VOL. 17 (1957) GRAVIMETRIC DETERMINATION OF BARIUM 285

Le baryum peut &trc do& grav1m&riqucmcnt en quontltes allant dc o z B z o rng (A 0.x mg). dans le chlorurc de tuconylc hydrate. et clans lc zirconium mbtolllquc. aprb complhte sbparatton du zirconium On pcut Bhmmer Jusqu’Q xo g dc zirconium par double prCc1pitation dane l’acldc chlorl1ydr1quc (3 I), et ensultc par pr6clpltat1on au moycn dc cupfcrron ct extractton au chloro- formc du zirconium restant 1-e baryum cst flnalcment dosd gravlmdtrlqucmcnt comma sulfntc de baryum dans lc f1ltrat (cxcmpt dc fer ct de zlrcomum). au moycn d’un cxctis dc sulfate d’am- monlum On a d&ccl& lusqu’h o o15O/, dc baryum dans un ctilortirc dc zlrconylc impur. o 004% dans un chlorurc de rtrconylccommcrcJal , .purlf&“, 0 ooo”A, dans Ic zirconium mCtalhquc crlstalluie, en bnrre5, et 0 003% dans lc 2Irconium en fcuillc Reproduct1bilit& 0 ooi”A,

ZWSAJIMEXFASSUNG

Das Barrum kann grnvrmctrlsch 1n Mcngcn von o 2 bls 2.0 mg (o I mg) 1n hydrnt1crtcm Zlr- konylchlorld und in Zlrkonmmmctall nach vollstandlgcr hbtrennung dcs Z1rkonmms bcstlmmt wcrdcn I31s tu xo g Z1rkourum k&men durch doppcltc lrallung rn cmcm saltsaurcn (3 zu I) MI~JCU. gcfolgt von Cupferronf.?llung-Chloroformextraktlon dcs noch vorhandcncn 21rkomums. cntfcrnt wcrtlcn Das l3artum wlrd dann gravlmctrlsch als Bnrrumsulfat In dcm clscnfrclcn, tlrkonlum- frcrcn Irlltmtc durch I;Yllung mlt hbcrschusslgcm Ammonmmsulfat bestlmn1t. I31s zu o 015% I3ar1um wurdc 111 unsnukcrcm Zukonylchlorltl gcfundcn. o 0047:, in clncm ,.gcrclnlgtcn” Handels- produkt \on Z1rkonylct1lorul. o ooo%, Barium 1n knstalhs1crtcm ZIrkon1un1mctnll In Stnngcn und o 003Ok, Banurn In Ztrkon1ummctnll 1n Blattcrn Rcproduzlcrbarkctt o oor?L

l I: P. VENAI,LL, %rrco~cru~r~ am3 Ifs Comporo~ds. 1711c1nllold Pub. Corp , New York. 1922. Cllap II, p 22

’ 1: I’ VENAI~LE. abtd, p 66 s I3 A J LI~THW ANU I, r\ ~~C~)OSALD, / Clrent Sot , (1952) 4315 4 A SLIDI-LL. SolubtltItcs o/ Irtorgrtutr und il4efal Orgunw Comporcnds, Yol t, 3rd cd , I) Van

h’ostrantl Co , Inc . Sew York, 1940, p 1597 8 1 hl I<OLTHOPP r5hn 13 B SASDRLL. Tcr(booh o/ Qtra~tlrtafrr~e Iirorgaarc jlnalyses, 3rd cd,

~lacn11llnn Co , New York, 1952. (hop XX. p 326 e p. PLIOL, spot ‘Iesfs. \‘ol I, 4th ctl , Ekvtcr hl~ co , Kcw York, 1954, p 203 7 S B DEAL. Auul Cltmt , 27 (1955) 109 B h’ H Fuwa1~s. \V U XI ASOS hsn J S I’IZKOLA. /I ttrtl C/ton . 21 (1949) I 325 ’ L SILVIXb1A.S ASD 1) \t’ IiAWLl’V. /?IIN/ C/MW , 28 (1956) 806

lo I\’ TAKAGI, / Cltrnt Sot Jnpau. Chew .+cl. 72 (1951) 364; C A . 46 (1952) g54a

