Laser Raman, Infrared And Far Infrared Spectra Of 3,4,5 . - CORE
View metadata, citation and similar papers at core.ac.ukbrought to you byCOREprovided by IACS Institutional RepositoryIn d ia n J . Phys.64B (l), 50-5b (1990)Laser Raman, infrared and far infrared spectra of 3,4,5trimethoxybenzaldehydeShabbir Ahmad and P K Verma]:)epi\rlnieiil- ol IMiysics, AliKtuh lUuslnn ITtnvcisUy, Alij;ru h-202 002, IiuliaRecc'iviMl 0 Mau'li 19S9, accci3lc019S9A b stract: The infiarcil, far iiitraieO and l. rist'i' Kainan spLudi a aic i ectii decjin tlie4000-200 cm "‘. 500-50 cni"‘ and 4000-100 c n r * i o pccli\ cly. TOe viljratioual analysis is carried out and assignments of ilie baiidii aiem adeinteinis oi fundanienlal, cnnibinalicm and diftc ieiice frequencies.Keywords : Uani.in s]3eelia, iidiaitMl si'»ertia, far iniraied speelni, d.‘l,5-lii n ielliox vbeii aldeli} de, assign in eii is.PAGS Nos : :s3 10. 33.20.1. IntroductionThe vibrational spectra of benzaldehydc, monosubstituted benzaldehyjjcs anddisubstituted benzaldehydcs have been extensively investigated by many earliervyorkers (Garg 1954, Scrocco and Liberti 1954, Heincrt and Marlell 1959, Padheyand Viladker 1960, Singh et a! 1967, Dwivedi 1968, Singh and Singh 1968,Srivaslava et a! 1968, 1969 and 1972, Singh and Sanyal 1972, Lai et al 1973 Greenand Harrison 1976, Singh and Singh 1978, Sanyal et al 1981, Tariq et al 1982,Yadav cf d/ 1982, Shashidhar cf a/ 1984, Venkoji 1984. 1986). Isomeric monomelhoxybenzaldehyde were reported by only few w'orkers (Purvis 1914, M orton andStubbs 1940, Dwivedi 1968 and Kahovec and K ohlrausdi 1937). Singh and Singh(1978) have reported the infrared spectra of isomeric dim elhoxybenzaldehydcs.The infrared and Ram an spectra of 3,4,5-trim ethoxybenzaldehyde (3,4,5-TMB)were reported by Gupta et al (1988). But only thirteen fundam ental vibrations havebeen observed. In the present investigation laser Ram an, infrared and Fourier’stransform far infrared spectra of 3,4,5-TMB are recorded and forty four funda mentals are reported. Rest of the bands are assigned in terms of com binationaland difference frequencies. The depolarisation ratio of R am an bands are measuredwhich ascertain the symmetry of the vibrations.2. Experimental3,4,5-Trim ethoxyben/aIdehyde was obtained in pure solid form from M/S K-LightLabs and used without luithcr purification. The infrared spectrum was recorded50
Laser Raman infrared and far infrared spectra etc51in the region 200-4000 cm" on PE-983 spectrophotometer using KBr pellettechnique. The PT far infrared spectrum was recorded in the region 50-500 cm" on Polytech FIR 30 spectrophotometer. The polarized and depolarized Ramanl 'igure 1. liiliarcd ami far luii aied speclia of 3,-l,5-tuiiieUioxybeu7ahlehyiie:(a) hiftaied, (b) fai iiiftined.spectra were recorded, in CHCI. solution, in the region 100-4000 en r , onCary-82 Laser Ram an spectrometer using 5145 A line of Argon-ion laser as theif)zUJI 0\AOOO 3500 ' 3000 2 500200015001000500b100WAVENUMBER (cm"')Flgur«.'2. Ranian spectia of a,4.S-uimellu»xvbeii7iihlel.vde * (a) iiaitiiUd atid(b) ijerpemiicubir polaiizFiliuii. UrtTimn bainl of solvciu.source of excitation. The bands observed at 265, 370, 670 and 3071 cm '* ared u e to C H C lj. The traces of infared, far infrared and Raman spectra are shownin Figures 1-2.
