Can someone help me in naming cyclo-alkanes, -alkenes, and -alkynes?

I'm confused as to what is necessary and what isn't.





1-methyl-2-ethyl-cyclohexane or methylethylcyclohexane?


3-ethyl-1-cyclohexyne or 3-ethylcyclohexyne?


4-methyl-1,2-cyclononadiene or 4-methylcyclononadiene?





Thanks so much for any help!

Can someone help me in naming cyclo-alkanes, -alkenes, and -alkynes?
1-methyl-2-ethyl-cyclohexane or methylethylcyclohexane


You can just use methylethylcyclohexane. The numbers are not important because they are right next to eachother, on the 1 and 2 C positions. They could be in any order also, depending on which way your number it.





3-ethyl-1-cyclohexyne or 3-ethylcyclohexyne


Again, you can just go for the easier name, 3-ethylcyclohexyne. This one has the "yne" ending, so you do not need to designate that it is in the "1" position. When you draw it, you draw the alkyne portion, and then start numbering from there until you get to the 3rd carbon. That is where you would draw the ethyl.





4-methyl-1,2-cyclononadiene or 4-methylcyclononadiene


This is the same thing as the 2nd one, except it is a diene. Draw the diene at the 1 and 2 positions and then on the 4th carbon, draw a methyl group.