December 10, 2024, 12:14:59 AM
Forum Rules: Read This Before Posting


Topic: Alkyne rxns...?  (Read 6955 times)

0 Members and 1 Guest are viewing this topic.

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Alkyne rxns...?
« on: November 22, 2013, 01:02:42 AM »
Awful online homework, what else is new.


But afaik, these two don't even react? Solved

The textbook has nothing on alkynes + salts, just halides and stuff, so...?


It also says nothing about alkynes + these two, unless you also have some halogen stuff laying around to react with first...


----------------------------------------
Edit2: What am I doing wrong here? It's neither of these apparently...?

« Last Edit: November 22, 2013, 03:23:13 AM by Sonoris »

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Alkyne rxns...?
« Reply #1 on: November 22, 2013, 01:25:44 AM »
So what is your question(s)? And have you any thoughts on the answers to your question(s)?
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Re: Alkyne rxns...?
« Reply #2 on: November 22, 2013, 01:30:05 AM »
So what is your question(s)? And have you any thoughts on the answers to your question(s)?

I have absolutely no idea how to go about these. The entire rest of the chapter questions I can do, but I can't find anything resembling these in the book. What is the mechanism going on here, and what would be the correct answer?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Alkyne rxns...?
« Reply #3 on: November 22, 2013, 01:34:03 AM »
Start with question A. It says acid/base reaction, so identify an acid and a base in that scheme.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Re: Alkyne rxns...?
« Reply #4 on: November 22, 2013, 01:51:08 AM »
Start with question A. It says acid/base reaction, so identify an acid and a base in that scheme.
Acetylene is acidic, and NaOH is a base. Alright, so... an H can get pulled off the acetylene and there's gonna be ions and crap around and... ok, I got the right answer for it now. (quote from my textbook: "Because water is a stronger acid than acetylene, the hydroxide ion is not a strong enough base to convert a terminal alkyne to an alkyne anion" so uh, yeah...)

#2 still confuses me, but for #3 - is it just throwing a fit because I put NaNH2 and not Na+ and NH2- in the second box?

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: Alkyne rxns...?
« Reply #5 on: November 22, 2013, 02:54:11 AM »
Acetylene is acidic, and NaOH is a base. Alright, so... an H can get pulled off the acetylene and there's gonna be ions and crap around and... ok, I got the right answer for it now. (quote from my textbook: "Because water is a stronger acid than acetylene, the hydroxide ion is not a strong enough base to convert a terminal alkyne to an alkyne anion" so uh, yeah...)

There is no NaOH in the question.
My research: Google Scholar and Researchgate

Offline Archer

  • Chemist
  • Sr. Member
  • *
  • Posts: 1001
  • Mole Snacks: +85/-20
  • Gender: Male
Re: Alkyne rxns...?
« Reply #6 on: November 22, 2013, 02:57:52 AM »

but for #3 - is it just throwing a fit because I put NaNH2 and not Na+ and NH2- in the second box?


Is that NH2- or NH2-?
“ I love him. He's hops. He's barley. He's protein. He's a meal. ”

Denis Leary.

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Re: Alkyne rxns...?
« Reply #7 on: November 22, 2013, 03:04:38 AM »
Acetylene is acidic, and NaOH is a base. Alright, so... an H can get pulled off the acetylene and there's gonna be ions and crap around and... ok, I got the right answer for it now. (quote from my textbook: "Because water is a stronger acid than acetylene, the hydroxide ion is not a strong enough base to convert a terminal alkyne to an alkyne anion" so uh, yeah...)

There is no NaOH in the question.
The now-solved, strikethrough question had NaOH

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Re: Alkyne rxns...?
« Reply #8 on: November 22, 2013, 03:05:25 AM »

but for #3 - is it just throwing a fit because I put NaNH2 and not Na+ and NH2- in the second box?


Is that NH2- or NH2-?
NH2-

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Alkyne rxns...?
« Reply #9 on: November 22, 2013, 03:22:10 AM »
same thing which is the acid and which the base?


did you delete the previous one? If so please don't.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Re: Alkyne rxns...?
« Reply #10 on: November 22, 2013, 03:39:32 AM »
same thing which is the acid and which the base?


did you delete the previous one? If so please don't.
No, I turned the statement into a link to the picture and put solved next to it - still there, just not obnoxiously huge.

Acetylene is still the acid, and the... lithium thing is the base I guess. If it's like the last one, ...oh, REALLY. That double bond in my answer should be a triple. Would that make it correct?

For the next one, with the alcohol + NaNH2 + NH3 - it won't accept any type of answer I think it might be (see Edit2, same issue)

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Alkyne rxns...?
« Reply #11 on: November 22, 2013, 03:42:10 AM »
OK, the ethyl lithium is the base the acetylene the acid, so what could the products be?

Same for the alcohol, what are the products?
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Alkyne rxns...?
« Reply #12 on: November 22, 2013, 04:01:54 AM »
Think about the very first question, what did you do to get the answer?
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Sonoris

  • New Member
  • **
  • Posts: 8
  • Mole Snacks: +0/-1
Re: Alkyne rxns...?
« Reply #13 on: November 22, 2013, 04:15:31 AM »
OK, the ethyl lithium is the base the acetylene the acid, so what could the products be?

Same for the alcohol, what are the products?
For the lithium one - I want to say it'd be this, but in drawing it out I get this, but I guess the Li+ would go hang out with the C-

For the -OH one, the OH compound is the base and the other is the acid. I still stand by the organic part of my answer, but... I guess there would just be Na+ around instead of NaNH2
edit: this answer for my -OH problem doesn't help for the edit to the main post I made, since neither of those are right and it just wanted the organics

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Alkyne rxns...?
« Reply #14 on: November 22, 2013, 04:20:02 AM »
The acetylene one is now ok, you get
[C-]#C[H].[Li+]
and ethane.

Now do the same for the alcohol, replace the O-H by O-Na+ and the NH2- by NH3.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Sponsored Links