Topic: cyclooctylethyne to 1-cyclooctylpent-1-yne (Read 4924 times)

dubz · « **on:** February 03, 2014, 01:05:27 AM »

hi guys! i was wondering if this reaction is possible:

cyclooctylethyne to 1-cyclooctylpent-1-yne..what would be the reagent if ever?

i drew it but i'm a confused if this is even possible.

thanks in advance.

discodermolide · « **Reply #1 on:** February 03, 2014, 01:14:05 AM »

This is your starting compound?
C#CC1CCCCCCC1

If so what do you know about the chemistry of acetylenes?

dubz · « **Reply #2 on:** February 03, 2014, 01:16:00 AM »

there i drew it above ^^^ but i'm confused if it's even possible..if so, what would be the reagent?

discodermolide · « **Reply #3 on:** February 03, 2014, 01:20:19 AM »

Yes, this is possible.
What do you have to add to the end of the acetylene, a compound with how many carbons?

dubz · « **Reply #4 on:** February 03, 2014, 01:24:18 AM »

honestly, i dont really know because i'm trying to answer this one on a practice set but it just asks what reagent is needed..i'm sorry i dont know much, i'm still an O-chem student but i'm trying my best.

discodermolide · « **Reply #5 on:** February 03, 2014, 01:30:36 AM »

Yes, I understand.
But the question is simple, how many carbons do you have to add to the starting material to get to the product?

dubz · « **Reply #6 on:** February 03, 2014, 01:32:58 AM »

3 carbons? but how can i do that? what kind of reagent is that?

discodermolide · « **Reply #7 on:** February 03, 2014, 01:36:23 AM »

Yes you add 3 carbons. Now what sort of compound could you use for this?
Think making an anion and reacting it with an electrophile.

dubz · « **Reply #8 on:** February 03, 2014, 01:44:27 AM »

i was thinking of adding a propane but it's not enough without the proper reagent..is it correct? what reagent can i use?

discodermolide · « **Reply #9 on:** February 03, 2014, 01:47:21 AM »

Yes but it is a derivative of propane, with a reactive group on the end carbon, an electrophillic group.
You can make this anion from the acetylene by treating it with sodium in liquid ammonia or another strong base.
[C-]#CC1CCCCCCC1.[Na+]

dubz · « **Reply #10 on:** February 03, 2014, 01:52:22 AM »

so is this correct?

discodermolide · « **Reply #11 on:** February 03, 2014, 01:59:14 AM »

No, sorry it is not correct.
Look at the structure I posted, it has a negative charge on the end acetylene carbon.
So what could you react that anion with to get the compound you want?
[C-]#CC1CCCCCCC1.[Na+]

dubz · « **Reply #12 on:** February 03, 2014, 02:08:35 AM »

well, it needs an electrophile there..i was thinking of NaNH2 as the reagent so it can kick off the H and add to the acetylene..is it correct or is it a radical one that involves Na NH3 or Li NH3?

discodermolide · « **Reply #13 on:** February 03, 2014, 02:12:09 AM »

The NaNH₂ forms the anion of the acetylene, so you need a 3 carbon electrophile.

dubz · « **Reply #14 on:** February 03, 2014, 02:15:05 AM »

ok thanks, i think i'm getting it already.

Topic: cyclooctylethyne to 1-cyclooctylpent-1-yne (Read 4924 times)

dubz

cyclooctylethyne to 1-cyclooctylpent-1-yne

discodermolide

Re: cyclooctylethyne to 1-cyclooctylepent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylepent-1-yne

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Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

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Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

discodermolide

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

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Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

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Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

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Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

dubz

Re: cyclooctylethyne to 1-cyclooctylpent-1-yne

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