Effect of Fluorine Substitution on Color and Fastness of Monoazo Dyes J. B. DICKEY, E. B. TOWNE, >I. S. BLOOM, G. J. TAYLOR, H. RI. HILL, R. A. CORBITT’, M. A. 3ScCALL, W. H. MOORE, AND D. G. HEDBERG Research Laboratories, Tennessee Eastman Co., Kingsport, Tenn.
A
S PART of a continuing program to synthesize cellulose acetate dyes which exhibit superior light and gas fastness, a large number of azo dyes which contain fluorine have been prepared. Many of these dyes exhibit greater stability to light than their unfluorinated homologs. However, this property is not so general as to warrant the conclusion that all fluorinated dyes have excellent light fastness ( 1 7 ) . I n fact, it was found in this study that the proper choice of diazonium and coupling constituents is necessary to obtain light-fast dyes. In general, however, gas fastness of the fluorinated azo dyes was found to be excellent. In addition to the Naphthol AS dyes ( 2 5 ) , there are several other monoazo dyes containing fluorine in the coupling and diazonium constituents. Dyes containing trifluoromethyl groups in the ring of an aniline (11)or tetrahydroquinoline ( 1 2 ) coupler have been patented, as have those containing a trifluoroacetamido group ( 6 ) . 2-iiitro-4-( trifluoromethy1)aniline has been diazotized and coupled with naphthols and pyrazolones to yield yellow dyes (18). 2,4Dinitro-6-(trifluoromethyl)aniline has been diazotized and coupled with aniline and naphthol derivatives to form violet dyes ( 5 ) . Diazotized 4-nitro-2-(trifluoromethyl)aniline has been coupled with N-hydroxyalkylamino-5-naphthols ( 2 4 ) , with pyrazolones and naphtholsulfonic acids (4), and with A7-(2-cyanoethyl)-N-(hydroxyalkyl)anilines ( 8 ) . Brownish-red dyes have been made by coupling diazotized 4-nitro-2,6-bis(trifluoromethy1)aniline with iV-substituted m-ethylanilines ( 7 ) and by coupling diazotized 4-nitro-2-halo-6-(trifluoromethyl)anilines with N,N-bis(2-hydroxyalkyl)anilines (10). Diazotized 4-nitro2-fluoroaniline has been coupled with N-(hydroxyalky1)tetrahydroquinolines and phenomorpholines to give pinkish-red dyes (RW) and with N-(hydroxyalky1)anilines to yield dyes which on reduction form developed dye bases (Wl). The influence of fluorine on the fastness properties and color of the dyes of this study are considered on the basis of the two dye constituents-fluorinated couplers and fluorinated diazonium compounds. Comparative light fastness evaluations given in Tables I and I1 are based on Fade-Ometer tests on pastel dyeings. Gas-fastness tests were made by exposing pastel dj-eings to “burnt gas” fumes. Fluorine substitution in the N-alkyl group of the coupler was found to have much more effect on color than fluorine substitution in the diazonium constituent. DYES FROM FLUORINATED ANILINE COUPLERS
This study is primarily concerned with the monoazo dyes made from N-(polyfluoroalky1)aniline couplers, such as N-( 2,2-difluoroethy1)-hT-(2-hydroxyethyl)aniline. These dyes and couplers (9, 27) have not been previously described except in patents from this laboratory. A detailed report on the preparation and properties of the N-(fluoroa1kyl)anilines and their N-hydroxyalkyl derivatives is the subject of another paper (13). I n general, these couplers were prepared by treating aniline or a substituted aniline with a fluoroalkyl bromide or chloride to yield an N-(fluoroalky1)aniline. The latter was then treated with ethylene oxide, propylene oxide, 3-bromo-l-propanol, or l-chloro-2,3-propanediol to 1
Present address, Eastman Kodak Co., Rochester, N. Y .
