Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: jcmtz on July 03, 2010, 02:50:56 PM
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Hi im having problems oxidizing 2-phenyethanol, to his carboxilic acid, or to his aldehyde. i own a chemical supply, also with a partner we are trying to enter the cleaners industries, and i need several compounds of this carbinol.
since it not dissolves in water, and the oxidation of the KmNO4 its so fast, im having problems.
also, i want to try the jones reagent, or even hot CuO.
any toughts?
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I don't think KMnO4 is a good idea, since you will get benzoic acid and not 2-phenylethanoic acid.
I think Jones reagent should be OK. I don't think it will disturb the aromatic part.
Please correct me of I am wrong
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I don't think KMnO4 is a good idea, since you will get benzoic acid and not 2-phenylethanoic acid.
I think Jones reagent should be OK. I don't think it will disturb the aromatic part.
Please correct me of I am wrong
well actually im trying to get phenylacetaldehyde, or ethyl phenylacetate.
2-phenylethanol would give me 2-phenylethanoic acid?
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The Jones oxidation is fairly acidic and likely to push all the way to the carboxylic acid, which you could esterify if you desire.
However, if phenylacetaldehyde is your desired product then a mild oxidant like IBX or Dess Martin Periodinane will stop at that stage of oxidation.
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I dunno if this will work, but you could try a DMSO oxidation to the aldehyde. First do a nucleophilic substitution via PX3 where X = Cl, Br. Then react this halide with DMSO to form an aldehyde via an oxysulfonium salt intermediate.
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To get to the Aldehyde several methodologies will work:
1) Chromium-based (therefore toxic): PDC, PCC
2) DMSO-based: Swern-Oxidation, Parikh-Doering...
3) IBX (potent explosive), Dess-Martin-Periodinane (expensive)
To get directly from 2-Phenylethanol to Phenylacetic acid:
Jones reagent (again toxic, but works well)
Or stepwise:
Having the aldehyde in hand you can mildly oxidise it with Sodium chlorite.
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ok thanks a lot, any toughs on the hot copper?
i was thinking jones but is highly toxic, and we want to run a green company so lets see.
sodium chlorite? ok and can i oxidize 2-phenylethanol to the aldehyde via sodium chlorite?
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The Jones oxidation is fairly acidic and likely to push all the way to the carboxylic acid, which you could esterify if you desire.
However, if phenylacetaldehyde is your desired product then a mild oxidant like IBX or Dess Martin Periodinane will stop at that stage of oxidation.
can you give me the amount of jones i need or the best way to prepare it?
also how long will the reaction be?
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Woops, made a mistake, editting.
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Here is the original procedure for the Jones oxidation:
http://www.orgsyn.org/orgsyn/default.asp?formgroup=basenpe_form_group&dataaction=db&dbname=orgsyn
I would use twice the equivalents for the conversion of a primary alcohol into an acid.
The reaction works well, I have done it often.
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Here is the original procedure for the Jones oxidation:
http://www.orgsyn.org/orgsyn/default.asp?formgroup=basenpe_form_group&dataaction=db&dbname=orgsyn
I would use twice the equivalents for the conversion of a primary alcohol into an acid.
The reaction works well, I have done it often.
i guess the link was broken, i dont know how much cromate to add to the H2S04
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Perhaps http://www.orgsyn.org/orgsyn/pdfs/CV6P0644.pdf is the link required?
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Perhaps http://www.orgsyn.org/orgsyn/pdfs/CV6P0644.pdf is the link required?
This is the preparation for the so-called Collins reagent which will only give the aldehyde selectively.
Here is the reference: Organic Syntheses, Vol. 45, p. 28 (1965); Coll. Vol. 5, p.310 (1973).
@jcmtz: There is a procedure (which is very mild) giving the acid directly from the alcohol using a combination of catalytic TEMPO/NaOCl (gives the aldehyde) and sodium chlorite (NaClO2 --> further oxidation in situ to the acid). Organic Syntheses, Vol. 81, p. 195 (2005); Coll. Vol. 11, p.107 (2009).
Both can be found on: www.orgsyn.org
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odorless corey-kim oxidation may work?
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Hi im having problems oxidizing 2-phenyethanol, to his carboxilic acid, or to his aldehyde. i own a chemical supply, also with a partner we are trying to enter the cleaners industries, and i need several compounds of this carbinol.
since it not dissolves in water, and the oxidation of the KmNO4 its so fast, im having problems.
also, i want to try the jones reagent, or even hot CuO.
any toughts?
Why not just use bleach/Tempo in dichloromethane, you get the aldehyde exclusively. Remember to stir well.
