anhydrous - rare. earth - bromides for the following'reasons? 12. Iii Conversion of the oxides to the bromides was incomplete under conditions prescribed by Bourion, 2. Contamination of the products with H20 and S frequently occurred unless the most rigi d precautions were exercised. 3. QuartE>iapparatus used i n the process was badly eroded and often v i t r i f i e d by the-action of unconverted rare-earth oxides at" higher temperatures. Further study of the method was not attempted. •B. Sublimation Process. • •.Reed,Hopklas-and.Audrieth Mccessfully 1 obtained anhydrous rare earth chlorides and bromides by heating a mixture of rare earth oxides with an excess of the corresponding ammonium halide to • 200°C u n t i l the reaction mixture was completely water soluble. The remainder of the ammonium salt was then removed by vacuum sublimation at ;3Q0~52©°G. . Partial hydrolysis • to- the-^Wsie ~sal^s>does'hot-OCG^'-during the processing by virtue of the fact that the excess ammonium halide, acting as a strong a c i d i n accordance-with the- Bponsted-concept, produces faarorable displacement: ef.;"the- equilibrium given %grs ' La s0 3 + SM^Er * 2LaBr3 + 3HS0 Following i s a modification of the apparatus designed by 10 Reed, Hopkins and Audrieth for vacuum sublimation of the free ammonium bromide, (diagramtic form). The -reaction, mixture- i s .-placed i n the 500 ml., pyrex flask Of equipped with S.T. ^'/AZ joints. This flask i s inserted i n furnace a 15 (Cenco Multiple Unit, 18 amps., 115 volts, with built in rheostat), and other parts of the apparatus are assembled as shown. bb» is a two piece l i d , consisting of an asbestos board, perforated to permit egress of delivery tube _f, surmounted by an iron l i d to which 3 sheets of asbestos board are bolted. The delivery tube leads to a 590 ml. flask, into which the excess NIL.Br sublimes, A small, bulb h, removed from a Kjeldahl trap, is blown onto the sublimation condenser, and serves to retain any fine particles of rare earth bromide carried over by the NH4Br. Stopcock 1 controls the inrush of a i r on dismantling;, the-apparatus -at: the ••conclusion of the sublimation. At500 ml. pyrex flask _j_ , equipped with S.T. 2 9/42 jpint, and f i l l e d with lumps.of fused KOH, dries the admitted a i r . The apparatus-is connected-- 'by- pressure--: tubing: through a~ closed, end Eanometer 1 to e Cenco Hivac pump. The sublimation temperature i s followed by means of thermometer d inserted in a pyrex well c^ When-the--above -described sublimation -condenser was- i n " use, violent Jj3pl©si-©B-fr,equent3y-occurred--©B-: evacuation, due--'to- presence? of weak points in the glass. More satisfaction in performance was obtained with condenser m,. constructed from two S.T. ^/4Z pyrex joints, two short lengths- of 24- mm-9'pyrex- tubing - and- S@em*- of - :46mm. pyrex tuning. No implosions occurred, a vacuum was more rapidly created and more easily maintained, and the length of cooling surface proved sufficient to retain a i l sublimate. Drying flask J. was: modified with 3-way stopcock n, which"; served-as - the- a i r inlet-valve*- - 'N©:lubricant was necessary on the S.1E,. jpints in the furnace. Glass hooks attached to each joint were wired together to keep the parts in place, Two samples each of oxides X x and Y x were converted to the 1 3 A . 14. anhydrous bromides by this method. In a l l cases, the treatment was identicals l i 25g. (0.07 moles) of rare earth oxJ.de were ground together with lOOg. (1.0 moles) NH4Br(A,R») in a glass mortar and transferred to a vi t r e o s i l casserole, - which was-heated- ©n a wire:- gauae over a Maker burner whose flame was so adjusted to permit maintenance of a temperature ca.275°C. The contents were stirred continuously during heating, otherwise lumps tended to form, Reaction was accompanied by a rapid characteristic color change, as the dark oxides passed t© the bromides* Heating.was- continued -untile -attest sample of the reaction mixture dissolved in water with no appreciable turbidity, the -average-time -required being-1-1/2 hours. 