52Shabbir Ahmad and P K Verma3. Results and discussionThe molecule under present investigation is tetrasubstituted benzene. If we assumeeach of the substituent groups as a single mass point, it may belong to Cj pointgroup. There will be only two types of vibrations that are a' (planar) and a '(non-planar). For analysis of the spectra, particularly for assigning the funda mentals to different modes of vibration, assistance are taken from the studies madein the similar molecules by earlier workers and the depolarization ratio of Ramanbands. Observed frequencies and probable assignments for 3,4.5-TMB arepresented in Table 1.3.1. C—X (X —substituent) stretching and bending vibration :Earlier reports on substituted bcnzaldehydes (Padhey and Viladker 1960, Garg1954, Dwivedi 1968, Singh and Singh 1978) show that C —CHO stretchingfrequency, which generally gives rise to strong band, appears at 1175 cm ' in3,4,5-TMB. Out of three expected C -O C H stretching vibrations, only two at928 and 944 cm" are observed in 3,4,5-TMB, These assignments are based onthe studies made by Syam Sunder (1986) in 3,5-dimethoxyphenol, A very strongband appears at 525 cm“ in the infrared spectrum of 3,4,5-TMB which may beassigned to C-'OCH in-plane bending vibration. This frequency was identifiedat 520 and 425 cm“ in 3,4-DMB and 2 , 3 -DMB by Singh and Singh (1978). Areview of the earlier studies on substituted bcnzaldehydes (Venkoji 1986, Srivastavact al 1968 and Tariq et al 1982) shows that the frequency at 445 cm “ appearingin the infrared and far infrared corresponds to C -C H O planar bending vibrationand the frequency at 240 cm“ to C -C H O out-of-planc-bending vibration.5.2. Internal vibration of substituent groups :C 0 stretching vibration gives rise to a strong absorption in the region 1680-1815cm" . The study of M orton and Stubbs (1940) shows that this frequency remainnearly the same on substitution of phenyl ring in place of hydrogen atom informaldehyde. A review of earlier studies (Srivastava ct 1968, Sanyal cr «/1981, Singh and Singh 1978 and Venkoji 1986) shows that the bands observed at1685 cm“* in 3,4,5-TMB may be assigned to C O stretching vibration. The C - Hstretching mode of vibration in aldehyde group is expected in the region 27302870 cm" . The weak band observed at 2738 cm" is assigned to this vibrationin 3,4,5-TMB. The strong band at 620 cm" may be assigned to C 0 out-of plane bending vibration. Venkoji (1986) has identified this band at 625 cm" in disubstituted benzaldehyde.One CHs asymmetric stretching vibration is assigned to the band observedat 2990 cm" in the molecule presently investigated. The bands observed at2830 and 2940 cm "' arc assigned to CH 3 symmetric stretching vibration. CH«
Laser Raman, infrared and far infrared spectra etcT a b le t. Observes] vibi atio n freq u en cies (in cm *) and th e ir p ro b ab leaeiingum ent for 3,4,5-lrim ethoxybenzaldcljytleIR I'rcq u cn cies (cni’' )—3078 ins306'i m29b)0 w 2940 w2S30 m2738 w2860 w2610 w'2.520 w2S00 w2440 w2310 ni2320 m229() w2270 w22S8 w2210 w2180 w—211 S w2075 w1055 w1032 w1S7 3 vvv1S55 sli1840 w1820 wI S I01705 w1700 sh16S5 b1674 w1648 vw1620 s1578 s1550 sli1535 wL aser R am anficq u en cic s(cm '*)3280 w—3062 m, p—2910 s, p2832 ms. p2738 w. p2660 in——————————21 55 111. p——1032 m, p—““.——16S5 vs. p1618 w1620 w1580 vs. p——A ssig n m en tA" 3C62 2‘20 t' C —H .stretchinga ' C —H B tretchingu" C H i tt.sym m etric stre tc h in gIf' CH» sy in n ieliic stretc h in gIt' C lfi sy m m etric s tre tc h in ga ' C —H stre tc h in g in C H O g io n pA ' 16i0 1040A ' I6S0 928A ' 1.S78 944A ' 1578 928A ' 1402 1040A" 16'20 692A ' 1680 640A ' 1515 772A ” 1578 692a" 1343 915A" 1515 692A ' 1680 495A ' 1456 706A ' 16‘i 0 495A ' 1578 495A" 168t) 272A ' 1410 525A ' 1578 297A" 1578 i 272A" 1620 i-2'.'OA' 1'29 5 52 5A ' 151.5-1-297A" 1.57S 220A' U 75 52.5if' C - O st 1etch in gA" 1402 272A" 1402 240If' C - C stretc h in gIf' C —C stre tc h in gA" 915 640A" 1295 24053