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Ok i cant get this reaction done, ive got the aldehyde, but i cant get the carboxilic acid and i want the ester of it.
ive tried to disolve it in acetic acid to do a KMnO4 oxidation but it remains a black solution and i need to know when is done....
have any of you guys succed in this type of oxidation?
has anyone make the ester of this in good yields?
any other form to make the ester of the phenylacetic acid?
thanks in advance
Hi im having problems oxidizing 2-phenyethanol, to his carboxilic acid, or to his aldehyde. i own a chemical supply, also with a partner we are trying to enter the cleaners industries, and i need several compounds of this carbinol.
since it not dissolves in water, and the oxidation of the KmNO4 its so fast, im having problems.
also, i want to try the jones reagent, or even hot CuO.
any toughts?
Why not just use bleach/Tempo in dichloromethane, you get the aldehyde exclusively. Remember to stir well.
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Usually the best and mild reagent for the conversion of aldehydes into acids is sodium chlorite. Yields are in most cases >90%.
I don´t know why KMnO4 is not working in your case. Normally you should get the acid easily. Can you post your procedure? Aldehyde is confirmed by NMR and mass?
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well i can confirm the aldehyde because its odor, and green color when i do a hot CuO oxidation, but my general procedure is with the jones reagent is to disolve the dichromate in H2SO4, and the add this to water, in a ice bath, after that start dropping the alcohol disolved in acetone. i suppose that the carboxilic acid will float because of the cold water....am i doing something wrong? i have a strong agitation in the whole process.
the KMnO4 reaction, i make a 1N solution of NaOH in water, i disolve the 2-phenylethanol in acetone and added to the 1N NaOH solution, i start dropping KMnO4 at 1N, and the water gets green because the permanganate is decomposing in Mn dioxide and Oxygen, and with strong agitation the water changes to brown thats when i stop my reaction, and should be the sodium salt of the phenylacetic acid disolve on it?
next i should extract it, and acidify for further purification?
Usually the best and mild reagent for the conversion of aldehydes into acids is sodium chlorite. Yields are in most cases >90%.
I don´t know why KMnO4 is not working in your case. Normally you should get the acid easily. Can you post your procedure? Aldehyde is confirmed by NMR and mass?
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Confirmation of correct structure only by its odor and colour is a bit inaccurate.
The Jones reagent should have an orange colour. When the reaction is finished it will turn into a green solution indicating the presence of Cr(III). Aldehyde should be only detectable in traces. After quenching the reaction with isopropanol you should dilute with water and then extract with ethyl acetate which is the best solvent for extraction of polar compounds.
Moreover, your procedure for permanganate oxidation sounds fine. Did you really changed the pH to around 3-4?
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yes i changed the ph to 3-4, but maybe i was a bit impacient.
as for the jones reagent, my reaction turn brown, and i saw in other place, that after the adition of the alcohol, i should wait around 12 hours and the it would change color....
am i right?
Confirmation of correct structure only by its odor and colour is a bit inaccurate.
The Jones reagent should have an orange colour. When the reaction is finished it will turn into a green solution indicating the presence of Cr(III). Aldehyde should be only detectable in traces. After quenching the reaction with isopropanol you should dilute with water and then extract with ethyl acetate which is the best solvent for extraction of polar compounds.
Moreover, your procedure for permanganate oxidation sounds fine. Did you really changed the pH to around 3-4?
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Brownish colour sounds a bit strange. Are you really using chromium trioxide CrO3 because you have mentioned dichromate earlier.
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Hi im having problems oxidizing 2-phenyethanol, to his carboxilic acid, or to his aldehyde. i own a chemical supply, also with a partner we are trying to enter the cleaners industries, and i need several compounds of this carbinol.
I think there are some people here that are more on the commercial side, but is phenylacetic acid so expensive that you can make a profit by doing the oxidation yourself? What scale are you developing and how much does it cost to manage your waste stream?
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Brownish colour sounds a bit strange. Are you really using chromium trioxide CrO3 because you have mentioned dichromate earlier.
well i use sodium dichromate in h2so4 and thats the jones oxidation.
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Hi im having problems oxidizing 2-phenyethanol, to his carboxilic acid, or to his aldehyde. i own a chemical supply, also with a partner we are trying to enter the cleaners industries, and i need several compounds of this carbinol.
I think there are some people here that are more on the commercial side, but is phenylacetic acid so expensive that you can make a profit by doing the oxidation yourself? What scale are you developing and how much does it cost to manage your waste stream?
well im in the comercial side by doing some products that are expensive and i can do it for cheap, for example the odor of phenylacetaldehyde.
in spectrum chemicals for saying one option is at 260 dlls for 500 grms, and thats expensive.
with a oxidation of this type i could do it for 30 dlls the same 500 grms.
please help a really desperate man.
thanks
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I see Sigma Aldrich charges $145/500 mL (90%). The note may be a clue to their synthesis, contains styrene oxide. I am not verifying that is how they make it, I haven't searched for a synthesis, but it is a plausible route. I imagine stoichiometric toxic inorganic salts need not be an added expense.