Indeno[1,2?d]pyridazine derivatives have wide applications in pesticides,pharmaceuticals,and other fields due to their excellent biological activities.Therefore,the development of rapid and efficient synthetic methods for these compounds has attracted increasing attention from researchers.A novel acid?catalyzed cyclization reaction between allylbenzene and tetrazine was designed.Reaction intermediates were trapped,and their structures,along with those of the products,were characterized using nuclear magnetic resonance spectroscopy.The results indicate that the reaction proceeds through intermolecular [4+2] cycloaddition and intramolecular Friedel?Crafts alkylation processes,enabling one?step synthesis of indeno[1,2?d]pyridazine derivatives.The reaction also exhibits a broad substrate scope and good functional group compatibility,yielding a series of indeno[1,2?d]pyridazine derivatives with 67%~95% yields.In gram scale experiments,the target product was obtained with an 81% yield, demonstrating the potential practical value of this reaction.

During the development of the Fuyu oil reservoir in the Longxi block of Daqing,hydrogen sulfide (H₂S) was discovered and exceeded the threshold value (15.0 mg/m³), but its generation mechanism is still unclear. To investigate this, the mechanism of H?S generation in the Longxi block formation was investigated through laboratory experiments on H?S generation,combined with numerical simulations using PHREEQC and CMG software.The results show that the mechanism of H₂S generation in high?temperature reservoirs (100~125 ℃) is sulfate thermochemical reduction reaction, with viscosity of H₂S generated ranges from 3.20 mg/m³ to 6.10 mg/m³.In low?temperature reservoirs (≤60 ℃),the mechanism of H₂S generation is sulfate?reducing bacteria reduction reaction,with a maximum H₂S viscosity of up to 29.70 mg/m3.Fracturing fluid reduces the temperature in the near?wellbore zone, promoting SRB proliferation, and the viscosity of H₂S generated in a short time increases by 7.5 times compared to the sulfate?reducing bacteria reduction reaction in produced water. The mass concentrations of H₂S generated by the reaction of 1 m³ acid with the core and plug containing 0.80 mol FeS are 3 330.69 mg/m³ and 11 466.75 mg/m³,respectively. Therefore, fracturing and acidification are the main mechanisms for the generation of H₂S during the development of the Fuyu oil reservoir in the Longxi block.