T H E RA1VIAN S P E C T R A OF D I O X A N E A N D T E T R A L I N .

BY C. S. VEN1G~TESWARAN. (From the Department of Physics, Indian Instit,~te of Science, Bangalore.)

Received August 23, I935.

(Communicated by Sir C. V. Raman, t<% it.ms., ~r

7. Introduction.

I..~ spite of the fact tha t organic compounds generally give rather compli- cated Raman spectra, the extensive researches in this field carried out in the last few years have enabled, in many eases, the modified lines to be classified into groups which can be identified as due to certain characteristic groups or chemical bonds in the molecule. In order to interpret the results in relation to the molecular structure, it is important to obtain the Raman spectra of the compounds studied as completely as possible. The simple ring com- pounds repeatedly investigated by several workers include benzene, cyclo- hexane and naphthalene. But comparatively li t t le work has been done in other cyclic compounds possessing a somewhat similar structure. The present paper gives the results obtained by the author with dioxane and tetralin.

Ex~hzr~ation of ~,mbols.

Symbol

a

b

d

e

f

g

h

Wavelength

3650

3655

4047

4078

4339

4348

4358

W avenumber

27358

27353

24705

24516

23039

22995

22938

279

280 C .S . Venkateswaran

T . ~ L x I.

The Ramanfmquencies of Dioxanefrom 4:047 3~, U , - -5100 X. U.

C I-Is C H.

o / \ ( ) \ . . . . /

CH2 CH:~

2No.

1

2

3

7

8

9

I0

Ii

12

13

14

15

16

17

18

19

20

Raman lines

4062.5

4067,3

4076.6

4086.8

4092-7

4099,5 (double)

4111.7

4116.6

4118-5

4127-6

4140,1

4148.7

4156.8

4188.5

4191.1

4204.7

4207,7

4220,2

4221.4

4237.1

Av in cm. "I

I I nt ensity I

] Assignment Without With filter

filter t

24609

24580

24523

24462

24427

24387

24314

24285

24273

24220

24147

24097

24050

23868

23854

23771

23759

23689

23682

23596

2779

2773

2863

243

2961

1449

3075

421

433

485

~206

419

466

837

851

S35

946

i016

834

1109

1

0

4

2

6b

3b

1

0

3

5

0

0

O b

8sh

lsh

3

0

8

2

3

1

1

0

(%

b

(%

d

a

h

(%

d

d

d

h

e

d

d

h

d

d

8

4

T/ze R~man Spectrcc o f Dioxane and Tetr~zH~

TA~Ln I (contd.)

281

No.

21

22

23

2 i

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

,4240

4255

Raman lines

3

0

8

5

4

i

4256

4272

4277

4291

4297 8

4306 0

4307 9

4393 0

4441 0

4442 3

4451.6

4523.2

4525.6

4535-2

4546.7

4554.5

4560.3

4576.3

4552.2

23576

23495

23485

23399

23372

23297

23261

23249

23207

22757

22512

22504

22458

22102

22090

22044

21988

21950

21922

21846

z~ v in cm. -i

Intensity

21818

1129

1210

1221

1306

1333

1219

1444

1455

1299

1817

426

434

480

836

848

2662

2718 } 950

2756

2783 } 1006

2860 } 1109

888 l 1120 f

Without filter With filter

3 . ,

0 . .

5 0

6 0

,o

1 . .

6 0

0 . .

0 . .

0 . .

0 0

2 2

4 3

lOsh 8

0 0

3 0 0

0 , .

6 4

8 2

3 1

]Assignment

d

d

d

d

d

e

d

d

h

h

h

h

h

h

d

d h

d

d h

d h

d h

282 C. S. Venkateswaran

TA~L~ I (concId.)

No.

Raman lines

4597.7

4600.8

4603.4

4616-8

4621.4

4626.2

4640.3

4650.8

4652-6

4929.6

4944.5

4960.7

4980.9

4986.1

4991-6

5006.0

5032.8

21744

A y in cm. "x

2962

In t ens i ty

W i t h o u t filter W i t h filter

10 1

21729

21717

21654

21632

21610

21544

21496

21487

20279

20220

20153

20071

20050

20027

19970

19864

1209

1221

2863

3074) 1306 ~

1328

2973

1442

1451

2659

2718

2785

2867

2888

2968

2968

3074

0

1

1

3

8

2

1

8b

1

6 4

, .

8 4

2 1

3(b) . .

8 6

0

1

1

2

6

1

i 0 [ i 8 i

0

Ass ignment

g

h

h

8

d h

h

h

h

h

h

h

h

h

g

h

2. Experimental Arrangements and Results.

The exper imenta l set up was the same as t h a t p rev ious ly u s e d in t h e

investigations of the author, 1 T h e two l iquids used in this i n v e s t i g a t i o n

were those used for the measurements of dipole moments at the Institute

1 Venkateswaran, C. S., Proc. Ind. Acad. Sci., 1935, 1, 850.

T~e Raman Spectra of Dioxane and Tetra[in 283

TA~L~ II.

