Triethylamine → 3-Ethyl-5-[5,5-dimethyl-1-(1-pyrrolidinyl)-1-cyclohexen-3-ylidene]rhodanine

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Reaction Steps

N-(3-Chloro-5,5-dimethylcyclohex-2-en-1-ylidene)-pyrrolidinium perchlorate (3.1 g., 0.01 mol.), 3-ethylrhodanine (1.6 g., 0.011 mol.) and triethylamine (3.1 ml.) are dissolved in ethanol (20 ml.) and heated at reflux for 10 minutes. After chilling, the solid is collected on a filter, rinsed with ethanol and dried. After one recrystallization from pyridine/methanol, the yield of purified dye is 2.2 g. (65%), m.p. 234°-235°C. with decomposition. This dye is an excellent spectral sensitizer for photographic silver halide emulsions in the minus blue region of the spectrum as set forth in Table 2 hereinafter.

Provenance & Evidence