2, The contents of the casserole were transferred to flask e, , the apparatus connected as shown, a vacuum ca.lmm. applied by means of a Cenco Hivac pump, and the temperature of the furnace raised over 3 hours to 310°C, at which point i t was maintained u n t i l sublimation • ©f- the-NH4Br was -complete,'- (Remove--the" outer-- lid-of the :'§aiSace- and note whether any sublimate forms on the exposed parts of the delivery tube at. f)Sublimation- required- 24™30; hours,, 3, » After cooling, --dry a i r was admitted--to- the --apparatus - by - opening cock i or and the•product was quickly transferred to a dry weighed stoppered bottle by means of a funnel fashioned from a 125ml. erlenmeyer |cut-©ff the-bottom -with a- hot- wire).-4, Small samples of each product were tested with like results -(a) on heating;- in--a- dry test- tube, -n©-water vapor, - or 15. white sublimate, condensed on the cooler parts of the tube indicating the product to be perfectly anhydrous and free from NH4Br, (b)solvation i n H20 was accompanied by characteristic • f i s s l i n g and slight opacity was evident, showing traces of oxybromlde had been formed through hydrolysis. Discussion The sublimation process developed by University of Ill i n o i s investigators is generally satisfactory for preparation of anhydrous rare earth bromides in quantity, requiring a minimum of manipulative s k i l l , and no great outlay of time or costly apparatus. When necessary, tracds of oxybromides may be separated from the neutral salts by extraction with absolute alcohol, followed by evaporation of the solvent and f i n a l removal of alcohol of crystallisation from the solute by heating i n a current of dry (vide infra.p. [8). C, Extraction Process f 14 ' ' Brauman and Takvorian ' found that when anhydrous rare earth bensoates were extracted with dry ether saturated with HC1 gas, quantitative conversion to the anhydrous chlorides occurred. The following represents an attempt to extend their method to synthesis of anhydrous rare earth bromides. Exjoerimentai 55g. (o,2 moles) each of oxides Y and Z'-were carefully treated with 40 ml. concentrated HK03, and the resultant solutions diluted 16 to 1750 ml., thus giving a 2% rare earth and approximately 0,2% free acid content. After warming each solution to 80°G, excess 2n NaOBs solution was slowly added with constant stirring, which was continued for 1 hour more. The heavy flocculent precipitates thus obtained were filtered off , washed with' a- l i t t l e water, transferred to casseroles, dried in a hot air oven at 110°G. for 40 hours, ( the long drying period was necessitated by the large quantities handled), and transferred to tightly stoppered bottles» The dehydration temperature of the benzoates must not exceed 125° C, otherwise noticeable pyrolytic decomposition occurs. Small amounts of dissolved rare earths were subsequently recovered from the f i l t r a t e and washings. The yield of benzoates averages 95$ by the above. Apparatus was assembled-as shown in the 'subsequent•' diagram. Dry HBr is generated by the action of Br 2 on dry benzene!5 (Erdmann's process). CgH^ + 2Br 2 •*C 6H 4Br 2 + 2HBr. lOOg. dry bensene are poured into flask m , containing a few grams of finely divided Al powder* 155 ml. Br 2 are placed in tap funnel n, whose ti p i s drawn to a fine point 0 Flask m is seated i n a closely f i t t i n g beaker and i t s upper surface packed with ice chips i n order to minimise subsequent vaporization of i t s contents, Br 2 is allowed to drip slowly into the bensene. The issuing current of HBr i s scrubbed free of CqHq and Br a.vapors by passing i t through paraffin o i l contained in wash bottle JL which i s immersed in a CaCl 2 - ice mixture, at -20° Traces of H20 and organic vapors are absorbed during subsequent passages over freshly fused GaBrg i n drying tube k which i s directly connected to the extraction assembly by adapter i , f i t t e d with a stopcock and S.T. 29/42 joint. 