The Raman frequencies of Tetralin from 4:0~7 &. U.--5100 ~. u.

CH CH

C H 2 C H ~

N o .

15

16

17

18

19

R a m a a l ines

4071.7

4089.1

4095-5

4104.6

4117.6

4119-9

4123-2

4130.8

4139-9

4143.8

4164.6

4168.1

4176.5

4181.8

4184.5

4200-8

4214.0

4223.2

4228.0

24553

24448

24410

24356

24279

24266

24246

24202

24148

24128

24005

23985

23946

23906

23891

23798

23724

23672

23645

/Xv in cm, "1

I n t e n s i t y

153

258

2944

1418

427

440

460

5O4

557

578

701

721

760

8OO

815

9O8

982

1034

1061"

..... A s s i g n m e n

W i t h o u t W i t h f i l ter f i l ter

6 1

2 0

1 , ,

0 . .

2 0

2 . ~

0 . ,

1 . .

0 . ,

3 . .

1 . .

8 2

0 ~

"~ . ~

2 . ,

2 , ,

0 , ~

10 3

0 . ,

d

d

b

h

d

d

d

d"

d

d

d

d

d

d

d

d

d

d

* A n a s t e r i s k m a r k a g a i n s t s o m e of t he f r e q u e n c y n u m b e r s s h o w s t h a t t h e y p o s s e s s a d o u b l e t structure.

2 8 4 C. S. Venkateswaran

TABLE II (con~d.)

1No.

20

21

22

23

24

25

26

27

28

29

31

32

33

34

35

36

37

i

38 r

39 ~ I

40 ,

Raman lines

4239.0

4245.8

4253-1

4258-4

4268.2

4277.0

4279.5

4285.7

4293.8

4298-4

4307.9

4309.7

4322.0

4326.6

4329.3

4387-9

4408.1

4469.9

4440.0

4443.1

4446.0

23584

23546

23506

23476

23421

23369

23360

23327

23278

23258

23207

23197

23130

23106

23092

22784

22680

22670

22511

22500

22486

A v in cm. "!

In tens i ty

[ Without filter With filter

0 � 9

[

I 1 . .

8 2 i

I i

I 0 �9 ,

3 . .

I 3 . .

0 2

1122

1160

1200

1230'

1285

1336

422

1379

1427

1448

1499

259

1575

1600

154

154

258

268

427

438

457

2

6

1

0

1

0

8

4

5

3

3

1

1

2

�9 i

2

4

8

4

0

6

0

4

Assignmenl

d

d

g

d

c~

d

h

d

d

d

d

h

d

d

h

h

h

h

h

h

h

* An asterisk mark against some of the frequency numbers shows that they possess a doublet structure.

l' e Ranran Speclra a/e Dioxane and TetzMin 285

TABL~ II (contd.)

No.

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

4455.4

4467.0

4470.5

4495.0

4499.6

4508.1

4515.8

4518.7

4537.0

4544.1

4552.7

4560.3

4570.3

4576.9

4584.5

4590-5

4594.0

4601.4

4607.0

4617.1

4627.8

22438

22380

22363

22241

22218

22176

22138

22124

22035

22004

21959

21903

21874

21843

21806

21778

21762

21726

21704

21653

21602

A v in cm, "z

505

558

575

697

720

762

800

814

903

1035

1035 } 979

1035

1064"

2863

2902

2930 } 1160

2943

1202

1234

3052 } 1285

1336

In tens i ty Raman lines

1

W i t h o u t filter With f i l ter

2 5

0 1

3 4

1 1

8 10

0 0

0 1

1 2

. , 0

0 0

0 2

8 10

3 2

1 . ,

1 . ,

4b 4

0 0

5 6

0 1

3

2

Assignment

h

h

h

h

h

h

h

h

h

f

g, h

h

h

el

el

d

d

h

h

d, h

h

286 C. S. V e n k a t e s w a r a n

T .~LE I I (concId.)

