Organic Synthesis in Simulated Submarine Hydrothermal Vent Environments by Using a Supercritical Water Flow-Reactor

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Submarine hydrothermal vents (SHVs) were regarded as models of hellish primeval ocean where chemical evolution toward the generation of life occurred. A number of simulation experiments have been conducted to study possible organic reactions in SHVs, but closed systems have been used in most cases. SHV systems can be regarded as a flow reactor where water was heated rapidly over supercritical point and then suddenly quenched by cold water. We constructed a brand new supercritical water flow reactor (SWFR) to simulate possible organic reactions in SHV environments.Our SWFR consists of a HPLC pump, a Hasteroy reaction tube in an infrared gold image furnace, a cold bath and back-pressure regulator. Temperature outside and inside the reaction tube can be monitored with thermocouples.When a glycine solution was injected into the SWFR, new unidentified peaks were appeared when reaction temperature was 400℃, which suggests that new types of reactions occur under supercritical conditions .In order to investigate Strecker-type reactions in SWFR, a mixture of KCN, HCHO and NH_4HCO_3 was injected. At 50℃, only glycine was detected. When the reaction temperature increased, other amino acids could be seen, such as alanine (100℃) and sarcosine (150℃). Reactions over 300℃ gave the following complicated amino acids were found in the product, such as β-alanine, γ-aminobutyric acid, δ-Aminovaleric acid and ε-aminocaproic acid. It was shown that a wide variety of organic compounds including amino acids could be formed in hydrothermal systems. Further works shoulc be done to test the effects of pH, red-ox potential and roles of metal ions.