The rhombic crystal system is a colorless needle shaped or sheet-like crystal. Has a strong pungent odor, soluble in ethanol, ether, and acetone, but insoluble in petroleum ether and carbon tetrachloride. It reacts with hot water to form maleic acid. Mainly used as raw materials for the production of unsaturated polyester resin, alkyd resin, pesticide malathion, high-efficiency and low toxicity pesticide 4049, and long-acting iodamine. It is also a comonomer of coatings, maleic rosin, polymaleic anhydride, and maleic anhydride styrene copolymers. It is also an organic chemical raw material for the production of ink additives, papermaking additives, plasticizers, tartaric acid, fumaric acid, tetrahydrofuran, and other chemicals.

Mainly used for reacting with isobutene to prepare isooctane, used as a gasoline octane number improver, and can also be used as a refrigerant. It is a colorless, slightly odorous gas that is slightly soluble in water, flammable, explosive, and toxic.

Propane is a three carbon alkane, usually in a gaseous state, but is usually transported after being compressed into a liquid state. After processing crude oil or natural gas, propane can be obtained from finished oil. Propane is commonly used as fuel for engines, barbecue food, and household heating systems.

Carbon five is mainly used in the production of petroleum resins, used in industries such as rubber, paint, coatings, hot melt adhesives, inks, etc. It is also known as pentane. Carbon five is an extremely flammable substance, and its vapor can form an explosive mixture with air. Highly flammable and explosive when exposed to open flames and high heat.