form the corresponding N-(fluoroalky1)-N-(hydroxyalkg1)aniline. The dyes were made by condensing these fluorinated couplers with a variety of fluorinated and unfluorinated diazotized aniline derivatives. The couplers used contained the following fluoroalkyl groups : 2-fluoroethyl, 2,2-difluoroethj-I, 2,2,2-trifluoroethyl, 2,2-difluoropropyl, 3,3-difluoropropyl, 3,3,3-trifluoropropyl, 3,3-difluorobutyl, 4,4-difluoroamyl, and 2,2,3,3,4,4,4-heptafluorobutyl. The effect of these various groups on the color and light fastness of a dye molecule is shown in Table I. The general formula of the dyes is given a t the top of the table. The R-groups are listed in the order that the color of the dye shifts from yellow to violetthat is, shifts the absorption maxima to longer wave length. The 2-cyanoethyl, 2-hydroxyethyl, and ethyl groups are included for comparison with the groups containing fluorine. The gas fastness of all the fluorinated dyes is excellent, being equal to or better than that of the corresponding unfluorinated dyes in every case. They also have good exhaustion and level dyeing properties, discharge well, and are resistant to crocking and sublimation.
TABLE I. EFFECT OF FLUOROALKYL GROUPSON COLOR AKD LIGHT FASTNESS CHzCHzOK
Noz-~-N=N-c>.;, ‘SO2CH3 IiO.
1 2 3 4
5 6
7
8 9 10
11 12
R CFjCFnCFzCHz CFsCHz CHFzCHz CHnCFzCHz C S C HICHz CFGHzCHz C H €IC HzC Hz CHaCFzCHzCHz CHzFCH2 CHZCF~CHZCHZCHI HOCH2CHz CHsCHz
Color of Dye Yellow Scarlet-orange Orange-red Orange-red Red Reddish-rubine Reddish-rubine Rubine Rubine Violet-rubine Violet-rubine Violet-rubine
Light Fastness Excellent Excellent Very good Excellent Good Excellent Good S’ery good Fair Good Fair Poor-fair
From a study of this series, the following observations can be made: -4s the number of fluorine atoms on a single carbon atom is increased (for example, 2-fluoroethyl to 2,2-difluoroethyl to 2,2,2-trifluoroethyl), the color shifts from rubine to scarletorange. As the distance from fluorine to nitrogen is increased (for example, 2,2-difluoroethyl to 4,Cdifluoroamyl), the color shifts from orange-red to violet-rubine. The heptafluorobutyl group causes a n even more pronounced shift toward yellow than the trifluoroethyl group. The 2-cyanoethyl group gives about the same color (red) as the 3,3,3-trifluoropropyl group. The 2-hydroxyethyl and ethyl groups have a greater effect than the 4,4-difluoroamyl group in shifting the color toward violet. The light fastness of the fluorinated dyes is generally excellent. The effect of replacing the 2-hydroxyethyl group in the general formula of the dye of Table I by a 2-hydroxypropyl, 3-hydroxy-
1730
August 1953
INDUSTRIAL AND ENGINEERING CHEMISTRY 2.5
I
1
tt-" I
2.0
1731
R
C3F,CH,
CHF, CHI 1-( 7 CHFpCHpCHp 10 CHSCF, GHpCHpCHp 3
1.5
t= w
1.0
2 W 0
0.5
WAVE LENGTH, rnp WAVE
LENGTH, m p
Figure 1. Absorption Spectra of Fluorine-Substituted Dyes of Table I propyl, or 2,3-dihydroxypropyl group is to shift the color slightly from orange toward rubine. Substitution of a methyl group in the meta position of an N (fluoroalky1)aniline coupler has the same pronounced effect that it has in an unfluorinated coupler. If the coupler is derived from m-toluidine instead of aniline, the color of the dye is shifted definitely from orange toward rubine. On the other hand, if the coupler is substituted in the meta position with a trifluoromethyl, chloro, or fluoro group, the change in shade is less noticeable. The substitution of a methyl group in the ortho position of an N-(fluoroalky1)aniline shifts the color of the dye from red toward yellow. Figure 1 shows absorption spectra in the ethyl series, CF~CHZCHF2CHz-, CH2FCHz-, and CHaCH2--. The color shift is from scarlet-orange to violet a8 the number of fluorine atoms is decreased. Figure 2 shows absorption spectra in the series, C~F~CHZ-,CHFZCHZ-, CHF~CHZCHZ-,and CHaCF2CHzCHzCHZ-. The color shift is from orange-red to violet-rubine as the fluorine atoms are moved away from the nitrogen atom. The C3F7CH2- group gives a yellow dye. DYES FROM FLUORINATED DIAZONIUM COMPOUNDS
