Chemistry Forum

I am interested to see if anyone knows the easiest way to mono-esterify a mono-phosphate salt group to a carboxylic acid.

How to facilitate the resultant -> product ?

CH₃COOH + NaH₂PO₄ ‐> C₂H₄NaO₅P

First it's not a ester. Ester made from acid and alcohol.
What you talking about is a mixed acid anhydride.

To get this take acetylchloride CH₃COCl and disodium hydrogen phosphate Na₂HPO₄.

CH₃COCl + Na₂HPO₄ => CH₃CONaHPO₄ + NaCl

Thank you for the reply!
I thought that an acid anhydride is a compound that has two acyl C(O)R groups bonded to the same oxygen atom.

Thanks for the clarification. I'm still learning.

Also, what prevents di-linkage at both sodium positions of the phosphate by acetylchloride?

The stoechometric mixture of the reactants guid to it. Probably take more of the phosphate.

Anhydride means remove water. The anhydride can made by 2 CH₃COOH => (CH₃CO)₂O + H₂O but also with different acids.

CH₃COOH + C₂H₅COOH => CH₃CO(C₂H₅CO)O + H₂O

H₃PO₄ + CH₃COOH => CH₃COH₂PO₄ + H₂O

Ok so treat the carboxylic acid with thionyl chloride ( SOCl₂ ) to form the intermediate acid chloride in aqueous solution

Neutralize with NaOH

Then simply stoichiometrically add the disodium phosphate (Na₂HPO₄)

Then collect precipitate final product .

(What ratio of H₂O to the CH₃COOH do you suggest for optimal reactivity?)

You can not use aqueous solution. SOCl₂ either CH₃COCl will decompose in presence of water.
Why to produce acetylchloride from acetic acid and thionylchloride, from cost side buy directly acetylchloride and add it to the dry phosphate.

So what if I want to use a different carboxylic acid, so what would be the system to do this
if I can't buy a chlorinated acid form?

So for example could I use sulfuric acid in aqueous solution to functionalize the carbonyl to
(CH₃COOH + NaH₂PO₄) cat H₂SO₄ -> CH₃CONaHPO₄ +H₂O

I'm just confused on how to go about this.

No, the product is water sensitive. The Anhydride will decompose if in contact with water. Sulfuric acid will any way convert the phosphate to phosphoric acid.
You can only make it in absense of water.
Of course if you cannot buy the chlorinated Acyl ,then you have to do the chlorination first.

Yes, can you tell me the optimal route for this chlorination, for a full synthesis.

You already chosed it. Thionylchlorid SOCl₂, but also phosphorous trichloride PCl₃ or phosphorous oxychloride POCl₃ are possible.

Thanks for you help.

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