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# Organic Chemistry

Hi friends. Can you tell me how many different possible isomers can the compound C5H8 have (including the cyclic ones)? First of all I tried to find out the different possible isomers of C4H6 and found out 9 of them. Then I jumped to C5H8 and got 23 of them..but I think I've missed some of them. So please help me.

Note by Abhimanyu Swami
3 years, 8 months ago

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$$C_5H_8$$ clearly is of the form $$C_{n}H_{2n-2}$$, which means it could be:

• an alkyne

• a diene

• a cycloalkene

• a double-cyclic alkane (I don't think the exercise considers this ones, they are very complicated)

Let's go.

Alkynes: 1-pentyne; 2-pentyne; 3-methyl-1-butyne (or methyl-butyne); 3-methyl-1-butyne.

Cycloalkenes: cyclopentene; methylene-cyclobutane; 1-methyl-cyclobutene, 3-methyl-cyclobutene; vinyl-cyclopropane; ethylidene-cyclopropane; 3,3-dimethyl-cyclopropene (or dimethyl-cyclopropene); 1,2-dimethylcyclopropene; 1,3-dimethyl-cyclopropene (very unstable, not listed); 1-methyl-2-methylene-cyclopropane.

Double Cyclic Alkanes: spiropentane; bicyclo(2.1.0)pentane; bicyclo(1.1.1)pentane; 1-methyl-bicyclo[1.1.0]butane; $$\text{HOLD ON, I'M PUTTING ANOTHER ONE MORE}$$.

Most of these I got in ChemSpider and some I got by myself. I think the other possible ones are more "theoretic" and very unlikely to exist. · 3 years, 8 months ago

Thanks for the help. · 3 years, 8 months ago