Organic Chem - Cis and Trans?

Question

1. )when do you use cis and trans? I am so confused..
i am learning about alkynes . . and while naming them
some have trans or cis before them..how do i know when to
put them?

2.) When do you use nonen?

Answer 1

r u sure it's not alkenes? because alkynes (triple bonds) form a linear structure, and usually there is no cis or trans.
cis or trans configurations usually applies to alkenes, because the double bond fixes the two carbons and it's adjacent molecules, thus preventing them from rotation. so it is necessary to note which one is where.
Cis - if two similar groups are on the same side. Both top and both bottom, when u draw it out horizontally
Trans - the two similar groups are on the opposite sides, one top, one bottom, when u draw it out horizontally.

Answer 2

1) Maybe if you put up more of the question it would make sense. I presume you have multiple functionality or a ring. Anyway, cis means on the same side and trans means opposite sides.

2) I presume there was a number in front, 1-nonene for example? If so, it is the nine carbon chain with a double bond starting with the prefix number.

Answer 3

You get cis and trans with alkenes, because groups can be on the same side or opposite sides of the double bond. However, there is no difference between cis and trans unless each ofthe doble-bond carbons is single bonded to two different groups (try it with pencil and paper). ClHC=CHCl has cis and trans isomers, but ClHC=CH2 does not.

You don't use cis or trans with alkynes because they are linear.

Never heard of nonen