The spectra of polycyclic oxazines and azines—II. The infrared spectra of triphenodioxazines

Spectrcchimica Acta, 1965,Vol. 21, pp. 1081to 1086. Perggsmgn Press Ltd. Printed in NorthernIreland

The spectra of polycyclic oxazines and azines-II*. The infrared spectra of triphenodioxazines JOHN F.

CORBETT

Research Laboratories, Gillette Industries, Reading, Berkshire (Received 2 October 1964) Abstract-The infrared spectra of triphenodioxazine, 13 of its methyl and two of its methoxy derivatives are reported. In the region 1620-l 100 cm-l, nine characteristic ring vibrations are observed. A useful correlation between the substitution pattern and the C-H out-of-plane vibrations is noted. INTRODUCTION IN THE course of a study of the autoxidation of aminophenols, a number of triphenodioxazines have been isolated and their infra-red spectra have been recorded. Musso and BEEKEN [l] have reported the spectra of seven triphenodioxazine derivatives between 1650 and 1350 cm-l but did not discuss any correlations with the structure or substitution pattern. In the present work the main absorption bands in the region 4000-650 cm-l are assigned to the various C-H and ring vibrations. EXPERIMENTAL

The infrared spectra were recorded, using KC1 discs, on a Perkin-Elmer model 22 1 spectrophotometer. The data are given in Tables l-4. Triphenodioxazine (I) and its 1,6,8-, 4,6,11;trimethyl derivatives were obtained by passing oxygen through a hot aqueous solution of 2-aminophenol hydrochloride and its 3- snd 6-methyl derivatives respectively. Yields were low (4-s%) due to the fall in pH as the reaction proceeded. Much better yields csn be obtained by the occasional addition of alkali to maintain the pH in region 45. The l&3-, 2,9-, 3,10- and 4,11-dimethyl and the 1,4,8,11- and 2,4,9,11-tetra-. methyl and 2,9- and 3,10-dimethoxy derivatives were obtained by condensing 2,5-, dihydroxybenzoquinone with the 3-, 4-, 5- and 6-methyl and 3,6- and 4,6-dimethyl and 4- and 5-methoxy derivatives of o-aminophenol in acetic acid at SO-90°C. The 6-methyl and 2,9,13-trimethyl derivatives were obtained, similarly, by the condensation of 3-methyl-2,5dihydroxybenzoquinone with o-aminophenol and its 4-methyl derivative respectively. 4,6- and 1,13-dimethyItriphenodioxazines were obtained by the condensation of 1,9-dimethyl and 4,6-dimethyl 2-hydroxyphenoxazin-3-one with o-aminophenol. 6,13-Dimethyltrjphenodioxazine was obtained by the condensation of 3,6-dimethyl-2,5-dihydroxybenzoquinone and o-aminophenol in molten benzoic acid. No reaction

occurred when the two compounds

* For Part I-Spectrochim. [I] H. Mnsso ad 4

were heated under reflux in acetic acid.

Acta 20, 1665 (1964).

H. BEECKEN, Ber. 94, 585 (1961). 1081

1082

JOHN

F.

CORBEIIT

All the triphenodioxazines were purified by chromatography on B.D.H. alumina (basic) with benzene as eluant. The compounds moved rapidly as orange zones and gave a yellow eluate with a strong greenish fluorescence. On concentrating the eluate, the products separated as dark red crystals. Melting points and analytical data are given in Table 1. Table

1 Analytical

data Cskxdeted

Found m.p.

Compound Triphenodioxazine f3-Mdethvl l&Di&+hyl* 2,9-Dimethyl* 3,10-Dimethyl* 4,1LDimethyl* 4,6-Dimethyl 1,13-Dimethyl* 6,13-Dimethyl 1,6,8-Trimethyl* 2,9,13-Trimethyl+ 4,6,11-Trimethyl* 1,4,8.11-Tetramethyl* 2,4,9,11-Tetramethyl* 2,9-Dimothoxy* 3,10-Dimethoxy*

> > > > > > > > > > >

360° 345’=(d) 360° 3800 360’ 360” 276O 360” 360’ 332” 360° 334” 350° 360° 360° 360’

C

H

C

H

75.3 76.0 76.5 76.7 76.7 76.7 76.4 76.4 76.7 76.5 76.9 76.8 76.9 76.9 70.2 68.9

3.52 4.21 4.60 4.48 4.44 4.48 4.50 4.42 4.47 6.10 6.04 4ao 5.59 5.61 4.32 4.02

75.4 76.0 76.4 76.4 76.4 76.4 76.4 76.4 76.4 76.7 76.7 76.7 77.0 77.0 69.4 69.4

3.49 4.00 4.45 4.46 4.45 4.46 4.45 4.45 4.45 4.87 4.87 4.87 5.30 6.30 4.05 4.05

* New compounds.