The preparation of the various fluorinated diazonium compounds used in this study is given in the experimental section of this paper. The diazonium compounds are represented by the following formula :
/y N02-C>-NyX
Figure 2. Absorption Spectra of Fluorine-Substituted Dyes of Table I aminating the resulting products. The compounds in which Y is chloro or bromo were prepared by halogenating 4-nitro-2(trifluoromethy1)aniline. The compound in which Y is trifluoromethyl was prepared by fluorinating 2,6-bis(trichloromethyl)-I-chlorobenzene, then aminating the latter compound. 4-Nitro-2-fluoroaniline was prepared by nitrating 1,2-difluorobenzene, then aminating the resulting nitrodifluorobenzene. The influence of these various fluorinated diazonium compounds on the color and light fastness of dyes is shown in Table 11. The general formula of the dye is given a t the top of the table. The R-groups of the diazonium compounds are listed in the order that color shifts from blue to orange. Several unfluorinated R-groups are included for comparison with those containing fluorine. A fluorinated coupler was used because the dyes obtained have much better light fastness than those made from an unfluorinated coupler. The gas fastness of all the fluorinated dyes is excellent, being equal to or better than that of the coir+ sponding unfluorinated dyes in every case. From a study of this series, the following observations can be made: The effect of a fluoro or trifluoromethyl group in the nucleus of a diazotized aniline derivative is not nearly so pronounced as it is in the nucleus of the N-(fluoroalky1)aniline couplers. For example, dyes from a diazotized 4-nitroaniline derivative containing a trifluoromethyl, fluoro, chloro, methyl, or hydrogen group ortho to the amino group have about the same color, ranging from orange-red for trifluoromethyl, fluoro, and chloro (6, 7, and 8 of Table 11) to orange for methyl and hydrogen (9 and 10). Thus, when the methyl group is replaced by the trifluoromethyl group, the color of $he dye is shifted toward blue. Similarly, the dyes from 4-nitro-2-(trifluoromethyl)aniline substituted in the 6position with a trifluoromethyl, bromo, or chloro group (11, 12, and 13) have the same brownish-orange color. These dyes have excellent fastness to light. The influence of two nitro groups in the diazonium compound is to shift the color toward blue, as shown by dyes 1, 2, 3, and 5 in Table 11. These four dyes have very poor light fastness, a e
where Y = H, C1, Br, NOz, CFI
\
CF3
The compounds in which Y is hydrogen or nitro were prepared by mono- and dinitrating 2-(trifluoromethyl)chlorobenzene, then
INDUSTRIAL AND ENGINEERING CHEMISTRY
1732
Vol. 45, No. 8
2.5 OF FLUORLNATED DIAZOXIGM COMPOUXDS ON TABLE 11. EFFECT
COLORA K D LIGHTFASTNESS CHzCHFz
/
-N
/
CH3
R
NO
\CHzCHaOH
Color of Dye
2.0 Light Fastness
NO2 Violet
1
Poor
5 -
1.5
0 W-
s Rubine
2
Poor
>t VI z w n
3
. 0 . - a -
Pink-rubine
Poor
Red
Good
Red
Poor
Orange-red
Good
1.0
\
'cl
0.5 4
YO*-c_7>80*CHa NO2
5 6
x 0 - a -
WAVE
Figure 3.
