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Pyrolysis of chlorophyll a after preliminary heating at a moderate temperature: Implications for the origin of prist-1-ene on kerogen pyrolysis

1991; Elsevier BV; Volume: 18; Issue: 3-4 Linguagem: Inglês

10.1016/0165-2370(91)87002-4

1873-250X

Mariko Ishiwatari, Ryoshi Ishiwatari, Haru Sakashita, Takashi Tatsumi, Hiro-o Tominaga,

Molecular spectroscopy and chirality

Pyroprobe pyrolyses of chlorophyll a were performed to investigate the possible precursors and formation mechanisms of prist-1-ene often observed in the products of kerogen pyrolysis. Thermal maturation was simulated by preheating chlorophyll a for different times at 250°C. Phytadienes dominated the pyrolyzates from unheated or briefly preheated samples. Little prist-1-ene was produced from unheated chloropyll a during pyrolysis at 400°C for 1 s, whereas a considerable yield was obtained after preheating. Pyrolysis at 470°C for 15 s produced prist-1-ene from both unheated and preheated chlorophyll a. The yield of prist-1-ene increased with the time of preheating, relative to the yield of phytadienes. Additional isoprenoid hydrocarbons (C9C20) were formed from the fragmentation of chlorophyll a. Possible pyrolysis mechanisms to explain these results are presented.