submitted papers

The Infrared Spectra and Vibrational Assignments of Crystalline 1,2-, 1,3-, and 1,4-Naphthalenediols

H. William Wilson and Nadav Friedmann

Department of Chemistry, Western Washington State College, Bellingham, Washington 98225

(Received 10 December 1973; revision received 11 March 1974)

The infrared spectra of crystalline 1,2-, 1,3~, and 1,4-naphthalenediols in KBr or CsI pellets have been interpreted on the basis of a comparison with the spectra of other naphthalene de- rivatives. Assignments have been proposed for all but four vibrations which are expected to fall below 300 cm -1. INDEX HEADINGS: Naphthalenediols ; Infrared spectra; Crystalline phase; Vibrational assign- ments.

INTRODUCTION

Although found among the oxidation products of many naturally occurring materials, such as bituminous substances, ~ the naphthalenediols are relatively diffi- cult to s tudy in the infrared. They are essentially insol- uble in common nonpolar or weakly polar infrared solvents, and they are so unstable tha t they cannot be studied in the gas phase / In fact, they cannot even readily be isolated from natural materials for spectro- scopic s tudy as they are sensitive to both light and air even at room temperatures.

The situation is worse in the Raman where the highly colored polymeric decomposition products of these materials completely absorb any Raman emission. Since even crystalline a- and /~-naphthols have been observed to decompose within a few minutes in mixed gas laser beams, it is impractical to consider the sensi- tive naphthalenediols for a Raman study.

The purpose of this s tudy was to examine the pellet spectra of the three naphthalenediols which have both OH groups on the same ring. Assignments have been made by comparing their spectra with those of other disubstituted naphthalene derivatives which have been reported in the l i tera ture /

A limited study of the 1,3 and 1,4 isomers in polar solutions has been done. 4

I. EXPERIMENTAL

A. Instrumentation

Several infrared spectrophotometers were used to obtain the spectra. They included a Beckman IR-10 for preliminary surveys and a Beckman IR-12 and a Perkin-Elmer model 521 for more detailed work.

All frequencies were calibrated with atmospheric water and COs or with HC1 or NH3. OH stretching frequencies were obtained from saturated solutions of

the diols in common infrared solvents and 10-cm quartz cells. Otherwise, 4% (w/w) KBr or CsI pellets were used throughout the study. For reasons which we were unable to explain, the pellet spectra failed to show sig- nificant or reliable features between 200 and 300 cm -1. Nujol mulls were of little or no help.

B. Samples

The 1,2 and 1,4 isomers were freshly synthesized for this study, 5 but the 1,3 compound was obtained commercially. The samples were checked by a variety of analytical techniques including melting points, solu- bilities, mass spectrometry, and GLC. In all cases, they were judged to be at least 99% pure, with the remaining 1% being some form of high molecular weight polymeric materials.

II. RESULTS AND DISCUSSION

Crystallographic studies 6 show that 1,4-naphthalene- diol has an orthorhombic Pna2, (C~v g) crystal symmetry, but we were unable to find any data on the other iso- mers. We have not a t tempted to carry out a detailed crystal spectrum assignment for the 1,4-diol, but in comparing the observed frequencies for the crystalline naphthalenediols with those reported in the literature for other naphthalene derivatives in various physical states, it becomes obvious that in spite of the disturb- ing influence of molecular association, bands in the pellet spectra fall into recognizable patterns for most of the vibrational modes. There is certainly a danger in mislabeling some of the observed bands, but a routine correlation of the experimental frequencies with the corresponding C~v and C~ symmetries of the free mole- cules should still be of great aid in doing normal coordi- nate calculations on naphthalene derivatives. A com- puter selection of groups of observed frequencies to

418 Volume 28, Number 5, 1974 APPLIED SPECTROSCOPY

TABLE I. Infrared vibrational assignments for 1,2-, 1,3-, and 1,4-naphthalenediols (cm-~). •

Mode 1,2-Cl0HaO2 1 , 3 - C 1 0 H ~ O 2 1,4-CioH802

~(CH) 3053 KBr 3036 KBr 3015 CS~ 3035 CS~ 3094 CS2 3105 CS2

p(CC) 1631 s~ 1627 st 1641 st 1601 s t 1592 s t 1596 st 1585 sh 1583 reed 1580 sh 1515 wk 1520 reed 1520 wk 1507 wk 1504 wk 15~2 wk 1449 reed 1464 wk 1439 wk 1405 sh 1410 sh 1408 sh 1343 reed 1376 med 1355 med 1022 wk 1621 med 1020 sh

~(CH) 1476 st 1452 rned 1477 st 1389 st 1392 reed 1396 reed 1263 st 1257 st 1257 reed 1208 st 1214 sh 1209 sh 1155 med 1156 med 1155 sh 1145 sh 1128 st 1142 st

a(CCC) 1323 wk 1315 wk 1317 wk 940 sh 935 sh 942 sh 908 sh 891 reed 897 reed 752 st 766 st 744 st 658 sh 650 st 052 sh 539 sh 528 med 535 sh 422 reed 428 st 407 reed 348 wk 355 wk 340 wk