54Shabbir Ahmad and P K VerntaT a b le 1(Could.)IR Vieqnt:‘n-cie*4 (cm ')1525 b1500 sh145H b—MiO sj :i6a shlO.Sn b1290 s1280 w1270 w1 175 s1150 sh1105 w1117 w1070 vs1050 sh1010 s998 ni941 s928 111915 vsHOO vs775 vs755 Ills725 sh715 vs090 vs605 sh610 vs620 S525 v s, 495 sh495 s485 w490 nis465 w165 wLaser R am anfi cq n en cies(cni-M-1498 v s , p1456 111, dp1435 w , sh1415 in. p1380 w—1330 vs, V1292 in—1178 in , ] 1135 s———1040 s, V99S Til. p970 in, p—925 w915 w--780 in. p755 in, dp725 w720 vv690 w—645 w, p625 w525 111, p—A ssign m en tA' 998-f 525a' C - C stretch in ga ft C r i , asyrnineLric b en d in g915 525C —C stretch in gA 626'»“755A" 445 915a' CH* sy in in eliic defm niatiuna* C - C st retchingA' 803 477A" 998 273a' C -C IIO stretch in gA" 928 220a ' CII« rockingA' 640 477a* C —II in -p lan e bendingA" 772 272a O - C I I i stic tc liin ga C H b lu ck in gA' 755 220n ' C OGIIp Bl let tilin gC —OCIT b sti etchin ga ' C —11 out-of-plane bending([' R in g bi eath in ga' C H , ro ck in ga ‘ C —C o n t'o f“planc IjondingA" 272 455C —IT oiil-of-ph\ne bendingf/" C C oiil-of-phinc b en d ingA" 415 220a ' C - C in-plane bendinga" C —() out-of“plaue b en d in gu ‘ C -O C II# in -p lan e bendinga ‘ C - C iu-plaue bending—A"’ 325 160—A' 220 240
L'lSer Raman, infrared and far infrared spectra etc55T able 1. (Contd.)lU Frequen cies (cm“ )445 s445 w*412 111412 wLaser Ramanfrequenciesrt' C -C IIO in-plane bendinR405 shA' 240 175385 w325 vs390 m. pi?" C —C out“of“plane bendiiiRa' C - O - C in-plane bemlinj a' C - O - C in-plane bemlinR,300 s* 100 w272 s240 V9’ 230 w220 vs220 wi«180 sli 175 w 160 w*127 w*125 w300 w, pa' C - O - C in-plane bcncUiiKvs.316sh316 w.Assignm ents(cnrM(/" Cris torsionC —C lio oiit-of-planc hemline240 wn" CTIa torsiona" CIT» torsion220 w— 412-230d" OCIIa torsiond" OCTTii torsion160 in, (Ipd* C -O C IU P)isioud" t -CTTO tw isting— 41S-300*120 Pli— 465-385*75 ni*.-/fro( iu-ncy observod in the fai inflated spectrum ; s slro n g :vs - very slrong : ms - medium strong , m “ medium ; w *weak ;A'vv“ veiy weak. ; sli sliouldci « p polaiixed » dp dcpolaiized.a'asymiiiclric and symmeliic bending vibrations arc identified at 1458 and 1335in 3,4,5-TMB. The bands observed at 1135, 998 and 775 cm"" are assignedto CH„ rocking vibiations in 3,4,5-TMB. These assignments are made on thebasis of com parison w-ith studies made by earlier workers (Srivastava d a/ 1968,Scherer and Evans 1963, Singh and Singh 1978, G upta et al 1983,Syam Sunder 1986,Babu ct al 1987 and Goel ct al 1986). The strong band at 1040 enV may be assignedto O - C H , stretching vibration in 3,4,5-TMB. Singh and Singh (1978) have reportedthis v i b r a t i o n a l 1035,1025 and 1030 cm -‘ in three isomericdim ethoxybenzaldehydcs.The weak bands at 175 and 160 cm“ may be assigned to O C H , torsion in3 4 5-TMB. N early at the same frequency Sanyal ct al (1981) have reported thesevibrations. Goel et al (1986) have also reported these vibrations at 172 and 169cm -‘ in 3 4 5 -trim ethoxytoluene and Goel and Agarwal (1982) have assigned at155 cm - in 4 -m ethoxybenzonitrile. The observed bands at 272, 230 and 220 cm '*arc assigned to CH« torsional vibrations in 3,4,5-TMB. Goel et al (1986) havereported these vibrations at 259 and 223 c m - in 3.4,5-trimethoxytoluene. The