\
CF3 7
0.0,
Orange-red
LENGTH,
mp
Absorption Spectra of Fluorinated Dyes of Table I1
Fair
8
Orange-red
Good
9
Orange
Poor
10
Orange
Poor-fair
I n general, these dyes have absorption maxima a t longer wave lengths than the dyes containing only one nitro group. Figure 4 shows absorption spectra of dyes from 4-nitro-2-substituted diazonium compounds (6, 7 , 8, and 9 of Table 11). The trifluoromethyl, fluoro, and chloro groups give approximately the same color. Compared to the corresponding methyl compound, the color is shifted toward blue. Figure 5 shows absorption spectra of dyes from 4-nitro-2-trifluoromethyl-6-substituteddiazonium compounds (11, 12, and 13 of Table 11). All three exhibit approximately the same brownish-orange color. EXPERIMENTAL PROCEDURE
11
Brownish-orange
Very good
12
Bronnish-orange
Excellent
13
Brownish-orange
Very good
Preparation of Intermediates. The preparation of the N (di- or trifluoroalkyl)-N-(2-hydroxyethyl)aniline couplers is to be the subject of another paper (IS). The following procedure is typical : ~ ~ - ( ( 2 , 2 - D I F L U O R O E T H Y L ) - ~ r - ( ~ - H Y D R O X Y E T H Y L ) A ~ I L I N E2,2. Difluoroethyl bromide (H),73 grams (0.5 mole), 47 grams (0.5 mole) of aniline, 42 grams (0.5 mole) of sodium bicarbonate, and 1 gram of sodium iodide were heated in a rocking autoclave for 15 hours a t 150" C. The reaction product was dissolved in toluene, washed with water, and the solvent removed. Rectification yielded 58 grams (74%) of Ar-(2,2-difluoroethyl)aniline, boiling point 104" to 106" C. a t 19 mm. A solution of 15.7 grams (0.1 mole) of N-(2,Z-difluoroethy1)aniline and 5.2 grams (0.12 mole) of ethylene oxide in 15 ml. of ethanol cooled to 5" C. was placed in a cooled rocking autoclave and then heated a t 200" C. for 15 hours. Rectification of the product yielded 15 grams (75%) of Ar-~2,2-difluoroethyl)AV-(Z-hydroxyethyl)aniline, boiling point 123 to 125" C. a t 3 mm.
well-known defect of dyes from dinitrodiazonium compounds with unfluorinated couplers. The first dye in Table I1 is a poor violet, but if N-(4,4-difluoroamyl)-N-(2-hydroxyethyl)-m-toluidine is used as the coupler, a deep, bright violet-blue dye results; this blue dye, however, also has poor light fastness.
The various fluorinated-aniline diazonium constituents were prepared as follows:
Figure 3 shows absorption spectra of dyes which contain two nitro groups in the diazonium constituent (1,3, and 5 of Table 11).
4-hTITRO-2-(TRIFLUOROMETHYL)ANILINE (4). A Suspension Of 100 grams (0.445 mole) of 4-nitro-2-trifluoromethyl-I-chlorobenzene (7, 16, 19) in 300 ml. of concentrated aqueous am-
INDUSTRIAL AND ENGINEERING CHEMISTRY
August 1953
monium hydroxide was heated in a rocking autoclave for hours a t 170' C. Filtration yielded 78.5 grams (86%) of nitro-2-(trifluoromethyl)aniline, melting point 90" to 92" The amination was also conducted in ethanolic ammonia 120" C. for 8 hours. Results were equally good.
12 4C.
at
1733
bromo-4-nitro-6-(trifluoromethyl)anilinewas 26 grams (91.3%))
melting point 140" to 142" C.
2-AMINO-N-El"YL-3,5-DINITROBENZENESULFONAMIDE. This compound was prepared as described in the patent literature (13). 2-METHYLSULFONYb4-NITROANILINE. The preparation O f this compound was similar to that of the ethyl homolog (16). 2Methylsulfonyl-4-nitro-1-chlorobenzenewas treated with excess 28% ammonium hydroxide in a rocking autoclave at 170" to 180 C. for 12 hours. The product melted a t 204" to 205' C. 2-Methylsulfonyl-4-nitro-1-chlorobenzene was prepared by first reducing 2-chloro-5-nitrobenzenesulfonylchloride (14) Tith sodium sulfite in alkaline solution to obtain the corresponding sodium sulfinate (10). The sulfinate was then treated with sodium chloroacetate in aqueous solution in the presence of a trace of potassium iodide. The yield of product melting at 171" to 173' C. was 80%.
