Question

Please help. Could you draw and tell me the three ethylmethylcyclobutane constitutional isomers?

Is one of them 1-ethyl-1-methylcyclobutane, and 1-ethyl-2-methylcyclobutane and I'm not sure of the other one?

Answer 1

1-ethyl-3-methylcyclobutane

Explanation:

You are correct with the first two constitutional isomers (1-ethyl-1-methylcyclobutane and 1-ethyl-2-methylcyclobutane) and the third one is going to be 1-ethy-3-methylcyclobutane.

Constitutional isomers have the same molecular formula but different connectivities.

This one is the 1-ethyl-1-methylcyclobutane

This second structure is 1-ethyl-2-methylcyclubutane. *you can ignore the dash and wedges for now (just know that those are normal carbon bonds but drawn in 3D; the methyl is going into the screen and ethyl is coming out of the screen). Once you learn about chirality centers and R/S configurations, it will make more sense to you as to why it is drawn like that.

And lastly, 1-ethyl-3-methylcyclobutane. And again, you can see the same kind of drawing (dashes and wedges). I could explain the idea of chirality but that's another topic.

If you have questions about chirality, R/S configurations, dashes and wedges, etc. please do post your question(s) and either me or someone else will answer it.

Hope this helps (c: