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The separation of molybdenum valencies by paper chromatography part II1
126
THE
ANALYTICA
SEPARATION
OF
CfiIMICA
MOLYRDENUM
ACTA
VALENCES
VOL.
BY
14
(x956)
PAPER
CHROMATOGRAPHY PART
II”
bY I-1. M.
STEVENS
fNTRODUGTION
Molybclcnum has been rccognizcd as an essential element of plant metabolism AND STouTa. Nrcrrot~s AND NASONQ since the work of STnIN13~1~G2,and ARNON hnvc shown that the metal is an csscntial constituent of the enzyme nitrate reductase, and that a change in the valcncy of the metal takes place during the cnzymic rcduction of nitrate to nitrite A method for separating the valency states of molybdenum was necessary in order to dctcrmine the valency changes undergone in the metabolism of micro-organisms and higher plants 6. The separations were achieved using paper chromatography. The quantitative separation of MovI and Mov as thiocyanatcs has already been describe&. The prcscnt work deals with the separation of hexa- and pentavalcnt molybdenum as oxine complexes, and of pentavalent and trivalent molybdenum. EXPERIMENl'AL
MovI 0xitmt.ewad prcparcd by mixing a solution of sodium molybdato dthydratc (I g in ~0 ml wntcr), acidified with zN hydrochloric acid (5 ml), and 8-l~yclroxyquinohne in ethanol (2 g in 20 ml). The mixture was heated and filtcrccl through a Blichner funnol using Whatman No. I paper, and the bright yellow residue washed with water and ethanol and dried. Tho solid was rccrystnllizcd by allowing a hot filtered chloroform solution to stand overnight in the rcfrigcrator, filtering off the deposited solid and hyashing it wrth ether. The complex was soluble to a smafl extent in acetone and chloroform, but almost insoluble in other organic solvents and water. Absorption maxima at 250 xnp and 370 m,u, and a minimum nt 280 mpc wcrc obtained with a chloroform solution as shown in Fig I. If csccss of ctbanolic oxine was added to a solution of sodium molybdnto acidificcl with hydrochloric acid, and the mixture shaken with zinc dust, a Jarlc purple colour was produced which on adding water and chloroform could be cxtractcd into the latter. A compound purporting to bc Mov oxinate, which has not previously been rcportccl, was obtainer1 by (i) the addition of a solution of molybdenum l~cntncl~loride in roN hydrochloric acid (0.3 g tn 5 ml), which was treated with a littfc sodium amalgam to reduce traces of &Iovr, to a solution of 8-hydroxyquinolinc in ethanol (5 g in 50 ml) followed by zo ml of water. The reddish-purple solution’was allowed to stand for 5-10 minutes, filtered, (Whatman No. 41 paper) and poured into 500 ml of water. The mixture was heated to 3o”-Go Ot filtcrcd through a Buchnor funnel (Whatman No. I paper), and the dark purple residue washod with cold water, ether and
Asferences
p. x30
VOL.
14 (1956)
SEPARATION
Or:
MOLVBDDNUX
VALENCXES.
II
1537
Fig. I. MoVl oxine complex: the U.Iv. and visible range.
spectrum
111
than dried in an oven at 4o”-50~. (n) dm3oivmg sodium molybdnto dlhydratc (I g) and potassium thiocyanate (5 g) in water (20 ml). adding ION hydrochloric acid (20 ml) and warmmg to Go*-70“. After allowing to stand for IO-IS mmutcs, the m$xturc W;IY cooled and shaken with ether (rgo ml). The upper cthcreal layer was separated, ftltcrcd and then added to a solution of oxine in other (5 g in 10 ml). The dark brown precipitate was filtered off, (Uuchncr funnel, Whatman No. I paper), and bowled with water for a few mmutes, The purplish-bfack residue w.as fittered off, waahcd with cold water, ether and dried at 40”-50~. The same compound was formed if solutions of molybdenum pcntechloride and oxtne in carbon tetrachloride were mixed, and the resulting dark grcon prccipitste was warmed with water for 5-10 min. hlethod (i) gave the purest product which contained molybdenum and oxmc, and only a trace of chloride. The dark purple solid when dissolved in ethanol, acetone, ethyl acctnte and chtoroform gave reddish-purple solutioos, but was almost msoiublc tn ether, carbon tctrachloridc, and water. Absorption mtlx~ma at 243 rnp and 540 rnp, and a minlmum at 480 mlr were obtained with ethanol sofuttone. (See Figs. 2 and 3.) The dark brown precipitate obtained in method (ii) contained molybdenum
Fig. 2. MoV oxinc complex:
U.V. spectrum.
