Medhi, K C

English

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INFRARED AND RAMAN STUDY OF PARA- CHLORONITROBENZENEK. C. MEDHlOrTJ(;s D k pabtm ent ,I n d ia n  AssoriATioN fur  thk  C u i/m  \ rjON of Sciknuk ,Ca l c u t t a -32 .{Rfctwed October 10, 1061)Plate inABSTRACT. T h o  in frared  a b so rp tio n  s p e r tm in  in th e  4 0 0 0 -6 3 0  <m~' reg ion  in  th e  s o lid  states a t  la id  in  s o lu t io n  in  ca rb o n  te tr a c lilo r id i' a n d  th e  R a m a n  sp o e tru m  in th eIkjukI s ta te  a t  00°C  hav^(‘ b(*en rep o r ted  for para-eh loron itrob ori7 .on o . A  c o m p le te  a s s ig n ­m e n t  o f  th e  o b se r v e d  freq u e n c ie s  is  g iv e n .I N 4' K 0  D  U 0 I 0 NIn a pn^vioiis jiapiT (McdJii, 1064) tJio infnmvl and Uainaii spectra of tb<‘. thr(H^  isomers of Hiioronitrol>(^nz(mt‘ were* presented and a (‘oiu])let(‘ assignment of the vibrational frequencies given. In continuation of that work tlu* investi­gation has h(^ en extended to jiara-chloronitrohenzt'iie. The infrared spectrum of this compound was studied previously by L(‘eomt<‘ (li)IlS) over the limited rangt- 1400-500 cm * anrl by Mooney (1064). Earlier works on tli<^  Raman s])ectrum of this molecule relate to tliose of High (lOIU), Manzoni-Ansidei (1035), Reitz and Stockinair (1036) and Wittek (1042), and only a partial assignment of some of tlio fundamentals is given in Landolt-B6rnsU‘in Table (1051).In the pres(*4it investigation a detailed study of the infrared and the Raman sjiectrum of para-chloroaitrobenzene has been mad( .^ Several new Raman lines which were not detected by the earlier workers havt‘ Ikho observed. Esstm- tially complett‘ vibrational assignments, based largidy on eomparison with thost  ^proposed for para-fliioronitrobenzene (Medbi, 1064) aiv given.E X P E R T M E N 4’ A bThe jmre sampk^ of para-chloronitrobenz(*m» was supplied by Riedel-d(^ Haeii A. G. It w as jmrified by fractional tlistillation. The fractions boiling at 242"C were colleuU'd and distilled again under reduced pressure before use.A Perkiri-Elmer Model 21 s^iectrophotometer equipped with sodium chloride prism was used to record the infrared absorption spectrum in the region 4000-630 cm"^. The instniment w'^ as calibrated wdth the standard atmospheric water vapour and carbon dioxide bands. The spectrum was obtained using a thin polyerystalline film grown by melting the substance between two NaCl39043K C. MedhiIndian Journal o f Physics. V o l. X X X I X .  N o . 8P L A T E - I I I(.1)I &Fig. 2.-~Raman Spectrum of Para-cliloronitrobenzcnc.(a) Short exposure.