Preparation of Dyes. DIAZOTIZATION. The fluorinated and unfluorinated aniline derivatives listed in Table I1 were all diazotized by the nitrosylsulfuric-acetic acid method, with the exception of 2-chloro-4-nitroaniline and 2-fluoro-4-nitroaniline which were diazotized in dilute sulfuric or hydrochloric acid. The diazotization of 2-methylsulfonyl-4-nitroanilineis typical :
I
I
I
1
I WAVE
Figure 4.
LENGTH. rnp
Absorption Spectra of Fluorinated Dyes of Table I1
2-FLUORO-4-NITROANILINE (6, 31). A suspension O f 144 grams (0.9 mole) of 4nitro-l,2-difluorobenzene (6, 81) in 630 ml. of 28% ammonium hydroxide was heated in a rocking autoclave for 6 hours a t 150' to 160" C. After cooling, the reaction mixture was removed from the autoclave, and the solid roduct was crystallized from 4 liters of 50% aqueous alcohoy. The yield was 126.4 grams (96%) of 2-fluoro-4nitroaniline, melting point 135' to 136' C. 2,4DINITRO-6-(TRIFLUOROMETHYL)ANILINE (3). 2,4-Dinitro6-trifluoromethyl-1-chlorobenzene (16),210 grams (0.77 mole), was added to 1500 ml. of ethanol which had been saturated with ammonia. Ammonia was then bubbled into the solution for 2.5 hours at 25" to 30' C. The solution was heated on a steam bath for 30 minutes. The flask was then stoppered, and the solution was allowed to stand overnight. The product was poured into 3 liters of cold water. The yellow precipitate that formed was washed and dried. The yield was 188 g r a m (9i'0/0j of 2,4-dinitro-6-(trifluoromethyl)aniline, melting point 114 to 115' C. 4-NITRO-2,6-BIS(TRIFLUOROMETHYL)ANILINE (4, 7 ) . A SOlUtion of 30 grams (0.102 mole) of 4-nitro-2,6-bis(trifluoromethyl)1-chlorobenzene (4, 7 ) in 300 ml. of alcohol was saturated with 33 grams of ammonia, then heated in a rocking autoclave for 7 hours at 105' C. The cooled product was poured into water, filtered, and dried. The yield was 21 grams (75%) of 4-nitro2,6bis(trifluoromethyl)aniline, melting point 145" to 147' C. ; from alcohol, melting point 147' to 149' C. 2-CHLORO-4-NITRO-6-(TRIFLUOROMETHYL)ANILINE (7, 10). A solution of 10.3 grams (0.05 mole) of 4-nitro-2-(trifluoromethyl)aniline (4) in 50 ml. of acetic acid, containing a trace of iodine as catalyst, was treated with chlorine at room temperature until the theoretical amount was absorbed. The tem erature during this time rose to 40" C. Bright yellow crystaI)s separated on standing overnight at room temperature. These were filtered, washed, and dried. The yield of 2-chloro-4-nitro-6-(trifluoromethy1)aniline was 6 grams (50%), melting point 115" to 116' C. 2-BROMO-~NITRO-6-(TRIFLUOROMETHYL)ANILINE (7, 10). A solution of 20.6 grams (0.1 mole) of 4nitro-2-(trifluoromethyl)aniline (4) in 100 ml. of acetic acid was treated dropwise with 16.8 grams of bromine in 100 ml. of acetic acid a t 40' C. The reaction mixture was then heated under reflux on a steam bath for 4 hours. The cooled reaction mixture was poured into water and filtered. T h e product was washed with sodium bisulfite solution and water, respectively, then dried. The yield of 2-
Dry sodium nitrite, 7.6 grams (0.11 mole), was added portionwise with stirring to 92 grams of 96y0 sulfuric acid, keeping the temperature below 70" C. during the addition and then cooling to 15' C. Then 100 grams of acetic acid was added dropwise with stirring a t 15' to 20' C. T o this solution, 21.6 grams (0.1 mole) of finely powdered 2-methylsulfonyl-4-nitroaniline was added portionwise with stirring at 15' to 20" C. This was followed by the dropwise addition of 100 grams of acetic acid a t the same temperature. Stirring was continued until solution and diazotization were complete. The cold diazonium solution was then poured onto 500 grams of crushed ice, filtered, and treated with 1 gram of either urea or sulfamic acid to destroy excess nitrous acid.