l:rg. 3. iMov oxine complex:
visible spectrum,
(3.6%), oxine, and thiocyanate, rrrtd the dark green preclpltate from the carbon tctrachloride reactlon contained molybdenum, oxine and chloride. ’ Analysis of the purple compound gave the following composition: IMO, x~.z~/~ (spectrographic method); C. 50.3O/o; f-I, 3.x%; N, G.z5Qj& When the complex was warmed with potassium th$ocyanate and l~ydrochloric acid, it was This afforded LLcolorimctrz method decomposed yielding an orange solution of IMOVthiocyanate. mg of the complex was heated with x0 ml of for estimating the molybdenum content; 15-20 a 100/o w/v solution of potassium thiocyanatc in 2N hydrochloric acid and 2 ml of acctonc. The orange-red solution was diluted to IOO ml with the thlocyanate reagent, and 5 ml portionscxtracted with known volumes of ethyi acetate. The colour of the extracts was mcasurcd on the Hilgcr was obtained. A “blank” detcr%pckker” as described previously 1. A mean value of 22.0*/~ mination using x5-20 mg of oxine was performed and coufd be neglected, References
p. x30
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SrJlutl(Jll
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(Jf
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STISVENS
VOL.
14 (rgfj6)
im inital
problcrr~. by tltc CfcChYJfyYlS a&i nt a current of 7-H amp illld of the n~olylxlcnun~ ix&w the pcEltilV;lle:lt state with not using it Jllil.ti:ltlWl cathOclCc, rcrliicliotl Molyb~lci~~r~u trlclllorltlc, prepa IJy hcatlng complctcly cfhxtcd after about G hours cqcration. tfic puntacl~lnriclc in hydrogen, wilb founcl to IX insnlubfc in all solvcnts except those wlrlcll clccompolic it (e.g. nitric acid, sodium lrydroxtclc). h satisfacCory method for obtnlnlng itn cfftctent rccluctron of m0lyl~clcnum trmxirle I~clow the pctita-stat0 consistctl of adtling zinc Clust to a mixed ~~~lut~o~r 0i sotl~iin~ rr~olylxlatc (0.5 g in 5 nil water) ~rd roN hyclrocl~loric acid (to ml) until tlx hcJlilL$Un cc:iScd to givt: iL red c0l0ur when l>ortltms weru tested with pOtas!%~\im tbi0cvanatc. ‘I’hc soltrtion was then filLcrcc1 (WhaLman No. 41 paper) from c’xcess of zinc dust. zinc1 freed from MOV nnd zinc as follows: A celtulosu colutnn was prcprcct by drawing out one cnrl of it ptcca of ylnfis tubing 30 cm x t -5 cm (inlernul cliamctcr) into il jet into which was inserted ;I plug of glass wool tn act a8 a porous rct:iining WilSllCr. ‘l%c tube waq flllcd with zLsuspension of WllaLn~;tn powdt:rutl cellulose in water, and a, comprasscd ittr stqq~ly was attaclicrl LO Llic upper on& Water was Lltcreby forcccl out of tfic tulo, and Llm ccllulosc paclcctl tightly nncl cvcnly into iL column approxiinntcly tg cm in lcn@lt. 5 ml ot the rIXfllCC!t~ 1YiofybtkltC SotUtiCM WilS pkWCtt OI1 ttlc Coltlmn itnd XffOWcCl to soak In; ttlc inner wtill of Llic Lirlx2 iLl>CJVC! tlic ccllolosc was then wlpctl with filter paper. Elution was cnrricrl tJttL using it solution of Lliiocvanic ncid in cthcr until at lcust 1fj lllinuks ikftcr tlic rctl fJ:ind of %loV thiocyirrlatc, togctllcr t&t11 zinc, llad p:tSsCd Olit Of tflC C~Jfliinll. ‘lb clnnnt wns lzrcparcd by ritldrng toN ltydrocllloric acid (.lo ml) to i\ solution of pOtitSSium thiiicynnate (.