Abstract
IN connexion with the growing interest in the phenomenon of thermochromism1, we should like to describe some experiments with 1 : 3-diketo-2-phenyl-5-bromoindan (I). In contrast to 1 : 3-diketo-2-phenylindan, which exists only in a colourless, solid form, (I) exists in a deep violet, solid form (IIa or IIb) and an almost colourless, solid, ketonic form (I). Koelsch2, who discovered these forms, stated that by crystallization from non-polar solvents the white modification is obtained, and from polar solvents the violet-black modification is formed; he mentioned only acetic acid and benzene as solvents. According to our observations, dilute solutions of the violet-black form in ethyl benzoate are orange at − 10°, whereas at the boiling point of the solutions they are light-yellowish. The process is reversible and may be explained by assuming that, at high temperatures, the keto form is predominant, whereas in the cold the enol form (IIa or IIb) is present in greater concentration. This opens a route for the investigation of the position of the equilibrium between the keto and the enol forms in relation to temperature by the investigation of the visible spectrum.
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Schönberg, Ismail and Asker, J. Chem. Soc., 442 (1946). Hukins and Le Fèvre, J. Chem. Soc., 2088 (1949). Grubb and Kistiakowsky, J. Amer. Chem. Soc., 72, 419 (1950). Theilacker, Kortüm and Friedheim, Ber., 83, 508 (1950). Bergmann, Weizmann and Fischer, J. Amer. Chem. Soc., 72, 5009 (1950). Pullman and Berthier, Bull. Soc. Chim., (5), 17, 1097 (1950). Koelsch, J. Org. Chem., 16, 1362 (1951). Knott, J. Chem. Soc., 3038 (1951). Hirshberg, Loewenthal, Bergmann and Pullman, Bull. Soc. Chim., (5), 18, 88 (1951). Schönberg, Mustafa and Asker, J. Amer. Chem. Soc., 73, 2876 (1951). Mustafa and Hilmy, J. Chem. Soc., 1343 (1952).
Koelsch, J. Amer. Chem. Soc., 58, 1328 (1936).
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SCHÖNBERG, A., MUSTAFA, A. & ASKER, W. Thermochromism and Keto-Enol Tautomerism of Solutions of 1 : 3-Diketo-2-phenyl-5-bromoindan. Nature 171, 222 (1953). https://doi.org/10.1038/171222a0
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DOI: https://doi.org/10.1038/171222a0
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