16*. APPARATUS FOR HBr - ETHER EXTRACTION Of= ANHYDROUS RAKE EARTH BENZQATSS 17, Worm condenser h, which prevents vaporization of the extraction medium into drying tube k when the HBr gas line i s open, leads to 3-necked extraction flask a, of 500 ml. capacity and f i t t e d with 3 S.T. 29/42 necks, Temperature is follSwed by means of thermometerj. inserted through adapter f_. <s i s a Soxhlet extractor, equipped with S.T. joints and a small tap_d for withdrawal of test samples» The top of bulb condenser b, which condenses the extraction solvent, i s f i t t e d with an inverted drying tube fy,. which is f i l l e d with fused CaBr2 to prevent ingress of atmospheric water vapor. Escaping acid fumes are tubed thence to the fume closet, - 1^-apparatus-.ms :^ ing of a 1:1 mixture of concentrated H 2S0 4 + HN03, rinsed thoroughly, dried for 3 hours i n a hot a i r oven at 150°C and then washed with a l i t t l e anhydrous-vether- prior -to- assembly^ . •- . . A'blank test was made by pouring 300 ml. dry ether (A;R«) into flask e_, and passing in a slow current of dry HBr. Within two to , : three minutes , developed a golden color which deepened to a maximum within 15 minutes. Four hours passage of HBr failed to darken the color further, even when the ether was boiled. The HBr current was then cut off, drainage tap d opened and the ether allowed to d i s t i l l over. The d i s t i l l a t e was pale yelltfVr i n color, boiling at 34„5°C, and fuming violently due to dissolved HBr. A faw cc. of a reddish-brown high boiling liquid remained i n the flask. This residual liquor was heavier than and immiscible with water, burned slowly with a smoky flame, and carbonized upon prolonged heating. 14g» bensoate Y were weighed into a paper extraction 18. thimble which was placed in the extraction chamber of the apparatus, 300 ml, of ether saturated with HBr (obtained by di s t i l l a t i o n from the blank runs) was poured into flask e and extraction was commenced by heating over an electric hotplate. Reaction, as given by the equation - i Nd(0Bz)3 + 3HBr •* NdBr3 + 5H0Ba was so rapid that the siphoning liquor consisted of a heavy suspension of HOBs crystals. Extraction was discontinued when the siphoning liquor was clear. Meanwhile, the liquid i n the extraction flask had once again assumed a golden hue. Since some HOBs crystals s t i l l adhered to the walls of the extractor and to the outer surface of the thimble, the thimble was quickly transferred to a clean dry apparatus and extracted 1 hour more with fresh dry ether. A'small deposit of rare earth bromide settled out i n the extraction flask due to slight ether solubility (vide infra)» A small sample of material removed from the thimble dissolved i n 5 ml. H20 with considerable fizzling to .give-a-.transparent-.lilae solution, \f^e^from''o£iaei1^''a&d .devoid of any detectable odor of HOBz. The thimble and contents were transferred to a clean---dry -bottle--fitted.with-a -2~h©led -cork-and-glass tubes, the whole was placed i n the hot-air oven at 70°G« and a current of a i r , predried over concentrated H 2S0 4 and fused KOH pellets, passed in un t i l the emerging gas current was free from odors of HBr and Et 20, (1 1/2 hours). The product was quickly scooped out of the thimble into a dry weighing bottle, weighed (8.15g,= 81,5$ yield) and stored i n a dessicator over fused KOH. Since the salt thus obtained was entirely water soluble, without turbidity, even after heating to 550°C, conversion to the anhydrous bromide may be assumed complete. 14g. of benzoate Zcwere converted to the corresponding bromide by the same method with analogous results• 19. The products were analysed for bromide according to Mobr's method t Sample % Bromide Found % Bromide Calculated Y 65.38 s 62.70 s 63,85 . 62.43 (assuming NdBr3) ZZ - 63,89 g 63.66 s 63,49 63.18 (assuming 60$LaBr3+40$ PrBr 3) Attempts made to determine the rare earth contents of the products by precipitation with 8 - quinolinol were unsuccessful (vide Sect, III). . During; t r i a l runs with the extraction apparatus, 14g, of bensoate Y were placed i n paper thimble, and extraction initiated with 300 ml. dry ether (AiR.), with the simultaneous passage of dry HBr from the generator. The aforementioned golden color developed i n the ether within a few minutes and the siphoning liquor became turbid with HOBs crystals * Surprisingly, the extraction liquor i n the flask gradually developed the characteristic Nd absorption spectrum which became intensified as the color of the medium deepened. After 5 hours processing - thuslyj the 'extraction liquor was-, quite- transparent, free from residual crystals, a deep red i n color and showed heavy Nd absorption spectrum bands. The liquor was transferred to a well-stoppered flask overnight. By the following morning, two layers had formed, each showing the Nd absorption spectrum. These were separated by means of a tap funnel. Neither showed presence of H20 when small amounts were tested with KEfo04 crystals. On standing two days more, both solutions deposited fine granular crystals, l i l a c i n color after washing with fresh dry ether, and completely water soluble without turbidity. These crystals were probably anhydrous NdBr3. 20. Aft.sample of bensoate Z tested tinder the same conditions showed parallel ether solvation. Finally, 52g. NdBr3 (Series Y-J v prepared i n the anhydrous state by the Sublimation Process, were extracted in a paper Sbxhlet thimble with 500 ml. dry ether (A.R.) i n the apparatus previously describediAfter one hour, a fine suspension of l i l a c crystals was noted in the extraction liquor, indicating slight ether solvation of the NdBr3. A^.steady current of dry HBr was then passed i n over a four hour period, with simultaneous ether extraction. The suspended crystals dissolved rapidly, and the golden color developed in the ether within a few minutes. Nd absorption spectrum lines were visible i n the colored solution, gradually becoming denser as extraction proceeded. The mixture was allowed to stand for 2 days i n the apparatus , atmospheric moisture being excluded by drying tubes- a^and; k,.. .500 ml* of: fresh-, ether, were then introduced into the extraction flask: two sharply defined layers formed. Extraction was carried out once more (no HBr was passed in) over a 50 hour period. After 10 hours extraction, only one uniform layer was apparent, with a heavy deposit of NdBr3 crystals carried down from the thimble. Thirty hours sufficed to extract a l l NdBr3 from the thimble to the extraction flask. The mixture was boiled with simultaneous passage of dry HBr for 5 hours. The NdBr3 gradually dissolved- to gi^^deepsredatransparent. solution i n which Nd absorption bands were extremely dense. This solution was quickly f i l t e r e d through a f r i t t e d glass gooch to remove any solid matter (none), then transferred to a well stoppered flask. After standing 2 days, a heavy crop of well formed crystals, comparable to those described i n the preceding paragraph, settled out. The Nd content of the supernatant solution, a dark brown i n color, was s t i l l high, as shown by the heavy 21. absorption spectrum bands. A few ml. poured carefully into 5 ml.H20 settled to the bottom of the test tube (indicating density greater than 1)^ but on shaking the mixture well for several minutes, a l l rare earth went into aqueous solution, and a transparent brown etheric layer rose to the surface. ' \ Lack of time prevented further investigation of the cause ©f these anomalous effects. A l l rare earths were recovered from the ether residues by aqueous extraction. The close approximation of the, bromide content of the .products-.herein"-obtained to theoretical-values indicates-that the method of Brauman and Takvorian i s applicable to the synthesis of anhydrous rare earth bromides» Due to slight ether solvation of the products, yields attained only <90£- in. the runs made.,: However^ the short period of less than 8 hours required to effect the transformation to the anhydrous rare: earth- bromides-free- from traces•'of" basic salt^::speaks i n favor of the process, as compared to those in current use. "-. TM:s:.investigation- was-only preliminary-in-scope t further-, work should' greatly - increase- the yield, and /clarify certain -anomalies, in behavior of the ether described in the experimental record. The apparatus employed requires two outstanding improvements? 1. Sintered pyrex thimbles (not at present available in this laboratory) •Paper thimbles used herein proved rather troublesome, tending to become somewhat'brittle--through deleter slightly i f the drying temperature was allowed to greatly exceed 70°C. 22. 