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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: fantom on March 05, 2015, 10:44:06 AM

Title: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 10:44:06 AM: If anyone can help with this, that would be awesome. (see attached)

The photo that we have worked on may be wrong.. not happy with the mechanism..

*MOD Edit -- give useful title*
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Dan on March 05, 2015, 12:17:20 PM: Quote from: fantom on March 05, 2015, 11:11:14 AM
I may have done something wrong?

Yes, you didn't read the forum rules.

You must show you have attempted the question, this is a Forum Rule (http://www.chemicalforums.com/index.php?topic=65859.0).

These are all named reactions, it should not be difficult to find some information and get started. Do you have any ideas?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 12:24:09 PM: Yes, I have an idea for #2, possibly a pinacol rearrangement? and as for only one of the alcohols being converted into a tosylate, this could be sterics?

The one where the lab experiment would not work, the only thing I can come up with is the absence of heat being applied.. the way it is set up now does not allow for enough energy for the reaction to move forward..

A few other classmates and I are all working on these together as we speak since they are due tomorrow by noon..

I'm sorry to have offended you with my involuntary disregard for the forum rules. But, be assured that I am indeed working on these at this very moment.. although my answers may be wrong.
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Dan on March 05, 2015, 01:38:55 PM: Quote from: fantom on March 05, 2015, 12:24:09 PM
Yes, I have an idea for #2, possibly a pinacol rearrangement? and as for only one of the alcohols being converted into a tosylate, this could be sterics?

Sounds good to me.

Quote
The one where the lab experiment would not work, the only thing I can come up with is the absence of heat being applied.. the way it is set up now does not allow for enough energy for the reaction to move forward..

That could certainly be a factor, good thinking. Also consider Babcock_Hall's hint.

Quote
A few other classmates and I are all working on these together as we speak since they are due tomorrow by noon..

...But, be assured that I am indeed working on these at this very moment.. although my answers may be wrong.

That's all very well, but unless you show your working it looks like you just expect someone to dump the answers in your lap. It doesn't matter if your ideas are wrong, if we can see how you are approaching the problem, we can steer you in the right direction.

To be blunt, the deadline is your problem, not ours.

Quote
I'm sorry to have offended you with my involuntary disregard for the forum rules.

I take no personal offence. When you registered your account, you (presumably voluntarily) clicked a button to confirm that you agreed to the terms, which included:

"Finally, by registering at the forum you agree to the separately expressed forum rules, and you confirm you have read them."
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 01:51:14 PM: i will update the post with what we have so far.
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 02:02:38 PM: Quote from: Babcock_Hall on March 05, 2015, 01:12:16 PM
With respect to the synthesis of an ether, what is the nucleophile? Are there possible side reactions? With respect to your title, the phrase in parentheses is needlessly combative.

The nucleophile --> methyl iodide? (MeI)

This is a Williamson Ether synthesis. I don't think the instructor intends for any side reactions to occur unless the chart and protocol given allow for them to occur.. do you think there is a chance that any of the reagents may react with one another instead of the cyclohexanol being deprotonated followed by the attachment of the CH₃ to the Oxygen?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Arkcon on March 05, 2015, 02:10:19 PM: Quote from: fantom on March 05, 2015, 01:51:14 PM
i will update the post with what we have so far.

In the future don't do that, especially after several posts. It muddles the discussion. Also don't change topics, it makes threads difficult to search. I re-wrote the title to be more search friendly, as well.
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 02:29:38 PM: thanks
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Babcock_Hall on March 05, 2015, 03:24:34 PM: Methyl iodide is the electrophile in a Williamson ether synthesis. The deprotonated form of cyclohexanol is the nucleophile that lead to the product you want. Nucleophiles have at least one one pair of electrons that will participate in the reaction. Are there other potential nucleophiles present?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 04:48:27 PM: no, should not be any other Nuc- present.

Are you saying that there may be a reaction between the MeI and another potential reagent?

Possibly the order in which things are added in this case?

All I can come up with is the temperature at which the reaction is allowed to run...
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Babcock_Hall on March 05, 2015, 04:53:31 PM: What reagent deprotonates the cyclohexanol?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 05:24:19 PM: I would assume that the NaOH deprotonates the alcohol and leaves it with the nucleophile and then MeI comes next to bond with the O-. Leaving Na⁺ -- I^- and H₂O.

Or this is what is supposed to happen?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Babcock_Hall on March 05, 2015, 05:30:12 PM: Is hydroxide ion a nucleophile?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 05:40:39 PM: For this reaction, I believe that the carbon attached to the iodine is the electrophile while the alkoxide formed by the NaOH is the nucleophile..

I don't know what type of situation you mean when you ask if NaOH a nucleophile.
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Babcock_Hall on March 05, 2015, 05:44:28 PM: Does hydroxide ion have lone pairs of electrons?
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: fantom on March 05, 2015, 05:57:40 PM: Yes, i would assume that the ion would indeed have an extra lone pair and have a -1 formal charge..
Title: Re: {diol w/ mesyl chloride, cyclohexyl methyl ether, pinacol rearrangement}
Post by: Babcock_Hall on March 05, 2015, 07:57:11 PM: I am not entirely sure what you mean by extra, but it has a total of three lone pairs. So could it act as a nucleophile?