PHENOL BLUEDERIVATIVES OF INDOANILINE DYES
Nov., 1946
Anal. Calcd. for CJIlrOS: C, 77.8; Found: C, 77.9; H, 5.27; S, 11.7.
H,5.08; S, 11.5.
2,4-Difumuylidene-3-ketotetrahydrotMophene (Xvm,
R = C4HaO).-Under the conditions described above for the analogous dibenzylidene derivative, 0.3 g. of 3ketotetrahydrothiophene yielded on treatment with furfural (1.0 g.) the difurfurylidene derivative (0.75 g.); the brick red needles from glacial acetic acid gave a m. p. 193 Anal. Calcd. for CleHl003S: C, 65.1; H,3.88. Found: C, 65.1; H, 4.16.
'.
[COMMUNICATION
NO. 1091 FROM
THE
2235
summarp The Dieckmann cyclization of a,P'-dicarbomethoxymethylethyl sulfide under two different sets of experimental conditions has been shown to result in the formation of two different cyclic Bketo-esters, namely, 4-carbomethoxy-3-ketotetrahydrothiophene and 2-carbomethoxy-3-ketotetrahydrothiophene. CAMBRIDGE, MASS.
RECEIVED JUNE 17, 1946
KODAKRESEARCH LABORATORIES]
Indoaniline Dyes. I. Some Phenol Blue Derivatives with Substituents in the Phenol Ring BY PAULW. VITTUMAND GORDON H. BROWN The indoaniline dyes have received little attention in recent years because their usefulness is limited by a general instability.' With their increasing use2 as cyan dye images in color photography, however, a more complete examination of these and related dyes is now of interest. This paper describes the ireparation and properties. of a selected group of indoaniline dyes related to the simple dye, Phenol Blue, but having substituents in the phenol ring. Phenol Blue has been prepared most conveniently by oxidizing an alkaline solution of p-aminodimethylaniline and phenol. The reaction has been reported to be effected by various oxidizing
(
c
H
~
)
~
N +
0 ~
-
~ + ~2
[~ + ~ ~
+
( C H ~ ) ~ N ~ - - N ~ ZH*O = = O
h y p o c h l ~ r i t e . ~Of ~ ~these, ~ ~ the last reagent, as used in the procedure of Fieser and Thompson,' proved the most satisfactory for the preparation of the substituted dyes, but in some cases the phenol was attacked by the hypochlorite, leading to side products which made the isolation of the pure dye very difficult or impossible. The search for a more satisfactory procedure led to an adaptation of the photographic process of color developmerit2 which could be used to great advantage.
TABLE I PHYSICAL PROPERTIES OF DYES:(CH3)2N \--/
X Substituent,
X
M.P., O C . '
-H 2-CHI
161-162b 123-124'
3-CHa
ll8-119d
2x1 3-Cl 2-Br
125 (dec.)' 144-145J 119-120 (dec.)
2-OCHa 167-168 141-142' 3-OCHa 2-NHCOCHa 184-185 3-NHCOCH1 150-151 2-CH9OH 157-158 ~-CH=CHC:OC~HI 1 58- 159
Crystallized
Appearance of from crystals Dark purple needles Ethanol Dark purple crystals, green Ligroin reflection Black metallic crystals, gold Ligroin reflection n-Butanol Lustrous dark green needles Carbon tetrachloride Dark purple metallic needles Fine dark blue needles, green n-Butanol reflection Ethanol Dark purple crystals Ligroin Purple-black crystals Ethanol Dark golden needles Ethanol Gold crystals Dark purple crystals n-Butanol Ethyl acetate Fine green needles
Hydrogen, % Nitrogen, % Carbon, % Calcd. Found Calcd. Found Calcd. Found 74.34 7 4 . 2 9 6 . 1 9 6 . 2 1 12.39 12.54 6 . 7 8 11.67 11.86 7 5 . 0 0 74.83 6 . 6 7 7 5 . 0 0 74.84
6.67
6.54
11.67 1 1 . 8 5
64.49 64.58 64.49 64.28 55.10 55.29
4.99 4.99 4.26
5.10 4.64 4.10
10.75 10.75 9.18
70.31 70.31 67.84 67.84 70.31 77.53
6.25 6.25 6.01 6.01 6.25 5.62
6.38 6.16 6.08 5.65 6.40 5.41
10.94 1 0 . 7 4 10.94 10.86 14.84 14.91 14.84 1 4 . 8 0 10.94 10.91 7.87 7.93
70.02 70.25 67.72 67.85 70.29 77.24
10.87 10.67 9.25