2. Rubber corks y_ and connection o, should be replaced by standard taper pyrex ware to ascertain their influence on the changes observed in ether upon passage of HBr. Other parts of the apparatus, designed and assembled as shown only after considerable deliberation and experimentation, require but slight attention, having been found very satisfactory. No great manipulative s k i l l i s required for successful operation. Preparation ©f <&y-HBrrby interaction,of Br g and G6H^; i s superior to wet inorganic methods, (e.g. P + Br 2 + H20), and with the freezing trap described, permits steady generation of gas with but scant attention* Some workers prefer' to-use- naphthalene-instead" ©f benzene. It is suggested that dry saturated hydrocarbons known to dissolve benzoic acid be substituted in place of ether as the extraction medium, i n order to eliminate the peculiar behavior of the latter sub-stance* Such solvents would conceivably permit extension of the method to synthesis ©f- pure anhydrous-- rare -earth iodides-, which- can not be prepared by extraction of benzoates by extraction with dry ether saturated with HI due to mutual reation (vide infra.) . ";- -Although- the- cause- of the color: change observed when dry HBr was passed into dry ether was not ascertained, some speculation, as to the nature of the reaction i s necessary. The thought that vapors of Br 2, C 6H 6 5 or products thereof from the HBr generator may be the caus-ative agent (M) f a l l s into discard quickly, since such substances should be completely removed by the ioed paraffin; furthermore, the same effects were noted when the HBr was generated by interaction of P, Br 2 and H20 -a method avoiding a l l organic substances. Although rubber stoppers J_ and connection o, expanded and hardened considerably due to action of HBr, 23. no volatile product should be formed therefrom, since such action primarily involves addition of HBr to the double bonded system of an isoprene polymer. Sulfur, used i n vulcanisation, does not react with dry HBr,-according to Mellor (vol;II) . Antimony, present in rubber, forms a tribromide which melts at 98°C. and hence is not volatile* Nevertheless, a l l glass conn-ections should be introduced in place of the rubber, i n case this should have some,effect, . HSl-~gas-- dissolves- copiously-in • ether- without chemical reaction,--- while Bl promotes hydrolytic decomposition^ as-given by EtgO '+• HI EtI + EtOH cold ' • • cone. - . . • . ' .  ' ..EtgO + 2HI -»-2EtI + H20 -. hot ' • cone. : HBr -ii^"react:-:to-'-a-'-vl'iiBited- extent-'in-- the -same fashions • -EtgO -+ .HBr- 'EtBr + EtOH EtgO +'"2HBr2EtBr,-+ Hg0 , although no-mention-of such'hydrolysis- could be- found i n any -current test • of organic chemistry* Further ? such reaction does not-explain-the color- .-ation which developed in the ether. Also, no water was detected in the . extraction liquors with H!fa04 crystals, .which would indicate-presence of-any more than a--trace, > . -:~ . • , - Ether usually contains, traces of peroxidefto atmospheric oxidation on prolonged standing* - This peroxide -could-conceivably'act with HBr as follows: -Et20g. + 2HBr 2EtOH + Br 8. The Br 2 i n a dissolved state lending the golden color to the solution and 'br-ominating the alcohol formed-.to-give high boilingsubstituted derivat-ives. •t 24. None of the above hypothetical reactions provide adequate explanation for the complete solvation of the rare earth bromides up to 2.0% concentration, followed by the subsequent crystalline deposition already described. Diethyl ether is known to act in an electrodomic 19. 