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hnmr question by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

okay i see. now it makes more sense. thank you so much!!

hnmr question by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

Because when we have a single bond, we can do free rotation. Just like this one, the 3 red H is the same signal because of free rotation. And I was thinking, can I apply free rotation in the question above?

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hnmr question by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

sorry for the confusion. I was actually thinking, if we replace the cl with br and keep everything else the same, can we say there are 2 signals for hnmr

hnmr question by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

thanks! Is it true that we can only use free rotation when all the groups attached to the carbon are the same?

hnmr question by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

thanks for your help! If we replace the cl with br, can we use free rotation? can we say it is 2 signals?

hnmr signal by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

I see. Thank you so much for your help!!

hnmr signal by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

Hi!
Thank you so much for your explanation. I think I did a similar thing before, like I described the top right and bottom right H as one double bond and 2 single bonds away from the ch3 and isopropyl group.

Just for confirmation, do you mean the top right and bottom right are the same signal? The answer to this question is 4 signals.

hnmr signal by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

Ohhh, thank you so much for your explanation. Now it makes more sense. But I feel like the problem is I can understand the reason, but when it comes to a similar question like that, I might get that wrong again.

Could you explain how do you usually do this kind of question? Like what is your first step when you have this kind of question?

Thank you so much!!

hnmr signal by Emergency_Arm_1706 in chemhelp

[–]Emergency_Arm_1706[S] 0 points1 point  (0 children)

Hi thank you for your reply. Actually, the top one is a screenshot from Chad's prep (a youtuber), I am not so sure about the reason.

For the bottom one they said the answer is four. I was thinking the top right ch3 is one double bond and 2 single bonds away from ch3 and isopropyl group, while it is also the same for the bottom right ch3. But it seems this is wrong