When chromatographed on acid alumina (Woelm) or on acid washed silica gel the triphenodioxazines formed slow moving blue bands. The triphenodioxazines exhibit characteristic electronic spectra. In carbon tetrachloride they give three peaks between 420 and 520 rnp, the intensity of which increases with wavelength. In concentrated sulphuric acid, the blue solutions, have a maximum near 650 rnp, on dilution with water the blue solutions become purple and the maximum absorption is near 580 m,u. For triphenodioxazine itself the following 3,max. (log E) values were obtained and the three spectra are assigned to the neutral molecule and its mono- and di-protonated species respectively:-carbon tetrachloride: featureless between 270 and 400 rnp, 405’; 4178; 443 (4.26); 471 (4.61); 505 (4.74): 10% sulphuric acid: 247 (4.51); 572 (4.43); 610”: 98% sulphuric acid 256 (4.60); 278’; 285 (4.25); 595 (4.42); 644 (481). DISCUSSION The infrared spectrum of triphenodioxazine (I) is relatively simple and contains bands due to C-H, and aromatic C-C, C-N and C-O ring vibrations. In the region 4000-1650 cm-l there is a single weak maximum at 3030 cm-l due to C-H stretching vibrations. The methyl derivatives also absorb in the region 2970-2800 cm-r due to aliphatic C-H stretching. The ring vibrations occur in the region 1650-l 100 cm-l. Inspection of Table 2 shows there to be eight characteristic bands in this region, the frequency range for each being very narrow, w&(i) 15781558 (strong); (ii) 1528-1510 (medium-strong); (iii) 1495-1455 (m-s); (iv) 1400-1385 (weak-medium); (v) 1375-1368 (w-m); (vi)

The spectra of polycyclic oxazines and wines-II

1083

Table 2 Spectra of triphenodioxazines* Triphenodioxazine g-Methyl 1,8-Dimethyl 2,9-Dimethyl 3,10-Dimethyl 4,6-Dimethyl 4.1 I-Dimethyl 1,13-Dimethyl 6,13-Dimsthyl 1,6,8-Trimethyl 2,9,13-Trimethyl 4,&l I-Trimethyl 1,4,8,11-Tetramethyl 2,4.9,11-Tetramethyl 2,9-Dimethoxy 3,10-Dimethoxy

1603 1608 1615

1570 1576 1576 1558 15858 1572 1572

1593 1572 1687 1668 16078 1~585~ 1672 1576 1602 1579 1564 1610 15838 1564 1590 1571 1612 1582 1586

1599

1603

1568

1585

1560 1568 (0

16OS

1622 1621 1524 1621 1528 1623 1628 1622 1521 1520 1535 1521 1626 1.526 1515 1618 (ii)

1468 1460 1470 1482 1481 1461 1470 1467 1460 1471 1480 1470 1494 1462 1480 1485 (iii)

1439 1430 1462 1450 1436 14~58 1443 17708 2439 1430 1450 1462 1435

1390 1393 1390 1413

1392 1392 1399 1387

1414

1439 1436 1442 1438

1372 1373 1370 1377 1375 1370 1370

1372 1369 1370 1375 1371 1372 1370 1370

1391 1393 1390 1390 1393 1400

1426 1390 14228 14108 1.3906 1368 (iv)

1316 1317 1304 1321 1295 1312 1313 1342 1307 1315 13428 1318” 1201 1309 1318 1320 1312 1307 1306 1331 1297 1289 1321 1308

(v)

(vi)

* Frequencies (bold)-strong. Frequencies (reman)-medium. Frequencies (italic)-weak.

Table 3 Spectra, of triphenodioxszines* Triphenodioxazine B-Methyl 1,8-Dimethyl 2,9-Dimethyl 3,10-Dimethyl 4,6-Dimethyl 4,11 -Dimethyl 1,13-Dimethyl 6,13-Dimethyl 1,6,%Trimethyl 2,9,13-Trimethyl 4,6,11 -Trimethyl 1,4,&U-Tetramethyl 2,4,9,11-Tetremethyl 2,9-Dimethoxy 3,1 O-Dimethoxy

1267 1271 1249 1271

1291 1292

1282

1242 1222 1260 1227 1233 1238 1246 1250 1248 1268 1244 1268 1250 1235 1244 1270 12108 1267 1245 1242

