Chidambaram, S.

Pathy, M.S.V.

Udupa, H.V.K.

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(j,OVBRNMBN r OF IN 011\. THE PA. rEN r OFFICE214. ACHARYA JAGAOISH ROSE ROADCA LCUITA-7000 I7.Complete Specification No. 14,172 daled 6th Decembe.r, 19'16Applica'ion No. '50/ Dell 76 dated 6th December, 1916Aooeptaeoe of the complete spocIftcation advertj~ed on 2nd Septe*ber. 1918Index at acceptance- 32 F2a70 6'}L- IX(1) JC LVIII(5) JInternational aauiftcation - C O? c 851 16, 87/ "" AN BI,ECTfioonSMICAt PROCBSS FOO TIm PRODUCTI (If 01'PARA TOLUIDINE mOM PARA NITROTOLU£H8".COUNCIL OF SCIENTIFIC & INDUSTRIAL ItJJ.:mAUlCH,Hari Marg, Nev DeIhl 1t Indiii., an Indian n•• 1Irtered b0d7Lneorl-orated under the Registration or Societie. ~t,(Act XXI of 1860 )._._.,----------------The IoIIoWiaIlPOCiftcaaion partilxl&arly dcIoribei aDd ucenai.. 1MnaU. of thia iD'I.cion .Dd the mauD« in which it i. to be PlrfOlWId I-PRICE: TWO RUPBBSThis invention relate. to an electrochemical p;"OC!J88 for thepl'l)dtJotion of P-toluldine hOll1 P-nHro toluene which tfJletes to thetl'!!:,d of organic ch... ical industry with epEIC1.11 refat'snoe t.oInbJr"'Gdiat,~ ,.'or dyestuff' Indu.tries.Hitherto it h•• been ~ropo.ed to pr.oduce para toluidine chamlos11,by Jtmploy1nq gener.lly zinc or iron powder tor the reductiot. 0' P-nJ trntoluer'<9. It has been mentioned that p-tolui.dine cen b. pr8pu."~l~::troCh8"liCBllY el1lploying etstionano .coppar cathode. torttwl'f,lduc Uon ()f p-nl trotoluena.The Ploce •• hitherto report~ lnlitereturs IUttara 'roa·thg',I,110.,1nO 1~t'awb8Ck•• (1) It 18 l'eth.r tediou8 .m laborious to ..,.ratetl'\iEl product; frQII the react.nt. whil • .-playing oh.lc.l I'adualng ....... t.,(2) The ,elfICtrolytic .... thod 1'8POttad SO tar giv •• low _lne cont.ntof the products and _lnophenole are aha obhlned a8 byproducta IIIhlCfa.1'_ to be eeparated.The ftlttSin.1bJeot ar t:Iw invention i. to obvla'. the dr_eck. lay.dopting an i.proved .lectrochemical zedUct10n technique.~ord1ng to the pra.ent invention chemical reducing .gent •• ~.lIl\loided by uaing e1 the I' et.Uanary ot' t'otat1nu copper cathode for thwIdectrolyU.c reduaUon 0' po-nitrotolu8na to produce p-tDluidlne.The ~Iusant procea. i •• uparior to the ohMica1 proc ••• e., hithertodtlllCdbed 1n literatun, sinCa it. not only eU_inst •• the tedJ.out andbbodou. proce •• 0' .eparating the product '1'- the re..,tanta. bUt.eleo glvee • very pure product.. Thia process i. a180 superior to theelectrochemical •• tt,oda. hitherto described in literature, ainca high•y leld 0' BIIl1n.1. obtained end _noc~8.oh are not fOEll8d, thua.UlllnaUng probl •• concerned 1111th their ...peration. AdditionaladVtantagfl8 •• tabl.hhed by U8 ara (a) the pJ'oduct 1•• eparatad a. _no-aulphate aftd that can be eeparately neutrali •• d to gat the a~na. Thue1ealat!ol' 0' the produCt 1. Ed.pllfJ.ad and the coat 0' nautl'.l1 .. Uon;i.a "duGad, (b) the electrolyte oan ba reu.ed at l ... t e ltini- fitl:hree \1.... , ~'~I'-.k1ng up ~tW acid concantNtlon withoUt .".U..of h.... "feilltttev of.