#o g in ‘$0 ml waler) antI sliulcing the mixtiirc with cthcr (150 ml). The upper cthcrcal luycr was filtcrcd ancl stored in n rcfrigerntor. A furtlicr clution wab tlicn c:rrricd out using pure utlicr (to wash out: thiucynnic acid) until ttlc Clllittc Was colourlcus. IXstillcd water was pnssctl through ttic culiiniri itlltl the ornnjic cluatc was collcctcd iUlC1 warm4 to 40”“45” In a strcain of carbvn dioxide to cxpol ctl~cr. IL wa then diluted to x00 ml with rlistillctl water. Tit0 cliloritlc soliitiun thus prcparcri was found to bc free of zinc, thiocyetnic acid. alid &loV nncl to pusscs~ strong reducing pt’opcrties. In thcr. prcscncc of sulphnn~lmnitlc (I’;{, in N hydraCflffJrk ilcitf) nitrate was clircrntitat~vcly reduced to nitrite. ‘l%c cstimntion of Chc nitrite produccd was ycrformcd colortnlctric:rlly using N-( t-~~~Ll3l~Ltl~l) ctf~ylc~~ctIi;~~~~~t~cciihyctr0clrloriclc (o.oot o<, in wvatcr)‘. ‘I’hC XllOfyfXl~nlltll Collt~llt CJf th Sofiltkln WilS Cstllll;LtCXl by mixillg 0.5 ml WlLfL JO lllf Of iO~z;J poinssiurn thiocy:urntc in zN hydrocltlorlc &cl: z-3 CfrCJpS Of hyCfrO&Cn fmYJ?CfCb2 ( l0 VOf.) WOrU adtfcd rrlltl Lhc rctl coloiir ~rllowcd to appear iLlId begin to fiidC. .t S~fU~kItl Of SLallil(JtiS CfIfCJrklC was then addctl clrop by drop until tlicrc Wi1Y no further rluepcr~iiiy 0f tlic rcstorccl reel culour. The? solution wus cstractcci wtth ‘lo-50 ml of ethyl acctatc and Llw extract filtcrcd and mcasurcd on Lhc **Spckkcr” III tlw ~sunl way. Tlic valrncy state of t.hc zinc-rcduccd soluL~0lI of 310 was detcrmiriecl ii9 follows: ‘To x ml of n solution of 5iorltum ~~iolyl~latc, acidified wittt hydrochlortc acid, anti contirining f 2.5 mg $10 per ml, 5 ml of roN hyclrochloric acid and 2.5 ml of wntcr \VRY added. Zinc dust wnzi then ~lclcd until the solution was orange-brown nnd cci~scd to yiva R red colour wllcn it spot was mrxcd with potassium thiocynnntc on n. wllitc tile. When all the zinc llati tlissolvcrl, the soltrtmn \vi\s clilutcd to IOO ml wiCll distilled wrrtcr. 1’0rtions w0rc then mixed with 50 ml of zAI sulplluric acid and titIXt&I with standard potassium pcrlI\ttlIgaXIilt~ so’ution. of
fxUp;lri~tloJl
M.
pure
Xll~fy~~~l~llm
solirtlorl
oi
Lrmx’dc
‘15 ml of rcduccd molybdatc solutron (Cslc. for &IolIf + Move -l- 30, 3.5r
~MoflJ
in
loff
prcsct~tctl
t~sCfrCJ~fl]~rfc
(G 5Gz5 ,ug MO) reqt~md 3.5 ml A!/zo KiHnO,. ml; for MoLV +- RloV~ + zc, 3.34 mt).
dlo ml of rcdueud molyhdntc soluCion ( f JOOO ,~g &IO) rcquircd (Cnlc. for >IolIl + MovI -#- 3c, rg.Ga ml; for MoIv --j MoVI ‘l’ho molybdenum thcrrfore by previous worlccr#8*~“, Re/evences
p.
130
appcarb
to
bc trivulcnt,
15.6 ml N/r00 fi.\‘lnO,, t_ zc, ro+ ml).
w11ich ngrccs
with
tlic
results
obtatncd
VOL.
14 (r956)
SEPARATION
OF
MOLYBDENUM
VALENCIES.
II
=9
Good qualitative separations between Mom and MoV wcrc obtained on acidwashed \\‘liatman No. I paper strips using the ether-thibcyanic acid eluant, RF values being 0 for ;LIorxrand 0.8-0.5, for lUov. The separations could not be performed qu~tntitati~ycl~~ owing to the oxidation of some of the Moxn to MoV by thiocyanic acid in the presence of air. The RF value for 310v1 in this system was o.8-o.g, but a separation between MO”’ and MO”’ could not be performed as these valency states interacted in thiocyanate solution giving 310~. When solutions containing trivalent molybdenum and potassium thiocyanate were mixid and shaken with ether, no molybdelluln was extracted unless air or hydrogen peroxide was added, when red 310v thiocyanate Ijassed into tbc ether. Similarly no molybdenum could IX cstractcd by chloroform from mixed solutions of in water, and oxinc in ethanol unless air was admitted, when reddish purple MO’” 3110~oxinate passed into the chloroform layer. ‘I’hesc observations suggested that thiocyanatc and oxinc compounds of trivalent molybdenum, if they exist,’ are less stab% than those of 3310~ancl arc not formed under these conditions. The luck of acid system may be due to the adsorpmovement of i\lo”* in the ether-thiocynnic tion of the chloride onto the ccllulosc, while the more covalent molybclcnum pentatlliocyanatc dissolves in, and moves with the organic &ant.
