Selective and Rapid Oxidation of Alcohols

java · Consumer

Selective and Rapid Oxidation of Primary, Allylic and Benzylic Alcohols to the corresponding Carbonyl Compounds with NaNO2-Acetic Anhydride under mild and Solvent -free Conditions.
Babasahe P.Bandgar, Vaibhav S. Sadavarte and Lavkumar S. Uppalla

djvu

java · Consumer

It seems to me that photographic supply acquired benzyl alcohol can easily be converted to benzaldehyde with the study provided in the previous post ......java

IndoleAmine · Dreamreader Deluxe

Uhm - pluto.. erh, mean acetic anhydride, for making benzaldehyde? I don't know if this isn't overkill maybe...

For the photo chem idea, why not do an elbs persulfate oxidation on the benzyl alcohol?

Equimolar proportions, or better slight excess of sodium or ammonium persulfate (since overoxidized benzoic acid is way more easy to separate than unreacted benzyl alcohol), and with only cupric acetate and ferrous sulfate in catalytic amounts...
(original patent reference; check example 9 "anisic alcohol" Wink

)

i_a

anime · Wed Apr 13, 2005 11:19 am

WoW nice find..

Full Patent:

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4146582.WKU.&OS=PN/4146582&RS=PN/4146582

Vanadium Pentoxide (0.05eq), H2O2 (1.2-2.0eq) and PTC BTEAB (0.05eq) at ph4 can be used to convert the benzyl alcohol to the benzaldehyde in 6 hours (reflux). The yield is lower ~80% range but the catalyst is reusable.

n00dle · Wed Apr 13, 2005 12:46 pm

Vanadium pentoxide is also used in an electrolytic cell setup to selectively oxidise tolune to benzaldehyde in 100% yeilds. (yes, 100% according to the ref, which i've lost since hive-collapse)

Either way, is there a way to adapt the method for bzOH --> bzaldehyde method listed above to go from toluene --> bzaldehyde?

methinks that same method with more h2o2 should oxidise anything down to bz-aldehyde but no further..

prove me entirely wrong please Smile

IndoleAmine · Dreamreader Deluxe

Entirely correct! Wink

The elbs persulfate oxidation of toluene to benzaldehyde (using persulfate oxidant and cupric/feric salt catalysts) proceeds in two steps, the intermediate being benzylalcohol.

You can use the same procedure with an equimolar amount of benzyl alcohol instead toluene, and use half of the oxidant - and you will get the same yield in less time. At least the patent decribing this procedure does it on anisic alcohol as well as on toluene, with 0.5x as much oxidant being used for the alcohol, resulting in anisaldehyde and benzaldehyde, respectively.

Seems as such metal-catalyzed oxidations would proceed via the OH intermediate anyway, at least to me...

The fact that the yield is even higher and the catatlysts reusable makes this new vanadium pentoxide "find" extremely interesting IMO - anyone know more about it?

cheers!

i_a

anime · Sat Apr 16, 2005 6:05 am

Vanadium pentoxide can also be used to convert benzyl halides to benzylaldehydes, the yields are slightly lower, in the 80% range, benzyl chlorides are oxidized faster than benzyl bromides.

The only downsides to the vanadium pentoxide is the toxidity, it has a 3 on health and absorbs through the skin.

IndoleAmine · Dreamreader Deluxe

Too bad, together with benzyl chloride's very nasty lachcrymatoric properties this sounds like risking a bit too much for benzaldehyde... Shocked

(although I was just about to ask you about a ref..)

i_a

anime · Tue Apr 19, 2005 7:12 am

hehe precisely. I personally would opt for hydrolysis of the benzyl halide after the reaction, and then go with the nice persulfate oxidation that you found.

http://rapidshare.de/files/1330518/Vanadium-Catalyzed_Oxidation.pdf.html

stratosphere · Wed Apr 20, 2005 10:31 pm

don't ask me to find it cuz im sure i never will agian but i saw ref once that benzyl alcohol can be oxidized to benzaldyde using Mn02 in DCM.

Hriss · Wed Apr 20, 2005 11:40 pm

I know about the Sommelet Reaction of benzyl chloride with hexamethylene tetramine(urotropine) to bezaldehyde by the scheme:
ArCH2Cl + C6H12N4 = (ArCH2-C6H12N4+)Cl-....heat(-H2O)....ArCHO

IndoleAmine · Dreamreader Deluxe

Stratosphere: I once read about that patent too (was it a patent?), but yields were low for both toluene and BzOH oxidation..

Hriss: Yeah it is known and a commonly accepted large-scale method for BzCHO, but the nastiness of benzyl halides like BzCl, or worse BzBr, makes this route a bit, lets say, inattractive for clandestine chemistry on small to medium scale...
(believe me! or cry.. Wink

)

pharmakon · Fri Jun 24, 2005 7:40 pm

Mechanism of MTO/HBr/TEMPO catalyzed Reaction

http://forkat.anorg.chemie.tu-muenchen.de/2/pdf/f2be00b1.pdf

For example, Benzylalcohol is selectivly converted to the aldehyd within 2 hours, yield 91%.

Can be also used for various alcohols, like anisalcohol
(p-Methoxyphenylethylalcohol)

Major drawback: High prices of MTU (Rhenium-catalysator)

It might be possible to produce MTU from Rhenium (cheap on ebay ...)

stratosphere · Fri Jun 24, 2005 7:53 pm

i posted a request for the article
A new, highly selective synthesis of aromatic aldehydes by aerobic free-radical oxidation of benzylic alcohols, catalysed by n-hydroxyphthalimide under mild conditions. Polar and enthalpic effects.
Minisci F, Punta C, Recupero F, Fontana F, Pedulli GF.
Chem Commun (Camb). 2002 Apr 7;(7):688-9.
in journal articles wanted, im not sure how much traffic that section gets but also sounds like a very promising method.

epck · Sat Jun 25, 2005 4:45 am

stratosphere, here's that article you wanted.

http://www.uploadtemple.com/view.php/1119654682.pdf