Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Twickel on May 03, 2012, 05:29:36 AM
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Hi
Attachee dis an image of a ring with three substituents, please check if my chair conformation is right.
I made sure both cis substituents were below the hydrogens ( to allow the big group to be equatorial) then trans one above the hydrregn.
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Hi
Attachee dis an image of a ring with three substituents, please check if my chair conformation is right.
I made sure both cis substituents were below the hydrogens ( to allow the big group to be equatorial) then trans one above the hydrregn.
I would say the molecule looks like the picture I have attached.
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so in exam, would I get mine wrong?
Have you made the carbon connected to the bromine number 1?
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so in exam, would I get mine wrong?
Have you made the carbon connected to the bromine number 1?
Yes, it would be wrong as you drew it.
As you drew it in the flat picture the OH is down, the bromine and tBu are up.
Your chair conformation shows the OH up and the bromine down.
Make some models.
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ok, just checked my lecture notes, and the bottom right corner of the chair is always C1, so when I frew it like they set out ( for another example), I got t but equaltorial above H, Br axial above H and OH axial below H.
Thats better right?
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ok, just checked my lecture notes, and the bottom right corner of the chair is always C1, so when I frew it like they set out ( for another example), I got t but equaltorial above H, Br axial above H and OH axial below H.
Thats better right?
Yes, as I drew it.
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Thank you very much.
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Anything that has a wedge is "up" (it points above the ring)
and the dashes are "down" (it points below the ring)
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I think this one is right
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Ffile%3A%2F%2F%2FC%3A%2FUsers%2FWen%2FDesktop%2FUntitled.png&hash=8ec6c4c4a29c139b0be93074b7e64bf923caec5c)
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I think this one is right
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Ffile%3A%2F%2F%2FC%3A%2FUsers%2FWen%2FDesktop%2FUntitled.png&hash=8ec6c4c4a29c139b0be93074b7e64bf923caec5c)
This file is on your hard disk, nobody but you can see it.
Post it as an attachment.
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Switch each functional groups' position with the hydrogen that is attaching to the same carbon then you should have the right answer.
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I think this one is right
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Ffile%3A%2F%2F%2FC%3A%2FUsers%2FWen%2FDesktop%2FUntitled.png&hash=8ec6c4c4a29c139b0be93074b7e64bf923caec5c)
This file is on your hard disk, nobody but you can see it.
Post it as an attachment.
Sorry about that. Is there any easier way to post a picture?
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Posting as an attachment is very simple. Look below edit field (in advanced editor) - there is a link saying "Additional options...". Click it and select image, it will be uploaded automatically to our server.
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Here is what I think is right~
By the way, I didn't draw the hydrogens.
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Here is what I think is right~
By the way, I didn't draw the hydrogens.
Use Chemdraw or a freeware version of Chemsketch.
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Compare with my drawing of this molecule.
The t-Butyl group cannot be in this position, axial due to unfavorable 1,3-diaxial interactions with the hydrogens.
The t-Butyl group must be in an equatorial position.
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here are two pictures.
Cyclohex 01 is mine, cyclohex 02 is yours
Drawn with ChemDraw 3d, not energy minimized.
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Can someone please check that the one I have just done is correct?
Would be much appreciated.
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Can someone please check that the one I have just done is correct?
Would be much appreciated.
Here is my interpretation.
Wedged bonds point up, hashed bonds point down. Start by drawing the cyclohexane ring as I do then put in the substituents according to the previous sentence.
Could you please elaborate just what it is that you do not understand?
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My groups are in the same postion as yours, just that they are shifted by one carbon, was what I did correct?
I do not understand how to draw the trans linked cyclohexanes
Thanks for the help.
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My groups are in the same postion as yours, just that they are shifted by one carbon, was what I did correct?
I do not understand how to draw the trans linked cyclohexanes
Thanks for the help.
Your structure is not correct the methyl and the chlorine are both "up" in your structure the methyl group is "down" and the chlorine is down in your structure it should be up.
I don't understand what you mean by"trans linked cyclohexanes".
Start off by drawing the ring as I have done. See picture. Then put the substituents on it.
As I said before solid bolds mean the substitiuent is "up* wedged bonds it is "down", this applies to the first structure of latest question. Have a look at the second set of pictures and study the relationship between the various bonds in both structure representations.
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I thought that, because all the bonds are pointing in the same direction, then yo just have to be consistent when drawing the chair ( iin this make all the groups be below hydrogens)
Looking at the diagram you drew ( the latest one) all the cls are above the hydrogens, which is what I thought I did for the example I posted
Ahh, I see what I did, the tert butyl group is not above the H
Does it matter which carbon I start iwth on the chair. aka can I make any carbon number 1?
I always start with the bottom right corner being carbon one on the ring, but working like that I get the tert butyl group axial and thats not good.... can I just do a ring flip
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If I drew that, can I just do a ring flip and get the correct answer?
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No I'm sorry your answer is wrong, ring flip will not help.
Again look at my pictures, and compare them with yours.
The other structure is a decalin. I've drawn it for you.
Have you got any molecular models? Or can you get some?
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Thank you, I do have a set and started building some, just one question, when you draw your chair conformations, which carbon the chair do you denote as number 1? I thought the top most center carbon on the hexagon corresponding to the bottom right corner of the chair as 1 worked all the time, obviously it does not.
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Thank you, I do have a set and started building some, just one question, when you draw your chair conformations, which carbon the chair do you denote as number 1? I thought the top most center carbon on the hexagon corresponding to the bottom right corner of the chair as 1 worked all the time, obviously it does not.
It does not matter which is carbon number 1 on the unsubstituted ring.
I just know that a t-Butyl group will always be equatorial due to it's size, it also prevents ring flip. So if you have a t-Butyl group there are only 3 positions it can go on the run and be "up" i.e. equatorial.
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hmm, ok I knew that I just need to stop over complicating things maybe.
I thought that the CH3 needs to be equatorial as well, or is that not considered bulky?
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hmm, ok I knew that I just need to stop over complicating things maybe.
I thought that the CH3 needs to be equatorial as well, or is that not considered bulky?
Sure it does if there is not a t-Butly group present. If the methyl group happens to be axial the ring can flip then it's equatorial.
Try and keep it simple, you got that right :o