The iutthor’s thanks are due to IW. 13. J. 1,. ~1CIloL~s for informnturn concerning the chemical ~:I.II~IWIW for unctcrtnking reduction uf nrtratc by &lofIr, to hllss hNS L’nors*r and hlr. iZrrrtu~ the cstimatron of nitrogen m the .41ov oxrne Cc~mplcx. and to L)r. I\IITCII1ILL (JI the Macaulay Institute, Abcrdccn, for the estimation of molybdenum in tlio complex by spcctrograplnc analysis.
Tim preparation of MOVE oxinatc and a purported MoV oxine complex IS &scribed. The latter was analyscd, arid a numtcr of its propcrtics, includmg scparatlon from the lMoV1 compound by paper cliromatograpl~y, wcrc studied. The prcparatlon of a solution containing trivalent molybdenum and the separation of this valcncy from the pcntavalcnt state by chromatography upon cellulose IS also tlcscribcd. Suggestions as to the stnbthtp of thiocyanatc and oxinc compounds of MoIfl were made from the results of some extractron expcrmlcnts performed upon tr~vntcnt molybdenum solutrons,
La prdpnratron dc l’oxinatc dc molybdbncvfi CL d’un complcxc molybdhncv-oxinc cst dbcrito. Cc dcrnicr a bt.6 annlysb; un certain nombrc clc scs proprl6tds ont dt6 btudldes, comprcnant sa sdparation d’avcc le compose du molybdbncv~ prir chromntographic. La prdparntion d’une solution rcnfcrmant lc molybdencI~r et la sbparation du molybdhnc~I1 J’evcc lc molybd8ncv, par chromatographic sur cellulose, sont d&rites. Des hypothbses ont 1518 faites au sujet dc la stabilit& dcs thiocyanatc ct oxinatc dc molybd&nef~I, B partir dcs r&&tats dc quelqucs cssals d’cxtraction cffcctu6s avec dcs solutions de molybdhneW ZUSAMMENFASSUNG Die Dnrsteilung von MolybdanVI-Oxtnat und von einem MolybdZnv-Oxin-Kompicx wird beschricbcn. Dleser Letztcrc wurde analysicrt; einc gcwisse Anzahl seincr Eigcnschaften wurdc untersuch& untcr anderen scmc Abtrcnnung von dcr MolybdBnvfi-Verbindung mtttels Papierchromatographie. Die Darstcllung einer Losung, welchc MolybdtinfII cnthsllt und die Abtrennung Zellulosccl~romatograpl~ic sind tcschriebcn. Es dos MolybdanIII vom Mo~ybd&nV mittels wurdcn Hypothescn aufgcstcllt in Bczug auf die Stabilitat dcs iMolybdYnrIr-‘l’l’lliocyanats und -Oxinats, ausgehcnd von Result&en einiger Extraktionsversuchc, welche mit L6sungen von MolybdtinIIx ausgeffihrt wurdcn,
Referewes
p. x30
130
H.
hi. SrnvENS
VOL.
14 (x956)
REFERENCES M. 1. CAXDELA, E. J. HIZWXTT ASD H. M. STWENS, And. Chtwz. Ada, 14 (rg,gG) 66. Ii. A. STEINDF,RG, J. .4gv. Research, 52 (xg3G) 439. D, I. ARNoN hNf1 I>, R. STOUT, .PimL Physiol., 14 (x939) 599. D. J. D. N~CEJOLAS ASD h. I?JASON, J. UiOt. ~ficm., Zxl (1954) 183. D, j. D. NxCWOLAS AND f-1, M. %.EVENS, Nalw'e, 176 (1955) 1066. w. WnnnIAw AND IL L. WORMIZLL, J. Chent. sot., (1927) 1087. F. ID. SNELL AND C. T. SNELL, Colovimelvac Methods of Rnolysis, D. Van Nostrand Co. Inc., New York, 1953, p. 422. W. WARDLA\V ANI-J N. 33. SYLVXSTEII, J. Chew. Sot., (1923) 969. CHILDSOTTI, il. Etehkockcm., ~2 (rgo6) 173.