20 fashion. by virtue of the presence within the molecule of two unshared electron pairs. This feature, considered in conjunction with the electronic structure of the rare earth halides, permits the hypothetical postulation of an unstable ether soluble complex ion formation, according to the following equation; EWOS + H°Brt + NdjBrt Et XBrt EtiOSH Et + £Br* »+ ;BrjNd'-Bri - •••»+• Although no such derivatives of the rare earths have yet been described, their existence is quite possible in non-aqueous solvents. xxxx 24a. III. • QUANTITATIVE ESTIMATIONOF--.BARE EARTHS AND DETERMINATION OF: MEAN EQUIVALENT WEIGHT WITH • S-QtJINQLINOLl 2 1 Pirtea successfully developed procedures with a sensitivity of 1/500000 for quantitative determination of cerium and lanthanum with 8-quinolinol (oxine). Alcoholic oxine reacts with ammoniacal NH40Ac solutions of La salts to give a flocculent precipitate which f i l t e r s readily, and dries to constant composition at 150° C. Gravimetric determination is thus readily effected, or the precipitate may be dissolved in HC1, and the La estimated therefrom by bromometric titration. The aim of the author was to extend Pirtea*s method to the quantitative estimation of other rare earth elements, and to apply the results of such analyses to computation of the mean equivalent weight of mixtures of rare earth elements in their salts i n a fashion to be subsequently explained, (cf. Discussion) Unfortunately, insufficient time allowed only a cursory study to be made. ^^erjLmentalj. 0.1 g. (0.001 moles) samples of bromides Y and Z, prepared by the ether extraction process, were accurately measured from a weighing bottle and dissolved in 200 ml. freshly d i s t i l l e d water. Each solution was warmed almost to the boiling point, treated with 25 ml. 22 2n. HOAc, then a slight excess of 5% alcoholic oxine so l u t i o n — added (ca. 5 ml.). 6n. NH40H was then added dropwise unt i l the solution smelled strongly of NH3" (ca. 20 ml.). Heavy floccules of the rare earth oxinates settled out. The suspensions were warmed almost to boiling to facil i t a t e precipitation, then allowed to digest at room temperature for 1 hour. After warming once more for several minutes, the precipitates 25. were filtered off by passage through accurately weighed dry sintered giass gooches of fine porosity, with the aid of a water pump. On some occasions, the rare earth oxinates tended to pass through the f i l t e r during the i n i t i a l stages of fi l t r a t i o n * However, this was readily recovered by passing the liquor repeatedly through the f i l t e r u n t i l a clear f i l t r a t e resulted. If the precipitate passing through the f i l t e r dissolves on heating, i t is merely excess oxine, which i s much less soluble in hold than i n hot water. On the other hand, i f the precipitate f a i l s to dissolve on heating, this shows that heavy metal oxinates have slipped through the f i l t e r , and further f i l t r a t i o n is required. After washing the precipitates with 5 ml. portions of hot d i s t i l l e d water •until the wash liquor was colorless (ca. 25 ml.), in order to remove excess oxine, the gooches were transferred to the hot a i r oven at.130° C. and dried to constant weight (90 min. proved ample). The weighed oxinates were then dissolved in 2n. HC1, by pouring small portions into the gooch (up to 100ml.), and applying the water pump. 2 g. KBr (A.R.) were added to each resulting solution, which was 2g subsequently titrated with 0.1002n. KBr0 3— unt i l a drop of the mixture gave a positive test with a drop of KI starch indicator on a spot plate. 10 ml. of freshly prepared KI s o l u t i o n ^ and 2 ml. starch solutions-were added, and the excess KBr03 then determined by backtitration with pa 0.1136n. Na 2S 20 3. ):'••"••' 26. . i 1 • • • " -I -; Following ere the Analytical Results. ! .-Seriesj; Series Z 1. 2. .1.. 2, Wt. of bromide 0.1090 0.1288 0.0923 0o1694 g. Wt. of oxinate 0.1136 0.1257 0.0756 0.1535 g. 0,10Q2n,KBrQ3 21.47 22,10 17.00 38.00 ml. 0.1136n„NagS2Q3 0.90 ' -0,10- 0*37 0,10 ml. KBr03 reacting 20*45 21.39 16,59- 27,89 ml. Now 2KBr03= 5C3H70N s SCgHoON-or. ."