2,5-Dimethyl-2,4-hexadiene is an electron-rich alkene. It induces photodechlorination of 9,10-dichloroanthracene and its mechanism has been investigated. Asymmetric cyclopropanation of 2,5-dimethyl-2,4-hexadiene with tert-butyl diazoacetate catalyzed by the new copper-bisoxazoline complex has been reported. 2,5-Dimethyl-2,4-hexadiene has been investigated as a singlet oxygen acceptor in various solvents. Mechanism of addition reaction of aromatic and aliphatic thiols with 2,5-dimethyl-2,4-hexadiene has been investigated.