.'-
t^
I
,CH,CH,OH
CH e CHF,
I
I
R
.o
3
0
a-
s
>-
5
8
0.5
I
1
nn
w'~OO
450
500 WAVE
550
600
650
700
LENGTH, rnp
Figure 5. Absorption Spectra of Fluorinated Dyes of Table I1
COUPLING.A solution of 10 grams of sulfuric acid in 20 ml. of water was cooled to 5" C., and 20.1 grams (0.1 mole) of N(2,2-difluoroethyl)-N-(2-hydroxyethyl)anilinewas added a t this temperature. When solution was complete, 400 grams of ice water was added. To this cold coupler solution, the diazonium solution, prepared as previously described, was added with stirring. After about 15 minutes, 100 grams of sodium carbonate was added portionwise to neutralize the mineral acid. After coupling for about 1 hour, the dye was filtered, washed with water t o remove salts, then air-dried. The yield of dye melting at 125' to 130' C. was 40.6 grams (95%). Dyeing and Testing. The dyes were applied in the desired concentration to 10-gram samples of cellulose acetate jersey fabric from an aqueous dispersion by standard procedures. Test-
INDUSTRIAL AND ENGINEERING CHEMISTRY
1734
Vol. 45, No. 8
LITERATURE CITED
ing of the dyed fabric for light fastness ( 1 ) and gas fastness ( a ) was conducted by the standard procedures of the American Association of Textile Chemists and Colorists. Determination of Absorption Spectra. The absorption spectra were determined using a General Electric recording spectrophotometer. The dyes were dissolved in methanol. The concentration used was 1 part in 20,000 by weight.
(1) American rissociation of Textile Chemists and Colorists, “Technical Manual and Year Book,” Vol. 27, p. 101, New York, Howes Publishing Co., 1951. (2) Ibid., p. 91. (3) Daudt, H. W., and Woodward, H. E. (to E. I. du Pont de Nemours & C o . ) , U. S. Patent 2,194,925 (1940). (4) Ibid., 2,194,926 (1940). (5) I b i d . , 2,194,927 (1940). (6) Dickey, J. B. (to Eastman Kodak Co.), U. S.Patent 2,436,100 SUMMARY (1948). (7) Ibid., 2,491,481 (1949). N-Fluoroalkyl groups in the coupler cause the color to shift Ibid., 2,492,972 (1950). from violet toward yellow in the following order: CH~CFZCHZ- (8) (9) Ibid.. 2,516,106, 2,616,107, 2,516,302, 2,516,303 (1950); 2,590,CH*CH*--, CHzFCHz-, CH3CFzCHZCHa-, CHFzCH2CHz-, 092, 2,594,297, 2,615,013, 2,615,014, 2,618,630 (1952). C F I C H ~ C H ,CHaCFzCHz-, CHFzCHg-, CFzCHz-, CFa(10) Ibid., 2,618,631 (1952). CFzCFzCHz--. Thus, the degree of color shift is dependent (11) Dickey, J. B., and McXally, J. G. (to Eastman Kodak C o . ) , upon the number and position of the fluorine atoms. When at U. S. Patent 2,432,393 (1947). least two fluorine atoms are present on the second or third carbon (12) Ibid., 2,442,345 (1948). atom from the nitrogen atom in the N-fluoroalkyl group, the dyes (13) Dickey, J. B., et al., to be presented before the Division of Inhave enhanced light fastness and excellent gas fastness. dustrialand EnpineerinRChemistrv at the 124th Meeting A4.C.S., A 2-trifluoromethyl or 2-fluor0 group in a 4-nitrodiazonium Chicago, Ill., 1953. constituent shifts the colorof the dye slightly toward blue and (14) Fischer. Paul, Ber., 24, 3196 (1891). gives enhanced light fastness. When a 