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Topic: Reduction of carboxylic acids to aldehydes with CaH2  (Read 40337 times)

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Offline yufgyfyu

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Reduction of carboxylic acids to aldehydes with CaH2
« on: May 12, 2011, 09:31:51 PM »


      2 RCOOH + CaH2 ----> 2 RCOH + Ca(OH)2
 

    Would this work? Might it be cheaper than sodium borohydride?

Offline discodermolide

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #1 on: May 13, 2011, 12:56:59 AM »


      2 RCOOH + CaH2 ----> 2 RCOH + Ca(OH)2
 

    Would this work? Might it be cheaper than sodium borohydride?

CaH2 is not a reducing agent for carboxylic acids you will get H2 and the calcium salt of the acid, nor is sodium borohydride. Look up the Rosenmund reduction
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Offline yufgyfyu

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #2 on: May 17, 2011, 07:32:46 AM »
Sodium borohydride can reduce carboxylic acids, look up; Rohm and Haas The sodium Borohydride Digest!, I do think that Cah2 can reduce %100 percent acetic acid to acetaldehyde in the absence of solvents.

Offline discodermolide

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #3 on: May 17, 2011, 08:08:46 AM »
Sodium borohydride can reduce carboxylic acids, look up; Rohm and Haas The sodium Borohydride Digest!, I do think that Cah2 can reduce %100 percent acetic acid to acetaldehyde in the absence of solvents.

NaBH4 itself will not reduce carboxylic acids. You need to generate some BH3, which does reduce them.
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Offline yufgyfyu

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #4 on: May 17, 2011, 08:13:52 AM »
Wrong, it will reduce them at high temperatures with no solvent. Once again look up Rohm and Haas The Sodium borohydride digest.

Offline discodermolide

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #5 on: May 17, 2011, 10:47:10 AM »
Wrong, it will reduce them at high temperatures with no solvent. Once again look up Rohm and Haas The Sodium borohydride digest.

No I'm not wrong! 300°C is not a practical lab procedure, the digest says further;
Sodium borohydride alone does not normally reduce carboxylic acid but the addition of triphenylborate ……….
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Offline yufgyfyu

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #6 on: May 17, 2011, 11:17:45 AM »
Practical or not, You stated NaBH4 it's self will not reduce carboxylic acids. However, it can.
Sodium borohydride can reduce carboxylic acids, look up; Rohm and Haas The sodium Borohydride Digest!, I do think that Cah2 can reduce %100 percent acetic acid to acetaldehyde in the absence of solvents.

NaBH4 itself will not reduce carboxylic acids. You need to generate some BH3, which does reduce them.

Offline discodermolide

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #7 on: May 17, 2011, 11:46:31 AM »
Practical or not, You stated NaBH4 it's self will not reduce carboxylic acids. However, it can.
Sodium borohydride can reduce carboxylic acids, look up; Rohm and Haas The sodium Borohydride Digest!, I do think that Cah2 can reduce %100 percent acetic acid to acetaldehyde in the absence of solvents.

NaBH4 itself will not reduce carboxylic acids. You need to generate some BH3, which does reduce them.

NaBH4 decomposes at 300°C and above. I would suggest that it is the H2 produced under these conditions that causes the reduction with the boron coordinating to the carbonyl oxygen and the acid oxygen assisting hydrogenation.
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Offline yufgyfyu

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #8 on: May 17, 2011, 12:20:00 PM »
 Possibly. But tell me this, how could CaH2 react with acetic acid to produce H2. My point being you stated you will get H2 and the calcium salt of the acid.


      2 RCOOH + CaH2 ----> 2 RCOH + Ca(OH)2
  

    Would this work? Might it be cheaper than sodium borohydride?

CaH2 is not a reducing agent for carboxylic acids you will get H2 and the calcium salt of the acid, nor is sodium borohydride. Look up the Rosenmund reduction

Offline yufgyfyu

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #9 on: May 17, 2011, 12:27:15 PM »
 The melting point of NaBH4 is 400 C.
Practical or not, You stated NaBH4 it's self will not reduce carboxylic acids. However, it can.
Sodium borohydride can reduce carboxylic acids, look up; Rohm and Haas The sodium Borohydride Digest!, I do think that Cah2 can reduce %100 percent acetic acid to acetaldehyde in the absence of solvents.

NaBH4 itself will not reduce carboxylic acids. You need to generate some BH3, which does reduce them.

NaBH4 decomposes at 300°C and above. I would suggest that it is the H2 produced under these conditions that causes the reduction with the boron coordinating to the carbonyl oxygen and the acid oxygen assisting hydrogenation.


Offline discodermolide

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #10 on: May 17, 2011, 01:23:10 PM »
Possibly. But tell me this, how could CaH2 react with acetic acid to produce H2. My point being you stated you will get H2 and the calcium salt of the acid.


      2 RCOOH + CaH2 ----> 2 RCOH + Ca(OH)2
  

    Would this work? Might it be cheaper than sodium borohydride?
In the same way that any acid or water will react with a hydride of a group I orIi metal to give H2 and the metal salt

CaH2 is not a reducing agent for carboxylic acids you will get H2 and the calcium salt of the acid, nor is sodium borohydride. Look up the Rosenmund reduction
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Offline discodermolide

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #11 on: May 17, 2011, 01:25:55 PM »
The melting point of NaBH4 is 400 C.
Practical or not, You stated NaBH4 it's self will not reduce carboxylic acids. However, it can.
Sodium borohydride can reduce carboxylic acids, look up; Rohm and Haas The sodium Borohydride Digest!, I do think that Cah2 can reduce %100 percent acetic acid to acetaldehyde in the absence of solvents.

The MPt is not an indicator for stability, thermal decomposition can begin well before the MPt.


NaBH4 itself will not reduce carboxylic acids. You need to generate some BH3, which does reduce them.

NaBH4 decomposes at 300°C and above. I would suggest that it is the H2 produced under these conditions that causes the reduction with the boron coordinating to the carbonyl oxygen and the acid oxygen assisting hydrogenation.

Development Chemists do it on Scale, Research Chemists just do it!
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Offline g-bones

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #12 on: May 17, 2011, 01:31:31 PM »
CaH2 is a base not a reducing agent.  much like you cant reduce carbonyls with NaH.  The s-orbitals of the hydride are non-directional (by definition) and are, therefore, terrible nucleophiles.  Reflux with LAH or use borane

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #13 on: May 17, 2011, 01:36:45 PM »
<--- grabs popcorn and watches teh battel of teh scientists. :)
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Offline yufgyfyu

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Re: Reduction of carboxylic acids to aldehydes with CaH2
« Reply #14 on: May 17, 2011, 02:16:34 PM »
 In any case, How can CaH2 react to produce H2 and the calcium salt of the acid?

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