Jan. 20, 1955
UNSATURATED ALDEHYDES,KETONES AND CARBOXYLIC
ACIDS
383
TABLE I1 (Continued) Cpd. Calcd. Obsd. Carbon disulfide 1 427 428 2 427 424 3 427 423 4 451 451 >5 451 449 I? 451 449 7 453 451 8 458.5 459 9 458.5 459 10 458 5 459 12 804 504 13 504 50Zd 18 538 53Qd 16a 483 494 16b 491 494 17a 483 492 17b 494 492 18 481 479 19 481 479 21 478 478
Cpd. Calcd. Obsd Cyclohexane 13 478 475d 15 510 503d Chloroform 4 431 433 5 431 430 6 431 430 8 438 438 9 438 438 438 437 10 12 483.5 485 13 483.5 488d 515 516d 15 474 16a 462 474 16b 471 472 17s 462 17b 471 474 18 460.5 460 21 457 459
Cpd. Calcd. Hexane 419 5 426 8 15 501.5 18 448 I9 447 Alcohol 398.5 421 421 428.5 428.5 362 473 352 450 350
3 5 6 9 10 11 13 14 18 20
Obsd. 422b 427 500d 449 449 403 421 421 430 427 370’ 472d 352 450 347
Cpd. Calcd. Obsd. Pyridine 10 444 443 13 490 48Qd 16a 468 477 16b 477 477 17a 468 477 17b 477 477 Light ligroin 5 421 422* 16a 452 460 16b 460 460 17a 452 459 459 17b 460 18 451 452 19 451 451.5 21 448 448
Cpd. Calcd. Obsd. Ether 13 473 473d 4 5 8 9 10 13 16a 16b 17a 17b 21
Benzene 434 434 434 430 442 440 442 439 442 439 487 48Gd 464 472 474 472 464 472 474 472 461 460
Cpd. Calcd. Obsd. Methanol 5 417 420b 457 16a 447 457 16b 457 17s 447 457 17b 457 457 Petroleum ether 4 420 422 5 420 421 6 420 421 10 427 426 12 471 475 13 471 472d
a Experimental data: P. Karrer and E. Jucker, “Carotenoids,” Elsevier Publishing Co., Inc., Houston, Texas, 1950, unless otherwise indicated. b R. Kuhn and H . Brockmann, 2. physiol. Chem., 213, 192 (1932). e P. Karrer and C. H. EugP. Karrer and E. Leumann, ibid., 34, 445 (1951). e B. C. L. Weedon and R. J. ster, Helv. Chinz. Acta, 34, 1805 (1951). IVoods, J . Chem. Soc., 2687 (1951).
not be discussed at present, as there are no other data. Nrj was computed from the observed values for Amax of compounds 18 and 19 (Table 11); the value (Nr5= -0.9) is very close to that of Nrl as expected. However, in the case of compounds 16 and 17, better agreement was obtained with Nr5 = -0.3; therefore the structural formula of either dihydrorhodoxanthin (Table 11, 18) or aphanin (Table 11, l B j , probably the latter, is doubtful. In the case of the oxide substituents of caro-
[CONTRIBUTION FROM
tenoids, the ol,@-epoxyalkylgroup exerts a rather large bathochromic effect, but the effect of the furanoid oxide group (FO), computed from the observed values for xma, of compounds 1-10 (Table IT), is almost zero (NPO= f0.02). The ring of dihydro-bis-anhydro-0-carotene(r6, Table I) exerts a hypsochromic effect (NrR = -0.4) quite unexpectedly in view of its exocyclic ethylene structure. OSAKA,JAPAN
INSTITUTE O F POLYTECHNICS,
OSAKA ClTY UNIVERSITY]
Absorption Spectra and Chemical Structure. IV. Unsaturated Aldehydes, Ketones and Carboxylic Acids BY K E N ZHIRAYAMA ~ RECEIVED JULY 16, 1953 The wave length of the first absorption maximum of a conjugated system, with either a carbonyl or carboxyl group a t the a-position or a t both the a- and w-positions, also can be expressed by the functional relationship (Xmax)P = A - B C N .
The following equations, which are applicable t o polyene derivatives, were discussed in the appendix to Part I.
