Pinachrome (1,1'-diethyl-6,6'-diethoxy-2,4'-cyanine iodide) is an organic compound , a methine dye with the chemical formula C 27 H 31 N 2 O 2 I. Used as an acid-base indicator , also previously used in photography as an optical sensitizer.
| Pinahrom | |
|---|---|
| Are common | |
| Chem. formula | C 27 H 31 N 2 O 2 I |
| Molar mass | |
| Classification | |
| Reg. CAS number | |
| SMILES | |
| Inchi | |
| Chemspider | |
| Pinahrom ( pH indicator ) | ||
| lower limit of pH 5.6 | upper limit pH 8.0 | |
| # FFF9F9 | β | Violet |
Pinachrome should not be confused with other related compounds: violet pinachrom and pinachromic blue (pinachrom blue, pinacyanol derivative).
History
After the discovery in 1902 of the sensitizing ability of ethyl red , the first cyanine dye, produced on an industrial scale from the end of the 19th century, the search began for more effective sensitizers in the long-wave region of the spectrum. Mita and Traube attempted to achieve this by extending the N-substituted chain with various alkyl substituents, but their attempts did not produce results. As a result, the maximum sensitization of ethyl red, lying at 520-570 nm., Was succeeded in raising Ernst KΓΆnig by weighting the molecule by introducing various substituents at positions 6,6 β² of the isocyanine molecule. This approach led to the creation of pinachrom, as well as other related dyes: pinaverdol , orthochrome T and pinachromium violet . However, all these dyes quickly became outdated, being replaced by more effective compounds [2] [3] .
Physical and chemical properties
Dark green crystalline powder. Weak base. Poor soluble in water, soluble in alcohol, hydrochloric acid [4] [5] . Usually used as iodide, it can also be isolated as other salts, but the name pinachrome refers only to iodide [5] .
Photographic emulsions sensitize up to 640 nm with a maximum in the range of 540β615 nm [6] .
Getting
Pinachrome is obtained from 6-ethoxyquinoline in the usual way of obtaining cyanine dyes. The method of obtaining pinachrome and other related compounds is described in German patent DE167770 [7] , issued in 1903 [8] .
Application
It was used as an acid-base indicator with a border transition of 5.6β8.0 pH from slightly pink to violet [9] [4] . For this purpose, prepare a 0.1% solution of the substance in ethyl alcohol [5] .
In the photo, it was used as a panchromatic sensitizer for the yellow and orange parts of the spectrum. For sensitizing photographic materials, pinachromium was usually used in a mixture with other sensitizers in order to create a continuous sensitivity curve, since the sensitivity band of each sensitizer individually is rather narrow. When using the pinachrom as a single sensitizer, dilutions of the order of 1: 50,000 can be used, such as, for example, in the recipe of the pinchromic sensitizer for photographic plates [10] .
Notes
- β 1 2 ChemSpider - 2007.
- β Venkataraman, 1957 , p. 1310-1312.
- β Mees, 1942 , p. 971-972.
- β 1 2 Kolthoff, 1928 , p. 1604.
- β 1 2 3 Townshend et al, 1993 , p. 804.
- β Glafkides, 1958 , p. 792.
- β Hoechst .
- β Mees, 1942 , p. 971-972, 985.
- β Nikolsky, 1967 , p. 362.
- β Joffe, 1929 , p. 333-335.
Literature
- Venkataraman K. Chemistry of synthetic dyes. - L .: State Scientific and Technical Publishing House of Chemical Literature, 1957. - Vol. 2.
- Nikolsky B.P. Chemist Handbook . - L .: Chemistry Publishing House, Leningrad Branch, 1967. - Vol. 4.
- Technique of physical experiment / ed. Ioffe A. f . - M., L .: State Publishing House, 1929.
- Glafkides P. Photographic chemistry. - London: Fountain Press, 1958. - Vol. 2.
- Kolthoff IM The one of the color indicator (Eng.) // Journal of the American Chemical Society: Journal. - 1928. - Vol. 50 . - β 6 . - p . 1604-1608 . - DOI : 10.1021 / ja01393a011 .
- Mees, CEK The theory of photographic process (English) . - New York: The Macmillan Company, 1942.
- Townshend A., Burns DT, Guilbault GG, Lobinsky R. et al. Dictionary of Analytical Reagents (English) . - Chapman & Hall, 1993.
Links
- German Patent DE 167770: Verfahren zur Darstellung von sensibilisierend wirkenden Farbstoffen der Cyaninreihe (German) . Farbwerke vorm. Meister Lucius & BrΓΌning in HΓΆchst a. M. (26. Mai 1903). The appeal date is December 5, 2017.