disclosed herein are compounds and methods of using such compounds for treating or suppressing oxidative stress disorders , including mitochondrial disorders , impaired energy processing disorders , neurodegenerative diseases and diseases of aging , or for modulating one or more energy biomarkers , normalizing one or more energy biomarkers , or enhancing one or more energy biomarkers , wherein the compound is a compound of formula i or formula ii : wherein : r 1 and r 2 are independently hydrogen , alkyl or — oalkyl ; or r 1 and r 2 together represent — ch ═ ch — ch ═ ch —; r 3 is alkyl ; x is — ch ═ ch — or — c ≡ c —; m is 1 - 10 ; n is 1 - 5 ; k is 1 - 3 , with the proviso that when k is an integer of 2 or 3 , n is independently 1 - 5 in each occurrence of the — x — n — group ; y is — or 4 , — cn , — cor 5 , — cr 5 , or — cn 2 ; r 4 and r 5 are independently selected from the group consisting of hydrogen , — alkyl , — haloalkyl , — c — alkyl , — c — haloalkyl , — c — nhalkyl , — c — nalkyl ) 2 , — c — nh 2 , and phenyl , wherein the phenyl group may optionally be substituted with a substituent selected from the group consisting of — alkyl , — o — alkyl , — haloalkyl , and halo ; each r 6 is independently hydrogen or — alkyl ; and m is — h , — c — r 7 or — co — r 7 , wherein r 7 is — alkyl or phenyl ; or a stereoisomer , mixture of stereoisomers , pharmaceutically acceptable salt , crystalline form , non - crystalline form , hydrate or solvate thereof .