Conjugated systems, alternant

Ambident conjugated systems, alternative protonation sites in, 11, 267... 

Carotene (a carotenoid) and (d) lutein (a xanthophyll) are accessory pigments in plants. The areas shaded pink are the conjugated systems (alternating single and double bonds) that largely account for the absorption of visible light. 

If the 71 bonded electrons are linked to a conjugated system (alternate double and single carbon-carbon bonds), the absorption will shift to a lower frequency, and the substance may be coloured. The colour observed will be the complementary colour of that absorbed. 

Ambident conjugated systems, alternative protonation sites in, 11, 267 Ammonia liquid, isotope exchange reactions of organic compounds in, 1, S56 Anions, organic, gas-phase reactions of,... 

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