56Shabbiv Ahmad and P K Vermabands appearing at 325, 316 and 300 cm" are assigned lo C - O - C in-plancbending vibration. These assignment are based on the report of Sanyal et al (1981)and Owen and Hester (1969) in substituted benzaldehyde and anisole respectively.AcknowledgmentsWe are thankful lo the C hairm an, Physics Departm ent, A M U , Aligarh for theencouragement and help in the research work. The authors are grateful to theHead, RSIC, M adras for providing facilities to record the spectra and to the UGC,New Delhi for financial assistance.ReferencesAsliok V, l akvshmaili U, Rtuiiulii Shiee K amt Kniuaiiu Ran O 19S7 I n d i a n J . P u r eA p p L P hy s, 25 58Dwivedi C 1’ D 1968 I n d i a n J P u r e AJipl. P h y s . 6 440Garj( S N 1954 J . Set Res , B a n a n r s H i n d u U n i v 4 42G od R K, Shainia S and Gupta A 1986 I n d ia n J . P h y s , 60B 375Goel R K and A arwal M L 19Hli S p e c t r o c h i m . A c t a 38A 583Green J H S and H airison D J 1976 S p c c i r o c h im A c t a 32A 1265Gupta S V, Shaiiiiu S IC and G od R IC 1983 A c t a P h y s Pol 64A 495Gupta S r . Gupta C, Miss Sema and Goel R K 198S I n d i a n J . P h y s 62H 560Ilciu crl Dietrich and M artell Arther R 1959 J. Ain. Chetn. Soc, 81 3933Kahovee R A and K oliliausch K W V 1937 Z. P h y s . C h a n . 38B 119Dal JJ U, Srivastava M P andI S 1973 I n d i a n J P u r e A p p l. P h y s . II 615M oiton R A and Stubbs A D 1940 y. C h a n . Soc. 1347Owen N L and Hester R K 1969 Sp e c t r o c h im . A c t a 25A 243Padhey M R and Viladker B G I960 J. Sci I n d Res. 19B 45Purvis J K 1914./. C h a n . Soc. 2482Simyal N itish K, G od R K and Agarwal M D 1981 I n d i a n J . P u r e A pp L P h y s . 19 ISOSchoiei J R and Evans J C 1963 S p e c t r o c h i m . Ac ta 19 1739Sciocco Maiisa and Dibeiti Arnaldo 1954 Re c ce rr a Sci 24 16S7Suashidhar M A, Slianbhaf P V, Ayachit N II and Rau Sniyanaraviiiia K 1981 I n d i a n J . P u r eA p p i P hy s. 2 2 mSin li V B anil SinKh 1 S 1968 I n d i a n J . P u r e Af pl. P h y s 0 81Sin b G N, Srivastava M P and Sinj»li 1 S 1967 Ctirr. Sci. (India) 36 630Sinpli S J and Sin li Ranjcct 1978 I n d ia n J P u r e A p p l Phys. 16 939Siii h II S and Sanyal N itish K 1972 I n d i a n J . P u r e App l. P h y s 10 545Srivastava, Dal B B and Siujjh I S 1972 I n d ia n J . P u r e Apfyl P h y s 10 570Srivastava M P, Singh 0 N and Singh S 1 1968 Cu rr. S ci (India) 37 lot)1969 I n d i a n J . P u r e A pp l. P h y s . 7 504Syain Sundei NI n d i a n J . P h y s . 60B 490Tariq S, Verma P K and Rashid A 1982 I n d i a n J . P u r e A p p l. P hy s. 20 974Venkoji 1984 Proc. I n d i a n A c a d . Sci. (C h em . Sc i ) 93 l05------ \9S6 I n d i a n J . P u r e A pp l. P hy s. 24 166Vadav K A, Rainakaiilf Mishra P C and Singh 1 S 1982 P r a v i n n a 18 311
The infrared and Raman spectra of 3,4,5-trimethoxybenzaldehyde (3,4,5-TMB) were reported by Gupta et al (1988). But only thirteen fundamental vibrations have been observed. In the present investigation laser Raman, infrared and Fourier's transform far infrared spectra of 3,4,5-TMB are recorded and forty four funda mentals are reported.
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