Rccc1vcd March xzth, x957

SODIUM 31ETAVANADATE AS VOLUMETRIC REAGENT

V. DETERhIINATION OF ORGANIC DERIVATIVES OF HYDRAZINE, IODINE MONOCHLORIDE METHOD

B,\L\VA?U’T SINGH AND S s SAHOTA

Panlab Utttversaly College. Hoshtarpttr (Indta)

The nature and proportions of the end-products of the oxidation of hydrazine and its derivatives vary with the specific nature and the osidatlon-reduction potential of the oxidlsing system and with the plr of the medtum. BROWN@ found that hydrogen peroxide reacted with hydrazme to form hydrogen azlde. B~towsa AXD SHATTERLY~

studied the action of a number of oxidismg agents upon hydrazinc. In most cases nitrogen was the primary product and under certain conditions ammonia and hydrogen

Rsfercwces /, 188

286 l3ALWAN.r 5INCIi, S. S. SAHOTA VOL. 17 (1957)

azidc were also produced as a result of the secondary reaction EMXL I;xscrie~~ stated

that an cmuls1on of phenylhydrazlnc and water rcactcd with iodine as follows

P. C,H,NEi.Ntil + 2 I, = C,i-i,NH, Hi + C,H:,N, + 3 Hi

Accordmg to E. vos MEYEI@ 1f an c’xccss of phcnylhydrazlnc 1s used the rcactlon that ’

occurs 1s: C,H,NH NH, + 2 I, = C,H,I f 3 Hi + N,

Fchllng’s solution ox1d1scs pl1enylhydrazlnc to benzene, water and nitrogen; and the

gasometric method of WATSON S~rTlr~ is based on this rcactlon. According to KUI~TES-

ACI<ER nsu KUMNA~ d1rcct titration of phcnylhydraz1nc and scmicarbazide with iodatc

to the 1odme monochlorldc end-point is possible. MILLER AND FURMAN~ have shown

that the oxldatlon of pl1enyll~ydraz1ne in acidic solution by potassium 1odatc 1n presence

of mercuric ions results 1n the formation of diazonium salt wh~chslowly hydrolyscs6iving

off nitrogen and forming phenol ‘I’hey have also suggcstcd that the rapid reaction of

scmlcarbazlclc with lodatc 1n acid solution is not due to hydrolysis, but depends upon

direct attack of the hydraz1nc group wrth intcrmedlatc formation of unstable carbamlc

acid, ~111~11 1mmcd1ately breaks clown to 61vc carbon d1ox1dc and ammonia. According

to BIU~~ON AND CLISSOLI~~, phcnylhydrazinc on oxldatlon with cupric ions or with

Fchling’s solution yields bcnzcnc andphcnol. SINGII elnl.Ollavc shown that the oxldatlon

of hydrazmc with potasslurn metapcrlodatc to iodine monochloride and roclinc bromide

end-point rcspectlvcly g1vcs nitrogen. Srsc~ ct ~1.~0 11ave also used cl1loram1nc-B,

cllloramlnc-?‘, sodium mctavanadatc and dlcthylenc tctraammonlum sulphatoccrate 1n

hydrochloric acid mcd1um for the oxidation of hydrazinc to nltrogcn and water with

a four-electron change N,I-I, -t 2 0 6 N, + 2 l.I,O

%k~IUlX, ~-lI<SRY AND SI<OLNII< l1 have shown that the hydraz1no group 1n mono-

substltutcd hydrazincs, tl1c1r hydrakones and acyl dcrlvatlvcs, 1s oxidlsed with a four-

electron change to nitrogen with potassium 1odatc in both hydrochlonc and sulphurlc

acid solutions. l’hc rccluctlon of iodatc takes place to todinc monochlondc 1n hydrochlo-

ric acid and to 1od1nc 1n sulphurlc acid.

