Triflic Acid
Hazard to Others
Posts: 486
Registered: 27-9-2020
Member Is Offline
Mood: Slowly Oxidizing into Oblivion
|
|
NaBH4 substitute
Would a Hunsdiecker reaction followed by hydrolysis reduce a carboxylic acid to an alcohols. Using iodine as the halogen has two benefits, it's easy
to make iodine, and the waste product is hydroiodic acid. The silver could be recycled as well. Is this a good NaBH4 substitute? https://en.wikipedia.org/wiki/Hunsdiecker_reaction
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
It's not the same reaction. A carboxylic acid RCO2H could be reduced to an alcohol RCH2OH with LiAlH4 (I don't think sodium borohydride would work),
whereas your suggestion would result in the formation of ROH.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
Triflic Acid
Hazard to Others
Posts: 486
Registered: 27-9-2020
Member Is Offline
Mood: Slowly Oxidizing into Oblivion
|
|
Oh, I don't know how I didn't notice that CO2 coming out of that reaction  .
|
|
|
ArbuzToWoda
Hazard to Self
Posts: 98
Registered: 15-7-2020
Member Is Offline
|
|
Quote: Originally posted by DraconicAcid  | | It's not the same reaction. A carboxylic acid RCO2H could be reduced to an alcohol RCH2OH with LiAlH4 (I don't think sodium borohydride would work),
whereas your suggestion would result in the formation of ROH. |
The nice thing is... that you CAN use NaBH4! But not alone 
Add iodine or sulfuric acid to produce diborane in situ, and that guy can reduce most things. Carboxylic acids included!
|
|
|
Triflic Acid
Hazard to Others
Posts: 486
Registered: 27-9-2020
Member Is Offline
Mood: Slowly Oxidizing into Oblivion
|
|
But NaBH4 is a pain to get
|
|
|
Corrosive Joeseph
National Hazard
Posts: 915
Registered: 17-5-2015
Location: The Other Place
Member Is Offline
Mood: Cyclic
|
|
What exactly are you trying to do......? The must be 3 or 4 or 5 members selling borohydride on here right now!
Carboxlic acids are reduced to alcohols with ZnCl2-NaBH4 in refluxing THF..... And also NaBH4-I2 in THF at RT.
https://tinyurl.com/y32nhymk
I have also seen amino acid to amino alcohol reduction with a huge excess of NaBH4-NiCl2 in alcohol, if I remeber correctly, excess was 10 or 15
equivalents.
Shit, Arbuz beat me too it....
/CJ
Attachment: enhancing.nabh4.reactivity.and.selectivity.pdf (333kB)
This file has been downloaded 321 times
Being well adjusted to a sick society is no measure of one's mental health
|
|
|
NaK
Hazard to Self
Posts: 83
Registered: 12-9-2019
Member Is Offline
|
|
There is none. At least no good one. NaBH4 is awesome on small scales - very versatile, easy to use, high yielding and clean. For some reductions you
might find alternative ways like hydrogenation over Pd/C , Al/Hg, Zn/HCl, dithionite, etc. but for the most part they are more labor intensive /
dangerous / expensive / messy.
I would advise spending the time you are researching NaBH4 substitutes on researching NaBH4 suppliers. I think that will get you further in most cases
|
|
|
Triflic Acid
Hazard to Others
Posts: 486
Registered: 27-9-2020
Member Is Offline
Mood: Slowly Oxidizing into Oblivion
|
|
I don't actually need NaBH4 right now, I just came across this reaction while looking for a synthesis route for haloalkanes and thought that it might
be useful
|
|
|
Texium
|
Thread Moved
17-11-2020 at 15:56 |
Corrosive Joeseph
National Hazard
Posts: 915
Registered: 17-5-2015
Location: The Other Place
Member Is Offline
Mood: Cyclic
|
|
More carboxylic acid to alcohol with NaBH4.....
| Quote: |
2-(3-Hydroxyphenyl)ethanol
2-(3-Hydroxyphenyl)acetic acid (0.5 g) was dissolved in anhydrous methanol (50 mL) and two drops of concentrated H2SO4 were added. After 2 h, the
reaction was concentrated in vacuo, diluted with ethyl acetate, washed with brine until the pH was neutral, dried with anhydrous sodium sulfate, and
the solvent evaporated under reduced pressure. The methyl ester (0.45 g; 82%) was obtained and immediately treated with an aqueous solution of excess
NaBH4. After 2 h, the solution was acidified with 2 N HCl, extracted with ethyl acetate, and worked up as reported above. The residue obtained was
purified by silica gel column chromatography, eluting with CHCl3/MeOH (9:1), gave pure 25 (0.37 g; 98%).
|
Reference: Eur. J. Org. Chem. 17, 3407-3411 (2003)
/CJ
Being well adjusted to a sick society is no measure of one's mental health
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
