Materials Liable to Form Peroxides in Storage

Aldehydes
Ethers, especially cyclic ethers and those containing primary and secondary alcohol groups
Compounds containing benzylic hydrogen atoms (particularly if the hydrogens are on tertiary carbon atoms)
Compounds containing the allylic structure, including most alkenes.
Vinyl and vinylidene compounds.

Among the more widely-used compounds which may form peroxides in storage are:

acetal 
cumene 
cyclohexene 
cyclooctene 
decahydronaphthalene 
decalin 
diacetylene 
dicyclopentadiene 
diethyl ether 
diethylene glycol 
diisopropyl ether 
dimethyl ether 
dioxane 
divinyl acetylene 
ethylene glycol dimethyl ether (glyme) 
isopropyl ether 
methyl acetylene 
sodium amide 
tetrahydrofuran (THF) 
tetrahydronaphthalene 
tetralin 
vinyl acetate 
vinylidene chloride