[cheesewithwhine]

I'm trying to find a reference on the experimental procedures for the base hydrolysis of a methyl ester (specifically glycine methyl ester, but any similar esters would do), but what I found was:

"The enthalpies of hydrolysis were determined by first measuring
the enthalpies of reaction of the esters with 0.8 M sodium hydroxide
in 60% aqueous ethanol. In all cases, the reactions
proceeded rapidly and to completion"

Does anyone have a link to a reference that highlights specific procedures, or give a rough outline of the procedures? Is acid workup required?

[fledarmus]

Look up "saponification". Procedures for this are abundant.

As for the workup, it depends on what you are trying to isolate. In some cases, you want the protonated carboxylic acid, in some cases it is easier to work with the deprotonated form.

[orgopete]

I would search for something close to your compound. Since you indicated you have an amino acid, a simple saponification procedure probably won't result in an easy isolation of your product. I haven't looked at this chemistry for sometime, but I think they may use Ba(OH)2 so the barium salt can be precipitated and the zwitterionic amino acid isolated from the aqueous layer. Perhaps someone with better information could contribute.

[Dan]

Glycine is cheaper than its methyl ester - it would be more economical to buy the amino acid.

But anyway - I don't have a great deal of experience with amino acids, but I have a little. I worked for a while with a poly-hydroxylated proline synthesis, and in order to isolate the zwitterion I used ion exchange.

If I were you, I would dissolve the amino ester in NaOH(aq), alcohol free.

Once the reaction is complete (I'd probably monitor by IR), acidify the mixture with HCl, to neutralise the NaOH and protonate the glycine (for this reason, I would not include ethanol as a solvent). Load your reaction mixture onto a short column of strongly acidic resin. The protonated amino acid will exchange with protons on the resin and be immobilised. The sodium cations will also be immobilised.

Pass deionised water through the resin, to wash out the HCl, until the effluent is neutral.

Now pass dilute aqueous ammonia through the resin (1-2 M is sufficient). The ammonia will exchange with your amino acid - it basically deprotonates the immobilised protonated glycine, freeing it from the resin. Collect the ammoniacal effluent, this is an aqueous solution of ammonia and glycine. Remove the water and ammonia on a rotary evaporator (in a fume hood otherwise you will stink the place out) to leave glycine.

Note: This will not separate glycine from any other amine impurities, so ensure the reaction is complete.