[jcmtz]

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.

[OC pro]

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?

[jcmtz]

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?

[OC pro]

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?

[jcmtz]

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?

[OC pro]

Brownish colour sounds a bit strange. Are you really using chromium trioxide CrO3 because you have mentioned dichromate earlier.

[orgopete]

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?

[jcmtz]

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.

[jcmtz]

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

[orgopete]

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.