I!
For polyenes with the same chromophoric substituents in aand w-positions
+ b,,,t + R G e , 2 ( 1 - C*’) = .4” - R“/Ch’ =
(trnar)2
a
(3) (4)
Similarly for conjugated systems with only one heterochromophore which is in the a-position, the following equations may be applied ( h x ) *
= a’
f
= A’ -
kt
2
f BC’het’(1
-
CN)
B’CN
where a’ is the intercept value when N
(5) (6)
=
0, and
B and C have the meanings given in previous cases; the value for C used in 2 and 4 should be satisfactory for 6. For conjugated polyene a-aldehydes, A’ and B’ were computed from the observed values for A,, in petroleum ether’ with C = 0.920 and substituted in 6 to give (xe;:;)~ = (39.78 - 39.33 x o.92oq x 104 1 1 1 ~ 2 ( 7 ) The values calculated by 7 (Table I, 1-91 show good agreement with the observed values. Ketones, which can be considered as derivatives of aldehydes in which the hydrogen of the -CHO (1) As shown in part 11, the Xmax of polyenes in hexane, petroleum ether and light ligroin vary only slightly with the solvent; therefore in this part, the same value for B’ is used for the calculation of the Xmax in these three solvents. ConSequently, in many cases the observed values in light ligroin and in hexane are a little longer and a little shorter, respectively, than the corresponding calculated values.
VOl. 77
K&NZ6HIR.4YAMA
384
TABLE I ABSORPTION MAXIMA OF N0
P O L Y E N E S WITH ONE C A R B O X Y L OR
CARROXYI. S V B S l I I ‘ U E N T
Subst. and structurea rl .4c n R
Compound
I N @!-POSITION
Xmax, 0hsd.c
S o l v ,b
17
nip
Calcd.
” 1 lIc*. n o 2.4-Hexadienal 2 Ilex. 0 (i 3.1 3 2,4,6-0ctatrienal I ICY. 1 0 4 7 3 Retinene1 0 0 S .j ?,e. X a-Apo-2-carotenal 0 0 s .5 I’.e. 8 5 a-Citraurin li I’ e 1 0 8.9 9 p-Apo-2-carotenal , I lex. 1 0 8 $1 13-Citraurin $1 S (’ 0 9 , t; I. i. Apo-3-1ycoperictl 0 10 .(i T,,!. 10 0 0 Apo-2-lycopenal 9 1 I Lex 0 0 2.1 10 3,5-Heptadieii-Z-oiie n n o 9 .5 P e. 11 Dihydroxyseini-P-carotenorie 10 P.e. 1 0 9.9 12 &Butyl 8-apo-1-carotenyl ketone IO 9.9 ]..I. 73 1 1) Capsanthin 9 .9 I’.c. 10 1 (1 14 Capsanthin dipalniitate 9.9 I’.e. 10 I 0 15 Semi-p-carotenone 8 0 I 2 8 licx. 1t i 2,4,6-0ctatrien-l-oic acid 0 1 2.0 Flex. 17 3 3-Methyl-2,4,6-octatrien-l-oicacid 4 0 1 3 8 Ties. 18 2,4,6,8-Decatetraen-l-oic acid I,.]. 0 1 7.1 I In Meth ylazafrin 20 12 1 1 11.7 I>,l, Torularhodin L.1. 1 1 11.7 21 12 Torularhodin methyl ester a R = number of alkyl substituents; ri = number of conjugated rings rl (see Table I , part 111); Ac = number of carExperimental data, unless boxyl groups in a-position. b Hex. = hexane; p.e. = petroleum ether; 1.1. = light ligroin otherwise indicated, from P. Karrer and E. Jucker, “Carotenoids,” Elsevim Publishing Co , Inc., Houston, Texas, 1950. I(.Dirnroth, Angew. C h m . , 5 2 , 545 (1939). e L. F. Fieser, J . Org. Chem., 15, 930 (1950)
1 2 3 4
-
,
2
-