__t:Iw OI'M~'" W...tba.. wlllmt ~f_'-9~~c;lII-"''''1'14-r;/72ae;he eel:..which 1teel! will act ae cathode would help 11lth_ cle.1pof high ampe~ge cells in order to adopt the proc ••• tor larse .oalepre~r& tl0!18.A.coi)rdlngly the proce •• for the electrooheJD.1cal preparatioD of'p- toluidine trom para ni trotoluene which condsts in the eleotro17t1orE'(!.uction of p-ni trotoluene using • oopper cathode. either .tatlonal7~~ \ .OJ:' rotatirlg and a 1.ea4 -..t lea4 alloy anode •• parated froa the oatbol1'\ •.bJI' meane (,t a porous diaphragm ohar.oteri.ed in tbat the eleo",rol1.i.cln'ried out using 27 to 54~ (W/V) ot .ulphurio ao14 contailliD« 0.5 ta1",';;" 0 f If:l O2 a. aa talye' ~re8.n t 1n the tor.titaniO ~pha te a.OI't.I.holyU and '5 to 54" ~V/V) of sulphur-10 aold aa allol"e.Thf~present illTention oonBiete 1n the electrolytio reduction ofp'.111trotoluene to giTe p-tolu1dlne in an eleotrolytio oell fitte4 ritbeither ataUonary or rotaUns oopper oathode or in an eleC?trol1t10oell made of oopper whioh aots also a.· the oathode. The oatbo17te ...'•• parated froa ·the .nolyte by •• al!8 of • ceramic porou8 d1aphragm.'~'h. oathCJ1,te •• ployed • was dilute aulphurlc aold the oOl1oen'tl'aUon(If wh1ch oould Tary froll 27 to 54" (V/V) oontalning t1"n10 8ulppteIIlclluUon a. ·catalyst. SUlphurio aoid af conoentration which could"i'8.17' from '5 to 54" (V/V) was uaed a. ano1y\8 and the .nod ....... le&4IU' &n .1101 of 18ad and .tlver with 0.5 to H' eilver. .& ourrentthtn81ty (It 5 to 20 I./da2 1n the oa•• of atat1ona1'1 cathode and 10 to~O 1.14.2 w1~h rotating oatho~e could be employ.4. The ,"mperature ofQ~tbol1i8 could vary froll 50 to 65°0. The depolariser conoentrationwae kept betw.en 15 and 25~. Sinoe a~1noor •• o18 are Dot formed. theproduct La fre. troll impuritie. and separation 1. eaaler. A ourr.~t.fficieney of 15 to 85" and an y1eld ot 85 to 95" oou14 be obtained.~xampl •. 1$ BlectrolytiQ prep!ratloD ot p:toluidine froa p:41trotolu~a!.toe 1.5 lUres of 45~ (W/V) Bulphuric aoid cODtailling t1tan10Ilulpbllte solution a8 cat.lyst was taken in oylindrical oopper " ••• el(:t 2.5 litre. capacity whioh acted also &8 the cathode. .oera.10.porou. pot _8 employed as the dlapbrap in vb10ti 115 sl ot 45~ (V/V)'tit .ulphurio acld VIl8 taken tbe ano17te. • le ..d .1rip va. \1.. 4 ...-&noa-. .,~e 801utio-' IIl.S .tl -.igorou811 by _D. ot • .ea~n1o&l......._~. 1 aatbod.•• ur ....... ~y ot 5 I4/d.2 va••• plo,M- )GO c/4-5/72of p-Di~rotolueD. was reduced. Temperature was maintainedbtt1ive8n 55 and 60°0 • Voltage of the oel1 wa. , to 4 v•.lA1"ter p&88iJ1@ 415 aap hra the oatholyte •• 0001e4 to,C1'e: and the .lI1n. 8ulphate was separated b7rlltraUon. The Bolid 8mine Belt "'as d.lsso1.vp.din water slidneutnU .. d with Boda aeh to pH 7.Amll;9 obtaJ.ned WBB 21u 9 withen yield f;lf!- 9:l% artd .. current erficiency or 7B}(. PUr!ty 91%.Electrolytic prepaution or p-.tollJidin8 from p-nJ.tro-toluene - reu.e of- the catholyte frQ/11example 1---_ ..-(xp.r!llIental .et u=, end condi lions IU9 the aalO(' a8 that given in.lC.-ple -" catholyte aft.r •• puat!on or amil"e sulphat. in .)(8IlIplB 1we•. reused in wh1ch 75 1111 cone. 8ulphuric acid "'88 added.or p-"lt~otoluena was r.~.d. .12 amp hre ",a. employed.320 gVoltageor the CIJll w•• i to 4 volt •• The emine .ulphate ",e8 .. paratld.,t.