P2P via 1-Phenyl-2-propanol?

[Moriarty]

I'm sure others have kicked this around, but the only real references I've found using the fuckin' search engine are halide (Br) substitutions.  Some involving hard to get oxygen sources and such, but none that look quit so simple as this.  Anyone ever thought about making P2P out of 1-phenyl-2-propanol using the Fenton Reaction, an oldie but a goodie.

                                       Fe++
C6H5CH2CHOHCH3 + H2O2--------------->C6H5CH2COCH3

P2P isn't really my forte, but interesting none the less.  I'm not positive how available 1-phenyl-2-propanol is, but I've found a couple of places that sell it and it appears to be unrestricted.  Any thoughts?
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[ChemicalSolution]

SWIm is gonna go with a 'negative' on being able to get 1-phenyl-2-propanol...

But, in the event that your SWIM does, there is a dichromate/H2SO4 oxidation in DMSO that is so easy you could probably train a monkey to do it. It's good for oxidizing primary alcohols to aldehydes and secondary alcohols to ketones.

xoxo
Julia

[Moriarty]

Here's the problem with that.  First SWIM's not really in the market for any P2P as he's more interested in MDP2P, but the thought of buying methylenedioxyphenyl-2-propanol is rediculous and so specific that it just could never happen.  In prior threads I hear people refer to being able to puchase it, so I read some synths and realized that second problem I mentioned.  Second, most currently accepted methods rely on oxygen sources that are seriously suspect.  I don't know if it's listed 1 or just a watched chemical, but sodium dichromate, for instance, is very difficult to obtain (don't hold me to that).  So I came up with this idea, having seen this method in a chem book sometime in the past.  Not to mention DMSO is another one of those watched chems.  I don't know.  Part of what we do, as a matter of principal, is discover new methods.  This is how production continues, is it not?
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[Aurelius]

Can you use that reaction to oxidize a terminal alcohol to the aldehyde without overoxidation?

[Antoncho]

Dear Julia, Moriarty, could you please post these procedures!

Thanx in advance,

Antoncho

[ChemicalSolution]

10g dichromate is disolved in 100g DMSO.  Benzyl alcohol (5.4g) is added.  Concentrated H2SO4 is added dropwise while keeping the temerature below 70C.   The reaction mixture is heated at 70C for an additional 30 min(somewheres in here the reaction mixture turnes dark green).

The reaction mixture is poured on ice and extracted with 3x100 portions of (DCM).  The organic layer is washed once with bi-carb (take advice from Julia-- do this in a beaker.. Otherwise you may blow the stopper off your sep funnel).  And again with water.

The paper uses et2O to extract this..  SWIM has done this extraction with both DCM and toluene.  Both have advantages and disadvantages--- DCM sometimes forms emulsions that take a while to seperate..  DCM can also carry DMSO with it--  this is usually not a problem with toluene..

Yields-- 85%


xoxo Julia

[slappy]

1-Phenyl-2-Propanol can be oxidized under swern conditions, DMSO and Trifluoroacetic Anhydride (or Oxalyl Chloride) in CH₂Cl₂, then Et₃N.

A better way, is to use a stiochiometric amount of CrO₃ with Periodic Acid (HIO4) in CH₂Cl₂. There is a paper in Tetrahedron Letters by the Merck process division about this, where they got P2P in 98% yields.  Only problem of course being the amount of Cr^VI used becomes a potential health hazard.

[Rhodium]

Slappy - that reference would be very appreciated.

[slappy]

The reference is Tetrahedron Letters 39 (1998) 5323-5326

I had it wrong though, it is a catalytic amount of CrO₃ with stoichiometric Periodic Acid (H₅IO₆) in wet MeCN. I think that a CrO₃/H₂SO₄ would work almost as well here, because you really wouldn't need the strong oxidising power of H₅IO₆, which is used in the paper to oxidise 1° Alcohols to Acids.

[foxy2]

Procedure for 1-phenyl-2-propanol
A stock solution of H5IO6/CrO3 was prepared by dissolveing H5IO6 (11.4 g, 50 mmol) and CrO3 (11.5mg, 0.6 mol%) in wet MeCN (0.75 v % water) to a volume of 114 mL (complete dissolution typically requires 1-2 hours).  Stock soln. 5.7 mL was then added to a solution of the alcohol (2.0 mmol) in wet MeCN (10mL, 0.75 v % water) in 30-60 minutes while maintaining reation temperature at 0-5C.  Mixture is aged at 0C for 0.5 hours and completion of reaction is confirmed by HPLC. The reaction is quenched by adding Na2HPO4 (0.60g in 10 mL H20).  Yeild 98% P2P.
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[Moriarty]

Aurelius:  Sorry for the delay in response, but I've been without a computer for a couple of days.  Very legitimate question.  "Carbohydrates undergo extensive decomposition when treated with Fenton's reagent."  Tetrahedron, 1963, Vol. 19, pp 1705.  That part is true.