THE
ANALYTICA
SEPARATION
OF
CfiIMICA
MOLYRDENUM
ACTA
VALENCES
VOL.
BY
14
(x956)
PAPER
CHROMATOGRAPHY PART
II”
bY I-1. M.
STEVENS
fNTRODUGTION
Molybclcnum has been rccognizcd as an essential element of plant metabolism AND STouTa. Nrcrrot~s AND NASONQ since the work of STnIN13~1~G2,and ARNON hnvc shown that the metal is an csscntial constituent of the enzyme nitrate reductase, and that a change in the valcncy of the metal takes place during the cnzymic rcduction of nitrate to nitrite A method for separating the valency states of molybdenum was necessary in order to dctcrmine the valency changes undergone in the metabolism of micro-organisms and higher plants 6. The separations were achieved using paper chromatography. The quantitative separation of MovI and Mov as thiocyanatcs has already been describe&. The prcscnt work deals with the separation of hexa- and pentavalcnt molybdenum as oxine complexes, and of pentavalent and trivalent molybdenum. EXPERIMENl'AL
MovI 0xitmt.ewad prcparcd by mixing a solution of sodium molybdato dthydratc (I g in ~0 ml wntcr), acidified with zN hydrochloric acid (5 ml), and 8-l~yclroxyquinohne in ethanol (2 g in 20 ml). The mixture was heated and filtcrccl through a Blichner funnol using Whatman No. I paper, and the bright yellow residue washed with water and ethanol and dried. Tho solid was rccrystnllizcd by allowing a hot filtered chloroform solution to stand overnight in the rcfrigcrator, filtering off the deposited solid and hyashing it wrth ether. The complex was soluble to a smafl extent in acetone and chloroform, but almost insoluble in other organic solvents and water. Absorption maxima at 250 xnp and 370 m,u, and a minimum nt 280 mpc wcrc obtained with a chloroform solution as shown in Fig I. If csccss of ctbanolic oxine was added to a solution of sodium molybdnto acidificcl with hydrochloric acid, and the mixture shaken with zinc dust, a Jarlc purple colour was produced which on adding water and chloroform could be cxtractcd into the latter. A compound purporting to bc Mov oxinate, which has not previously been rcportccl, was obtainer1 by (i) the addition of a solution of molybdenum l~cntncl~loride in roN hydrochloric acid (0.3 g tn 5 ml), which was treated with a littfc sodium amalgam to reduce traces of &Iovr, to a solution of 8-hydroxyquinolinc in ethanol (5 g in 50 ml) followed by zo ml of water. The reddish-purple solution’was allowed to stand for 5-10 minutes, filtered, (Whatman No. 41 paper) and poured into 500 ml of water. The mixture was heated to 3o”-Go Ot filtcrcd through a Buchnor funnel (Whatman No. I paper), and the dark purple residue washod with cold water, ether and
Asferences
p. x30
VOL.
14 (1956)
SEPARATION
Or:
MOLVBDDNUX
VALENCXES.
II
1537
Fig. I. MoVl oxine complex: the U.Iv. and visible range.
spectrum
111
than dried in an oven at 4o”-50~. (n) dm3oivmg sodium molybdnto dlhydratc (I g) and potassium thiocyanate (5 g) in water (20 ml). adding ION hydrochloric acid (20 ml) and warmmg to Go*-70“. After allowing to stand for IO-IS mmutcs, the m$xturc W;IY cooled and shaken with ether (rgo ml). The upper cthcreal layer was separated, ftltcrcd and then added to a solution of oxine in other (5 g in 10 ml). The dark brown precipitate was filtered off, (Uuchncr funnel, Whatman No. I paper), and bowled with water for a few mmutes, The purplish-bfack residue w.as fittered off, waahcd with cold water, ether and dried at 40”-50~. The same compound was formed if solutions of molybdenum pcntechloride and oxtne in carbon tetrachloride were mixed, and the resulting dark grcon prccipitste was warmed with water for 5-10 min. hlethod (i) gave the purest product which contained molybdenum and oxmc, and only a trace of chloride. The dark purple solid when dissolved in ethanol, acetone, ethyl acctnte and chtoroform gave reddish-purple solutioos, but was almost msoiublc tn ether, carbon tctrachloridc, and water. Absorption mtlx~ma at 243 rnp and 540 rnp, and a minlmum at 480 mlr were obtained with ethanol sofuttone. (See Figs. 2 and 3.) The dark brown precipitate obtained in method (ii) contained molybdenum
Fig. 2. MoV oxinc complex:
U.V. spectrum.