chromophore is substituted by an alkyl auxochrome, show a slight bathochromic effect in petroleum ether; however this effect is negligible in coniparison to that of the ethylene chromophore (about 4(r,), and equation 7 can be used without modification for a-keto conjugated polyenes. The examples given in Table I (1 0-15) show good agreement. On the other hand, carboxylic acids, in which the hydrogen of the -CHO chromophore is replaced by an -OH auxochrome, show a marked hypsochromic effect in petroleum ether, about 30% of the bathochromic effect of the ethylene chromophore. Therefore, the Amax of conjugated polyene a-carboxylic acids may be calculated by 7 if h7acid = -0.3 is taken into consideration2; actually the calculated values in Table I (16-21) agree well with the ~ b s e r v e d . ~ Now, a,a” and a’ in equations 1, 3 and 5 , respectively, are compensatory terms, representing partial effects which do not change in progression, and there exists an approximate relationship between them, 2a’ = a of’. Thus 2(a’
+
+
bhet/2)
a f (a” $-
bhet)
(8)
and for polyene apdialdehydes a”
+
=
3.02
which is obtained by substituting a = -2.12 found for polyenes and a‘ b h e t / 2 = 0.45 for polyene-a-aldehydes (see equation 7) in equation 8. From these data and the observed values, the
+
-
-
(2) -CHO -COR or -COOH cannot be regarded as simple auxo=CR--, because in the chromic substitution, such as =CHformer auxochromic substitution occurs not in the homochromophore, but in t h e heterochromophore. As there are insufficient data for t h e exact computation of parameters A’ and B’ (or A” and B ” ) , we assume t h a t t h e homoconjugation method is applicable t o these cases and that the change occurs in N. (3) T h e method of calculation of N and Xmax is illustrated in part 11.
TABLE I1 ABSORPTIONMAXIMAOF POLPENES WITH CARBONYL OR CARBOXYL GROUPSAT 01- AND LO-POSITIONS NO.
1 2 3 4 5 8 7 8 9 10
11 12 13
14 15
16 17 18
Compound Apo-3,12-lycopenediaI Apo-2,lZ-lycopenedial 8-Carotenone aldehyde 4-Hydroxy-8-carotenone aldehyde Capsylaldehyde Capsanthylal Apo-2-norbixinal methyl ester Apo-1-norbixinal methyl ester 8-Carotenone Physallienone Capsorubin Capsorubin dipalmitate Capsanthinone Azafrinone hlethylazafrinone Crocetin Crocetin dimethyl ester Methylbixin
” See a , Table I.
Subst. and structurea Xmax. my n R Ac N S01v.b 0bsd.c Calcd. 453 8 4 0 8 . 4 P.e. 452 468 9 4 0 9 . 4 P.e. 468 434 7 3 0 7 . 3 Hex. 43 1 7 7 8
3 3 4
0 0 0
7.3 7.3 8.4
Hex. 433 Hex. 431 P.e. 452
434 434 453
7
3
I
7.0
P.e.
424
428
8 9 9 0 9 9 7 7
4 4
1 0 0 0 0
8.1 9.4 9.4 9.4 9.4 9.4 7.0 7.0 6.8 6.8 8.8
P.e. Hex. P.e. L.1. Hex. Hex. L.1. L.I. L.1. L.I. Hex.
445 466 464 474 474 472 429 429 424.5 424.5 450
448 4fi7. B 467.5 467.5 487.5 467.5 430 430 424.5 424.5 469
7 7 D
4
4 4 4 3 3 4 4 4
0 1 1
2
2 2
See h, Table I. C Experimental data from P. Karrer and E. Jucker, “Carotenoids,” Elsevier Publishing Co., Inc., Houston, Texas, 1950. b
parameter B” was calculated to be 34.67. = (37.60 - 34 67 X 0.920”) X
Thus
lo4 mM2 (9)
is the equation for polyene a,w-dialdehydes (Table 11, 1 and 3 ) ; the same equation is also applicable to a-keto-w-aldehydes (11, 3-6) and to a,w-diketones (11, 9-13). Equation 9 also can be used for a-aldehyde-w-carboxylic acids (11, 7 and 8), Qketo-w-carboxylic acids (11, 14 and 15) and a,wdicarboxylic acid (11, 16-18), with ?LTacld = -0.3 as previously determined. OSAKA,JAPAN
