Dopamine (C6H3 (OH) 2-CH2-CH2-NH2) is a kind of brain endocrine, which can affect a person's mood. Its formal chemical name is 4-(2- ethylamino) benzene-1, 2- diol, or "DA" for short. Arvid karlsson won the 2000 Nobel Prize in Medicine for discovering that dopamine is the information transmitter in the brain. Dopamine is a neurotransmitter, a chemical used to help cells transmit pulses. This kind of brain endocrine is mainly responsible for the lust and feeling of the brain, transmitting information of excitement and happiness, and is also related to addiction. Love is actually the result of a large amount of dopamine produced by the brain. Therefore, smoking and drug abuse can increase the secretion of dopamine and make addicts feel happy and excited. According to research, dopamine can treat depression; However, the lack of dopamine will make people lose the ability to control muscles, which will seriously make patients' hands and feet shake involuntarily or lead to Parkinson's disease. Recently, some scientists have found that dopamine is helpful for further treatment of Parkinson's disease. The treatment lies in restoring the level of dopamine in the brain and controlling the disease. Its hydrochloride is often used as white or white-like shiny crystal; Odorless and slightly bitter; Exposed to air and light, the color changes gradually. Soluble in water, slightly soluble in anhydrous ethanol, very slightly soluble in chloroform or ether. The melting point is 243℃-249℃ (decomposition).