11,1-I, + -1_ IO,- -t I.&O + -+- Cl- = ICl -t N, + 4 H,O

5 N&i,+ -t 4 IO,- - 5 N, -I- I 1 I4,O + I-$0 -t 2 I,

In the present 1nvcstlgation sodium mctavanadate has been used for the volumetric

determination of scmlcarbazldc hydrocl~loride, bcnzalazlnc, bcnzal scmlcarbazone,

aminoguanidinc! hydrochlor1clc, chloralhydrrrzine, o-hydroxybcnzal scmicarbazonc, p-

mcthoxyben~nlsem1carbazonc, o-chlorobenzalscmicarbazonc and ethyl methyl ketone

sem1carbazonc. In presence of hyclrochlorlc acid these dcrlvatlves of hydrazmc react

with sodium mctavanadatc 1n accordance with the equations:

4 VO,- f StI,CONH.N1i, -t 12 1X+ = 4 VO+a + CO, + NH, + N, + 7 li,O

4 \‘O,- + (C,H,CH. N-), + I 2 EI+ - 4 VO+’ + P. C&i&HO -+- N, + 6 H,O

4 VO,- -I- C,I$&Xi N.NHCOXI-I, -#- I 2 l-1' = 4 VO c’ -t C,Fi,CI-IO + CO, + NH, + N, + 6 I-I,0

.I VO,- -!- HN C(NH~Ki&,)Ni-I, + 1 z I-i+ = 4VO+? -+ HN C(OH)E;ti, -+ N, + 7 H,O

4 VO,- + C CI,CH(Oi-i)NH.NI-I, -t 12 I-i+ = a+ VO+? + CCI,CH(OH), + N, + 7 H,O

4VO,--t_ iiO.C,H,CH. N NI-iCONH,+ 12 El+ =4VO+‘+ HOC,I_1,CHO + CO,+ NH,+ N, + 6H,O

Refe~emes fi 283

VOL. 17 (1957) SODIUM METAVANADATE. V 287

4 VO,-+CH,O C,H,CH NNHCON Ii,+ I 2 H+ =I 4 VO+Z+ CH,O C,H,CHO + CO, + NH,+ N, + 6 H,O

4 VO,- + Cl C,H,CH N NI-ICON H, + I 2 l-I+ - 4 VO+* + Cl C,H,CHO _t CO, + NH, + N, f 6 H,O

4VO,- + G,H,(CH,)C N NHCOBH, + I 2 H+ ~4VO+~+C2H&OCH3+C0,+NH3+N,f6Z-I,0

EXI’ERI3lEI4;TAL

A known amount of the hydrazmc dcrtvatrvc w.as tnkcn tn a comcal f&k and about 25 ml of water. 55 ml of cone hydrochloric acrd. 5 ml of 0 02A;l lodtnc monochlor~dc and 5 ml of chloroform wcrc ad- dcd to it The mlxturc wascoolcd to room tcmpcraturc and tltratccl qplnst 0 rnf sodlitnr mctavana- date solution The rcagcnt was atldetl from a burette until the solution. which wa% colourcd wcth lodlnc, bccamc pale green and the chloroform layer acqutrctl a purple colour tluc to lodmc Tlrc comcd flask was stoppcrcd and vigorously shaken during the tltratlon Addition ol smi~ll volumes of the mctavanadatc aolutlon was Lontlnucd. shaking vigorously nftcr each otlthtcon II ntll the chloro- form layer was faintly vlolct The rnctavanatlatc solutton W,L~ then ndtlcti rlropwlsc. with shnklug nftcr the addttron of each drop, until the chloroform Iaycr bccnmc I@t pale yellow The end-point was very sharp