• 1.I& = 3.6056 g. CgRgOir From this the oxinate content of the precipitates is readily computed. Series Y 1, 20,45 x F = 64,72$ 0,1156 2, g^M x F = 63.04$ • : Oil257 • • • Series Z- 1, 16.59 x F = 79*08$ 0,0756 2* 27,89 x F = 52.01$ where F = 5^6056 x 100 1000 The analytical results are so irregular that further computation i s without purpose• \ 27 KLscussign. The quantities of reagents employed in this determination 21 are exact multiples of those quantities employed by Pirtea in deter-mination of La. The rare earths should be completely precipitated by oxine under the conditions described according to the general equation. •WK3 + 3CaH70H •* 3HX + M (GgH^ON)3 HG1 treatment liberates the oxine from the precipitate. KBr03 used for t o g i v e B r a titration reactei with KBr^which acts on oxine i n a quantitative fashion thuslyr . KBr03 + 5KBr + 6HC1 •*-6KC1 + 3Br 3 + 3H30 - . G@E7QW;4 .2Br3^--CeHsp(Br2 + 2HBr. thereby making volumetric determination feasible. Further investigation i s required to explain the irregular analytical-results herein obtained. The:oxinate-content of the precip-itates should have closely approximated 75$ (e.g. oxinate content of the pure Las.= 75,67$). Taking 75$ as a hypothetical example, further calculation may be made; 1 mole of the oxinate of a trivalent metal contains 432„438g. oxinate radical 75 g. oxinate = 25 g. rare earth metal. 432.438 g, oxinate s 144.146 g, rare earth metal. = mean molecular weight or, mean equivalent weight = 48,048 Knowing the mean equivalent weight, the rare earth content of a salt i s quickly computed from the weight of oxinate obtained by gravimetric precipitation. It i s generally easier and certainly -less c^i : 28. costly to use compounds of xare earth mixtures rather than those of the pure elements in synthetic studies, hence the need for an a l l embracing method of determining the maan equivalent weight. Older procedures involving calcination of the oxalates, sulfates, etc. to the oxides are worthless when dealing with mixtures containing Ce, Nd, Pr, Tb, due to the tendency of these elements to form higher oxides of indeterminate composition. Neither volumetrio nor ppfctentiometric methods are of value for the same reason. Thus, i f further study shows-that oxine cam be successfully applied to the determination of rare earth elements, a new rapid method i s provided whereby not only the rare earth content of a newly synthesized compound may be found, but also the mean equivalent weight of any group of metals concerned. 29. I? - ORGANOMETALLIC COMPOUNDS of the BABE-EARTH ELEMENTS. The i n i t i a l purpose of this investigation was to attempt synthesis of organometallic derivatives of the rare earth elements. With this view, correspondence was carried on with Dr. B.S. Hopkins and Dr. LvF. Audrieth of the University of Illinois to ascertain whether any such work had been undertaken there. Following i s a resume of unsuccessful reactions attempted at the University of I l l i n o i s » 1* From the salts_in_ether (G3Hy)3La'i • 1. . C3H7lfeBr + L&C13 (G 3H 7) 2LaGl. • GgHyLaClg 2. C3H,JgBr + CeCl 3 ( c ^ j g S c i GaHyCeGla.-3« (G 2H 5) 3Zn + LaGl 3 •* (CgH s) sLaCl + ZnCl 2 4. (C 2H 5) 2Zn + CeCl 3 (C 2H s) 2CeCl + ZnCl 2 B. F£si„ti&§„ffiitela„is„si3a^ 1. 4La + 6C4H9Br 3(C 4H e) 2LaBr + LaBr 3 2. 2La + 3(CgH5)sZri - 2(C 2H s) 3La + 3Zn. 3, misch metal +(CgH5)sZn<> 4, 2La + 3(G2H5)gHg - 2(G gH 5) 3La + 3Hg. 5, misch metal + (GgH^gHg* 6. 2Ce + 3(C 2H s) 2Hg - 2(C 2H 5) 3Ce + 3Hg. This reaction was attempted i n March, 1937. Appropriate quantities of reactants were heated in a sealed tube at 100 - 150°C. for one week. Subsequent d i s t i l l a t i o n of the reaction mixture in an atmosphere of helium under 13 mm. pressure resulted i n a d i s t i l l a t e free of rare earth. The residue contained the powdered rare earth metal i n a 50. slightly amalgamated state'. Dr. LiF.Audrieth proposed study of the reaction given by: 3NaR + CeX3 •* 3NaX •+ CeR3. Since the sodium alkyl compounds are d i f f i c u l t to prepare and are generally spontaneously inflammable, the author recommends that a study be made of possible reaction between sodium amalgam + EtBr 4- LaBr 3 and between Na rare earth alloys + EtBr in an etheric medium, under an inert atmosphere to minimise danger of explosion. The author does not propose to discuss the various points offered pro and con existence of rare earth organometallies. The interested reader i s referred to the bibliography kindly offered by Dr. L'.F. Audrieth, now in possession of Dr. J.A; Harris of the U.B.C. Department of Chemistry. Although time did not permit experimental studies on this f i e l d i n this laboratory, preliminay problems relating thereto have been sufficiently c l a r i f i e d to permit direct attack on the problem. 