* Fieser' gives 161' from ethyl acetate; Heller,' 167"from a Melting points determined with Fisher-Johns apparatus. Fieser' gives 127"; Bayrac4 gives 123". Fieser' gives 121"; Bayrac' alcohol; and Gnehm, 160" from ethyl acetate. gives 117-11S0. e Bayrac' gives 125-126'. f Fieser' was unable to crystallize. Isolated as leuco form. agents : potassium potassium ferricyanidela potassium permanganate3 and sodium (1) See, for example, Bucherer, "Lehrbuch der Farbenchemie." 0. Spamer, Leipzig, 1914, p. 293. (2) R. Fischer. u. s. Patent 1,102,028 ( i g i 4 ) , and many more reent patents. (3) Koechlin and Witt, German patent 15,915 (1881). 14) Rayrac. A n n rhim., (71 10, 18 (1897)
In this procedure, the oxidizing agent was silver cltloride, which was found to react readily with the p-phenylenediaminewithout attacking the phenols. The dyes prepared from p-aminodimethylaniline and the substituted phenols are listed in Table 1(5) Gnehm, J . graM. Ckcm.. 69, 162 (1904). (6) Heller, Ann., 891, 16 (1912). (7) Fieser and Thompson. Tms J O T I R N A L . 61, 376 (1939)
PAULW. VITTUMAND GORDON H. BROWN
2236
+ 2Ag+ +2 [RlN-(I>-SH2
2RnN--C>-NHn
I
R
2
Vol. 68 d
e
1
] -k 2 Ag
b
a
I1
R
*
N
-
~
V
-~
N
--
R
~
=
o
N
~
+I1
N
H
IV
-
J.' -
-
~
0 - 0 111
+ OR~N--C~)--"~ + H+
-
1
Attempts to prepare the dyes from 2,6-dichloro- be considered to be oxidized to the dye (V) by anphenol, 2,6-dibromophenol and o-(N-methylacet- other semiquinone ion. amino)-phenol were unsuccessful. Dye formation The failure of phenols having o-CO- or groups to enter the dye-forming rewas obseded to occur, but the dyes were too un- -CH=Nstable to permit isolation. o-Hydroxyacetophe- action may be explained by a reasonable extennone, ethyl salicylate,, salicylamide, and salicylal- sion of this mechanism, taking into account the doxime also failed to yield dyes. With these phe- resonance systems of the phenolate ions. With nols, each with an o-carbonyl or -CH=N-group, phenol itself, struictures such as VI, in addition to little or no dye formation appeared to take place. the KekulC structures, probably make an appreciThe mechanism of the dye formation reaction able contribution to the state of the ion,1° and this probably involves,*f i s t , an oxidation of the diamine (I) to a iemiquinone ion, which is stabilized by 4=== )0 the resonance IIa t-f IIb,S and which reacts with \\ C-Othe phenolate ion (111) to yield the leuco dye (IV), I a second semiquinone ion acting as a hydrogen acVI1 VI ceptor for the latter step. The leuco dye may then structure probably contributes largely to the stable activated complex in the dye-forming reaction. When an o-CO- group is present, however, structures analogous to VI are probably relatively 30 unimportant compared to structures such as VII, l1 in which the carbon p- to the phenolic oxygen is not activated to the extent necessary for the dyeforming reaction. The absorption spectra of the dyes were deter'2 20 mined in four solvents selected to cover a wide X range of polarity. Figure 1 shows the absorption curves for some of the dyes in methanol, illustrating their general shape. The values for Amax. and Emax. are listed in Table 11, and some of them are 10 arranged graphically in Figs. 2 and 3. Interpretation of these absorption data follows that of the parent dye, Phenol Blue (VIII, X=H), which is best represented by the resonance scheme VIIIa ++ VIIIb.12 Brooker and SpragueI3showed 4 000 5000 6000 7000 that the absorption of Phenol Blue was affected by the solvent, the absorption band in the visible reA. gion moving in the direction of longer wave Fig. 1.-Absorption of dyes length as the polarity of the solvent was increased. (cHJ~N--
