Question

what does " cracking mean" when the lab say obtain cyclopentadiene by cracking dicyclopentadiene?

what do you check dicyclopentadiene for and why?

why are two solvent systems used in the diels-adler reaction?

what happens if the solution cools too fast?

Answer 1

Cracking is a familiar process in which bigger hydro carbons of high molecular weight with high boiling point are converted to low molecular hydrocarbons with low boiling point which can be carried out by either heat or catalyst.If craking takes place in presence of heat it is called thermal craking and if it takes place in presence of catalyst it is called catalytic craking.

So craking of dicyclopentadiene means breaking it into simple molecules cyclopentadiene through heating.

Dicyclopentadiene is obtained as a byproduct during fractional distillation of petroleum products with boiling point 170⁰c.Generally on distillation of dicyclopentadiene we get cyclopentadiene from it but sometimes it polymerizes or condenses to form other compounds which doesnot crack easily to form its monomer.It has to be check for impurities which causes less production.

Two solvent systems are used in Diels Alder reaction for faster rate of reactions and seperation of products formed.

If cooling takes place too fast then solid particles crushes out of the solution as powder along with impurities which will be difficult to seperate them.