## Cyclo-

Jonathan Enciso 1C
Posts: 16
Joined: Fri Jun 17, 2016 11:28 am

### Cyclo-

By just looking at the molecular formula alone, can we tell whether to draw a cycloalkane, cycloalkene, or cycloalkyne?

Vivian Nguyen 2A
Posts: 21
Joined: Wed Sep 21, 2016 2:58 pm

### Re: Cyclo-

Cycloalkanes have single C-C bonds in the parent chain, cycloalkanes have C=C double bonds, and cycloalkanes have triple bonds. To determine which to draw, we have to total the number of electrons given in the molecular formula and distribute them across the chain.

Da_Rhee_1O
Posts: 20
Joined: Wed Sep 21, 2016 2:59 pm

### Re: Cyclo-

One way to tell when to draw cycloalkane is when when the number of hydrogen atoms is exactly twice the number of carbon atoms present (thus the formula for cycloalkane: CnH2n).

The formula for cycloalkene varies on how many double bonds are present in the compound.
1 double bond= CnH(2n-2)
2 double bonds= CnH(2n-4)
3 double bonds= CnH(2n-6)

Kaitlin_Ryan_ 3K
Posts: 28
Joined: Fri Jul 15, 2016 3:00 am

### Re: Cyclo-

When numbering carbons on a Cyclo- molecule, which carbon is numbered first?

TramHo2G
Posts: 31
Joined: Wed Sep 21, 2016 2:59 pm

### Re: Cyclo-

Kaitlin_Ryan_ 3K wrote:When numbering carbons on a Cyclo- molecule, which carbon is numbered first?

Chem_Mod said in another post that "In the case of cycloalkanes, the substituent with the highest priority will have the first number, and then work to find the lowest constituent numbering".

Julie Barreto 3A
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

### Re: Cyclo-

how do you know which carbon to number first?
i know it has to do with the lowest substituents

Katherine_Zhuo_3B
Posts: 23
Joined: Wed Sep 21, 2016 2:57 pm

### Re: Cyclo-

For cycloalkanes,You look at the numbering for the lowest number on substituents, and if they are equal, you number based on first named.

Zulfiqar Lokhandwala 1H
Posts: 10
Joined: Fri Sep 25, 2015 3:00 am

### Re: Cyclo-

Also, I believe in lecture it was mentioned that if there is a double or triple bond in the structure, we start naming from the carbon on the double or triple bond then count the substituents