1266 1272

1248 (vii)

1210 1225

1198

1212 1202

1211 1220

11768 1167 1179 1147 1170 1149 1181 1172 1183 1170 1177 1164 1192 11182 1176 1168

1201 1180 1207

1185 1171 1182

1182 1186 1176 1196

1196

1178 1168 l167e 1160 (viii)

1103 1116 1074

1028

1032 1111

1091

1110 1111

1074 11056 1097

1020 1022 1029 1020 1005 1013

1045

1152

9fiI 961 946 963

1023 1020 1009

992

1137 1168 11580 1148

1097 1061

1104 11558 1103

1048

* Frequencies (bold)--strong. Frequencies (reman)-medium. Frequencies (italic)-week.

Table 4. Frequencies of C-H out-of-plane deformation bands Number of adjacent hydrogen atoms

Frequency ranges (cm-l)

4 3 2 1

760-750 and 740-730 780-760 and 755-730 821-808 900-830

-

1012 1030 1032 1022

1022

962 973 962 Q60

JOHN

1084

F. CORBETT

cm-’ 1620

1620

1580

1580

I 3,10-diMe0

4,6-diMe

I

4.11-diMe

3.10-diMeO-1,6,8-triMe*

I

4,6,11-triMe

I

Oblique

lines

represent

shoulders

“From

reference

4

Fra. 1

4.1

I -diMe I

1,4.8,11-tetMe

I

2.9-diMe 3,IO-diMe 2.4,9,1

I-ietMe

I I

I I

!I iI I

I ! 1 0

I

I

:I I

II1

3.10-diMe0 2.9-diMe0 Number of adjacent H ir

I *2

-)F

FIG.

2

3 -UL4

j ; , ,, I , : ; ! : , , 1

ji :: :I ,I ;; I, II I,#! !; I! :; I: ;; :I

:

7*3or4*

’

The spectra of polycyolic oxazines and azines-II

1085

1321-1304 (w-m); (vii) 1270-1240 (w-m) and (viii) 1200-1160 (m-s). Bands (i)(vii) are ascribeable to C-C and C--N ring vibrations while band (viii) is probably associated with the C-O-C stretching mode. It is interesting to note that the 6,13-dimethyl compound does not absorb in the region 1200-l 160 cm-l but shows strong and unique absorption at 1111 cm-l, B-methyl- 13-isopropyltriphenodioxazine also shows this characteristic behaviour. As is to be expected, the methoxytriphenodioxazines exhibit additional intense bands in the C-O-C region and those near 1270 cm-l are ascribed to the ether linkage of the methoxy groups. The weak absorption in the region 1450-1429 cm-l which is only observed in the spectra of the methyl derivatives is ascribeable to the asymmetric C-H deformation of the methyl groups, the symmetric mode is masked by the ring vibrations in the region 1390-1370 cm-l. Some triphenodioxazine derivatives exhibit absorption between 1615 cm-l and the frequency of their first intense band (i). This absorption (Fig. 1) is characteristic of the substitution pattern, thus the parent compound and its 6- (and 13-) substituted derivatives exhibit no bands in the region while compounds containing 3- (and/or lo-)methyl substituents exhibit a medium intensity peak near 1615 cm-l and those with methoxy groups in these positions exhibit a peak of intensity approaching that of the (i) band. Compounds with methyl groups in the l- (and/or 8-) position exhibit weak absorption near 1606 cm-l and either a medium intensity peak near 1578 cm-l or a shoulder on the high frequency side of the (i) band. The 2- (and/or 9-) methyl substituted compounds exhibit a weak band near 1608 cm-l and a shoulder near 1585 cm-l, here again the 2,9-dimethoxy derivative exhibits somewhat stronger absorption at 1608 cm-l and a strong band at 1585 cm-l. Finally, derivatives with 4- (and/or ll-) methyl substituents exhibit a single weak band near 1590 cm-l. There seems to be no correlation between the substitution pattern and the frequencies of the C-H in-plane deformation bands in the region 1200-950 cm-l but the frequencies of the out-of-plane deformation bands in the region 900-650 cm-l (Fig. 2) are related to the numbers of adjacent hydrogen atoms on the three individual carbocyclic rings. This correlation (Table 3) is similar to that observed for simple substituted benzenes and for phenazines [2]. AcLnowledgeme&s-The author is grateful to Mr. D. BAKER and Mr. A. FOOKS for assistance with the experimental work and to the Gillette Company for permission to publish the results. [2] J. F. CORBETT,Spectrochim.

Act~~20, 1665 (1964).