However, the article referenced above describes a modified interpretation of the Fenton Reaction by Weiss-Haber using Fe+++ instead of Fe++ salts to slow the reaction and, thus, decomposition.  So that's an option if decomposition were to become a problem.  I don't believe it would.

Did I fail to understand your comment, or is that what you meant?  Also, by terminal alcohol did you mean tertiary?  Isn't 1-phenyl-2-propanol a secondary alcohol?

Other processes stated in this thread are good, I'm sure, but it's been a goal of mine to use easier to get reagents.  Most mentioned up to date are difficult to obtain.  I could, however, be wrong about that fact.
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[ztion]

I think that by terminal alcohol he meant a primary alcohol. Generally when you oxidize such an alcohol it overoxidizes to the carboxylic acid. As far as I know the only way to oxidize such an alcohol to the aldehyde is with PCC. (Or if the aldehydes boiling point is lower than the alcohol, destilling it out before it can be oxidized further). It would be really useful to be able to oxidize for example phenethylalcohol to phenylacetaldehyd without the expensive PCC.

[Moriarty]

Actually that's interesting and clears a lot up for me.  This was also a major point of one source I read, however, not really to be a concern as 1-phenyl-2-propanol is a secondary alcohol, is it not?  We're not really trying to produce a aldehyde here as one might think if he or she were to read about the Fenton specifically.  This reaction was originally performed with primaries in mind, but H2O2 is great for secondaries as well.  Secondaries will not form aldehydes or carboxyls in the presence of an oxygen source, to my knowledge, they should form ketones.  Which is what we want.  Quoting an old high school chemistry book, "The middle [2 position] carbon in 2-propanol has an oxidation number of 0.  In propanone, it has an oxidation number of +2, an increase of 2.  Hence, 2-propanol is being oxidized to propanone", Chemistry: The Study of Matter, 1983, Allyn and Bacon, p. 613.  Sorry to bust out the high school chem, but that's all I had on hand.  It would be impossible to form aldehydes or carboxyl groups, which generlly form out of aldehydes.  Thanks for the help.  I now understand what was being said and would like to amend my answer to say yes, it is a legitimate concern with primaries, but not with 1-phenyl-2-propanol.
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[Aurelius]

aurelius was simply concerned with the oxidation of Phenethanol to its aldehyde and/or ethanol to acetaldehyde.  However, the chemistry you proposed is an interesting read.  thanks for taking the time to answer aurelius' question.  Chromates and Pyridine aren't in short supply around here, aurelius just wanted to find a green method.

[ChemicalSolution]

In this paper Julia has, these folks boast about NOT over-oxidizing the terminal OH to COOH.

1-phenyl-propan-2-ol your SWIM asks??

These folks oxidize C6H5CHOHCH3 as well as C6H5CHOHC6H6 to their respective ketones in yields of 85% or greater... Will it work on 1-phenyl-propan-2-ol???  Julia thinks so...

xoxo
Julia

[ChemicalSolution]

Now, SWIM is all about the theoretical.. But just where in the HELL is your SWIM going to get 1-phenyl-propan-2-ol ?

Want to try a Grignard with Benzyl chloride or (gasp) benzyl bromide with acetaldehyde???  Be SWIM's guest.

Now, here we are with a Markovnikof hydration of allylbenzene followed by oxidation to ketone..   Sure makes the O2 Wacker of allylbenzene seem much, much less troublesome..

[Prdy2GO]

Question: This makes P2P?
" 10g dichromate is disolved in 100g DMSO.  Benzyl alcohol (5.4g) is added.  Concentrated H2SO4 is added dropwise while keeping the temerature below 70C.   The reaction mixture is heated at 70C for an additional 30 min(somewheres in here the reaction mixture turnes dark green).

The reaction mixture is poured on ice and extracted with 3x100 portions of (DCM).  The organic layer is washed once with bi-carb (take advice from Julia-- do this in a beaker.. Otherwise you may blow the stopper off your sep funnel).  And again with water.

The paper uses et2O to extract this..  SWIM has done this extraction with both DCM and toluene.  Both have advantages and disadvantages--- DCM sometimes forms emulsions that take a while to seperate..  DCM can also carry DMSO with it--  this is usually not a problem with toluene..

I dont believe it...
Can it be that simple? Then WTF is everyone  else doing it the hard way?
Yields-- 85%"
85% of what the BzOH?
Thanks




Don't look at me I didn't do it!

[foxy2]

If you post a procedure Please post the details of the reference it came from.  Journal, year, issue, page ect

Thanks
Foxy
Those who give up essential liberties for temporary safety deserve neither liberty nor safety

[Rhodium]

Prdy2GO: The procedure you describe is probably an oxidation of benzyl alcohol to benzaldehyde. As it is run under anhydrous conditions, I believe that overoxidation to benzoic acid does not take place.

[Moriarty]

Okay.  I just priced some at some place I found at chemfinder.  Bad idea.  100 grams is worth more than the honey made from it.  Not really, but it's in the thousands.  I'm sure you could buy it with little suspicion, but who would want to.  Discussion is pretty much a mute point now.
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