51. SUMMARY 1. Mosander*s process of separating Ce from related earths by bromine treatment has been studied with the object of improving i t s efficiency. This was accomplished by -(a) use of extraction methods. (b) refluxing rare earth oxides, Br s and Hg0 in presence of ammonium salts. 2. Necker»s and Kremer*s method of separating Ge by nhosphate precipitation has been examined, and the effect of varying acid concentration and temperature of mixing the reagents confirmed. 5. Bourion's S gGl g process for preparing anhydrous rare earth halides has been found unsatisfactory for reasons described herein. 4, The synthesis of anhydrous rare earth chlorides and bromides by sublimation ©f rare earth oxides with the corresponding ammonium halide, as proposed by Reed, Hopkins and Audrieth, has been found satisfactory. Improvements i n the apparatus used are described and means of 'removing, traces- of basic salt-fr©m the product are suggested. • • • • • • 5, Anhydrous rare earth bromides have been successfully prepared by extrac t ionof- anhydrous- benamtes-; with ether-saturated-with dry HBr, Tentative explanations have been offered of the anomalous behavious of ether + HBr 4- rare earth bromides. 6, Attempts were made --to-employ-8 -quinolinol for quantitative estimations of the rare earth elements in their compounds and for determination of the mean equivalent weight of mixtures of rare earth elements including Ce, Pr, Nd and Tb. Insufficient time prevented success in this direction. Exemplary hypothetical 32 computations are given. A'-resume of unsuccessful reactions studied at the University of Illinois for synthesis of organometallic derivatives of the rare earth elements, together with ideas of the author on the subject, have been included. 33 VI. BIBLIOGRAPHY 1. Neckers,JiW. and Kremers,H.C. JJA&G.S., SO, 955 (1928). 2. Mellor,J.W. ?Comprehensive Treatise on Inorganic and Theoretical Chemistry Vol. V. Longmans, Green and Co. (1924). 3. Levy,S*X. "The Rare Earths" Edward Arnold and Co. (1924). 4. Mosander, G.G, Ann., 48, 210 (1843) 5. (a) Prandtl, W. Z. anorg. allgem. Chem. 143 , 277-84 (1926) (b) Prandtl, W. and Huttner, K. ibid, 136, 289-94 (1924) (c) Prandtl, W, and Losch,J. ibid, 122, 169 - 66, (19"2g| ibid, 127, 2Q9J.4, (1923) (d) Prandtl, Yf. and Rauchenberger, 3,1 Ber., J>3, 843 - 53, (1920) Z^anorg. allgem. chem., 12,0. 120 - 8, (1922) ibid 122, ,511:-„ 4, (1922) ibid JL29-, 176 - 80,(1923) 6. Mellor, "Comprehensive Treatise on Inorganic and Theoretical Chemistry". II, 95 (1922) Longmans,.Green and Go* 7. Latimer, W.M. "Oxidation Potentials", p.54 > Prentice-Hall, Inc. (1938) 8. Herzfeld, E. Zi anal.'chenw, 115. 421-3 (1959) 9* Stuart, F.Ai and Harris, J.IM unpublished findings. 10. Reed, J4B., Hopkins, B.S. and Audrieth, L.F. "Inorganic Synthesis", I, 28, (1959) McGraw-Hill Book Co., Inc. 54 .11. Mellor, J„W. "Comprehensive Treatise on Inorganic and Theoretical Chemistry" V, 646, (1924) Longmans, Green and Co. 12. Bourlon, M.F; Compt, rend., 145, 243-9* (1907) 15. Reed, •. J-iBi, Hopkins, • 3.S. and Audrieth, L.F. J<.'A*G.S., §ZS 1153, (1935). 14* Brauman, P* and Takvarian, S. Compt. rend., 194, 1579 (1952) 15. Mellor, j;w, • n Comprehensive Treatise on Inorganic and Theoretical Chemistry" II, 170 (1922) Longmans, Green and, Go.. 16. Dennis, L*-M» "Gas Analysis", p9254 IfeeHl£laii.tCd*r (1918) 17. Ger. patent 268827, cf. Chem. Abstr., £, 1861, (1914) 18. Vogel, A-« I* "Quantitative Inorganic Analysis" p.310 Longmansj,Green and Co. (195S) 19. Luder, W.F. Chem. Rev., 27, 562,(1940) 20s Pauling, Li" "The Nature of the Chemical Bond" Cornell Univ. Press, Ithaca, N.Y..- (1959). 21. Pirtea, Th. I. Z. anal, chem., 107, 191.(1936),..... cf. also O.Ai 34, 2277 (1940) 22. Vogel, A.I. "Quantitative Inorganic Analysis" pp.161, 453-8 Longmans, Green and Co. (1959). 23. ibid., p.451 24, ibid., p.408 25. ibi d . . p.406 26. ib i d . p.405. 


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