Question

Write all the ring- chain isomers of (a) pent-1-ene and (b) pent-1-yne including bicyclic and spiro compounds.

Answer 1

Isomers of any substance have the same molecular formula but different structures. Bicyclo compounds have 2 cyclic rings attached, while spiro compounds have 2 rings having one common atom, attached to each other. Ring- chain isomers contain a ring and a chain on them.

Complete step-by-step answer: Isomers of a molecule have the same molecular formula but different structures. Pent-1-ene consist of the formula ${{C}_{5}}{{H}_{10}}$, while pent-1-yne have the formula, ${{C}_{5}}{{H}_{8}}$.
Various isomers were found in both the compounds. Some isomers were rings, with 4 and 3 carbon atoms, while other isomers were bicycle and spiro. Bicycle isomers consist of two fused rings together. On the other hand, spiro consist of two rings fused in such a way that one atom is common among them.
Isomers of pent-1-ene are,
Ring-chain isomers:

Bicyclo, and spiro isomers,

While, the isomers of pent-1-yne, consist of one double bonds, and along with rings structures, they complete their molecular formula as,
Ring-chain isomers,

Bicyclo, and spiro isomers,

So, there are a total 7 chain-ring and bicyclic and spiro isomers of pent-1-ene; and a total 8 ring-chain and bicyclic and spiro isomers of pent-1-yne.

Note: No complete chain isomers, or complete ring isomers are mentioned, as ring-chain isomers are asked, and ring-chain isomerism consist of a carbon atom ring along with an open chain attached on it.