Decalin

(also decahydronaphthalene and perhydronaphthalene), C¹⁰H¹⁸, an alicyclic hydrocarbon; a colorless liquid with a strong odor. It exists in cis- and trans- stereoisomers, which differ in the mutual position of the rings. The more stable trans form has a boiling point of 185.5°C, a melting point of -31.5°C, and a density of 0.87 g/cm³ (20°C). The cis form has a boiling point of 194.6°C, a melting point of -43.2°C, and a density of 0.897 g/cm³ (20°C).

In industry decalin is obtained as a mixture of isomers (usually 60 percent cis and 40 percent trans) by catalytic hydrogenation of naphthalene. It is insoluble in water; has limited solubility in acetic acid, ethanol, and methanol; and is miscible in all proportions with ether and chloroform. Decalin is a good solvent for many organic substances and polymers.