l:rg. 3. iMov oxine complex:
visible spectrum,
(3.6%), oxine, and thiocyanate, rrrtd the dark green preclpltate from the carbon tctrachloride reactlon contained molybdenum, oxine and chloride. ’ Analysis of the purple compound gave the following composition: IMO, x~.z~/~ (spectrographic method); C. 50.3O/o; f-I, 3.x%; N, G.z5Qj& When the complex was warmed with potassium th$ocyanate and l~ydrochloric acid, it was This afforded LLcolorimctrz method decomposed yielding an orange solution of IMOVthiocyanate. mg of the complex was heated with x0 ml of for estimating the molybdenum content; 15-20 a 100/o w/v solution of potassium thiocyanatc in 2N hydrochloric acid and 2 ml of acctonc. The orange-red solution was diluted to IOO ml with the thlocyanate reagent, and 5 ml portionscxtracted with known volumes of ethyi acetate. The colour of the extracts was mcasurcd on the Hilgcr was obtained. A “blank” detcr%pckker” as described previously 1. A mean value of 22.0*/~ mination using x5-20 mg of oxine was performed and coufd be neglected, References
p. x30
)I.
rzti
‘I’l)c 3
SrJlutl(Jll
of
(Jf
ii
STISVENS
VOL.
14 (rgfj6)
im inital
problcrr~. by tltc CfcChYJfyYlS a&i nt a current of 7-H amp illld of the n~olylxlcnun~ ix&w the pcEltilV;lle:lt state with not using it Jllil.ti:ltlWl cathOclCc, rcrliicliotl Molyb~lci~~r~u trlclllorltlc, prepa IJy hcatlng complctcly cfhxtcd after about G hours cqcration. tfic puntacl~lnriclc in hydrogen, wilb founcl to IX insnlubfc in all solvcnts except those wlrlcll clccompolic it (e.g. nitric acid, sodium lrydroxtclc). h satisfacCory method for obtnlnlng itn cfftctent rccluctron of m0lyl~clcnum trmxirle I~clow the pctita-stat0 consistctl of adtling zinc Clust to a mixed ~~~lut~o~r 0i sotl~iin~ rr~olylxlatc (0.5 g in 5 nil water) ~rd roN hyclrocl~loric acid (to ml) until tlx hcJlilL$Un cc:iScd to givt: iL red c0l0ur when l>ortltms weru tested with pOtas!%~\im tbi0cvanatc. ‘I’hc soltrtion was then filLcrcc1 (WhaLman No. 41 paper) from c’xcess of zinc dust. zinc1 freed from MOV nnd zinc as follows: A celtulosu colutnn was prcprcct by drawing out one cnrl of it ptcca of ylnfis tubing 30 cm x t -5 cm (inlernul cliamctcr) into il jet into which was inserted ;I plug of glass wool tn act a8 a porous rct:iining WilSllCr. ‘l%c tube waq flllcd with zLsuspension of WllaLn~;tn powdt:rutl cellulose in water, and a, comprasscd ittr stqq~ly was attaclicrl LO Llic upper on& Water was Lltcreby forcccl out of tfic tulo, and Llm ccllulosc paclcctl tightly nncl cvcnly into iL column approxiinntcly tg cm in lcn@lt. 5 ml ot the rIXfllCC!t~ 1YiofybtkltC SotUtiCM WilS pkWCtt OI1 ttlc Coltlmn itnd XffOWcCl to soak In; ttlc inner wtill of Llic Lirlx2 iLl>CJVC! tlic ccllolosc was then wlpctl with filter paper. Elution was cnrricrl tJttL using it solution of Lliiocvanic ncid in cthcr until at lcust 1fj lllinuks ikftcr tlic rctl fJ:ind of %loV thiocyirrlatc, togctllcr t&t11 zinc, llad p:tSsCd Olit Of tflC C~Jfliinll. ‘lb clnnnt wns lzrcparcd by ritldrng toN ltydrocllloric acid (.lo ml) to i\ solution of pOtitSSium thiiicynnate (.