1,4-Dioxaspiro(4.5)decane, 8-(1,1-dimethylethyl)- 2223-71-4 50825-76-8 8-tert-Butyl-1,4-dioxaspiro(4.5)decane EINECS 218-739-4 p-tert-Butylcyclohexanone ethylene glycol ketal