March 28, 2024, 01:08:55 PM
Forum Rules: Read This Before Posting


Topic: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis  (Read 3275 times)

0 Members and 1 Guest are viewing this topic.

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« on: January 27, 2013, 10:32:30 AM »
What is the reaction of formaldehyde with acetylene (when the hydrogens get substituted) based on? I mean, how is it called and what is it based on (mechanism)?

When a lactone reacts with NH3, is an amide or an amide and an amino-acid (in less quantity) made?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #1 on: January 27, 2013, 10:36:42 AM »
I presume you mean the deprotonation of the acetylene hydrogens? If so I suppose it's an aldol reaction.
The lactone opens to give a an amide.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #2 on: January 27, 2013, 10:42:26 AM »
I presume you mean the deprotonation of the acetylene hydrogens?
The problem is I don't know what to mean. I only got a reaction of C2H2 and HCHO where the product is OH-CH2C≡CCH2-OH. What is the mechanism?

For the second one, I thought so either but in a problem I was solving, the product was an amino-acid. Could it be (at least in traces)?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #3 on: January 27, 2013, 10:57:50 AM »
The acetylene protons are abstracted by a strong base which attacks the C=O carbon atom to give the aldol.
No amino acid is formed, you get the amide. Draw it out, a lactone the carbonyl of which is attacked by NH3 it opens the ring to give an amide and an alkyl chain with an OH at the end.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #4 on: January 27, 2013, 12:14:51 PM »
How are these protons so acidic? Does it work for other alkynes or alkenes?

I thought that no amino acid can be formed too, but in the answer of a problem it was the product, so I guess that it is a mistake then.

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #5 on: January 27, 2013, 12:18:56 PM »
I can't remember the pka of the acetylene protons. You need a base like sodium amide, or LDA to remove them. It will work for any terminal acetylene, but it does not work for alkenes.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #6 on: January 27, 2013, 02:07:39 PM »
I guess it's something similar with the production of acetilides (only there is substitution and here addition). Thanks for helping me with this.

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #7 on: January 27, 2013, 02:48:49 PM »
I guess it's something similar with the production of acetilides (only there is substitution and here addition). Thanks for helping me with this.

Look at scheme 6 in this paper by Evans
http://chemistry.williams.edu/files/TSmith8.pdf

It shows alkylations and acylations of acetylene anions. It may be a bit complex for you but ask me questions if you need to.

Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: 2 quick q. Acetylene+Formaldehyde and Lactone amonolysis
« Reply #8 on: January 28, 2013, 09:00:16 AM »
Seems complex, but I could recognize where the reaction happens.

I read in a book that the protons in acetylene are acidic because of the triple bond and sp hybridized C atoms. Why is this so?
The triple bond is shorter than the single and double, so distance between the C atoms is reduced (they are closer to each other). Does this mean that the C-H bond gets stretched? If so, why?

Sponsored Links