62 i

64 1

65

66

67

68

69

70

7 1 i

72 i

73 i

4636.3

4647.4

4652 ~ * ~

21563

21511

21489

Av in cm. "1

4662.8

4680.8

4685.1

4980-8

4989.8

4993-7

4998-3

5018.7

5025

21440

21362

21339

20071

20035

20020

20001

19920

19892

1383

1427

1449

Intensity Raman lines

1498

1576

1599

2867

2903

2918

2937

3008

3046

Without With filter filter

1 2

6 6

1 2

0 0

2 2

3

3 3

1 1

0 0

6 6

1 1

I0 I0

Assignment

h

h

h

h

h

h

h

h

h

h

h

h

and the author's thanks are due to Dr. hl. A. Govinda Rau for kindly per- ~nitting the use of the extra-pure substances which he had carefully prepared for his work. In order to facilitate the proper assignment of the excited lines, spectrograms were taken with and without filters. An alcoholic solution of p-nitro-toluene was found to be an efficient filter which cut off almost completely the 4046 radiations while transmitting the 4B58 radiations of the source with maximum intensity. For dioxane, an alkaline solution of o-cresolpthalin helped to clear up the 4916 region considerably. The filter was contained in an outer jacket surrounding the experimental tube as in Fig. ]. It would be of interest to mention that tubes with almost per- fectly flat ends could be easily made in pyrex glass with the outer tube fused to the bottom and supported with a few spokes dug into its walls at the top. In order to prevent the evaporation of the filter solution when the tube was placed close to the arc, the top end was closed with plaster of Paris through which two small tubes were passed for t he i n t r o d u c t i o n of t h e s o l u t i o n . T h e

The R~zmc~n Spealra, of Dioxa**e a~d Te#'Miz

TA]31a~ I I I .

287

The intensities given in the brackets are for the 4358 cxcitations.

Dioxane

Author

181(o)~

24-3(1)

4-25(o)

433(2)

482(4-)

837(8)

84-9(1)

94.6(0)

1012(6)

1109(3)

1124(3)

1209(1)

1221(5)

1306(8)

1328(2)

1444(8)

Villars

o �9

291(0)

4~4(oo)

519(00)

837(4)

o ~

1117(1)

1214(1)

1442(2)

Tetralin Cyclohexane

Author

154(8~

259(4) 268(o)

427(6) 439(0)

459(4)

505(5) 558(i) 577(4) 699(1) 720(10) 761(0)

800(1)

814(2)

905(0) 98o(1)

lO35(lO) 1063(3)

1122(0)

1163(4)

12o1(6)

1232(i) 1285(3)

* Q

1336(2)

1427(6)

Mukerji Bonino and Celia Krishnamurti

381(~)

425(1)

695(0)

162(3)

265(2) �9 6

430(4)

511(3) 561(2) 582(3) 699(2) 723(5) 752(1)

814(2) 839(0)

1037(7)

1174(0)

1205(6)

12;;(1)

1438(3)

158(4)

265(3)

43~(2)

513(3) 567(2) 585(3)

759(1)

815(2) 848(o)

lo.38(5)

116o(1)

12o4(4)

12~/2)

134o(1�89

1433(3)

8o4(lo)

lo28(s)

1156(1)

1266(5)

1344(�89

1444(5)

Benzene

G r a s s i n 3 . 1 - 1 a l ' l d

Weiler (Incomplete)

4o4(1)

607(8) 692(1)

781(0)

602(0)

824(�89 849(4)

984(2) 992(15)

1034(1)

1176(4)

1~85(o)

1326(�89

1~o3(2)

288 C. S. Venkateswaran

T.aBi, m I I I (contd.)

Dioxane Tetralin Cyclohexane Benzene

Grassman and Author Villars Author Mukerji Bonino and Krishnamurti Weiler

C ella ( Incomp]ete).

14-51(1)

2660(1)

2718(1)

2784-(3)

2868(8)

2888(2)

2968(10)b

,o64.(1)

14-4-8(2) 1499(0) 1575(2) 16oo(4.)

* ~ �9 t

2720(00) ..

, . . .

2864.(3)

2967(3)

2865(4.)

29o2(1)

2937(6) 3oo8(1)

3049(10)

1458(5)

15~9L(a) 1602(3)

�9 �9

�9 ,

2865(4:)

294:0(4)

304.6(5)

14.56(3)

1602(3)

i �9

2862(2�89

I ~ .

2662(1)

2852(8)

2889(1)

2922(8)

14-4-9(�89 1480(0) 1585(12) 1606(8)

2615(2)

294-9(4) 3o4-9(8)

3o64(12)

. J

i

J Fro. 1.

spectrograms were measured as usual and the

results are tabulated in Tables I and II. The

photographs are also reproduced in the accompany-

ing plates. Dioxane was comparatively a poor

scattering medium and an exposure of forty hours

was required to bring out all the lines in its spectrum without any filter. Tetralin gave an

intense picture at an exposure of nine hours ; but in

this case a continuous spectrum was also present.