#o g in ‘$0 ml waler) antI sliulcing the mixtiirc with cthcr (150 ml). The upper cthcrcal luycr was filtcrcd ancl stored in n rcfrigerntor. A furtlicr clution wab tlicn c:rrricd out using pure utlicr (to wash out: thiucynnic acid) until ttlc Clllittc Was colourlcus. IXstillcd water was pnssctl through ttic culiiniri itlltl the ornnjic cluatc was collcctcd iUlC1 warm4 to 40”“45” In a strcain of carbvn dioxide to cxpol ctl~cr. IL wa then diluted to x00 ml with rlistillctl water. Tit0 cliloritlc soliitiun thus prcparcri was found to bc free of zinc, thiocyetnic acid. alid &loV nncl to pusscs~ strong reducing pt’opcrties. In thcr. prcscncc of sulphnn~lmnitlc (I’;{, in N hydraCflffJrk ilcitf) nitrate was clircrntitat~vcly reduced to nitrite. ‘l%c cstimntion of Chc nitrite produccd was ycrformcd colortnlctric:rlly using N-( t-~~~Ll3l~Ltl~l) ctf~ylc~~ctIi;~~~~~t~cciihyctr0clrloriclc (o.oot o<, in wvatcr)‘. ‘I’hC XllOfyfXl~nlltll Collt~llt CJf th Sofiltkln WilS Cstllll;LtCXl by mixillg 0.5 ml WlLfL JO lllf Of iO~z;J poinssiurn thiocy:urntc in zN hydrocltlorlc &cl: z-3 CfrCJpS Of hyCfrO&Cn fmYJ?CfCb2 ( l0 VOf.) WOrU adtfcd rrlltl Lhc rctl coloiir ~rllowcd to appear iLlId begin to fiidC. .t S~fU~kItl Of SLallil(JtiS CfIfCJrklC was then addctl clrop by drop until tlicrc Wi1Y no further rluepcr~iiiy 0f tlic rcstorccl reel culour. The? solution wus cstractcci wtth ‘lo-50 ml of ethyl acctatc and Llw extract filtcrcd and mcasurcd on Lhc **Spckkcr” III tlw ~sunl way. Tlic valrncy state of t.hc zinc-rcduccd soluL~0lI of 310 was detcrmiriecl ii9 follows: ‘To x ml of n solution of 5iorltum ~~iolyl~latc, acidified wittt hydrochlortc acid, anti contirining f 2.5 mg $10 per ml, 5 ml of roN hyclrochloric acid and 2.5 ml of wntcr \VRY added. Zinc dust wnzi then ~lclcd until the solution was orange-brown nnd cci~scd to yiva R red colour wllcn it spot was mrxcd with potassium thiocynnntc on n. wllitc tile. When all the zinc llati tlissolvcrl, the soltrtmn \vi\s clilutcd to IOO ml wiCll distilled wrrtcr. 1’0rtions w0rc then mixed with 50 ml of zAI sulplluric acid and titIXt&I with standard potassium pcrlI\ttlIgaXIilt~ so’ution. of
fxUp;lri~tloJl
M.
pure
Xll~fy~~~l~llm
solirtlorl
oi
Lrmx’dc
‘15 ml of rcduccd molybdatc solutron (Cslc. for &IolIf + Move -l- 30, 3.5r
~MoflJ
in
loff
prcsct~tctl
t~sCfrCJ~fl]~rfc
(G 5Gz5 ,ug MO) reqt~md 3.5 ml A!/zo KiHnO,. ml; for MoLV +- RloV~ + zc, 3.34 mt).
dlo ml of rcdueud molyhdntc soluCion ( f JOOO ,~g &IO) rcquircd (Cnlc. for >IolIl + MovI -#- 3c, rg.Ga ml; for MoIv --j MoVI ‘l’ho molybdenum thcrrfore by previous worlccr#8*~“, Re/evences
p.
130
appcarb
to
bc trivulcnt,
15.6 ml N/r00 fi.\‘lnO,, t_ zc, ro+ ml).
w11ich ngrccs
with
tlic
results
obtatncd
VOL.
14 (r956)
SEPARATION
OF
MOLYBDENUM
VALENCIES.
II
=9
Good qualitative separations between Mom and MoV wcrc obtained on acidwashed \\‘liatman No. I paper strips using the ether-thibcyanic acid eluant, RF values being 0 for ;LIorxrand 0.8-0.5, for lUov. The separations could not be performed qu~tntitati~ycl~~ owing to the oxidation of some of the Moxn to MoV by thiocyanic acid in the presence of air. The RF value for 310v1 in this system was o.8-o.g, but a separation between MO”’ and MO”’ could not be performed as these valency states interacted in thiocyanate solution giving 310~. When solutions containing trivalent molybdenum and potassium thiocyanate were mixid and shaken with ether, no molybdelluln was extracted unless air or hydrogen peroxide was added, when red 310v thiocyanate Ijassed into tbc ether. Similarly no molybdenum could IX cstractcd by chloroform from mixed solutions of in water, and oxinc in ethanol unless air was admitted, when reddish purple MO’” 3110~oxinate passed into the chloroform layer. ‘I’hesc observations suggested that thiocyanatc and oxinc compounds of trivalent molybdenum, if they exist,’ are less stab% than those of 3310~ancl arc not formed under these conditions. The luck of acid system may be due to the adsorpmovement of i\lo”* in the ether-thiocynnic tion of the chloride onto the ccllulosc, while the more covalent molybclcnum pentatlliocyanatc dissolves in, and moves with the organic &ant.