(b) Long exposure.Infrared and Raman Study of Parackloronitrobenzene 3 9 1plates and (*ooIing the si)eeimen slowly to room temperature. Th<‘ infrared spe(itrum in the frequency n'gion :1400-1()00 cm-i was also measured in wdutioii in carbon totrachloridt*.The R am an spo(jtruni was reconh^l pli<>togray)lncally using a Fu<*ss glass spee.trograpJi (dispersion lOA/mm in the 4tir)SA rt^gion) in tlu ‘ lupiid stat<* a t 90°C (i.e. a t a temperatur<' slightly abo\(' Uu‘ imdting point). Tlie spectrum was exeit(‘d i>y the Hg 4I5i)SA line. Tlu^ compound boiiig sliglitly y<‘llo\\isl» in cr>h>ur there is strong al)Sorpti(m in the region near 4358A, A fairly long <^xposur(‘ was necessary to re(‘ord the low-lying ftanian frequ<Micies. Tlu^ study of the polarisatimi of the Raman lines was also made by Uu‘ imdJjod described tdw*- where (Medhi, 1964).K  E  S V  L  T  S A N D  D  I S T  t J  S S \ O  NThe observed infrared and Ram an fn*<pien(3ies of .])ara-cJdoronitrobenzene and their approxim ate intensitu^s are given in Tabh^ I. The assignment of the fundam ental fre(pi(‘ncies is given n» the fourth column of the table. Fig. I shouts tl)o infrared spectrum in th(‘ range 1800-630 t*m •. Tlie Raman spectrum is reproduced in Fig. 2, T*lab‘ H I.F ig . 1. Jnfj-tirt'd sp ec tru m  of parHchlnronitroherizenoThe paradiloronitrobc-nzcno niolocule is (issunictl to liavc <\v syrntmotry. It should thus hav(  ^ thirty-six fundamental modes of vihratif)!) which are distri­buted over tlu' four svunmetry sjieeies as follows In-plane vibrations13 fl, (infrartvl and Raman active)-! J26, (infrand anil Haman active). Out-of-plano vibrations392 K. C. MedhiTABLE IInfrannl and Raman froquencic^s of ^)-chloronitrobenzoneInfrared, v in Solid at 20“(JRamaji, At' rm~i. Liquid at 90“CAssignmentSpecies Correspondingmodes of benzeneRemarks212 (Ob) hi 16B276 (2) dp b, 11314 (1) Ul 6A367 (0) ? h2 4416 (0) as lOA444 (0) bi NO2 rocking4G?t bi 18B535t 030 (1) bo NO2 out of plane rocking.569 (0) ba lOB597 (0) ho 17B645 (sh) 623 (3) dp hi 6B670 (sh) 074 (m) 677 (0) Hi NO 2 bending740 (vs) 734 (2) dp bj, aj 9B, ISA790 (0) ho 6820 (sh) 846 (vs)826 (0)12864 (vs) 936 (w)855 (5) p ai, ag 1, lOA966 (w) 980 (1)1013 (m) 1015 (0) ao 17A1046 (sh) 1065 (sh) 1056 (2b) dp ? bi 151093 (s) 1095 (3)p ai 19A1109 (s) 1110 (6)p1148 (0)ai 21174 (w) 1174 (2)p ai 9A1213 (vw) 1214 (0)1231 (vw) 1249 (0)1283 (m) 1290 (2) bi 31314 (m) b, 141347 (vs) 1355 (sh)1347 (10) p NO 2 stretching1380 (sh) 1387 (2) dp1426 (m) 1426 (3) p 20A1464 (sh) 131481 (vs) 1480 (3) p 7A1514 (sh) bi 19B1526 (vs) 1623 (3) dp bi NO2 asymmetric stretching1664 (vw)Infrared and Raman Study of ParacMoronitrobenezene 393TABLE I ((iontd.)Infrared, v in Solid at. 26"CKaman, Ar m cm -i. Liqiud at90°C1581 (s)1607 (s)1630 (w) 1660 (w)*  1690 (sh)* 1705 (Bh)* 1730 (vvw)* 1780 (w)* 1828 (vw)* 1840 (vw)* 1880 (sh)* 1920 (w)* 1974 (vw)* 2030 (vvw)* 2090 (v\^)* 2135 (vvw) 2215 (flli)* 2228 (vw)* 2291 (w)* 2454 (w)* 2570 (sh)* 2595 (vw)* 2630 (ww)* 2690 (vw)* 2757 (vw)* 2855 (w)* 2930 (vw)* 3050 (sh)* 3085 (sh)* 3110 (m)* 3157 (sh)* 3206 (sh)* 3300 (sh)* 3580 (vvw)* 3666 (sh)* 3690 (ww)* 3718 (sh)* 3825 (vvw)* 3920 (ww)*AssignmentSpeeies Correspundmgmodes ol benzonoJlonuvrks1577 (8) dp 1605 (2) dptilhi8A8B3087 (3) ph,h,7B20B(8)= 8trong; (m)=medram; (w) =weak; (vw)=very weak (sh)-^shoulder; (b) = broadjp =  polarised; dp ~  depolarised. fTaken from Mooney (1964).