~(CH) 964 st 987 st 1000 reed 954 sh 058 reed 967 sh 868 med 866 med . .- 808 reed 831 st 808 st 776 st 776 st 786 meal 699 st . .- 702 reed

~(CCC) 734 wk 752 st 728 st 539 reed 522 st 535 med

• .- 485 st 470 med 440 med 445 st 438 med 400 wk 397 wk 388 wk

b b b b b b

v(OH) 3655 C H C h 3612 C2C14 c 3630 C H C h 3670 C H C h 3604 CCh ¢ 3690 C H C h

3592 CS2 v(CO) 1072 st 1061 st 1031 st

1084 st 1072 st 1048 st fl(COH) 1283 st dif c 1278 st dif c 1317 st dif c B(CCO) 555 reed dif c 538 med dif c 560 reed dif c ~,(COH) 600 med dif c 600 med dif c 600 med dif c "~, (eGO) b b b

b b b

a st, strong, 0 to 50% transmittance for a 4% (w/w) KBr pellet; med, me- dium. 50 to 70% transmittance; wk, weak, 80 to 98% transmittance; dif, diffuse.

b Frequency below 300 cm-L c Two modes at each frequency.

give a best fit set of force constants is a distinct possi- bility.

Each isomer has 37 in-plane and 17 out-of-plane vibrational modes of which the substituents will ac- count for 8 and 4 modes, respectively. Virtually all of the remaining 42 vibrations will be naphthalene-like.

The assignments are listed in Table I, where a benzene-type notation has been used. 7

h . In -P lane Naphtha lene - l ike Vibrations 8-13

1. C--H Stretching v(CH) Each of the three isomers has a total of 6 CH stretch-

ing modes, but there is considerable overlap in the region where they are found. In associated phenolic materials, the broad absorption areas due to hydrogen

bonding all but occlude the relatively weak stretching bands. The bands observed in this work all lie, as expected, '4 between 3000 and 3150 cm -1, but none can be specifically identified. Only the 1,4 isomer was soluble enough to yield solution frequencies.

2. C--C Stretching ~(CC)

The higher frequency members of the 9 CC stretch- ing vibrations are relatively easy to identify, with 5 of them lying between 1500 cm -1 and 1700 cm -1. Unfor- tunately, the remainder are much less obvious. In par- ticular, a great deal of v(CC) stretching and in-plane deformation a(CCC) mixing undoubtedly occurs, n We feel that the higher frequency bands are mostly stretch- ing vibrations, while the lower frequency modes could just as well be labeled in-plane ring deformations. Per- haps the best example of this would be the 1020 cm -~ ring breathing mode listed here as a v(CC) vibration.

The listing in Table I is a best-fit pattern based on previous assignments.

3. C--H Bending B(CH) and CCC Ring Deformation ~(CCC)

Again, as is the case with v(CC) and a(CCC) modes, in situations where CH bending and deformation modes fall in the same symmetry species, enough coupling will occur to essentially prevent categorizing modes into individual classes. Nonetheless, a surprisingly good pattern for the 6/~(CH) and 8 a(CCC) in-plane species can be seen by comparing their frequencies with those of other derivatives reported in the literature. 8-13 In general, the ~(CH) modes tend to lie above 1000 cm -1 and the a(CCC) vibrations below this frequency. In a majority of instances, the fit includes not only frequen- cies, but Mso relative band intensities as measured by peak heights.

B. Out -o f -P lane Naphtha lene - l ike Vibrations

C--H Bending 7(CH) and Ring Deformations 4~(CCC) Based on recent work with gas phase dihydroxyben-

zenes, ~5 all of the out-of-plane modes will fall below 1000 cm-'. In fact, none of the type C band contours characteristic of out-of-plane modes in the three dihy- droxybenzene molecules or in phenol vapor occur above 900 cm-L

The frequencies of two of the ~b(CCC) modes are below the region studied. In three instances the pattern correlation between the three isomers failed, and they were all in cases where medium to strong bands oc- curred.

C. Subst i tuent M o d e s

The eight planar substituent modes consist of two OH stretches, ~(OH), two CO stretches, ~(CO), two COH bands, and two CCO bands,/~(COH) and/~(CCO) respectively. The OH stretching modes are sensitive to solvents, and several frequencies are listed in Table I with the specific solvents being noted. In addition, there are some structural complications which may modify the appearance of this region. The 1,2 isomer is undoubtedly intramolecularly hydrogen bonded and

APPLIED SPECTROSCOPY 419

the 1,4 isomer can exist in a t least three modifications since free rotation of the OH groups does not occur. Experimentally, two bands are observed for both the 1,2 and 1,4 compounds and only one band for the 1,3 isomer.