3. Discussion, of Results.

(a) Dioxane.--Except for a short report on the principal Raman lines by Villars,~ this compound has not been studied in any great detail. From the point of view of the Raman effect this is an interesting compound, for it affords the unique example of a molecule possessing a structure similar

2 Villal-s, four. Amer. Chem. Soc., 1930, 52, 4612.

The Rgrnas S~ectra ol c Dioxane a n d Te lra l i s 289

tol t h a t of cyclohexane, b u t with two of the methylene groups replaced by oxygen atoms. As can be seen from the first column in Table III , the spectrum of dioxane consists of twenty-four lines of which fourteen have been observed for the first time. The author has been fortunate to be able to examine the cyclohexane plate of Xrishnamurti 3 side by side with the latter and the comparison of the two reveals the following facts :--

(I) Both the compounds give only feeble wings accompanying the

liayleigh lines.

(2) All the important lines of cyclohexane appear more or less in the same position in dioxane.

(3) The region between 2863 and 2968 is covered by a band in both the cases which is attrib~lted to the rotational spectrum accompanying the vibrat ional line due to C-IzI linkage.

(4) The wing structure of 14.44 of cyclohexane is resolved into a close companion line in dioxane.

The outstanding differences in the two spectra are the following :--

(1) An intense line at 1306 (marked by the arrow in the accom- panying plate) which is absent in cyclohexane, is one of the fundamental lines in dioxane and this is to be attributed to the oscillation of the

CH.o / group O (~ .

\ CH2

(2) The line due to the symmetrical oscillation of the carbons in cyclo- hexene at 80-4 is shifted to a higher frequency 837 in dioxane, and the lines due to C-II from 2852 and 2938 to 2863 and 2968 respectix-ely.

(3) AIr the other lines belonging to C-C or C!-I 2 are shifted in the opposite

direction.

(4) The line at 425 which is assumed to be one of the characteristic lines of the cyclohexane nucleus, is resolved into three ]ines in dioxane.

(5) There is a group of lines present in dioxane at about 2750 which is not present in cyclohexane and they nlay be explained partly as arising from the combination of 144-I and 1306.

(6) The intense doublet due to C =I-I~ in cyclohexane at 2922 and 2938 appeals as a single broad line at 2968 in dioxane.

It is clear from the above that dioxane possesses a structure similar to that of cyclohexane and its vibrations are modified to some extent by the presence of the two oxygen atoms in the place of two CII2 groups in the ring.

a Krishnamurti, P., Ind. four. Phys., I932, 6, 543. A6 F

290 C. S. Venkateswaran

The presence of a weak line at 3064 which is characteristic of the aromatic linkage shows besides t ha t i t represents the transition between the aromatic and the aliphatic ring compounds.

(b) T e t r ~ i n . - - T h i s has been studied in great detail first by Bonino and Cella 4 and quite recently by l iukerji . 5 These authors have pointed out the great similarity of its spectrum to those of cyclohexane and naphtha- lene. The results given by them are in fair agreement with those 6f the author. As can be seen from Table I I I new Iines have been observed at 268, 439, 459, 800, 905, 980, 1083, 1125, 1232, 2902 and :3008. The fre- quency shifts of cyelohexane and of benzene 6 are also given for comparison. The new points tha t have been observed by the author in the spectrum of tetralin besides those reported by the previous investigators, are the follow-

ing :--

(1) The line at 1440 due to the deformation oscillation of C}t~ has been shifted slightly to a shorter wavelength and has been followed by a com- panion as in dioxane.

(2.) The line at 425 has been split up into three lines as in dioxane.

(3) The continuous spectrum between 2865 and 2937 in cyclohexane and dioxane is present weakly also in tetralin and thus appears to be charac- teristic of the molecules of the cyclohexane type.

(4.) The wings accompanying the Rayleigh lines are as prominent as in benzene.

(5) The important lines in the benzene spectrum at about ]600 due to C =C and above 3000 due to the aromatic CH appear also in tetralin.

(6) The line at 3040 shows a prominent wing on either side.

This similarity to the spectrum of cyclohexane on the one hand and of benzene on the other suggests that the molecule of tetralin is made up of one completed cyclohexane nucleus and one incomplete benzene nucleus.

In conclusiov, the author wishes to record his thanks to Sir C. V. IKaman for his interest in the work.

Sctmmary.

The l~aman spectra of dioxane and tetralin have been obtained using the filter technique. The spectrum of dioxane consists of twenty-four lines of which fourteen are reported for the first time and resembles closely tha t of cycIohexane. Tetral in has also given eleven new lines. The resuits obtained are discussed with reference to the structure of the molecules.

4 Bonino and Cella, Altl. Acad. Lincd, 1931, 13, 784; also 1932, 15, 572. Mukerji, Phil. Mag., 1935, 19, 1079.

G Grassman and Weiler, Zelt. f~r Phys., 1933, 86, 314.

$

I

I I

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I . D ioxane w i t h o u t f i l te r . I I . D i o x a n e wi th o-cresoI thMin fi l ter. I I I . T e t r a l i n wi th p - n i t r o t o l u e n e filter.