*Frequency observed in OCI4 solution.4 aotiv7‘) | llu (inframl and Raman activo).The spcr irs r^ , would gJV(‘ ris(^  to polarisenl Raman linens and the remainintr s]HM K‘s to dcp<>larised Raman Imos394 MedhitS/jrnrs The e](‘V(ui (r^  modes taking as a single group are dtifived from tluv im»des 1, li, i)A, 7A, KA, 9A, 12 Rl, JSA, HlA and 20A of benzene (Wilson, 11)114). In tlie disiihstituted ]>enzenes witii the substituents in the para positions, tlie fi{‘(|u<‘iieies of the Mod(^s 1, bA, 7A. SA. 12. l.‘l, ISA. U)A and 20A are (‘Xp(‘( ted to lx‘ 1(uut(mI ('onsiderably dm- to i-ho presemx- of the h(*avy atoms in tin- para positions. The prohabli* values ol th<‘ frecpieneies wliieli can be assigned to th('S(‘ unxles ai(‘ shown m the last hut om* eolumn of Tabk* 1. The intense polaris(‘d Raman liiK- Sbo cm  ^ has been as*sign(^d to v,. Its apjiearanee also as a strong infran-d baiul may lx- dm- to the difference in the two substituents Tlu- polarised Jim- 14S0 cm ‘ is assigned to V7  ^ and tlu^ strong infrared band at HSi cm * may be due to sujx-rposjtion of the bands dut^ to nnxlcs and The otJu-r polarisixl lim  ^ 142b cm  ^ is assigned to v2o  ^ and tlie infrared freepa-m'v JD()4(;m ' may be dm- to Vj^ . Tlx- intense depola?4s(‘d Raman line 1577 cm ^ is evidently due to and tJi(M\eak line 214 (*m Ms dm -to as sugg(-st(‘d by Mocke-K(irk!iof (1951). The strong polarised line 1110 cm ' is assigm-d to Vo and the jxilarised Raman line 1174 cm ’ to Vy^ , because this lattiu- mode is not affefded by the substitution in tlu^ jiara position. TJie strong infrared band a t S40 cm ’ is assigned to and it m a\ Jiave also ap])cait‘d feebly as a. weak mm\solved companion of the lim- S55 cm*’ in tlie Raman sjiectrnm. Tlie strong infrared band a t 740 cm~’ may lx- due to and the polarised line 1005 <;m ’ is probably due to as suggestinl by M(x*ke-lvh(-rkhof (1051) The otJuT tAvo modes of tliis species are the syimm-trie stn-tching and bending vibrations of N (>2 group giving tlu- Raman lines 1247 cm~’ and 077 cm*’ res]x^ctively.b^ . Out of tlu  ^ twelves mod(»s t>f this spi-cues tt-n are derived from the modes 2, OB, 7B, SB, OB, 14, 15, ISB, lOB and 20B of benzene respee- tivel}’’ and tlu? remaining two are fxmtrihuted by the NO2 group. The frequenei(?s of the modes OB, SB, 7B and 20B remain um^hanged on substitution. So, the Raman linos (>22 and 1005 cm ’ an  ^ assigned to Vy/j and respectively and the infrared bands at 2110 cm ’ and 205i) cm ’ are assigiu-d to the modes and v7£ n-spectively. The Raman line 1200 e n r ’ may be du(- to V3. The Raman line at 20S7 cm ' may be dm- to one of the tw\> modt-s wliich can lx- derived from a superposition of V2 aiul Tlu- depolariscxl Raman line 724 cm*’ is assigned to Vq2i tlu^  weak band at 407 cm ’ to Vjgjj. As mentionedliarlier, the infrared liand at 1481 (*ni“’ is due to Viy«. Tiie infrared bands at 1214 cm~’ and 1050 cm*’ may be assigned tentatively to V14 and Vj5 respectively, as the destrmdioii of ciHitre of s>nnm(dTy makes these- modes weakly allowed in the infrared. The remaining two inodes of this species are due to the asymmetricslrotehiug and rocking vibrations of tho . \ ( ) .  