Patent ID: 7381855

Claim:
A process for producing adamantane having an APHA color of 5 or lower by isomerizing trimethylenenorbornane, the process comprising: (A) isomerizing trimethylenenorbornane to produce a resultant liquid reaction mixture comprising adamantane; (B) concentrating adamantane contained in the resultant liquid reaction mixture until the adamantane concentration is 10 to 50 mass %; (C) precipitating the adamantane concentrated in the resultant liquid via crystallization at an operating temperature of about −20 to 50° C. and finally at a temperature at which the solubility of adamantane is about 0.5 to 25 mass % provide a slurry; (D) separating adamantane crystals from the slurry to provide isolated adamantane crystals wherein the degree of solid-liquid separation is such that a liquid content in a separated crystal cake is about 50 mass %; (E) washing the isolated adamantane crystals at a temperature of −20 to 50° C. using a solvent having a boiling point of 150° C. or lower; and (F) drying the washed adamantane crystals at a pressure of 5 to 101 kPa and a temperature of 20 to 60° C., wherein a mass ratio of endo-trimethylenenorbornane to adamantane contained in materials subjected to step (C) (endo-trimethylenenorbornane/adamantane) is 0.25 or lower and wherein the washed adamantane crystals have an APHA color of 5 or lower.