In thcsc titrations. normality of the \olutlon with rcspcct to hydrochloric wad was kept bcctwccn 7N to 7 51V Scvcral titrations were pcrformcd In CilClI C.L~C From the \*olumc of sodium mctavana- date used corresponding to the end-point in cnch titration. the amount of each substance was cdcul- ntcd The results showcti that o 02 too I 2 g of the substrrnccs as ltrtctl nbovc can bc tlctcrrnlncti by using so&urn mctavnnatl.ttc as an oxitlis~ny agent

SUMN,\RY

Sodium mctavanadatc II,L~ been uscscd as DII oxitiuitng ngcnt in liyclrochlorlc aid rnctllurn for the volumctrlc tlctcrmlnatlon of scmtcarbazlrlc hytlrochlorldc, bcnrnlaz~nc, lK?tianlsctntcarl~aronc. ammoguanithnc I~ydrochlortrlc. o-l~ytlroxyl~nzalscmicarba7onc, p-mctho~yl~nzalucn~~c~arbatonc. chlor.~llrydrar~nc. o-cl~lorol~ntalucm~carbntonc and ethyl methyl kctonc wmlcarbazonc. using IO- dint monochloritlc a9a catalyst and prcoxlciibcr Chloroform was irscdas an indicator It was colourctl vlolct due to tlic Iilx?rntion of ~otirnc during the titration and bccnmc light pole yellow *rt thccnd-point owing to the formation of iodine monochlortdc Enclr hydmzinogroupin thcsccompountis wasoxrtlls- cd quantltntivcly with a four-clcctron change to mtrogcri with sodium mctavanadatc as an oxidant m hydrochloric acid solutwn

Lc m6tnvnnndatc dc sotlrum a dtb utllisd commc oxydont cn mihcu chlorhydrlquc pour Ic dosage volumdtriquc dcs composds auivanta chlorliydmtc dc scmlcarbalKlc, bcn7alaainc. bcn7aiqcml- carbazonc,cl~lorhydratcti’nm~nogu.rn~d~nc,o-l~y~lroxyl>cnznlucn~~carba7onc,~-m~tl~oxy~nxnlum~- rarbazonc, chloralhydrazlnc, o-clllorobcnzal.scmIcnl ba7onc ct 6tllylmbtllylcbtoscmI~rbazonc. cn utili~ntlomonoc~ilorurod’~odccommocatalyscirrct,,prdoxydant” I_cchloroformccstutil~sdcommo inciicatcur, 11 sc colorc cn vlolct par I’lodc lrMr6 au tours du titrngc et dcvicnt JaUnC plilc au point final par formntlon dc rnonoLhlorurc d’lodc Chaquc groupcmcnt ,,hydrazmo” dans ccs compotis cst oxydb quantltotlvcmcnt, nvcc15chnngc dc 4 dlcctronsentrc i’nzoto ct Ic m6tovnnadatc dc sodium

Natrlummctavanadat wurtlc rn salzsaurcnr M111cu ale Oxytlatlonsmlttci fLtr d~c volumctrlschc Bcstimmung von Semrcarbat~dhydrochlor~d, Bcnlrrlazln, Bcnzal-scmrcarbnron. Ammoguanldm- hydrochlorici. o-Oxybcnzal-scmicarbazon. p-Mcthoxybcn7al-scmlcarbazon, Choraihydrazm, o- Chlorobcnznl-scmrcarbazon und nfcthylhtllylkcton-Ycmlcarbazon mlt Jodmonochlorld als Kataly- sator und Voroxydatlonsmrttel verwcndct Chloroform wurdc als Incitkntor bcnutzt. Es wurdc wiihrcnd tlcr Tttratlon ciurch d~c Frclmachung von Jod vlolctt gcfarbt unci wurdc am Endpunkt schwach gclb durch Blldung von Jodmonochlorld Alla Iiycirazmgruppcn dcr gcnanntcn Vcrbrn- dungcn wurdcn Irn L.aufc cmcr Vlcr-Elcktroncn-Umsctzung quantltatlv mlt Nntrlummetavnnndat als Oxydntlonsmlttcl rn salzsaurcr LOsung zu Stlckstoff oxydlort