j^rou]) giving tli(‘ dcjiolariscd Jiuo 1523 cm~^ and tlu ‘ W(uik lino 444 <111 1 n ‘sp(*( tivcly.Sppcies a .^ Thoro arc throe vibrations of this mok'culo belonging to  speoios corresponding to  tlie modes and of benzene. The frcHjueney''^ 104 should be S4b eni~* as benze>ne giv(‘S a Raman lin(‘ <4 tins frt‘(jm*ney bu t it  is not possible' to  re^solve th is lin(  ^ from the stremg line' a t Soo ein b The line 415 em~’ is given by the inode * i^'d jirobably the weak hm- 1015 cm ‘is due to v 7^ 4^, the eon*es]>onding infrared band 1013 eni ' being oi nu'dnmi strengtli. The fourtli vibration arisc^s fioni KO.j, twisting w hieli Jias not iq ip e a r e d  in file .sp(‘etra.Hpf'cies Six modes of this species arise* trom the* modesvi, Vr^ ,'^ii' ''^ 16/1 V|7jj of benzene All these inodf*s are (*\p('<te‘d to have* IVi*-({iK'neies lo\\(*r than tlie* <*orre‘sponding freeiuencies of benzeMU*. The* Raman lines 212. 270 and 307 e m ‘ can i>e* assigneMl to and v,, r(‘Spi*cti\ t*l\. TlieHainan line's 500 and 507 cm ‘ may lu* assigne*d to v,,)/j <md Vi7/i n*spi*ctive'I\ and the  lino 700 em~^ may be due* to The* se'\enth \ib ralion  arise*s from NOo e)ut of plane roe king and is assigiu'd tn the fr(*ejii(‘ney 5,30 cm  ^ ap}»e*aring both in the' R am an anel infraied spt'ctra.B(*sid(‘s tlie fn*(jueMU*.ies m(‘nli(uie‘d above* nmmroii.s banels, mostI\ vt*i'v \\e*ak have* l>e*e*n ol>st*rve*f| in the infrare*d spe*e'tiMim of the* seilution 111 the* n'giem irom 1030 en r ‘ te) :1020 cu r b The bariels a-re* e‘vule*nt/h dm to e*oinbinations of some* of the* hinelaine»ntal mofle*s me*nlioiie*fl above*\  (* K N  O \V L K J) (1 M K  NT TTlie au thor is gratclid to Dr (b S K astha, I) Sc.. I'eH ins he*Ipful eljse ii*'M‘»Infrared and Raman Study of Parachloronitrobenzenc 3 9 5K  \<: K  K  ti E  N  (I E  SHigh, TO E , UKtl, P h y s  75r., 38, JS37 Lo<*orate, rl., 193S , J  P h y < ,  l i < t i h u m  9 , l.'t.Manzoni-iVnsidei, K., 1035, ( h t z z .  C h t m .  f t a /  , 65, S7I Mo(*ke-Korkh(>l, 1051 Lmidolt'Ooriisle'm Table's, AulUge* <», O.uid I Meelhi, K. (J., 1064, iS p e c t r o e / im t  A c f n . ,  20, 67.5.M o o n o y , E .  E ,,  1064, S p e c i r o r h i m .  A c t a . ,  20, 1U2 J.Iloifcz, A. W. aneJ Stoclvmau*, 1036, Monalb-h. Chem , 67, 02.Wilson, E. B.. 1034, 7Vt</*-. 75*r., 45, 706.Wittek, H., 1942, Z .  P h y ^ f k .  C k e m ,  B  52, 153, 315.

Infrared and Raman Study of Parachloronitrobenzene

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Infrared and Raman Study of Parachloronitrobenzene

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