pentadiene

例句：

1. 1.This compound is a key intermediate in the synthesis of many important chemicals.
   这种化合物是合成许多重要化学品的关键中间体。
2. 2. The pentadiene ring has a unique structure that makes it difficult to synthesize.
   五元环烷的环状结构使其难以合成。
3. 3.Pentadiene is a colorless liquid that is used in the production of lubricants and plastics.
   五元环烷是一种无色液体，用于生产润滑油和塑料。