References p. 288

288 BALWANT SISGIi, S. S. SAIIOTA VOL. 17 (‘957)

REFERENCES

1 A W I~now.u~:, J Am C/rem Sac 27 , (1905) 551 a A \\’ UnowsohsD 1: 1: SIIATWRLY. J /f?u Chwt SOC , 29 (1907) 1305.30 (x9oS) 53, 3’ (1900)

221,783 J EMIL Flscllclt, /ICI , IO (I 887) 1335 * I3 VON MCYI.H, J fmcltf CIIC~II , 36 (1887) L rg ‘ \VA rSON ball r1t. Chcnr News. 93 (I 006) 83 a A ~~UHff:ShCKI:I< ANV 1.1 I<L’Is<.VA. % w&d Chenl , 64 (I924 388 ’ C 0 ~IILI.I:K AND N II l;u~trl~u, / /Ina Chew sot , 5’~ (1037) 161 m i-1 ‘1’ 5 I~HITION AND E >I CLI‘AOLD, J C/ret?r S-oc , (1~q2) 528 0 U hscir et ccl . J Induor Clrou hoc o 29 (1952) 3.4, Awl Chrr~i Acln. 9 (1953) 22

‘0 U SlNCll cl ccl , /fllUl Chrnr .dCtU. II (l954) 313. I3 (1055) 301. 10 (105.1) .pH. 1.4 (1956) 109 *I WILLIAM 12 MLUHIDIZ, IZOSALD A l41.sttv ASI) SOL SKOLSIK, /Jwl Chew , 25 (1953) 1042

Ihxxxvcd ~Inrch I rtlr. 1957

VOLUMETRIC IODATE METHOD FOR THE DETERMINATlON OF THIOCYANATE

Quzmtltatlvc oxhtlon of thiocyanatc by potassium lodatc has been studied by various workers. JA~~IESOX~ csttmatccl copper by titrating the prcclpltatcd CuSCN with lodatc to the iodmc rnonoclllorlde end-point m about half the final volume of concentrated llydrochlonc acid. Slmllar procedures for the dctcrminatlon of zinc2 and mcrcury3, bnscd upon the titration of %n[Hg(SCN),], were later proposed. LAKC~ rc- commcndcd the USC of cxccss lodatc for the oxldatlon of thlocyanatc m acid mcdlum, the cxccss being dctcrminccl lodometrlcally by thlosulphatc. While a direct titration against KIO, m one-third to one-half the volume of hydrochloric acid to the iodine monocliloridc or tlic iochnc cyanide end-point also yiclclccl trustworthy results, a prior addition of ICI or ICN to thiocyanatc was preferred to save Its atmosphcrlc oxidatlon6. In an clcctrometric investigation, FE~wicrca rcport&l good results for tllc estimation of tluocyanatc by regulatmg the final HCl concentration near about ro% Accordmg to HA~UMOCIC and co-workers’, the lugh acidity m the loclatc method causes a partial dccompositlon of SCN- and for greater accuracy they suggest the addition of tluo- cyanatc to loclinc monochloride solution bcforc commcncmg the titration. Concurrent studies by GAUGUIN 8, howcvcr, reveal that cluantltles of thlocyanatc exceeding IO-’ g

can be dctcrmmcd correctly m a minimum r:V HCl by a dlrcct potcntiomctric titration with lodatc. Smcc such divergent VICWS arc cxprcsscd m the literature, a rcinvestlgatlon of the SCN--IO,- reaction was consldcrcd dcslrablc. The prcscnt paper dcscnbes the optimum conditions for an accurate dctcrmmatlon of thiocyanate by standard KIO, using both the visual and the clcctromctrlc end-points.