~ cooling the catholyta and then it waB neutrall.ed to get the'1''' be.e. 228 9 0' p-toluldlne wa. obtained with an yield 0' 91.2_Purity 98~Electrolytio preparation 0' p-toluidlna rr~ p-nitro-tolu .... upng a rotaUnq cappaI' cathode1.5 litre. 0' 36~ (~V) of 8ulphur.lc acid containing t~tanl0aulphat. to the equivalent 0' 1~ TI02 .a. taken in a 3 litre pyt.~beek.... A roteUnQ d1ec type coppaI' cathod. w•• 8IIPloyed. The 1' ......A lead silver alloystrip ••• u•• d •• the anode. 200 .1 0' 46" (IIlIv) ....lphur!o ecld w..ti!kfln In the dia"hr ..... the anolyt •• 300 g 0' p-nitrotoluene we.reduced. rhe tl!'ilparatur. or the catholy t8 was kept between 50 and2" r;athodfl current denaity of 20 A/rtJa was 831ployed. VoltageI~r thll CII11 wa• .1 to • v. Arter paa.ing 400 AhI'S, the catholyt.,III8S coohd to S-t. Th. eolld amin. eulphata was aeparated bJ'UtriltilHl end theft ,"",' ..aUllad 8eparatel, to get the hee b.... 190 I_), p.tollJldin. was ie.lat. with .n 1aolatad yield 0' 85•• " andI:Uf1'8 ....t efrichncy 0''''''' Purity rt po-tolw.dlna hulaced. wa. 98'"A pl:oce •• has been invented tor tt'iiI .1_tl'ol,ue p.ducUon orj>-toluJ.dJ ne frolll p-nttrotoluiln.. 1hSe p..-OC•••• 11Il1na~•• the,iifficulti1'lQ of conventiDnal llIeth,d • .-uGh lnvoi .. t..... und labodau.Illethods elf separation and purification of ~ produCt.. The emPloyll8nt- ,'-1/1.L"·'2; "r·;.J I" .of co pper cc,ntainer which itself acts a8 oathode would help in thedesiS':1 of hlgh amperage oel1s in order to adopt the l»rooeB8 for lar..Boale operation.. The possibility of reusing the .lectrol,yteOODotttute. to economy in the proceas.1) .. pro'Jes. tor the electroohemical preparation ot p-toluicUnetrolD para ni trotoluene whioh COlH'lil5tS in the electrolytio reduotio.Of p,...rl1troto luene using a oOPltlercathode. 8i ther stationary or rot.till'(I""~ndil lead ~ lead alloy anode aeparated troll the oatholyte by • .-•• eanl of a porou8 41aphrap characteriaaCl. 1n thl1t the eleotro17.1 ...oar.rtl!d out 1181ng 27 to 54" (W/V) of eulphuric acid containing 0.5 t.. 4-1.5" 'elf '1'102 .a oatalyst present in the t~)rlll~tit.ftiO .alpha'. aloathb:~yte anll '5 to 54" (W/V) of 8ulphur1f) acid a. anolyte.2) A proues. as cla1med 1n olaim (1) "ljI'here!n a lead or leadBl1T~T alloy with 0.5 to 1_ silver 1s used as anode.,) A. prelle88 &8 claimed in (1) whereill a cathode ourrent den.it,2 ~ lof 5 '1;0 20 A/dll in. the caF!1~ of 1Itat1onary cathod8 .... t ,11,al."q t2 to 2tOA/'dlll ... ';0 'to '0 Ald. in the case of rotating cathode, .. :prefl'tJr'ably 2fl A/dm2 1&used"4) A pro,~:e8&as' olaimed 1n (1) vherein the te.perature rang. of"0 0the (I..,tholyt'l! u.ed). 50 to 65 C but preteral)ly 55 to 60 o.5) A proc.oe aa claimed in (1) wherein copper o~thode i•• tat~i.()nary aJnd an auxil1ary stirrer 15 employed or oopper oontaineris .*lP... used, acting both a& the cl!Il.l and (la.thode.6) ... pro.~e&s tor the electroohemioal preparation ot., p-tolulc!el1e frl>lll ,para ~trotoluene 8ubstanU,aly as bereinde.cr:. bed.Dated tb18 }l~ day ot Deoember, 1976.(" ... M!I.~"'t7". I .M.~. I·-..~_A. JSOIBNTlS'l' 'i '(PATENTS)aCUNOIL OF SCI6NTIFICAND IN~STRIAL IISBABCH.F;-

An electrochemical process for the production of p-toluidene from p-nitro toluene

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