The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

This discussion is now closed.

Check out other Related discussions

gemetric isomers pleeeeeeeeease help anyone!

How many gemetric isomers are in the compounds in the attachment? Please- how do you work it out?
isomers.jpg15.9KB
I cant view your attachement, try again and Ill take a look :smile:
What attachment?
Reply 3
Avatar for shenzys
shenzys
OP
17
lol sorry its there now! i forgot.
Reply 4
Avatar for Owly-woes
Owly-woes
7
Don't you look at the number of chiral centers, n, and put i like this: 2^n ?
2 and 3 Geometric isomers rite?
Reply 6
Avatar for Owly-woes
Owly-woes
7
Owly-woes
Don't you look at the number of chiral centers, n, and put i like this: 2^n ?


uh, wait... that is for something else.
To start with you need to draw out the full structural formulae of these molecules, then you can more clearly see which arrangements are different/the same.
(Just a starter, feel free to ask if this doesn't help :smile: )
Reply 8
Avatar for shenzys
shenzys
OP
17
martin-jesusfreak
To start with you need to draw out the full structural formulae of these molecules, then you can more clearly see which arrangements are different/the same.
(Just a starter, feel free to ask if this doesn't help :smile: )


Ok, for the first one, I got 2 isomers:

H H H H H H
H-C=C-C=C-C-C-H
H H

The second double bond has 2 different groups attched on both carbons- so 1 group on each, so you can get cis and trans isomers with that- is that correct???
Reply 9
Avatar for shenzys
shenzys
OP
17
Oh man the structure changed when i presses edit...
Reply 10
Avatar for shenzys
shenzys
OP
17
Owly-woes
Don't you look at the number of chiral centers, n, and put i like this: 2^n ?


Is this for optical isomers?
Reply 11
Avatar for Blocker
Blocker
5
Just apply the basic rule: for cis and trans isomers, you need two different functional groups, on either side of the double bond. So if the double bond is at the end of a chain, or in a ring, you wont be getting any isomers there. from that you should be able to work it out quite easily...
shenzys
Oh man the structure changed when i presses edit...

Yeah, it will do that.
Try drawing the strucures in paint. Or even better download chemdraw I think there's a free version available.
I think you have the general idea though :smile:
Reply 13
Avatar for Owly-woes
Owly-woes
7
shenzys
Is this for optical isomers?


Not sure about the english name - I call it diastereomery, I think:p:
Owly-woes
Not sure about the english name - I call it diastereomery, I think:p:


yeah diastereoisomerism - stereoisomers which are not enantiomers (often with more than one stereogenic centre), hence the 2n where n is the number of stereogenic centres (minus any meso compounds) :biggrin:
Reply 15
Avatar for Blocker
Blocker
5
dare i ask the meaning of meso compounds?
Blocker
dare i ask the meaning of meso compounds?


Compounds that have an internal plane of symmetry with stereocentres but which are not chiral :smile:

Related discussions

Latest

Trending

Trending

Articles for you