Dicyclopentadienes 4,7-Methanoindenes

Methyl (1R,5R) -5-hydroxy-2-cyclopentene-l-acetate 2-Cyclopentene-l-acetic acid, 5-hydroxy-, methyl ester, (lR-trans)- (9) (49825-99-2) Dicyclopentadiene 4,7-Methanoindene, 3a,4,7,7a-tetrahydro- (8) 4,7-Methano-lH-1ndene, 3a,4,7,7a-tetrahydro- (9) (77-73-6)... 

Cyclopentadiene is obtained by the thermal cracking of dicyclopentadiene (3a,4,7,7a-tetrahydro-4,7-methanoindene). Dicyclopentadiene is slowly distilled through a short fractionating column, collecting only that which refluxes below 44°. (Cyclopentadiene boils at 42.5°, dicyclopentadiene at 170°.) This cyclopentadiene must be used within 2 or 3 hours or stored at —78° until use, because slow dimerization occurs at room temperature. 

Meanwhile, cyclopentadiene is prepared from commercial dicyclopentadiene (3a,4,7,7a-tetrahydro-4,7-methanoindene) by heating it at the boiling point in a flask fitted with a Vigreux column with a distillation head and condenser. Monomeric cyclopentadiene distills over at about 42° as a colorless liquid, which should be used within one hour or kept at —78° until use. 

Synonyms/Trade Names Bicyclopentadiene DCPD 1,3-Dicyclopentadiene dimer 3a,4,7,7a-Tetrahydro-4,7-methanoindene [Note Exists in two stereoisomeric forms.]... 

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