Differentiation of the planar f~(COH) and the v(C0) vibrations which both occur between 1050 cm -1 and 1350 cm -~ is difficult even for simple phenols. On the basis of the gas phase work with other dihydroxy molecules, 15 we have assigned values between 1050 and 1325 cm -~ for these mixed vibrations.

There is a great deal of uncertainty as to where the planar B(CCO) modes are to be found. We have selected diffuse bands near 550 cm -~ as possibilities. Their widths would result from association effects.

The nonplanar substi tuent modes consist of two ~(COH) and two ~(CCO) bonding motions. The listed values have been selected on the basis of the diffuse nature of the observed bands. The two ~,(CCO) vibra- tions are probably below 300 cm -~, where we were unable to obtain good spectra.

I I I . C O N C L U S I O N S

The insolubility and sensitive, unstable nature of the series of the 1,2-, 1,3- and 1,4-naphthalenediols pre- vent vibrational assignments from being done on anything but K B r or CsI pellet spectra. As more crystal data become available, it m a y eventually be possible to do detailed crystal studies on them.

In the meantime, the pellet spectra yield band pat- terns which, in general, correlate well with vibrational assignments tha t have been carried out on other naphthalene derivatives in various physical states. Until such t ime as crystal work can be done, the pellet spectra should be valuable in at least semiquantita-

tively describing the infrared substi tuent effects of the two variously placed OH groups.

IV. A C K N O W L E D G M E N T S

We would like to thank the Gulf Research and De- velopment Company of Canada and the Bureau of Facul ty Research at Western Washington State College for their help in this work.

1. A. I. Scott, Quart. Rev. 19, 1 (1965). R. B. Thompson and J. A. Chemicek, Ind. Eng. Chem. 47, 1431 (1955).

2. Handbook of Chemistry and Physics, R. C. Weast, Ed. (Chemical Rubber Publishing Co., Cleveland, 1972), 52nd ed., p. C 380.

3. See, for instance, K. H. Michaelian and S. M. Ziegler, Appl. Spectrosc. 27, 13 (1973) and references therein; T. W. Wang and J. M. Sanders, Spectrochim. Acta 15, 1118 (1959); R. L. Werner, W. Kennard, and D. Rayson, Austra- lian J. Chem. 8,346 (1955).

4. J. T. van Gemert, Australian J. Chem. 21,2203 (1968). 5. I. Vogel, A Textbook of Practical Organic Chemistry. (Wiley,

New York, 1958), 3rd ed., p. 745. 6. J. Gautier and C. Hauw, Compt. Rend. Acad. Sci. Paris 8

Groupe, 261, 3818 (1965). 7. E. B. Wilson, Jr., J. C. Decius, and P. C. Cross, Molecular

Vibrations (McGraw-Hill, New York, 1955), Chap. 10. 8. S. S. Mitra and H. J. Bernstein, Can. J. Chem. 37, 583

(1959). 9. D. B. Scully and D. H. Whiffen, Spectrochim Acta 16, 1409

(1960). 10. N. I. Zhirnov, Opt. Spectrose. 9,385 (1960). 11. D. E. Freeman and I. G. Ross, Spectrochim. Acta 16, 1393

(196o). 12. D. M. Hanson, J. Chem. Phys. 51, 5063 (1969) and refer-

ences. 13. J. Brandmueller and E. Schmid, Z. Physik 144, 428 (1956). 14. L. J. Bellamy, The Infrared Spectra of Complex Molecules

(Methuen, London, 1958); W. Bruhn and R. Mecke, Z. Electrochem. 62,441 (1958).

15. H. W. Wilson, to be published.

Vibrational Spectra of Some Benzoyl Halides: CeHsCOCI , C6DsCOCI , and C6HsCOBr*

D. A. Condit, S. M. Craven, and J. E. Ka ton

Department of Chemistry, Miami University, Oxford, Ohio 45056

(Received 22 January 1974; revision received 22 April 1974)

The infrared and Raman spectra of benzoyl chloride, benzoyl chloride-dE, and benzoyl bromide have been measured between 75 and 4000 cm -1. Assignments for the fundamental modes of vibration are presented. 1ND EX HEADINGS : Infrared spectra; Raman spectroscopy; Isotopes; Benzoyl halides.

I N T R O D U C T I O N

The vibrational spectra of molecules of the type CeH~COY where Y = F, C1, Br, and I have been exten-

* This work was supported in part by the United States Air Force under Contracts F33615-70-C-1021 and F33615-72-C- 1040.

sively studied? -14 However, there is still disagreement as to assignment of some of the 36 normal modes of benzoyl chloride and benzoyl bromide. Disagreement also exists for the reported Raman spectra and the s tate of polarization of the Raman lines of benzoyl chlo- ride.l-5, 11 In this paper we report the infrared and

420 Volume 28, Number 5, 1974 APPLIED SPECTROSCOPY