The iutthor’s thanks are due to IW. 13. J. 1,. ~1CIloL~s for informnturn concerning the chemical ~:I.II~IWIW for unctcrtnking reduction uf nrtratc by &lofIr, to hllss hNS L’nors*r and hlr. iZrrrtu~ the cstimatron of nitrogen m the .41ov oxrne Cc~mplcx. and to L)r. I\IITCII1ILL (JI the Macaulay Institute, Abcrdccn, for the estimation of molybdenum in tlio complex by spcctrograplnc analysis.
Tim preparation of MOVE oxinatc and a purported MoV oxine complex IS &scribed. The latter was analyscd, arid a numtcr of its propcrtics, includmg scparatlon from the lMoV1 compound by paper cliromatograpl~y, wcrc studied. The prcparatlon of a solution containing trivalent molybdenum and the separation of this valcncy from the pcntavalcnt state by chromatography upon cellulose IS also tlcscribcd. Suggestions as to the stnbthtp of thiocyanatc and oxinc compounds of MoIfl were made from the results of some extractron expcrmlcnts performed upon tr~vntcnt molybdenum solutrons,
La prdpnratron dc l’oxinatc dc molybdbncvfi CL d’un complcxc molybdhncv-oxinc cst dbcrito. Cc dcrnicr a bt.6 annlysb; un certain nombrc clc scs proprl6tds ont dt6 btudldes, comprcnant sa sdparation d’avcc le compose du molybdbncv~ prir chromntographic. La prdparntion d’une solution rcnfcrmant lc molybdencI~r et la sbparation du molybdhnc~I1 J’evcc lc molybd8ncv, par chromatographic sur cellulose, sont d&rites. Des hypothbses ont 1518 faites au sujet dc la stabilit& dcs thiocyanatc ct oxinatc dc molybd&nef~I, B partir dcs r&&tats dc quelqucs cssals d’cxtraction cffcctu6s avec dcs solutions de molybdhneW ZUSAMMENFASSUNG Die Dnrsteilung von MolybdanVI-Oxtnat und von einem MolybdZnv-Oxin-Kompicx wird beschricbcn. Dleser Letztcrc wurde analysicrt; einc gcwisse Anzahl seincr Eigcnschaften wurdc untersuch& untcr anderen scmc Abtrcnnung von dcr MolybdBnvfi-Verbindung mtttels Papierchromatographie. Die Darstcllung einer Losung, welchc MolybdtinfII cnthsllt und die Abtrennung Zellulosccl~romatograpl~ic sind tcschriebcn. Es dos MolybdanIII vom Mo~ybd&nV mittels wurdcn Hypothescn aufgcstcllt in Bczug auf die Stabilitat dcs iMolybdYnrIr-‘l’l’lliocyanats und -Oxinats, ausgehcnd von Result&en einiger Extraktionsversuchc, welche mit L6sungen von MolybdtinIIx ausgeffihrt wurdcn,
Referewes
p. x30
130
H.
hi. SrnvENS
VOL.
14 (x956)
REFERENCES M. 1. CAXDELA, E. J. HIZWXTT ASD H. M. STWENS, And. Chtwz. Ada, 14 (rg,gG) 66. Ii. A. STEINDF,RG, J. .4gv. Research, 52 (xg3G) 439. D, I. ARNoN hNf1 I>, R. STOUT, .PimL Physiol., 14 (x939) 599. D. J. D. N~CEJOLAS ASD h. I?JASON, J. UiOt. ~ficm., Zxl (1954) 183. D, j. D. NxCWOLAS AND f-1, M. %.EVENS, Nalw'e, 176 (1955) 1066. w. WnnnIAw AND IL L. WORMIZLL, J. Chent. sot., (1927) 1087. F. ID. SNELL AND C. T. SNELL, Colovimelvac Methods of Rnolysis, D. Van Nostrand Co. Inc., New York, 1953, p. 422. W. WARDLA\V ANI-J N. 33. SYLVXSTEII, J. Chew. Sot., (1923) 969. CHILDSOTTI, il. Etehkockcm., ~2 (rgo6) 173.