Malononitrile → [5,5-Dimethyl-1-(1-pyrrolidinyl)-1-cyclohexen-3-ylidene] malonitrile

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Reaction Steps

N-(3-Chloro-5,5-dimethylcyclohex-2-en-1-ylidene)-pyrrolidiniumperchlorate (9.4 g., 0.03 mol.) and malononitrile (2.0 g., 0.03 mol.) are dissolved in warm ethanol (25 ml.). Triethylamine (4.6 ml.) is then added and a vigorous reaction takes place with a solid precipitating. The mixture is then heated at reflux for 5 minutes. After chilling, the crude dye is collected on a filter and rinsed with ethanol and dried. After one recrystallization from methanol, the yield of purified dye is 3.0 g. (83%), m.p. 246°-247°C. This purified dye is an excellent light-absorbing dye in photographic layers as shown in the absorption data in Table 1 hereinafter.

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