1,4-Dioxaspiro(4.5)decane, 8-(1,1-dimethylethyl)-2-methyl- 62406-83-1 8-(1,1-Dimethylethyl)-2-methyl-1,4-dioxaspiro(4.5)decane EINECS 263-534-5 p-tert-Butylcyclohexanone propylene glycol ketal