6-nitro group is also (15) Friedrich, 31. E., and Schniepp, L. E. (to E. I. du Pont de present in the diazonium constituent, the dyes are much bluer Nemours & Co.), U. S. Patent 2,257,093 (1941). but have poor light fastness. (16) Gesellschaft fur Chemische Industrie in Basel, Swiss Patent The diazonium compounds, 178,224 (1935). (17) Henne, A. L., in “Organic Chemistry-An Advanced Treatise,” 2nd ed., Vol. I, p. 963, Xew York, John Wiley & Sons, 1943. NG, - D - N z (18) Heyna, H., and Huber, H. (to General Aniline Works, Inc.), U. S. Patent 2,016,495 (1935). \ \ (19) I. G. Farbenindustrie, French Patent 745,293 (1932). SOdX CF3 (20) Krishna, Sri, J . Chem. Soc., 1923, p. 156. (21) McKally, J. G., and Byers, J. R., Jr. (to Eastman Kodak Co.), Br / U. S. Patent 2,391,179 (1945). (22) XcNally, J. G., and Dickey, J. B., I b i d . 2,342,678 (1944). N02--C>-N2X (23) I b i d . , 2,358,465 (1944). (24) I b i d . , 2,375,804 (1945). \ CF3 CF3 (25) Scherer, P., Angew. Chem., 52, 457 (1939). (26) Swarts, F., Bull. classe sci., h a d . roy. Belg., Ser. 4, 383-414 react with couplers containing a CF~CHZ-, CHFZCHZ-, (1901). CH3CF&Hz--, or CF3CH2CH2- group to give a series of superior (27) Towne, E. B., and Dickey, J. B. (to Eastman Kodak Co.), orange-to-red, gas- and light-fast dyes for cellulose acetate. U. S. Patent 2,500,218 (1950).
/”’
NO,--N,X
ACKNOWLEDGMENT
The authors are indebted to Sherman Hubbard, of the acetate yarn laboratory, for the absorption spectra.
RECEIVED for review November 17, 1952. ACCEPTED May 14, 1953. Presented as part of the Symposium on Fluorine before the Division of Industrial and Engineering Chemistry a t the 122nd Meeting of the AMERICAN CHEMICAL SOCIETY,Atlantic City, N. .J.
Oxide Film on Nickel-Chromium Allovs J
CRYSTAL STRUCTURE STUDIES EARL A. GULBRANSEN AND WILLIAM R . MCMILLAY Westinghouse Research Laboratories, East Pittsburgh, Pa.
B
ECAUSE of theirhighresistance to oxidation, the80%nickel20% chromium alloys are one of the most useful alloy systerns. Over the past 30 years the performance of alloys of this nominal composition in cyclic oxidation tests has been improved by over 600%, by reducing the manganese content, increasing the silicon content, and adding minor amounts of calcium, aluminum, zirconium, cerium, etc. Because of the complexity of the problem, comparatively little scientific work has been directed toward understanding the oxidation resistance properties of these alloys. The essential problem is: What factors
in the composition and crystal structure of the oxide film and alloy can be related to the improved protective properties? The resistance to oxidation a t constant temperatures of metals such as nickel and probably chromium (8, 9) can be correlated with the formation of cation vacancies and positive holes by solution of oxygen in the oxide and the diffusion of the severalmetal ions through these vacancies and electrons through the positive holes. Figure 1 shows two possible schemes of oxidation for a metal such asnickel. A shows the mechanism of diffusion of metal ions through the oxide to the oxide-gas interface where reaction
